1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" 2"http://www.w3.org/TR/html4/strict.dtd"> 3 4<html> 5<head> 6 <meta name="generator" content= 7 "HTML Tidy for Linux (vers 25 March 2009), see www.w3.org"> 8 9 <title>NCURSES Programming HOWTO</title> 10 <meta name="GENERATOR" content= 11 "Modular DocBook HTML Stylesheet Version 1.79"> 12</head> 13 14<body class="ARTICLE" bgcolor="#FFFFFF" text="#000000" link= 15"#0000FF" vlink="#840084" alink="#0000FF"> 16 <div class="ARTICLE"> 17 <div class="TITLEPAGE"> 18 <h1 class="TITLE"><a name="AEN2" id="AEN2">NCURSES 19 Programming HOWTO</a></h1> 20 21 <h3 class="AUTHOR"><a name="AEN4" id="AEN4">Pradeep 22 Padala</a></h3> 23 24 <div class="AFFILIATION"> 25 <div class="ADDRESS"> 26 <p class="ADDRESS"><code class="EMAIL"><<a href= 27 "mailto:ppadala@gmail.com">ppadala@gmail.com</a>></code></p> 28 </div> 29 </div> 30 31 <p class="PUBDATE">v1.9, 2005-06-20<br></p> 32 33 <div class="REVHISTORY"> 34 <table width="100%" border="0" summary="revisions"> 35 <tr> 36 <th align="left" valign="top" colspan="3"><b>Revision 37 History</b></th> 38 </tr> 39 40 <tr> 41 <td align="left">Revision 1.9</td> 42 43 <td align="left">2005-06-20</td> 44 45 <td align="left">Revised by: ppadala</td> 46 </tr> 47 48 <tr> 49 <td align="left" colspan="3">The license has been 50 changed to the MIT-style license used by NCURSES. Note 51 that the programs are also re-licensed under this.</td> 52 </tr> 53 54 <tr> 55 <td align="left">Revision 1.8</td> 56 57 <td align="left">2005-06-17</td> 58 59 <td align="left">Revised by: ppadala</td> 60 </tr> 61 62 <tr> 63 <td align="left" colspan="3">Lots of updates. Added 64 references and perl examples. Changes to examples. Many 65 grammatical and stylistic changes to the content. 66 Changes to NCURSES history.</td> 67 </tr> 68 69 <tr> 70 <td align="left">Revision 1.7.1</td> 71 72 <td align="left">2002-06-25</td> 73 74 <td align="left">Revised by: ppadala</td> 75 </tr> 76 77 <tr> 78 <td align="left" colspan="3">Added a README file for 79 building and instructions for building from 80 source.</td> 81 </tr> 82 83 <tr> 84 <td align="left">Revision 1.7</td> 85 86 <td align="left">2002-06-25</td> 87 88 <td align="left">Revised by: ppadala</td> 89 </tr> 90 91 <tr> 92 <td align="left" colspan="3">Added "Other formats" 93 section and made a lot of fancy changes to the 94 programs. Inlining of programs is gone.</td> 95 </tr> 96 97 <tr> 98 <td align="left">Revision 1.6.1</td> 99 100 <td align="left">2002-02-24</td> 101 102 <td align="left">Revised by: ppadala</td> 103 </tr> 104 105 <tr> 106 <td align="left" colspan="3">Removed the old Changelog 107 section, cleaned the makefiles</td> 108 </tr> 109 110 <tr> 111 <td align="left">Revision 1.6</td> 112 113 <td align="left">2002-02-16</td> 114 115 <td align="left">Revised by: ppadala</td> 116 </tr> 117 118 <tr> 119 <td align="left" colspan="3">Corrected a lot of 120 spelling mistakes, added ACS variables section</td> 121 </tr> 122 123 <tr> 124 <td align="left">Revision 1.5</td> 125 126 <td align="left">2002-01-05</td> 127 128 <td align="left">Revised by: ppadala</td> 129 </tr> 130 131 <tr> 132 <td align="left" colspan="3">Changed structure to 133 present proper TOC</td> 134 </tr> 135 136 <tr> 137 <td align="left">Revision 1.3.1</td> 138 139 <td align="left">2001-07-26</td> 140 141 <td align="left">Revised by: ppadala</td> 142 </tr> 143 144 <tr> 145 <td align="left" colspan="3">Corrected maintainers 146 paragraph, Corrected stable release number</td> 147 </tr> 148 149 <tr> 150 <td align="left">Revision 1.3</td> 151 152 <td align="left">2001-07-24</td> 153 154 <td align="left">Revised by: ppadala</td> 155 </tr> 156 157 <tr> 158 <td align="left" colspan="3">Added copyright notices to 159 main document (LDP license) and programs (GPL), 160 Corrected printw_example.</td> 161 </tr> 162 163 <tr> 164 <td align="left">Revision 1.2</td> 165 166 <td align="left">2001-06-05</td> 167 168 <td align="left">Revised by: ppadala</td> 169 </tr> 170 171 <tr> 172 <td align="left" colspan="3">Incorporated ravi's 173 changes. Mainly to introduction, menu, form, justforfun 174 sections</td> 175 </tr> 176 177 <tr> 178 <td align="left">Revision 1.1</td> 179 180 <td align="left">2001-05-22</td> 181 182 <td align="left">Revised by: ppadala</td> 183 </tr> 184 185 <tr> 186 <td align="left" colspan="3">Added "a word about 187 window" section, Added scanw_example.</td> 188 </tr> 189 </table> 190 </div> 191 192 <div> 193 <div class="ABSTRACT"> 194 <a name="AEN67" id="AEN67"></a> 195 196 <p><span class="emphasis"><i class="EMPHASIS">This 197 document is intended to be an "All in One" guide for 198 programming with ncurses and its sister libraries. We 199 graduate from a simple "Hello World" program to more 200 complex form manipulation. No prior experience in ncurses 201 is assumed. Send comments to <a href= 202 "mailto:ppadala@gmail.com" target="_top">this 203 address</a></i></span></p> 204 </div> 205 </div> 206 <hr> 207 </div> 208 209 <div class="TOC"> 210 <dl> 211 <dt><b>Table of Contents</b></dt> 212 213 <dt>1. <a href="#INTRO">Introduction</a></dt> 214 215 <dd> 216 <dl> 217 <dt>1.1. <a href="#WHATIS">What is NCURSES?</a></dt> 218 219 <dt>1.2. <a href="#WHATCANWEDO">What we can do with 220 NCURSES</a></dt> 221 222 <dt>1.3. <a href="#WHERETOGETIT">Where to get 223 it</a></dt> 224 225 <dt>1.4. <a href="#PURPOSE">Purpose/Scope of the 226 document</a></dt> 227 228 <dt>1.5. <a href="#ABOUTPROGRAMS">About the 229 Programs</a></dt> 230 231 <dt>1.6. <a href="#OTHERFORMATS">Other Formats of the 232 document</a></dt> 233 234 <dd> 235 <dl> 236 <dt>1.6.1. <a href="#LISTFORMATS">Readily available 237 formats from tldp.org</a></dt> 238 239 <dt>1.6.2. <a href="#BUILDSOURCE">Building from 240 source</a></dt> 241 </dl> 242 </dd> 243 244 <dt>1.7. <a href="#CREDITS">Credits</a></dt> 245 246 <dt>1.8. <a href="#WISHLIST">Wish List</a></dt> 247 248 <dt>1.9. <a href="#COPYRIGHT">Copyright</a></dt> 249 </dl> 250 </dd> 251 252 <dt>2. <a href="#HELLOWORLD">Hello World !!!</a></dt> 253 254 <dd> 255 <dl> 256 <dt>2.1. <a href="#COMPILECURSES">Compiling With the 257 NCURSES Library</a></dt> 258 259 <dt>2.2. <a href="#DISSECTION">Dissection</a></dt> 260 261 <dd> 262 <dl> 263 <dt>2.2.1. <a href="#ABOUT-INITSCR">About 264 initscr()</a></dt> 265 266 <dt>2.2.2. <a href="#MYST-REFRESH">The mysterious 267 refresh()</a></dt> 268 269 <dt>2.2.3. <a href="#ABOUT-ENDWIN">About 270 endwin()</a></dt> 271 </dl> 272 </dd> 273 </dl> 274 </dd> 275 276 <dt>3. <a href="#GORY">The Gory Details</a></dt> 277 278 <dt>4. <a href="#INIT">Initialization</a></dt> 279 280 <dd> 281 <dl> 282 <dt>4.1. <a href="#ABOUTINIT">Initialization 283 functions</a></dt> 284 285 <dt>4.2. <a href="#RAWCBREAK">raw() and 286 cbreak()</a></dt> 287 288 <dt>4.3. <a href="#ECHONOECHO">echo() and 289 noecho()</a></dt> 290 291 <dt>4.4. <a href="#KEYPAD">keypad()</a></dt> 292 293 <dt>4.5. <a href="#HALFDELAY">halfdelay()</a></dt> 294 295 <dt>4.6. <a href="#MISCINIT">Miscellaneous 296 Initialization functions</a></dt> 297 298 <dt>4.7. <a href="#INITEX">An Example</a></dt> 299 </dl> 300 </dd> 301 302 <dt>5. <a href="#AWORDWINDOWS">A Word about 303 Windows</a></dt> 304 305 <dt>6. <a href="#PRINTW">Output functions</a></dt> 306 307 <dd> 308 <dl> 309 <dt>6.1. <a href="#ADDCHCLASS">addch() class of 310 functions</a></dt> 311 312 <dt>6.2. <a href="#AEN298">mvaddch(), waddch() and 313 mvwaddch()</a></dt> 314 315 <dt>6.3. <a href="#PRINTWCLASS">printw() class of 316 functions</a></dt> 317 318 <dd> 319 <dl> 320 <dt>6.3.1. <a href="#PRINTWMVPRINTW">printw() and 321 mvprintw</a></dt> 322 323 <dt>6.3.2. <a href="#WPRINTWMVWPRINTW">wprintw() 324 and mvwprintw</a></dt> 325 326 <dt>6.3.3. <a href="#VWPRINTW">vw_printw()</a></dt> 327 328 <dt>6.3.4. <a href="#SIMPLEPRINTWEX">A Simple 329 printw example</a></dt> 330 </dl> 331 </dd> 332 333 <dt>6.4. <a href="#ADDSTRCLASS">addstr() class of 334 functions</a></dt> 335 336 <dt>6.5. <a href="#ACAUTION">A word of caution</a></dt> 337 </dl> 338 </dd> 339 340 <dt>7. <a href="#SCANW">Input functions</a></dt> 341 342 <dd> 343 <dl> 344 <dt>7.1. <a href="#GETCHCLASS">getch() class of 345 functions</a></dt> 346 347 <dt>7.2. <a href="#SCANWCLASS">scanw() class of 348 functions</a></dt> 349 350 <dd> 351 <dl> 352 <dt>7.2.1. <a href="#SCANWMVSCANW">scanw() and 353 mvscanw</a></dt> 354 355 <dt>7.2.2. <a href="#WSCANWMVWSCANW">wscanw() and 356 mvwscanw()</a></dt> 357 358 <dt>7.2.3. <a href="#VWSCANW">vw_scanw()</a></dt> 359 </dl> 360 </dd> 361 362 <dt>7.3. <a href="#GETSTRCLASS">getstr() class of 363 functions</a></dt> 364 365 <dt>7.4. <a href="#GETSTREX">Some examples</a></dt> 366 </dl> 367 </dd> 368 369 <dt>8. <a href="#ATTRIB">Attributes</a></dt> 370 371 <dd> 372 <dl> 373 <dt>8.1. <a href="#ATTRIBDETAILS">The details</a></dt> 374 375 <dt>8.2. <a href="#ATTRONVSATTRSET">attron() vs 376 attrset()</a></dt> 377 378 <dt>8.3. <a href="#ATTRGET">attr_get()</a></dt> 379 380 <dt>8.4. <a href="#ATTRFUNCS">attr_ functions</a></dt> 381 382 <dt>8.5. <a href="#WATTRFUNCS">wattr functions</a></dt> 383 384 <dt>8.6. <a href="#CHGAT">chgat() functions</a></dt> 385 </dl> 386 </dd> 387 388 <dt>9. <a href="#WINDOWS">Windows</a></dt> 389 390 <dd> 391 <dl> 392 <dt>9.1. <a href="#WINDOWBASICS">The basics</a></dt> 393 394 <dt>9.2. <a href="#LETBEWINDOW">Let there be a Window 395 !!!</a></dt> 396 397 <dt>9.3. <a href="#BORDEREXEXPL">Explanation</a></dt> 398 399 <dt>9.4. <a href="#OTHERSTUFF">The other stuff in the 400 example</a></dt> 401 402 <dt>9.5. <a href="#OTHERBORDERFUNCS">Other Border 403 functions</a></dt> 404 </dl> 405 </dd> 406 407 <dt>10. <a href="#COLOR">Colors</a></dt> 408 409 <dd> 410 <dl> 411 <dt>10.1. <a href="#COLORBASICS">The basics</a></dt> 412 413 <dt>10.2. <a href="#CHANGECOLORDEFS">Changing Color 414 Definitions</a></dt> 415 416 <dt>10.3. <a href="#COLORCONTENT">Color 417 Content</a></dt> 418 </dl> 419 </dd> 420 421 <dt>11. <a href="#KEYS">Interfacing with the key 422 board</a></dt> 423 424 <dd> 425 <dl> 426 <dt>11.1. <a href="#KEYSBASICS">The Basics</a></dt> 427 428 <dt>11.2. <a href="#SIMPLEKEYEX">A Simple Key Usage 429 example</a></dt> 430 </dl> 431 </dd> 432 433 <dt>12. <a href="#MOUSE">Interfacing with the 434 mouse</a></dt> 435 436 <dd> 437 <dl> 438 <dt>12.1. <a href="#MOUSEBASICS">The Basics</a></dt> 439 440 <dt>12.2. <a href="#GETTINGEVENTS">Getting the 441 events</a></dt> 442 443 <dt>12.3. <a href="#MOUSETOGETHER">Putting it all 444 Together</a></dt> 445 446 <dt>12.4. <a href="#MISCMOUSEFUNCS">Miscellaneous 447 Functions</a></dt> 448 </dl> 449 </dd> 450 451 <dt>13. <a href="#SCREEN">Screen Manipulation</a></dt> 452 453 <dd> 454 <dl> 455 <dt>13.1. <a href="#GETYX">getyx() functions</a></dt> 456 457 <dt>13.2. <a href="#SCREENDUMP">Screen Dumping</a></dt> 458 459 <dt>13.3. <a href="#WINDOWDUMP">Window Dumping</a></dt> 460 </dl> 461 </dd> 462 463 <dt>14. <a href="#MISC">Miscellaneous features</a></dt> 464 465 <dd> 466 <dl> 467 <dt>14.1. <a href="#CURSSET">curs_set()</a></dt> 468 469 <dt>14.2. <a href="#TEMPLEAVE">Temporarily Leaving 470 Curses mode</a></dt> 471 472 <dt>14.3. <a href="#ACSVARS">ACS_ variables</a></dt> 473 </dl> 474 </dd> 475 476 <dt>15. <a href="#OTHERLIB">Other libraries</a></dt> 477 478 <dt>16. <a href="#PANELS">Panel Library</a></dt> 479 480 <dd> 481 <dl> 482 <dt>16.1. <a href="#PANELBASICS">The Basics</a></dt> 483 484 <dt>16.2. <a href="#COMPILEPANELS">Compiling With the 485 Panels Library</a></dt> 486 487 <dt>16.3. <a href="#PANELBROWSING">Panel Window 488 Browsing</a></dt> 489 490 <dt>16.4. <a href="#USERPTRUSING">Using User 491 Pointers</a></dt> 492 493 <dt>16.5. <a href="#PANELMOVERESIZE">Moving and 494 Resizing Panels</a></dt> 495 496 <dt>16.6. <a href="#PANELSHOWHIDE">Hiding and Showing 497 Panels</a></dt> 498 499 <dt>16.7. <a href="#PANELABOVE">panel_above() and 500 panel_below() Functions</a></dt> 501 </dl> 502 </dd> 503 504 <dt>17. <a href="#MENUS">Menus Library</a></dt> 505 506 <dd> 507 <dl> 508 <dt>17.1. <a href="#MENUBASICS">The Basics</a></dt> 509 510 <dt>17.2. <a href="#COMPILEMENUS">Compiling With the 511 Menu Library</a></dt> 512 513 <dt>17.3. <a href="#MENUDRIVER">Menu Driver: The work 514 horse of the menu system</a></dt> 515 516 <dt>17.4. <a href="#MENUWINDOWS">Menu Windows</a></dt> 517 518 <dt>17.5. <a href="#SCROLLMENUS">Scrolling 519 Menus</a></dt> 520 521 <dt>17.6. <a href="#MULTICOLUMN">Multi Columnar 522 Menus</a></dt> 523 524 <dt>17.7. <a href="#MULTIVALUEMENUS">Multi Valued 525 Menus</a></dt> 526 527 <dt>17.8. <a href="#MENUOPT">Menu Options</a></dt> 528 529 <dt>17.9. <a href="#MENUUSERPTR">The useful User 530 Pointer</a></dt> 531 </dl> 532 </dd> 533 534 <dt>18. <a href="#FORMS">Forms Library</a></dt> 535 536 <dd> 537 <dl> 538 <dt>18.1. <a href="#FORMBASICS">The Basics</a></dt> 539 540 <dt>18.2. <a href="#COMPILEFORMS">Compiling With the 541 Forms Library</a></dt> 542 543 <dt>18.3. <a href="#PLAYFIELDS">Playing with 544 Fields</a></dt> 545 546 <dd> 547 <dl> 548 <dt>18.3.1. <a href="#FETCHINFO">Fetching Size and 549 Location of Field</a></dt> 550 551 <dt>18.3.2. <a href="#MOVEFIELD">Moving the 552 field</a></dt> 553 554 <dt>18.3.3. <a href="#JUSTIFYFIELD">Field 555 Justification</a></dt> 556 557 <dt>18.3.4. <a href="#FIELDDISPATTRIB">Field 558 Display Attributes</a></dt> 559 560 <dt>18.3.5. <a href="#FIELDOPTIONBITS">Field Option 561 Bits</a></dt> 562 563 <dt>18.3.6. <a href="#FIELDSTATUS">Field 564 Status</a></dt> 565 566 <dt>18.3.7. <a href="#FIELDUSERPTR">Field User 567 Pointer</a></dt> 568 569 <dt>18.3.8. <a href= 570 "#VARIABLESIZEFIELDS">Variable-Sized 571 Fields</a></dt> 572 </dl> 573 </dd> 574 575 <dt>18.4. <a href="#FORMWINDOWS">Form Windows</a></dt> 576 577 <dt>18.5. <a href="#FILEDVALIDATE">Field 578 Validation</a></dt> 579 580 <dt>18.6. <a href="#FORMDRIVER">Form Driver: The work 581 horse of the forms system</a></dt> 582 583 <dd> 584 <dl> 585 <dt>18.6.1. <a href="#PAGENAVREQ">Page Navigation 586 Requests</a></dt> 587 588 <dt>18.6.2. <a href="#INTERFIELDNAVREQ">Inter-Field 589 Navigation Requests</a></dt> 590 591 <dt>18.6.3. <a href="#INTRAFIELDNAVREQ">Intra-Field 592 Navigation Requests</a></dt> 593 594 <dt>18.6.4. <a href="#SCROLLREQ">Scrolling 595 Requests</a></dt> 596 597 <dt>18.6.5. <a href="#EDITREQ">Editing 598 Requests</a></dt> 599 600 <dt>18.6.6. <a href="#ORDERREQ">Order 601 Requests</a></dt> 602 603 <dt>18.6.7. <a href="#APPLICCOMMANDS">Application 604 Commands</a></dt> 605 </dl> 606 </dd> 607 </dl> 608 </dd> 609 610 <dt>19. <a href="#TOOLS">Tools and Widget 611 Libraries</a></dt> 612 613 <dd> 614 <dl> 615 <dt>19.1. <a href="#CDK">CDK (Curses Development 616 Kit)</a></dt> 617 618 <dd> 619 <dl> 620 <dt>19.1.1. <a href="#WIDGETLIST">Widget 621 List</a></dt> 622 623 <dt>19.1.2. <a href="#CDKATTRACT">Some Attractive 624 Features</a></dt> 625 626 <dt>19.1.3. <a href= 627 "#CDKCONCLUSION">Conclusion</a></dt> 628 </dl> 629 </dd> 630 631 <dt>19.2. <a href="#DIALOG">The dialog</a></dt> 632 633 <dt>19.3. <a href="#PERLCURSES">Perl Curses Modules 634 CURSES::FORM and CURSES::WIDGETS</a></dt> 635 </dl> 636 </dd> 637 638 <dt>20. <a href="#JUSTFORFUN">Just For Fun !!!</a></dt> 639 640 <dd> 641 <dl> 642 <dt>20.1. <a href="#GAMEOFLIFE">The Game of 643 Life</a></dt> 644 645 <dt>20.2. <a href="#MAGIC">Magic Square</a></dt> 646 647 <dt>20.3. <a href="#HANOI">Towers of Hanoi</a></dt> 648 649 <dt>20.4. <a href="#QUEENS">Queens Puzzle</a></dt> 650 651 <dt>20.5. <a href="#SHUFFLE">Shuffle</a></dt> 652 653 <dt>20.6. <a href="#TT">Typing Tutor</a></dt> 654 </dl> 655 </dd> 656 657 <dt>21. <a href="#REF">References</a></dt> 658 </dl> 659 </div> 660 661 <div class="SECT1"> 662 <h2 class="SECT1"><a name="INTRO" id="INTRO">1. 663 Introduction</a></h2> 664 665 <p>In the olden days of teletype terminals, terminals were 666 away from computers and were connected to them through serial 667 cables. The terminals could be configured by sending a series 668 of bytes. All the capabilities (such as moving the cursor to 669 a new location, erasing part of the screen, scrolling the 670 screen, changing modes etc.) of terminals could be accessed 671 through these series of bytes. These control seeuqnces are 672 usually called escape sequences, because they start with an 673 escape(0x1B) character. Even today, with proper emulation, we 674 can send escape sequences to the emulator and achieve the 675 same effect on a terminal window.</p> 676 677 <p>Suppose you wanted to print a line in color. Try typing 678 this on your console.</p> 679 <pre class="PROGRAMLISTING"> 680echo "^[[0;31;40mIn Color" 681</pre> 682 683 <p>The first character is an escape character, which looks 684 like two characters ^ and [. To be able to print it, you have 685 to press CTRL+V and then the ESC key. All the others are 686 normal printable characters. You should be able to see the 687 string "In Color" in red. It stays that way and to revert 688 back to the original mode type this.</p> 689 <pre class="PROGRAMLISTING"> 690echo "^[[0;37;40m" 691</pre> 692 693 <p>Now, what do these magic characters mean? Difficult to 694 comprehend? They might even be different for different 695 terminals. So the designers of UNIX invented a mechanism 696 named <tt class="LITERAL">termcap</tt>. It is a file that 697 lists all the capabilities of a particular terminal, along 698 with the escape sequences needed to achieve a particular 699 effect. In the later years, this was replaced by <tt class= 700 "LITERAL">terminfo</tt>. Without delving too much into 701 details, this mechanism allows application programs to query 702 the terminfo database and obtain the control characters to be 703 sent to a terminal or terminal emulator.</p> 704 705 <div class="SECT2"> 706 <hr> 707 708 <h3 class="SECT2"><a name="WHATIS" id="WHATIS">1.1. What is 709 NCURSES?</a></h3> 710 711 <p>You might be wondering, what the import of all this 712 technical gibberish is. In the above scenario, every 713 application program is supposed to query the terminfo and 714 perform the necessary stuff (sending control characters 715 etc.). It soon became difficult to manage this complexity 716 and this gave birth to 'CURSES'. Curses is a pun on the 717 name "cursor optimization". The Curses library forms a 718 wrapper over working with raw terminal codes, and provides 719 highly flexible and efficient API (Application Programming 720 Interface). It provides functions to move the cursor, 721 create windows, produce colors, play with mouse etc. The 722 application programs need not worry about the underlying 723 terminal capabilities.</p> 724 725 <p>So what is NCURSES? NCURSES is a clone of the original 726 System V Release 4.0 (SVr4) curses. It is a freely 727 distributable library, fully compatible with older version 728 of curses. In short, it is a library of functions that 729 manages an application's display on character-cell 730 terminals. In the remainder of the document, the terms 731 curses and ncurses are used interchangeably.</p> 732 733 <p>A detailed history of NCURSES can be found in the NEWS 734 file from the source distribution. The current package is 735 maintained by <a href="mailto:dickey@his.com" target= 736 "_top">Thomas Dickey</a>. You can contact the maintainers 737 at <a href="mailto:bug-ncurses@gnu.org" target= 738 "_top">bug-ncurses@gnu.org</a>.</p> 739 </div> 740 741 <div class="SECT2"> 742 <hr> 743 744 <h3 class="SECT2"><a name="WHATCANWEDO" id= 745 "WHATCANWEDO">1.2. What we can do with NCURSES</a></h3> 746 747 <p>NCURSES not only creates a wrapper over terminal 748 capabilities, but also gives a robust framework to create 749 nice looking UI (User Interface)s in text mode. It provides 750 functions to create windows etc. Its sister libraries 751 panel, menu and form provide an extension to the basic 752 curses library. These libraries usually come along with 753 curses. One can create applications that contain multiple 754 windows, menus, panels and forms. Windows can be managed 755 independently, can provide 'scrollability' and even can be 756 hidden.</p> 757 758 <p>Menus provide the user with an easy command selection 759 option. Forms allow the creation of easy-to-use data entry 760 and display windows. Panels extend the capabilities of 761 ncurses to deal with overlapping and stacked windows.</p> 762 763 <p>These are just some of the basic things we can do with 764 ncurses. As we move along, We will see all the capabilities 765 of these libraries.</p> 766 </div> 767 768 <div class="SECT2"> 769 <hr> 770 771 <h3 class="SECT2"><a name="WHERETOGETIT" id= 772 "WHERETOGETIT">1.3. Where to get it</a></h3> 773 774 <p>All right, now that you know what you can do with 775 ncurses, you must be rearing to get started. NCURSES is 776 usually shipped with your installation. In case you don't 777 have the library or want to compile it on your own, read 778 on.</p> 779 780 <p><span class="emphasis"><i class="EMPHASIS">Compiling the 781 package</i></span></p> 782 783 <p>NCURSES can be obtained from <a href= 784 "ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz" target= 785 "_top">ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz</a> 786 or any of the ftp sites mentioned in <a href= 787 "http://www.gnu.org/order/ftp.html" target= 788 "_top">http://www.gnu.org/order/ftp.html</a>.</p> 789 790 <p>Read the README and INSTALL files for details on to how 791 to install it. It usually involves the following 792 operations.</p> 793 <pre class="PROGRAMLISTING"> 794 tar zxvf ncurses<version>.tar.gz # unzip and untar the archive 795 cd ncurses<version> # cd to the directory 796 ./configure # configure the build according to your 797 # environment 798 make # make it 799 su root # become root 800 make install # install it 801</pre> 802 803 <p><span class="emphasis"><i class="EMPHASIS">Using the 804 RPM</i></span></p> 805 806 <p>NCURSES RPM can be found and downloaded from <a href= 807 "http://rpmfind.net" target="_top">http://rpmfind.net</a> . 808 The RPM can be installed with the following command after 809 becoming root.</p> 810 <pre class="PROGRAMLISTING"> 811 rpm -i <downloaded rpm> 812</pre> 813 </div> 814 815 <div class="SECT2"> 816 <hr> 817 818 <h3 class="SECT2"><a name="PURPOSE" id="PURPOSE">1.4. 819 Purpose/Scope of the document</a></h3> 820 821 <p>This document is intended to be a "All in One" guide for 822 programming with ncurses and its sister libraries. We 823 graduate from a simple "Hello World" program to more 824 complex form manipulation. No prior experience in ncurses 825 is assumed. The writing is informal, but a lot of detail is 826 provided for each of the examples.</p> 827 </div> 828 829 <div class="SECT2"> 830 <hr> 831 832 <h3 class="SECT2"><a name="ABOUTPROGRAMS" id= 833 "ABOUTPROGRAMS">1.5. About the Programs</a></h3> 834 835 <p>All the programs in the document are available in zipped 836 form <a href= 837 "http://www.tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs.tar.gz" 838 target="_top">here</a>. Unzip and untar it. The directory 839 structure looks like this.</p> 840 <pre class="PROGRAMLISTING"> 841ncurses 842 | 843 |----> JustForFun -- just for fun programs 844 |----> basics -- basic programs 845 |----> demo -- output files go into this directory after make 846 | | 847 | |----> exe -- exe files of all example programs 848 |----> forms -- programs related to form library 849 |----> menus -- programs related to menus library 850 |----> panels -- programs related to panels library 851 |----> perl -- perl equivalents of the examples (contributed 852 | by Anuradha Ratnaweera) 853 |----> Makefile -- the top level Makefile 854 |----> README -- the top level README file. contains instructions 855 |----> COPYING -- copyright notice 856</pre> 857 858 <p>The individual directories contain the following 859 files.</p> 860 <pre class="PROGRAMLISTING"> 861Description of files in each directory 862-------------------------------------- 863JustForFun 864 | 865 |----> hanoi.c -- The Towers of Hanoi Solver 866 |----> life.c -- The Game of Life demo 867 |----> magic.c -- An Odd Order Magic Square builder 868 |----> queens.c -- The famous N-Queens Solver 869 |----> shuffle.c -- A fun game, if you have time to kill 870 |----> tt.c -- A very trivial typing tutor 871 872 basics 873 | 874 |----> acs_vars.c -- ACS_ variables example 875 |----> hello_world.c -- Simple "Hello World" Program 876 |----> init_func_example.c -- Initialization functions example 877 |----> key_code.c -- Shows the scan code of the key pressed 878 |----> mouse_menu.c -- A menu accessible by mouse 879 |----> other_border.c -- Shows usage of other border functions apa 880 | -- rt from box() 881 |----> printw_example.c -- A very simple printw() example 882 |----> scanw_example.c -- A very simple getstr() example 883 |----> simple_attr.c -- A program that can print a c file with 884 | -- comments in attribute 885 |----> simple_color.c -- A simple example demonstrating colors 886 |----> simple_key.c -- A menu accessible with keyboard UP, DOWN 887 | -- arrows 888 |----> temp_leave.c -- Demonstrates temporarily leaving curses mode 889 |----> win_border.c -- Shows Creation of windows and borders 890 |----> with_chgat.c -- chgat() usage example 891 892 forms 893 | 894 |----> form_attrib.c -- Usage of field attributes 895 |----> form_options.c -- Usage of field options 896 |----> form_simple.c -- A simple form example 897 |----> form_win.c -- Demo of windows associated with forms 898 899 menus 900 | 901 |----> menu_attrib.c -- Usage of menu attributes 902 |----> menu_item_data.c -- Usage of item_name() etc.. functions 903 |----> menu_multi_column.c -- Creates multi columnar menus 904 |----> menu_scroll.c -- Demonstrates scrolling capability of menus 905 |----> menu_simple.c -- A simple menu accessed by arrow keys 906 |----> menu_toggle.c -- Creates multi valued menus and explains 907 | -- REQ_TOGGLE_ITEM 908 |----> menu_userptr.c -- Usage of user pointer 909 |----> menu_win.c -- Demo of windows associated with menus 910 911 panels 912 | 913 |----> panel_browse.c -- Panel browsing through tab. Usage of user 914 | -- pointer 915 |----> panel_hide.c -- Hiding and Un hiding of panels 916 |----> panel_resize.c -- Moving and resizing of panels 917 |----> panel_simple.c -- A simple panel example 918 919 perl 920 |----> 01-10.pl -- Perl equivalents of first ten example programs 921</pre> 922 923 <p>There is a top level Makefile included in the main 924 directory. It builds all the files and puts the 925 ready-to-use exes in demo/exe directory. You can also do 926 selective make by going into the corresponding directory. 927 Each directory contains a README file explaining the 928 purpose of each c file in the directory.</p> 929 930 <p>For every example, I have included path name for the 931 file relative to the examples directory.</p> 932 933 <p>If you prefer browsing individual programs, point your 934 browser to <a href= 935 "http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/" 936 target= 937 "_top">http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/</a></p> 938 939 <p>All the programs are released under the same license 940 that is used by ncurses (MIT-style). This gives you the 941 ability to do pretty much anything other than claiming them 942 as yours. Feel free to use them in your programs as 943 appropriate.</p> 944 </div> 945 946 <div class="SECT2"> 947 <hr> 948 949 <h3 class="SECT2"><a name="OTHERFORMATS" id= 950 "OTHERFORMATS">1.6. Other Formats of the document</a></h3> 951 952 <p>This howto is also availabe in various other formats on 953 the tldp.org site. Here are the links to other formats of 954 this document.</p> 955 956 <div class="SECT3"> 957 <hr> 958 959 <h4 class="SECT3"><a name="LISTFORMATS" id= 960 "LISTFORMATS">1.6.1. Readily available formats from 961 tldp.org</a></h4> 962 963 <ul> 964 <li> 965 <p><a href= 966 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/pdf/NCURSES-Programming-HOWTO.pdf" 967 target="_top">Acrobat PDF Format</a></p> 968 </li> 969 970 <li> 971 <p><a href= 972 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/ps/NCURSES-Programming-HOWTO.ps.gz" 973 target="_top">PostScript Format</a></p> 974 </li> 975 976 <li> 977 <p><a href= 978 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html/NCURSES-Programming-HOWTO-html.tar.gz" 979 target="_top">In Multiple HTML pages</a></p> 980 </li> 981 982 <li> 983 <p><a href= 984 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/NCURSES-Programming-HOWTO.html" 985 target="_top">In One big HTML format</a></p> 986 </li> 987 </ul> 988 </div> 989 990 <div class="SECT3"> 991 <hr> 992 993 <h4 class="SECT3"><a name="BUILDSOURCE" id= 994 "BUILDSOURCE">1.6.2. Building from source</a></h4> 995 996 <p>If above links are broken or if you want to experiment 997 with sgml read on.</p> 998 <pre class="PROGRAMLISTING"> 999 Get both the source and the tar,gzipped programs, available at 1000 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/ 1001 NCURSES-HOWTO/NCURSES-Programming-HOWTO.sgml 1002 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/ 1003 NCURSES-HOWTO/ncurses_programs.tar.gz 1004 1005 Unzip ncurses_programs.tar.gz with 1006 tar zxvf ncurses_programs.tar.gz 1007 1008 Use jade to create various formats. For example if you just want to create 1009 the multiple html files, you would use 1010 jade -t sgml -i html -d <path to docbook html stylesheet> 1011 NCURSES-Programming-HOWTO.sgml 1012 to get pdf, first create a single html file of the HOWTO with 1013 jade -t sgml -i html -d <path to docbook html stylesheet> -V nochunks 1014 NCURSES-Programming-HOWTO.sgml > NCURSES-ONE-BIG-FILE.html 1015 then use htmldoc to get pdf file with 1016 htmldoc --size universal -t pdf --firstpage p1 -f <output file name.pdf> 1017 NCURSES-ONE-BIG-FILE.html 1018 for ps, you would use 1019 htmldoc --size universal -t ps --firstpage p1 -f <output file name.ps> 1020 NCURSES-ONE-BIG-FILE.html 1021</pre> 1022 1023 <p>See <a href= 1024 "http://www.tldp.org/LDP/LDP-Author-Guide/" target= 1025 "_top">LDP Author guide</a> for more details. If all else 1026 failes, mail me at <a href="ppadala@gmail.com" target= 1027 "_top">ppadala@gmail.com</a></p> 1028 </div> 1029 </div> 1030 1031 <div class="SECT2"> 1032 <hr> 1033 1034 <h3 class="SECT2"><a name="CREDITS" id="CREDITS">1.7. 1035 Credits</a></h3> 1036 1037 <p>I thank <a href="mailto:sharath_1@usa.net" target= 1038 "_top">Sharath</a> and Emre Akbas for helping me with few 1039 sections. The introduction was initially written by 1040 sharath. I rewrote it with few excerpts taken from his 1041 initial work. Emre helped in writing printw and scanw 1042 sections.</p> 1043 1044 <p>Perl equivalents of the example programs are contributed 1045 by <a href="mailto:Aratnaweera@virtusa.com" target= 1046 "_top">Anuradha Ratnaweera</a>.</p> 1047 1048 <p>Then comes <a href="mailto:parimi@ece.arizona.edu" 1049 target="_top">Ravi Parimi</a>, my dearest friend, who has 1050 been on this project before even one line was written. He 1051 constantly bombarded me with suggestions and patiently 1052 reviewed the whole text. He also checked each program on 1053 Linux and Solaris.</p> 1054 </div> 1055 1056 <div class="SECT2"> 1057 <hr> 1058 1059 <h3 class="SECT2"><a name="WISHLIST" id="WISHLIST">1.8. 1060 Wish List</a></h3> 1061 1062 <p>This is the wish list, in the order of priority. If you 1063 have a wish or you want to work on completing the wish, 1064 mail <a href="mailto:ppadala@gmail.com" target= 1065 "_top">me</a>.</p> 1066 1067 <ul> 1068 <li> 1069 <p>Add examples to last parts of forms section.</p> 1070 </li> 1071 1072 <li> 1073 <p>Prepare a Demo showing all the programs and allow 1074 the user to browse through description of each program. 1075 Let the user compile and see the program in action. A 1076 dialog based interface is preferred.</p> 1077 </li> 1078 1079 <li> 1080 <p>Add debug info. _tracef, _tracemouse stuff.</p> 1081 </li> 1082 1083 <li> 1084 <p>Accessing termcap, terminfo using functions provided 1085 by ncurses package.</p> 1086 </li> 1087 1088 <li> 1089 <p>Working on two terminals simultaneously.</p> 1090 </li> 1091 1092 <li> 1093 <p>Add more stuff to miscellaneous section.</p> 1094 </li> 1095 </ul> 1096 </div> 1097 1098 <div class="SECT2"> 1099 <hr> 1100 1101 <h3 class="SECT2"><a name="COPYRIGHT" id="COPYRIGHT">1.9. 1102 Copyright</a></h3> 1103 1104 <p>Copyright © 2001 by Pradeep Padala.</p> 1105 1106 <p>Permission is hereby granted, free of charge, to any 1107 person obtaining a copy of this software and associated 1108 documentation files (the "Software"), to deal in the 1109 Software without restriction, including without limitation 1110 the rights to use, copy, modify, merge, publish, 1111 distribute, distribute with modifications, sublicense, 1112 and/or sell copies of the Software, and to permit persons 1113 to whom the Software is furnished to do so, subject to the 1114 following conditions:</p> 1115 1116 <p>The above copyright notice and this permission notice 1117 shall be included in all copies or substantial portions of 1118 the Software.</p> 1119 1120 <p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF 1121 ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO 1122 THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR 1123 PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE ABOVE 1124 COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 1125 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR 1126 OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 1127 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.</p> 1128 1129 <p>Except as contained in this notice, the name(s) of the 1130 above copyright holders shall not be used in advertising or 1131 otherwise to promote the sale, use or other dealings in 1132 this Software without prior written authorization.</p> 1133 </div> 1134 </div> 1135 1136 <div class="SECT1"> 1137 <hr> 1138 1139 <h2 class="SECT1"><a name="HELLOWORLD" id="HELLOWORLD">2. 1140 Hello World !!!</a></h2> 1141 1142 <p>Welcome to the world of curses. Before we plunge into the 1143 library and look into its various features, let's write a 1144 simple program and say hello to the world.</p> 1145 1146 <div class="SECT2"> 1147 <hr> 1148 1149 <h3 class="SECT2"><a name="COMPILECURSES" id= 1150 "COMPILECURSES">2.1. Compiling With the NCURSES 1151 Library</a></h3> 1152 1153 <p>To use ncurses library functions, you have to include 1154 ncurses.h in your programs. To link the program with 1155 ncurses the flag -lncurses should be added.</p> 1156 <pre class="PROGRAMLISTING"> 1157 #include <ncurses.h> 1158 . 1159 . 1160 . 1161 1162 compile and link: gcc <program file> -lncurses 1163</pre> 1164 1165 <div class="EXAMPLE"> 1166 <a name="BHW" id="BHW"></a> 1167 1168 <p><b>Example 1. The Hello World !!! Program</b></p> 1169 <pre class="PROGRAMLISTING"> 1170<span class="INLINEMEDIAOBJECT">#include <ncurses.h> 1171 1172int main() 1173{ 1174 initscr(); /* Start curses mode */ 1175 printw("Hello World !!!"); /* Print Hello World */ 1176 refresh(); /* Print it on to the real screen */ 1177 getch(); /* Wait for user input */ 1178 endwin(); /* End curses mode */ 1179 1180 return 0; 1181}</span> 1182</pre> 1183 </div> 1184 </div> 1185 1186 <div class="SECT2"> 1187 <hr> 1188 1189 <h3 class="SECT2"><a name="DISSECTION" id="DISSECTION">2.2. 1190 Dissection</a></h3> 1191 1192 <p>The above program prints "Hello World !!!" to the screen 1193 and exits. This program shows how to initialize curses and 1194 do screen manipulation and end curses mode. Let's dissect 1195 it line by line.</p> 1196 1197 <div class="SECT3"> 1198 <hr> 1199 1200 <h4 class="SECT3"><a name="ABOUT-INITSCR" id= 1201 "ABOUT-INITSCR">2.2.1. About initscr()</a></h4> 1202 1203 <p>The function initscr() initializes the terminal in 1204 curses mode. In some implementations, it clears the 1205 screen and presents a blank screen. To do any screen 1206 manipulation using curses package this has to be called 1207 first. This function initializes the curses system and 1208 allocates memory for our present window (called 1209 <tt class="LITERAL">stdscr</tt>) and some other 1210 data-structures. Under extreme cases this function might 1211 fail due to insufficient memory to allocate memory for 1212 curses library's data structures.</p> 1213 1214 <p>After this is done, we can do a variety of 1215 initializations to customize our curses settings. These 1216 details will be explained <a href="#INIT">later</a> .</p> 1217 </div> 1218 1219 <div class="SECT3"> 1220 <hr> 1221 1222 <h4 class="SECT3"><a name="MYST-REFRESH" id= 1223 "MYST-REFRESH">2.2.2. The mysterious refresh()</a></h4> 1224 1225 <p>The next line printw prints the string "Hello World 1226 !!!" on to the screen. This function is analogous to 1227 normal printf in all respects except that it prints the 1228 data on a window called stdscr at the current (y,x) 1229 co-ordinates. Since our present co-ordinates are at 0,0 1230 the string is printed at the left hand corner of the 1231 window.</p> 1232 1233 <p>This brings us to that mysterious refresh(). Well, 1234 when we called printw the data is actually written to an 1235 imaginary window, which is not updated on the screen yet. 1236 The job of printw is to update a few flags and data 1237 structures and write the data to a buffer corresponding 1238 to stdscr. In order to show it on the screen, we need to 1239 call refresh() and tell the curses system to dump the 1240 contents on the screen.</p> 1241 1242 <p>The philosophy behind all this is to allow the 1243 programmer to do multiple updates on the imaginary screen 1244 or windows and do a refresh once all his screen update is 1245 done. refresh() checks the window and updates only the 1246 portion which has been changed. This improves performance 1247 and offers greater flexibility too. But, it is sometimes 1248 frustrating to beginners. A common mistake committed by 1249 beginners is to forget to call refresh() after they did 1250 some update through printw() class of functions. I still 1251 forget to add it sometimes :-)</p> 1252 </div> 1253 1254 <div class="SECT3"> 1255 <hr> 1256 1257 <h4 class="SECT3"><a name="ABOUT-ENDWIN" id= 1258 "ABOUT-ENDWIN">2.2.3. About endwin()</a></h4> 1259 1260 <p>And finally don't forget to end the curses mode. 1261 Otherwise your terminal might behave strangely after the 1262 program quits. endwin() frees the memory taken by curses 1263 sub-system and its data structures and puts the terminal 1264 in normal mode. This function must be called after you 1265 are done with the curses mode.</p> 1266 </div> 1267 </div> 1268 </div> 1269 1270 <div class="SECT1"> 1271 <hr> 1272 1273 <h2 class="SECT1"><a name="GORY" id="GORY">3. The Gory 1274 Details</a></h2> 1275 1276 <p>Now that we have seen how to write a simple curses program 1277 let's get into the details. There are many functions that 1278 help customize what you see on screen and many features which 1279 can be put to full use.</p> 1280 1281 <p>Here we go...</p> 1282 </div> 1283 1284 <div class="SECT1"> 1285 <hr> 1286 1287 <h2 class="SECT1"><a name="INIT" id="INIT">4. 1288 Initialization</a></h2> 1289 1290 <p>We now know that to initialize curses system the function 1291 initscr() has to be called. There are functions which can be 1292 called after this initialization to customize our curses 1293 session. We may ask the curses system to set the terminal in 1294 raw mode or initialize color or initialize the mouse etc.. 1295 Let's discuss some of the functions that are normally called 1296 immediately after initscr();</p> 1297 1298 <div class="SECT2"> 1299 <hr> 1300 1301 <h3 class="SECT2"><a name="ABOUTINIT" id="ABOUTINIT">4.1. 1302 Initialization functions</a></h3> 1303 </div> 1304 1305 <div class="SECT2"> 1306 <hr> 1307 1308 <h3 class="SECT2"><a name="RAWCBREAK" id="RAWCBREAK">4.2. 1309 raw() and cbreak()</a></h3> 1310 1311 <p>Normally the terminal driver buffers the characters a 1312 user types until a new line or carriage return is 1313 encountered. But most programs require that the characters 1314 be available as soon as the user types them. The above two 1315 functions are used to disable line buffering. The 1316 difference between these two functions is in the way 1317 control characters like suspend (CTRL-Z), interrupt and 1318 quit (CTRL-C) are passed to the program. In the raw() mode 1319 these characters are directly passed to the program without 1320 generating a signal. In the <tt class= 1321 "LITERAL">cbreak()</tt> mode these control characters are 1322 interpreted as any other character by the terminal driver. 1323 I personally prefer to use raw() as I can exercise greater 1324 control over what the user does.</p> 1325 </div> 1326 1327 <div class="SECT2"> 1328 <hr> 1329 1330 <h3 class="SECT2"><a name="ECHONOECHO" id="ECHONOECHO">4.3. 1331 echo() and noecho()</a></h3> 1332 1333 <p>These functions control the echoing of characters typed 1334 by the user to the terminal. <tt class= 1335 "LITERAL">noecho()</tt> switches off echoing. The reason 1336 you might want to do this is to gain more control over 1337 echoing or to suppress unnecessary echoing while taking 1338 input from the user through the getch() etc. functions. 1339 Most of the interactive programs call <tt class= 1340 "LITERAL">noecho()</tt> at initialization and do the 1341 echoing of characters in a controlled manner. It gives the 1342 programmer the flexibility of echoing characters at any 1343 place in the window without updating current (y,x) 1344 co-ordinates.</p> 1345 </div> 1346 1347 <div class="SECT2"> 1348 <hr> 1349 1350 <h3 class="SECT2"><a name="KEYPAD" id="KEYPAD">4.4. 1351 keypad()</a></h3> 1352 1353 <p>This is my favorite initialization function. It enables 1354 the reading of function keys like F1, F2, arrow keys etc. 1355 Almost every interactive program enables this, as arrow 1356 keys are a major part of any User Interface. Do <tt class= 1357 "LITERAL">keypad(stdscr, TRUE)</tt> to enable this feature 1358 for the regular screen (stdscr). You will learn more about 1359 key management in later sections of this document.</p> 1360 </div> 1361 1362 <div class="SECT2"> 1363 <hr> 1364 1365 <h3 class="SECT2"><a name="HALFDELAY" id="HALFDELAY">4.5. 1366 halfdelay()</a></h3> 1367 1368 <p>This function, though not used very often, is a useful 1369 one at times. halfdelay()is called to enable the half-delay 1370 mode, which is similar to the cbreak() mode in that 1371 characters typed are immediately available to program. 1372 However, it waits for 'X' tenths of a second for input and 1373 then returns ERR, if no input is available. 'X' is the 1374 timeout value passed to the function halfdelay(). This 1375 function is useful when you want to ask the user for input, 1376 and if he doesn't respond with in certain time, we can do 1377 some thing else. One possible example is a timeout at the 1378 password prompt.</p> 1379 </div> 1380 1381 <div class="SECT2"> 1382 <hr> 1383 1384 <h3 class="SECT2"><a name="MISCINIT" id="MISCINIT">4.6. 1385 Miscellaneous Initialization functions</a></h3> 1386 1387 <p>There are few more functions which are called at 1388 initialization to customize curses behavior. They are not 1389 used as extensively as those mentioned above. Some of them 1390 are explained where appropriate.</p> 1391 </div> 1392 1393 <div class="SECT2"> 1394 <hr> 1395 1396 <h3 class="SECT2"><a name="INITEX" id="INITEX">4.7. An 1397 Example</a></h3> 1398 1399 <p>Let's write a program which will clarify the usage of 1400 these functions.</p> 1401 1402 <div class="EXAMPLE"> 1403 <a name="BINFU" id="BINFU"></a> 1404 1405 <p><b>Example 2. Initialization Function Usage 1406 example</b></p> 1407 <pre class="PROGRAMLISTING"> 1408<span class="INLINEMEDIAOBJECT">#include <ncurses.h> 1409 1410int main() 1411{ int ch; 1412 1413 initscr(); /* Start curses mode */ 1414 raw(); /* Line buffering disabled */ 1415 keypad(stdscr, TRUE); /* We get F1, F2 etc.. */ 1416 noecho(); /* Don't echo() while we do getch */ 1417 1418 printw("Type any character to see it in bold\n"); 1419 ch = getch(); /* If raw() hadn't been called 1420 * we have to press enter before it 1421 * gets to the program */ 1422 if(ch == KEY_F(1)) /* Without keypad enabled this will */ 1423 printw("F1 Key pressed");/* not get to us either */ 1424 /* Without noecho() some ugly escape 1425 * charachters might have been printed 1426 * on screen */ 1427 else 1428 { printw("The pressed key is "); 1429 attron(A_BOLD); 1430 printw("%c", ch); 1431 attroff(A_BOLD); 1432 } 1433 refresh(); /* Print it on to the real screen */ 1434 getch(); /* Wait for user input */ 1435 endwin(); /* End curses mode */ 1436 1437 return 0; 1438}</span> 1439</pre> 1440 </div> 1441 1442 <p>This program is self-explanatory. But I used functions 1443 which aren't explained yet. The function <tt class= 1444 "LITERAL">getch()</tt> is used to get a character from 1445 user. It is equivalent to normal <tt class= 1446 "LITERAL">getchar()</tt> except that we can disable the 1447 line buffering to avoid <enter> after input. Look for 1448 more about <tt class="LITERAL">getch()</tt>and reading keys 1449 in the <a href="#KEYS">key management section</a> . The 1450 functions attron and attroff are used to switch some 1451 attributes on and off respectively. In the example I used 1452 them to print the character in bold. These functions are 1453 explained in detail later.</p> 1454 </div> 1455 </div> 1456 1457 <div class="SECT1"> 1458 <hr> 1459 1460 <h2 class="SECT1"><a name="AWORDWINDOWS" id="AWORDWINDOWS">5. 1461 A Word about Windows</a></h2> 1462 1463 <p>Before we plunge into the myriad ncurses functions, let me 1464 clear few things about windows. Windows are explained in 1465 detail in following <a href="#WINDOWS">sections</a></p> 1466 1467 <p>A Window is an imaginary screen defined by curses system. 1468 A window does not mean a bordered window which you usually 1469 see on Win9X platforms. When curses is initialized, it 1470 creates a default window named <tt class= 1471 "LITERAL">stdscr</tt> which represents your 80x25 (or the 1472 size of window in which you are running) screen. If you are 1473 doing simple tasks like printing few strings, reading input 1474 etc., you can safely use this single window for all of your 1475 purposes. You can also create windows and call functions 1476 which explicitly work on the specified window.</p> 1477 1478 <p>For example, if you call</p> 1479 <pre class="PROGRAMLISTING"> 1480 printw("Hi There !!!"); 1481 refresh(); 1482</pre> 1483 1484 <p>It prints the string on stdscr at the present cursor 1485 position. Similarly the call to refresh(), works on stdscr 1486 only.</p> 1487 1488 <p>Say you have created <a href="#WINDOWS">windows</a> then 1489 you have to call a function with a 'w' added to the usual 1490 function.</p> 1491 <pre class="PROGRAMLISTING"> 1492 wprintw(win, "Hi There !!!"); 1493 wrefresh(win); 1494</pre> 1495 1496 <p>As you will see in the rest of the document, naming of 1497 functions follow the same convention. For each function there 1498 usually are three more functions.</p> 1499 <pre class="PROGRAMLISTING"> 1500 printw(string); /* Print on stdscr at present cursor position */ 1501 mvprintw(y, x, string);/* Move to (y, x) then print string */ 1502 wprintw(win, string); /* Print on window win at present cursor position */ 1503 /* in the window */ 1504 mvwprintw(win, y, x, string); /* Move to (y, x) relative to window */ 1505 /* co-ordinates and then print */ 1506</pre> 1507 1508 <p>Usually the w-less functions are macros which expand to 1509 corresponding w-function with stdscr as the window 1510 parameter.</p> 1511 </div> 1512 1513 <div class="SECT1"> 1514 <hr> 1515 1516 <h2 class="SECT1"><a name="PRINTW" id="PRINTW">6. Output 1517 functions</a></h2> 1518 1519 <p>I guess you can't wait any more to see some action. Back 1520 to our odyssey of curses functions. Now that curses is 1521 initialized, let's interact with world.</p> 1522 1523 <p>There are three classes of functions which you can use to 1524 do output on screen.</p> 1525 1526 <ol type="1"> 1527 <li> 1528 <p>addch() class: Print single character with 1529 attributes</p> 1530 </li> 1531 1532 <li> 1533 <p>printw() class: Print formatted output similar to 1534 printf()</p> 1535 </li> 1536 1537 <li> 1538 <p>addstr() class: Print strings</p> 1539 </li> 1540 </ol> 1541 1542 <p>These functions can be used interchangeably and it's a 1543 matter of style as to which class is used. Let's see each one 1544 in detail.</p> 1545 1546 <div class="SECT2"> 1547 <hr> 1548 1549 <h3 class="SECT2"><a name="ADDCHCLASS" id="ADDCHCLASS">6.1. 1550 addch() class of functions</a></h3> 1551 1552 <p>These functions put a single character into the current 1553 cursor location and advance the position of the cursor. You 1554 can give the character to be printed but they usually are 1555 used to print a character with some attributes. Attributes 1556 are explained in detail in later <a href= 1557 "#ATTRIB">sections</a> of the document. If a character is 1558 associated with an attribute(bold, reverse video etc.), 1559 when curses prints the character, it is printed in that 1560 attribute.</p> 1561 1562 <p>In order to combine a character with some attributes, 1563 you have two options:</p> 1564 1565 <ul> 1566 <li> 1567 <p>By OR'ing a single character with the desired 1568 attribute macros. These attribute macros could be found 1569 in the header file <tt class="LITERAL">ncurses.h</tt>. 1570 For example, you want to print a character ch(of type 1571 char) bold and underlined, you would call addch() as 1572 below.</p> 1573 <pre class="PROGRAMLISTING"> 1574 addch(ch | A_BOLD | A_UNDERLINE); 1575</pre> 1576 </li> 1577 1578 <li> 1579 <p>By using functions like <tt class= 1580 "LITERAL">attrset(),attron(),attroff()</tt>. These 1581 functions are explained in the <a href= 1582 "#ATTRIB">Attributes</a> section. Briefly, they 1583 manipulate the current attributes of the given window. 1584 Once set, the character printed in the window are 1585 associated with the attributes until it is turned 1586 off.</p> 1587 </li> 1588 </ul> 1589 1590 <p>Additionally, <tt class="LITERAL">curses</tt> provides 1591 some special characters for character-based graphics. You 1592 can draw tables, horizontal or vertical lines, etc. You can 1593 find all avaliable characters in the header file <tt class= 1594 "LITERAL">ncurses.h</tt>. Try looking for macros beginning 1595 with <tt class="LITERAL">ACS_</tt> in this file.</p> 1596 </div> 1597 1598 <div class="SECT2"> 1599 <hr> 1600 1601 <h3 class="SECT2"><a name="AEN298" id="AEN298">6.2. 1602 mvaddch(), waddch() and mvwaddch()</a></h3> 1603 1604 <p><tt class="LITERAL">mvaddch()</tt> is used to move the 1605 cursor to a given point, and then print. Thus, the 1606 calls:</p> 1607 <pre class="PROGRAMLISTING"> 1608 move(row,col); /* moves the cursor to row<span class= 1609"emphasis"><i class= 1610"EMPHASIS">th</i></span> row and col<span class="emphasis"><i class="EMPHASIS">th</i></span> column */ 1611 addch(ch); 1612</pre>can be replaced by 1613 <pre class="PROGRAMLISTING"> 1614 mvaddch(row,col,ch); 1615</pre> 1616 1617 <p><tt class="LITERAL">waddch()</tt> is similar to 1618 <tt class="LITERAL">addch()</tt>, except that it adds a 1619 character into the given window. (Note that <tt class= 1620 "LITERAL">addch()</tt> adds a character into the window 1621 <tt class="LITERAL">stdscr</tt>.)</p> 1622 1623 <p>In a similar fashion <tt class="LITERAL">mvwaddch()</tt> 1624 function is used to add a character into the given window 1625 at the given coordinates.</p> 1626 1627 <p>Now, we are familiar with the basic output function 1628 <tt class="LITERAL">addch()</tt>. But, if we want to print 1629 a string, it would be very annoying to print it character 1630 by character. Fortunately, <tt class="LITERAL">ncurses</tt> 1631 provides <tt class="LITERAL">printf</tt><span class= 1632 "emphasis"><i class="EMPHASIS">-like</i></span> or 1633 <tt class="LITERAL">puts</tt><span class= 1634 "emphasis"><i class="EMPHASIS">-like</i></span> 1635 functions.</p> 1636 </div> 1637 1638 <div class="SECT2"> 1639 <hr> 1640 1641 <h3 class="SECT2"><a name="PRINTWCLASS" id= 1642 "PRINTWCLASS">6.3. printw() class of functions</a></h3> 1643 1644 <p>These functions are similar to <tt class= 1645 "LITERAL">printf()</tt> with the added capability of 1646 printing at any position on the screen.</p> 1647 1648 <div class="SECT3"> 1649 <hr> 1650 1651 <h4 class="SECT3"><a name="PRINTWMVPRINTW" id= 1652 "PRINTWMVPRINTW">6.3.1. printw() and mvprintw</a></h4> 1653 1654 <p>These two functions work much like <tt class= 1655 "LITERAL">printf()</tt>. <tt class= 1656 "LITERAL">mvprintw()</tt> can be used to move the cursor 1657 to a position and then print. If you want to move the 1658 cursor first and then print using <tt class= 1659 "LITERAL">printw()</tt> function, use <tt class= 1660 "LITERAL">move()</tt> first and then use <tt class= 1661 "LITERAL">printw()</tt> though I see no point why one 1662 should avoid using <tt class="LITERAL">mvprintw()</tt>, 1663 you have the flexibility to manipulate.</p> 1664 </div> 1665 1666 <div class="SECT3"> 1667 <hr> 1668 1669 <h4 class="SECT3"><a name="WPRINTWMVWPRINTW" id= 1670 "WPRINTWMVWPRINTW">6.3.2. wprintw() and 1671 mvwprintw</a></h4> 1672 1673 <p>These two functions are similar to above two except 1674 that they print in the corresponding window given as 1675 argument.</p> 1676 </div> 1677 1678 <div class="SECT3"> 1679 <hr> 1680 1681 <h4 class="SECT3"><a name="VWPRINTW" id="VWPRINTW">6.3.3. 1682 vw_printw()</a></h4> 1683 1684 <p>This function is similar to <tt class= 1685 "LITERAL">vprintf()</tt>. This can be used when variable 1686 number of arguments are to be printed.</p> 1687 </div> 1688 1689 <div class="SECT3"> 1690 <hr> 1691 1692 <h4 class="SECT3"><a name="SIMPLEPRINTWEX" id= 1693 "SIMPLEPRINTWEX">6.3.4. A Simple printw example</a></h4> 1694 1695 <div class="EXAMPLE"> 1696 <a name="BPREX" id="BPREX"></a> 1697 1698 <p><b>Example 3. A Simple printw example</b></p> 1699 <pre class="PROGRAMLISTING"> 1700<span class= 1701"INLINEMEDIAOBJECT">#include <ncurses.h> /* ncurses.h includes stdio.h */ 1702#include <string.h> 1703 1704int main() 1705{ 1706 char mesg[]="Just a string"; /* message to be appeared on the screen */ 1707 int row,col; /* to store the number of rows and * 1708 * the number of colums of the screen */ 1709 initscr(); /* start the curses mode */ 1710 getmaxyx(stdscr,row,col); /* get the number of rows and columns */ 1711 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg); 1712 /* print the message at the center of the screen */ 1713 mvprintw(row-2,0,"This screen has %d rows and %d columns\n",row,col); 1714 printw("Try resizing your window(if possible) and then run this program again"); 1715 refresh(); 1716 getch(); 1717 endwin(); 1718 1719 return 0; 1720}</span> 1721</pre> 1722 </div> 1723 1724 <p>Above program demonstrates how easy it is to use 1725 <tt class="LITERAL">printw</tt>. You just feed the 1726 coordinates and the message to be appeared on the screen, 1727 then it does what you want.</p> 1728 1729 <p>The above program introduces us to a new function 1730 <tt class="LITERAL">getmaxyx()</tt>, a macro defined in 1731 <tt class="LITERAL">ncurses.h</tt>. It gives the number 1732 of columns and the number of rows in a given window. 1733 <tt class="LITERAL">getmaxyx()</tt> does this by updating 1734 the variables given to it. Since <tt class= 1735 "LITERAL">getmaxyx()</tt> is not a function we don't pass 1736 pointers to it, we just give two integer variables.</p> 1737 </div> 1738 </div> 1739 1740 <div class="SECT2"> 1741 <hr> 1742 1743 <h3 class="SECT2"><a name="ADDSTRCLASS" id= 1744 "ADDSTRCLASS">6.4. addstr() class of functions</a></h3> 1745 1746 <p><tt class="LITERAL">addstr()</tt> is used to put a 1747 character string into a given window. This function is 1748 similar to calling <tt class="LITERAL">addch()</tt> once 1749 for each character in a given string. This is true for all 1750 output functions. There are other functions from this 1751 family such as <tt class= 1752 "LITERAL">mvaddstr(),mvwaddstr()</tt> and <tt class= 1753 "LITERAL">waddstr()</tt>, which obey the naming convention 1754 of curses.(e.g. mvaddstr() is similar to the respective 1755 calls move() and then addstr().) Another function of this 1756 family is addnstr(), which takes an integer parameter(say 1757 n) additionally. This function puts at most n characters 1758 into the screen. If n is negative, then the entire string 1759 will be added.</p> 1760 </div> 1761 1762 <div class="SECT2"> 1763 <hr> 1764 1765 <h3 class="SECT2"><a name="ACAUTION" id="ACAUTION">6.5. A 1766 word of caution</a></h3> 1767 1768 <p>All these functions take y co-ordinate first and then x 1769 in their arguments. A common mistake by beginners is to 1770 pass x,y in that order. If you are doing too many 1771 manipulations of (y,x) co-ordinates, think of dividing the 1772 screen into windows and manipulate each one separately. 1773 Windows are explained in the <a href="#WINDOWS">windows</a> 1774 section.</p> 1775 </div> 1776 </div> 1777 1778 <div class="SECT1"> 1779 <hr> 1780 1781 <h2 class="SECT1"><a name="SCANW" id="SCANW">7. Input 1782 functions</a></h2> 1783 1784 <p>Well, printing without taking input, is boring. Let's see 1785 functions which allow us to get input from user. These 1786 functions also can be divided into three categories.</p> 1787 1788 <ol type="1"> 1789 <li> 1790 <p>getch() class: Get a character</p> 1791 </li> 1792 1793 <li> 1794 <p>scanw() class: Get formatted input</p> 1795 </li> 1796 1797 <li> 1798 <p>getstr() class: Get strings</p> 1799 </li> 1800 </ol> 1801 1802 <div class="SECT2"> 1803 <hr> 1804 1805 <h3 class="SECT2"><a name="GETCHCLASS" id="GETCHCLASS">7.1. 1806 getch() class of functions</a></h3> 1807 1808 <p>These functions read a single character from the 1809 terminal. But there are several subtle facts to consider. 1810 For example if you don't use the function cbreak(), curses 1811 will not read your input characters contiguously but will 1812 begin read them only after a new line or an EOF is 1813 encountered. In order to avoid this, the cbreak() function 1814 must used so that characters are immediately available to 1815 your program. Another widely used function is noecho(). As 1816 the name suggests, when this function is set (used), the 1817 characters that are keyed in by the user will not show up 1818 on the screen. The two functions cbreak() and noecho() are 1819 typical examples of key management. Functions of this genre 1820 are explained in the <a href="#KEYS">key management 1821 section</a> .</p> 1822 </div> 1823 1824 <div class="SECT2"> 1825 <hr> 1826 1827 <h3 class="SECT2"><a name="SCANWCLASS" id="SCANWCLASS">7.2. 1828 scanw() class of functions</a></h3> 1829 1830 <p>These functions are similar to <tt class= 1831 "LITERAL">scanf()</tt> with the added capability of getting 1832 the input from any location on the screen.</p> 1833 1834 <div class="SECT3"> 1835 <hr> 1836 1837 <h4 class="SECT3"><a name="SCANWMVSCANW" id= 1838 "SCANWMVSCANW">7.2.1. scanw() and mvscanw</a></h4> 1839 1840 <p>The usage of these functions is similar to that of 1841 <tt class="LITERAL">sscanf()</tt>, where the line to be 1842 scanned is provided by <tt class="LITERAL">wgetstr()</tt> 1843 function. That is, these functions call to <tt class= 1844 "LITERAL">wgetstr()</tt> function(explained below) and 1845 uses the resulting line for a scan.</p> 1846 </div> 1847 1848 <div class="SECT3"> 1849 <hr> 1850 1851 <h4 class="SECT3"><a name="WSCANWMVWSCANW" id= 1852 "WSCANWMVWSCANW">7.2.2. wscanw() and mvwscanw()</a></h4> 1853 1854 <p>These are similar to above two functions except that 1855 they read from a window, which is supplied as one of the 1856 arguments to these functions.</p> 1857 </div> 1858 1859 <div class="SECT3"> 1860 <hr> 1861 1862 <h4 class="SECT3"><a name="VWSCANW" id="VWSCANW">7.2.3. 1863 vw_scanw()</a></h4> 1864 1865 <p>This function is similar to <tt class= 1866 "LITERAL">vscanf()</tt>. This can be used when a variable 1867 number of arguments are to be scanned.</p> 1868 </div> 1869 </div> 1870 1871 <div class="SECT2"> 1872 <hr> 1873 1874 <h3 class="SECT2"><a name="GETSTRCLASS" id= 1875 "GETSTRCLASS">7.3. getstr() class of functions</a></h3> 1876 1877 <p>These functions are used to get strings from the 1878 terminal. In essence, this function performs the same task 1879 as would be achieved by a series of calls to <tt class= 1880 "LITERAL">getch()</tt> until a newline, carriage return, or 1881 end-of-file is received. The resulting string of characters 1882 are pointed to by <tt class="LITERAL">str</tt>, which is a 1883 character pointer provided by the user.</p> 1884 </div> 1885 1886 <div class="SECT2"> 1887 <hr> 1888 1889 <h3 class="SECT2"><a name="GETSTREX" id="GETSTREX">7.4. 1890 Some examples</a></h3> 1891 1892 <div class="EXAMPLE"> 1893 <a name="BSCEX" id="BSCEX"></a> 1894 1895 <p><b>Example 4. A Simple scanw example</b></p> 1896 <pre class="PROGRAMLISTING"> 1897<span class= 1898"INLINEMEDIAOBJECT">#include <ncurses.h> /* ncurses.h includes stdio.h */ 1899#include <string.h> 1900 1901int main() 1902{ 1903 char mesg[]="Enter a string: "; /* message to be appeared on the screen */ 1904 char str[80]; 1905 int row,col; /* to store the number of rows and * 1906 * the number of colums of the screen */ 1907 initscr(); /* start the curses mode */ 1908 getmaxyx(stdscr,row,col); /* get the number of rows and columns */ 1909 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg); 1910 /* print the message at the center of the screen */ 1911 getstr(str); 1912 mvprintw(LINES - 2, 0, "You Entered: %s", str); 1913 getch(); 1914 endwin(); 1915 1916 return 0; 1917}</span> 1918</pre> 1919 </div> 1920 </div> 1921 </div> 1922 1923 <div class="SECT1"> 1924 <hr> 1925 1926 <h2 class="SECT1"><a name="ATTRIB" id="ATTRIB">8. 1927 Attributes</a></h2> 1928 1929 <p>We have seen an example of how attributes can be used to 1930 print characters with some special effects. Attributes, when 1931 set prudently, can present information in an easy, 1932 understandable manner. The following program takes a C file 1933 as input and prints the file with comments in bold. Scan 1934 through the code.</p> 1935 1936 <div class="EXAMPLE"> 1937 <a name="BSIAT" id="BSIAT"></a> 1938 1939 <p><b>Example 5. A Simple Attributes example</b></p> 1940 <pre class="PROGRAMLISTING"> 1941<span class= 1942"INLINEMEDIAOBJECT">/* pager functionality by Joseph Spainhour" <spainhou@bellsouth.net> */ 1943#include <ncurses.h> 1944#include <stdlib.h> 1945 1946int main(int argc, char *argv[]) 1947{ 1948 int ch, prev, row, col; 1949 prev = EOF; 1950 FILE *fp; 1951 int y, x; 1952 1953 if(argc != 2) 1954 { 1955 printf("Usage: %s <a c file name>\n", argv[0]); 1956 exit(1); 1957 } 1958 fp = fopen(argv[1], "r"); 1959 if(fp == NULL) 1960 { 1961 perror("Cannot open input file"); 1962 exit(1); 1963 } 1964 initscr(); /* Start curses mode */ 1965 getmaxyx(stdscr, row, col); /* find the boundaries of the screeen */ 1966 while((ch = fgetc(fp)) != EOF) /* read the file till we reach the end */ 1967 { 1968 getyx(stdscr, y, x); /* get the current curser position */ 1969 if(y == (row - 1)) /* are we are at the end of the screen */ 1970 { 1971 printw("<-Press Any Key->"); /* tell the user to press a key */ 1972 getch(); 1973 clear(); /* clear the screen */ 1974 move(0, 0); /* start at the beginning of the screen */ 1975 } 1976 if(prev == '/' && ch == '*') /* If it is / and * then only 1977 * switch bold on */ 1978 { 1979 attron(A_BOLD); /* cut bold on */ 1980 getyx(stdscr, y, x); /* get the current curser position */ 1981 move(y, x - 1); /* back up one space */ 1982 printw("%c%c", '/', ch); /* The actual printing is done here */ 1983 } 1984 else 1985 printw("%c", ch); 1986 refresh(); 1987 if(prev == '*' && ch == '/') 1988 attroff(A_BOLD); /* Switch it off once we got * 1989 * and then / */ 1990 prev = ch; 1991 } 1992 endwin(); /* End curses mode */ 1993 fclose(fp); 1994 return 0; 1995}</span> 1996</pre> 1997 </div> 1998 1999 <p>Don't worry about all those initialization and other crap. 2000 Concentrate on the while loop. It reads each character in the 2001 file and searches for the pattern /*. Once it spots the 2002 pattern, it switches the BOLD attribute on with <tt class= 2003 "LITERAL">attron()</tt> . When we get the pattern */ it is 2004 switched off by <tt class="LITERAL">attroff()</tt> .</p> 2005 2006 <p>The above program also introduces us to two useful 2007 functions <tt class="LITERAL">getyx()</tt> and <tt class= 2008 "LITERAL">move()</tt>. The first function gets the 2009 co-ordinates of the present cursor into the variables y, x. 2010 Since getyx() is a macro we don't have to pass pointers to 2011 variables. The function <tt class="LITERAL">move()</tt> moves 2012 the cursor to the co-ordinates given to it.</p> 2013 2014 <p>The above program is really a simple one which doesn't do 2015 much. On these lines one could write a more useful program 2016 which reads a C file, parses it and prints it in different 2017 colors. One could even extend it to other languages as 2018 well.</p> 2019 2020 <div class="SECT2"> 2021 <hr> 2022 2023 <h3 class="SECT2"><a name="ATTRIBDETAILS" id= 2024 "ATTRIBDETAILS">8.1. The details</a></h3> 2025 2026 <p>Let's get into more details of attributes. The functions 2027 <tt class="LITERAL">attron(), attroff(), attrset()</tt> , 2028 and their sister functions <tt class= 2029 "LITERAL">attr_get()</tt> etc.. can be used to switch 2030 attributes on/off , get attributes and produce a colorful 2031 display.</p> 2032 2033 <p>The functions attron and attroff take a bit-mask of 2034 attributes and switch them on or off, respectively. The 2035 following video attributes, which are defined in 2036 <curses.h> can be passed to these functions.</p> 2037 <pre class="PROGRAMLISTING"> 2038 2039 A_NORMAL Normal display (no highlight) 2040 A_STANDOUT Best highlighting mode of the terminal. 2041 A_UNDERLINE Underlining 2042 A_REVERSE Reverse video 2043 A_BLINK Blinking 2044 A_DIM Half bright 2045 A_BOLD Extra bright or bold 2046 A_PROTECT Protected mode 2047 A_INVIS Invisible or blank mode 2048 A_ALTCHARSET Alternate character set 2049 A_CHARTEXT Bit-mask to extract a character 2050 COLOR_PAIR(n) Color-pair number n 2051 2052</pre> 2053 2054 <p>The last one is the most colorful one :-) Colors are 2055 explained in the <a href="#color" target="_top">next 2056 sections</a>.</p> 2057 2058 <p>We can OR(|) any number of above attributes to get a 2059 combined effect. If you wanted reverse video with blinking 2060 characters you can use</p> 2061 <pre class="PROGRAMLISTING"> 2062 attron(A_REVERSE | A_BLINK); 2063</pre> 2064 </div> 2065 2066 <div class="SECT2"> 2067 <hr> 2068 2069 <h3 class="SECT2"><a name="ATTRONVSATTRSET" id= 2070 "ATTRONVSATTRSET">8.2. attron() vs attrset()</a></h3> 2071 2072 <p>Then what is the difference between attron() and 2073 attrset()? attrset sets the attributes of window whereas 2074 attron just switches on the attribute given to it. So 2075 attrset() fully overrides whatever attributes the window 2076 previously had and sets it to the new attribute(s). 2077 Similarly attroff() just switches off the attribute(s) 2078 given to it as an argument. This gives us the flexibility 2079 of managing attributes easily.But if you use them 2080 carelessly you may loose track of what attributes the 2081 window has and garble the display. This is especially true 2082 while managing menus with colors and highlighting. So 2083 decide on a consistent policy and stick to it. You can 2084 always use <tt class="LITERAL">standend()</tt> which is 2085 equivalent to <tt class="LITERAL">attrset(A_NORMAL)</tt> 2086 which turns off all attributes and brings you to normal 2087 mode.</p> 2088 </div> 2089 2090 <div class="SECT2"> 2091 <hr> 2092 2093 <h3 class="SECT2"><a name="ATTRGET" id="ATTRGET">8.3. 2094 attr_get()</a></h3> 2095 2096 <p>The function attr_get() gets the current attributes and 2097 color pair of the window. Though we might not use this as 2098 often as the above functions, this is useful in scanning 2099 areas of screen. Say we wanted to do some complex update on 2100 screen and we are not sure what attribute each character is 2101 associated with. Then this function can be used with either 2102 attrset or attron to produce the desired effect.</p> 2103 </div> 2104 2105 <div class="SECT2"> 2106 <hr> 2107 2108 <h3 class="SECT2"><a name="ATTRFUNCS" id="ATTRFUNCS">8.4. 2109 attr_ functions</a></h3> 2110 2111 <p>There are series of functions like attr_set(), attr_on 2112 etc.. These are similar to above functions except that they 2113 take parameters of type <tt class= 2114 "LITERAL">attr_t</tt>.</p> 2115 </div> 2116 2117 <div class="SECT2"> 2118 <hr> 2119 2120 <h3 class="SECT2"><a name="WATTRFUNCS" id="WATTRFUNCS">8.5. 2121 wattr functions</a></h3> 2122 2123 <p>For each of the above functions we have a corresponding 2124 function with 'w' which operates on a particular window. 2125 The above functions operate on stdscr.</p> 2126 </div> 2127 2128 <div class="SECT2"> 2129 <hr> 2130 2131 <h3 class="SECT2"><a name="CHGAT" id="CHGAT">8.6. chgat() 2132 functions</a></h3> 2133 2134 <p>The function chgat() is listed in the end of the man 2135 page curs_attr. It actually is a useful one. This function 2136 can be used to set attributes for a group of characters 2137 without moving. I mean it !!! without moving the cursor :-) 2138 It changes the attributes of a given number of characters 2139 starting at the current cursor location.</p> 2140 2141 <p>We can give -1 as the character count to update till end 2142 of line. If you want to change attributes of characters 2143 from current position to end of line, just use this.</p> 2144 <pre class="PROGRAMLISTING"> 2145 chgat(-1, A_REVERSE, 0, NULL); 2146</pre> 2147 2148 <p>This function is useful when changing attributes for 2149 characters that are already on the screen. Move to the 2150 character from which you want to change and change the 2151 attribute.</p> 2152 2153 <p>Other functions wchgat(), mvchgat(), wchgat() behave 2154 similarly except that the w functions operate on the 2155 particular window. The mv functions first move the cursor 2156 then perform the work given to them. Actually chgat is a 2157 macro which is replaced by a wchgat() with stdscr as the 2158 window. Most of the "w-less" functions are macros.</p> 2159 2160 <div class="EXAMPLE"> 2161 <a name="BWICH" id="BWICH"></a> 2162 2163 <p><b>Example 6. Chgat() Usage example</b></p> 2164 <pre class="PROGRAMLISTING"> 2165<span class="INLINEMEDIAOBJECT">#include <ncurses.h> 2166 2167int main(int argc, char *argv[]) 2168{ initscr(); /* Start curses mode */ 2169 start_color(); /* Start color functionality */ 2170 2171 init_pair(1, COLOR_CYAN, COLOR_BLACK); 2172 printw("A Big string which i didn't care to type fully "); 2173 mvchgat(0, 0, -1, A_BLINK, 1, NULL); 2174 /* 2175 * First two parameters specify the position at which to start 2176 * Third parameter number of characters to update. -1 means till 2177 * end of line 2178 * Forth parameter is the normal attribute you wanted to give 2179 * to the charcter 2180 * Fifth is the color index. It is the index given during init_pair() 2181 * use 0 if you didn't want color 2182 * Sixth one is always NULL 2183 */ 2184 refresh(); 2185 getch(); 2186 endwin(); /* End curses mode */ 2187 return 0; 2188}</span> 2189</pre> 2190 </div> 2191 2192 <p>This example also introduces us to the color world of 2193 curses. Colors will be explained in detail later. Use 0 for 2194 no color.</p> 2195 </div> 2196 </div> 2197 2198 <div class="SECT1"> 2199 <hr> 2200 2201 <h2 class="SECT1"><a name="WINDOWS" id="WINDOWS">9. 2202 Windows</a></h2> 2203 2204 <p>Windows form the most important concept in curses. You 2205 have seen the standard window stdscr above where all the 2206 functions implicitly operated on this window. Now to make 2207 design even a simplest GUI, you need to resort to windows. 2208 The main reason you may want to use windows is to manipulate 2209 parts of the screen separately, for better efficiency, by 2210 updating only the windows that need to be changed and for a 2211 better design. I would say the last reason is the most 2212 important in going for windows. You should always strive for 2213 a better and easy-to-manage design in your programs. If you 2214 are writing big, complex GUIs this is of pivotal importance 2215 before you start doing anything.</p> 2216 2217 <div class="SECT2"> 2218 <hr> 2219 2220 <h3 class="SECT2"><a name="WINDOWBASICS" id= 2221 "WINDOWBASICS">9.1. The basics</a></h3> 2222 2223 <p>A Window can be created by calling the function 2224 <tt class="LITERAL">newwin()</tt>. It doesn't create any 2225 thing on the screen actually. It allocates memory for a 2226 structure to manipulate the window and updates the 2227 structure with data regarding the window like it's size, 2228 beginy, beginx etc.. Hence in curses, a window is just an 2229 abstraction of an imaginary window, which can be 2230 manipulated independent of other parts of screen. The 2231 function newwin() returns a pointer to structure WINDOW, 2232 which can be passed to window related functions like 2233 wprintw() etc.. Finally the window can be destroyed with 2234 delwin(). It will deallocate the memory associated with the 2235 window structure.</p> 2236 </div> 2237 2238 <div class="SECT2"> 2239 <hr> 2240 2241 <h3 class="SECT2"><a name="LETBEWINDOW" id= 2242 "LETBEWINDOW">9.2. Let there be a Window !!!</a></h3> 2243 2244 <p>What fun is it, if a window is created and we can't see 2245 it. So the fun part begins by displaying the window. The 2246 function <tt class="LITERAL">box()</tt> can be used to draw 2247 a border around the window. Let's explore these functions 2248 in more detail in this example.</p> 2249 2250 <div class="EXAMPLE"> 2251 <a name="BWIBO" id="BWIBO"></a> 2252 2253 <p><b>Example 7. Window Border example</b></p> 2254 <pre class="PROGRAMLISTING"> 2255<span class="INLINEMEDIAOBJECT">#include <ncurses.h> 2256 2257 2258WINDOW *create_newwin(int height, int width, int starty, int startx); 2259void destroy_win(WINDOW *local_win); 2260 2261int main(int argc, char *argv[]) 2262{ WINDOW *my_win; 2263 int startx, starty, width, height; 2264 int ch; 2265 2266 initscr(); /* Start curses mode */ 2267 cbreak(); /* Line buffering disabled, Pass on 2268 * everty thing to me */ 2269 keypad(stdscr, TRUE); /* I need that nifty F1 */ 2270 2271 height = 3; 2272 width = 10; 2273 starty = (LINES - height) / 2; /* Calculating for a center placement */ 2274 startx = (COLS - width) / 2; /* of the window */ 2275 printw("Press F1 to exit"); 2276 refresh(); 2277 my_win = create_newwin(height, width, starty, startx); 2278 2279 while((ch = getch()) != KEY_F(1)) 2280 { switch(ch) 2281 { case KEY_LEFT: 2282 destroy_win(my_win); 2283 my_win = create_newwin(height, width, starty,--startx); 2284 break; 2285 case KEY_RIGHT: 2286 destroy_win(my_win); 2287 my_win = create_newwin(height, width, starty,++startx); 2288 break; 2289 case KEY_UP: 2290 destroy_win(my_win); 2291 my_win = create_newwin(height, width, --starty,startx); 2292 break; 2293 case KEY_DOWN: 2294 destroy_win(my_win); 2295 my_win = create_newwin(height, width, ++starty,startx); 2296 break; 2297 } 2298 } 2299 2300 endwin(); /* End curses mode */ 2301 return 0; 2302} 2303 2304WINDOW *create_newwin(int height, int width, int starty, int startx) 2305{ WINDOW *local_win; 2306 2307 local_win = newwin(height, width, starty, startx); 2308 box(local_win, 0 , 0); /* 0, 0 gives default characters 2309 * for the vertical and horizontal 2310 * lines */ 2311 wrefresh(local_win); /* Show that box */ 2312 2313 return local_win; 2314} 2315 2316void destroy_win(WINDOW *local_win) 2317{ 2318 /* box(local_win, ' ', ' '); : This won't produce the desired 2319 * result of erasing the window. It will leave it's four corners 2320 * and so an ugly remnant of window. 2321 */ 2322 wborder(local_win, ' ', ' ', ' ',' ',' ',' ',' ',' '); 2323 /* The parameters taken are 2324 * 1. win: the window on which to operate 2325 * 2. ls: character to be used for the left side of the window 2326 * 3. rs: character to be used for the right side of the window 2327 * 4. ts: character to be used for the top side of the window 2328 * 5. bs: character to be used for the bottom side of the window 2329 * 6. tl: character to be used for the top left corner of the window 2330 * 7. tr: character to be used for the top right corner of the window 2331 * 8. bl: character to be used for the bottom left corner of the window 2332 * 9. br: character to be used for the bottom right corner of the window 2333 */ 2334 wrefresh(local_win); 2335 delwin(local_win); 2336}</span> 2337</pre> 2338 </div> 2339 </div> 2340 2341 <div class="SECT2"> 2342 <hr> 2343 2344 <h3 class="SECT2"><a name="BORDEREXEXPL" id= 2345 "BORDEREXEXPL">9.3. Explanation</a></h3> 2346 2347 <p>Don't scream. I know it's a big example. But I have to 2348 explain some important things here :-). This program 2349 creates a rectangular window that can be moved with left, 2350 right, up, down arrow keys. It repeatedly creates and 2351 destroys windows as user press a key. Don't go beyond the 2352 screen limits. Checking for those limits is left as an 2353 exercise for the reader. Let's dissect it by line by 2354 line.</p> 2355 2356 <p>The <tt class="LITERAL">create_newwin()</tt> function 2357 creates a window with <tt class="LITERAL">newwin()</tt> and 2358 displays a border around it with box. The function 2359 <tt class="LITERAL">destroy_win()</tt> first erases the 2360 window from screen by painting a border with ' ' character 2361 and then calling <tt class="LITERAL">delwin()</tt> to 2362 deallocate memory related to it. Depending on the key the 2363 user presses, starty or startx is changed and a new window 2364 is created.</p> 2365 2366 <p>In the destroy_win, as you can see, I used wborder 2367 instead of box. The reason is written in the comments (You 2368 missed it. I know. Read the code :-)). wborder draws a 2369 border around the window with the characters given to it as 2370 the 4 corner points and the 4 lines. To put it clearly, if 2371 you have called wborder as below:</p> 2372 <pre class="PROGRAMLISTING"> 2373 wborder(win, '|', '|', '-', '-', '+', '+', '+', '+'); 2374</pre> 2375 2376 <p>it produces some thing like</p> 2377 <pre class="PROGRAMLISTING"> 2378 +------------+ 2379 | | 2380 | | 2381 | | 2382 | | 2383 | | 2384 | | 2385 +------------+ 2386</pre> 2387 </div> 2388 2389 <div class="SECT2"> 2390 <hr> 2391 2392 <h3 class="SECT2"><a name="OTHERSTUFF" id="OTHERSTUFF">9.4. 2393 The other stuff in the example</a></h3> 2394 2395 <p>You can also see in the above examples, that I have used 2396 the variables COLS, LINES which are initialized to the 2397 screen sizes after initscr(). They can be useful in finding 2398 screen dimensions and finding the center co-ordinate of the 2399 screen as above. The function <tt class= 2400 "LITERAL">getch()</tt> as usual gets the key from keyboard 2401 and according to the key it does the corresponding work. 2402 This type of switch- case is very common in any GUI based 2403 programs.</p> 2404 </div> 2405 2406 <div class="SECT2"> 2407 <hr> 2408 2409 <h3 class="SECT2"><a name="OTHERBORDERFUNCS" id= 2410 "OTHERBORDERFUNCS">9.5. Other Border functions</a></h3> 2411 2412 <p>Above program is grossly inefficient in that with each 2413 press of a key, a window is destroyed and another is 2414 created. So let's write a more efficient program which uses 2415 other border related functions.</p> 2416 2417 <p>The following program uses <tt class= 2418 "LITERAL">mvhline()</tt> and <tt class= 2419 "LITERAL">mvvline()</tt> to achieve similar effect. These 2420 two functions are simple. They create a horizontal or 2421 vertical line of the specified length at the specified 2422 position.</p> 2423 2424 <div class="EXAMPLE"> 2425 <a name="BOTBO" id="BOTBO"></a> 2426 2427 <p><b>Example 8. More border functions</b></p> 2428 <pre class="PROGRAMLISTING"> 2429<span class="INLINEMEDIAOBJECT">#include <ncurses.h> 2430 2431typedef struct _win_border_struct { 2432 chtype ls, rs, ts, bs, 2433 tl, tr, bl, br; 2434}WIN_BORDER; 2435 2436typedef struct _WIN_struct { 2437 2438 int startx, starty; 2439 int height, width; 2440 WIN_BORDER border; 2441}WIN; 2442 2443void init_win_params(WIN *p_win); 2444void print_win_params(WIN *p_win); 2445void create_box(WIN *win, bool flag); 2446 2447int main(int argc, char *argv[]) 2448{ WIN win; 2449 int ch; 2450 2451 initscr(); /* Start curses mode */ 2452 start_color(); /* Start the color functionality */ 2453 cbreak(); /* Line buffering disabled, Pass on 2454 * everty thing to me */ 2455 keypad(stdscr, TRUE); /* I need that nifty F1 */ 2456 noecho(); 2457 init_pair(1, COLOR_CYAN, COLOR_BLACK); 2458 2459 /* Initialize the window parameters */ 2460 init_win_params(&win); 2461 print_win_params(&win); 2462 2463 attron(COLOR_PAIR(1)); 2464 printw("Press F1 to exit"); 2465 refresh(); 2466 attroff(COLOR_PAIR(1)); 2467 2468 create_box(&win, TRUE); 2469 while((ch = getch()) != KEY_F(1)) 2470 { switch(ch) 2471 { case KEY_LEFT: 2472 create_box(&win, FALSE); 2473 --win.startx; 2474 create_box(&win, TRUE); 2475 break; 2476 case KEY_RIGHT: 2477 create_box(&win, FALSE); 2478 ++win.startx; 2479 create_box(&win, TRUE); 2480 break; 2481 case KEY_UP: 2482 create_box(&win, FALSE); 2483 --win.starty; 2484 create_box(&win, TRUE); 2485 break; 2486 case KEY_DOWN: 2487 create_box(&win, FALSE); 2488 ++win.starty; 2489 create_box(&win, TRUE); 2490 break; 2491 } 2492 } 2493 endwin(); /* End curses mode */ 2494 return 0; 2495} 2496void init_win_params(WIN *p_win) 2497{ 2498 p_win->height = 3; 2499 p_win->width = 10; 2500 p_win->starty = (LINES - p_win->height)/2; 2501 p_win->startx = (COLS - p_win->width)/2; 2502 2503 p_win->border.ls = '|'; 2504 p_win->border.rs = '|'; 2505 p_win->border.ts = '-'; 2506 p_win->border.bs = '-'; 2507 p_win->border.tl = '+'; 2508 p_win->border.tr = '+'; 2509 p_win->border.bl = '+'; 2510 p_win->border.br = '+'; 2511 2512} 2513void print_win_params(WIN *p_win) 2514{ 2515#ifdef _DEBUG 2516 mvprintw(25, 0, "%d %d %d %d", p_win->startx, p_win->starty, 2517 p_win->width, p_win->height); 2518 refresh(); 2519#endif 2520} 2521void create_box(WIN *p_win, bool flag) 2522{ int i, j; 2523 int x, y, w, h; 2524 2525 x = p_win->startx; 2526 y = p_win->starty; 2527 w = p_win->width; 2528 h = p_win->height; 2529 2530 if(flag == TRUE) 2531 { mvaddch(y, x, p_win->border.tl); 2532 mvaddch(y, x + w, p_win->border.tr); 2533 mvaddch(y + h, x, p_win->border.bl); 2534 mvaddch(y + h, x + w, p_win->border.br); 2535 mvhline(y, x + 1, p_win->border.ts, w - 1); 2536 mvhline(y + h, x + 1, p_win->border.bs, w - 1); 2537 mvvline(y + 1, x, p_win->border.ls, h - 1); 2538 mvvline(y + 1, x + w, p_win->border.rs, h - 1); 2539 2540 } 2541 else 2542 for(j = y; j <= y + h; ++j) 2543 for(i = x; i <= x + w; ++i) 2544 mvaddch(j, i, ' '); 2545 2546 refresh(); 2547 2548}</span> 2549</pre> 2550 </div> 2551 </div> 2552 </div> 2553 2554 <div class="SECT1"> 2555 <hr> 2556 2557 <h2 class="SECT1"><a name="COLOR" id="COLOR">10. 2558 Colors</a></h2> 2559 2560 <div class="SECT2"> 2561 <h3 class="SECT2"><a name="COLORBASICS" id= 2562 "COLORBASICS">10.1. The basics</a></h3> 2563 2564 <p>Life seems dull with no colors. Curses has a nice 2565 mechanism to handle colors. Let's get into the thick of the 2566 things with a small program.</p> 2567 2568 <div class="EXAMPLE"> 2569 <a name="BSICO" id="BSICO"></a> 2570 2571 <p><b>Example 9. A Simple Color example</b></p> 2572 <pre class="PROGRAMLISTING"> 2573<span class="INLINEMEDIAOBJECT">#include <ncurses.h> 2574 2575void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string); 2576int main(int argc, char *argv[]) 2577{ initscr(); /* Start curses mode */ 2578 if(has_colors() == FALSE) 2579 { endwin(); 2580 printf("Your terminal does not support color\n"); 2581 exit(1); 2582 } 2583 start_color(); /* Start color */ 2584 init_pair(1, COLOR_RED, COLOR_BLACK); 2585 2586 attron(COLOR_PAIR(1)); 2587 print_in_middle(stdscr, LINES / 2, 0, 0, "Viola !!! In color ..."); 2588 attroff(COLOR_PAIR(1)); 2589 getch(); 2590 endwin(); 2591} 2592void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string) 2593{ int length, x, y; 2594 float temp; 2595 2596 if(win == NULL) 2597 win = stdscr; 2598 getyx(win, y, x); 2599 if(startx != 0) 2600 x = startx; 2601 if(starty != 0) 2602 y = starty; 2603 if(width == 0) 2604 width = 80; 2605 2606 length = strlen(string); 2607 temp = (width - length)/ 2; 2608 x = startx + (int)temp; 2609 mvwprintw(win, y, x, "%s", string); 2610 refresh(); 2611} 2612</span> 2613</pre> 2614 </div> 2615 2616 <p>As you can see, to start using color, you should first 2617 call the function <tt class="LITERAL">start_color()</tt>. 2618 After that, you can use color capabilities of your 2619 terminals using various functions. To find out whether a 2620 terminal has color capabilities or not, you can use 2621 <tt class="LITERAL">has_colors()</tt> function, which 2622 returns FALSE if the terminal does not support color.</p> 2623 2624 <p>Curses initializes all the colors supported by terminal 2625 when start_color() is called. These can be accessed by the 2626 define constants like <tt class="LITERAL">COLOR_BLACK</tt> 2627 etc. Now to actually start using colors, you have to define 2628 pairs. Colors are always used in pairs. That means you have 2629 to use the function <tt class="LITERAL">init_pair()</tt> to 2630 define the foreground and background for the pair number 2631 you give. After that that pair number can be used as a 2632 normal attribute with <tt class= 2633 "LITERAL">COLOR_PAIR()</tt>function. This may seem to be 2634 cumbersome at first. But this elegant solution allows us to 2635 manage color pairs very easily. To appreciate it, you have 2636 to look into the the source code of "dialog", a utility for 2637 displaying dialog boxes from shell scripts. The developers 2638 have defined foreground and background combinations for all 2639 the colors they might need and initialized at the 2640 beginning. This makes it very easy to set attributes just 2641 by accessing a pair which we already have defined as a 2642 constant.</p> 2643 2644 <p>The following colors are defined in <tt class= 2645 "LITERAL">curses.h</tt>. You can use these as parameters 2646 for various color functions.</p> 2647 <pre class="PROGRAMLISTING"> 2648 COLOR_BLACK 0 2649 COLOR_RED 1 2650 COLOR_GREEN 2 2651 COLOR_YELLOW 3 2652 COLOR_BLUE 4 2653 COLOR_MAGENTA 5 2654 COLOR_CYAN 6 2655 COLOR_WHITE 7 2656</pre> 2657 </div> 2658 2659 <div class="SECT2"> 2660 <hr> 2661 2662 <h3 class="SECT2"><a name="CHANGECOLORDEFS" id= 2663 "CHANGECOLORDEFS">10.2. Changing Color Definitions</a></h3> 2664 2665 <p>The function <tt class="LITERAL">init_color()</tt>can be 2666 used to change the rgb values for the colors defined by 2667 curses initially. Say you wanted to lighten the intensity 2668 of red color by a minuscule. Then you can use this function 2669 as</p> 2670 <pre class="PROGRAMLISTING"> 2671 init_color(COLOR_RED, 700, 0, 0); 2672 /* param 1 : color name 2673 * param 2, 3, 4 : rgb content min = 0, max = 1000 */ 2674</pre> 2675 2676 <p>If your terminal cannot change the color definitions, 2677 the function returns ERR. The function <tt class= 2678 "LITERAL">can_change_color()</tt> can be used to find out 2679 whether the terminal has the capability of changing color 2680 content or not. The rgb content is scaled from 0 to 1000. 2681 Initially RED color is defined with content 1000(r), 0(g), 2682 0(b).</p> 2683 </div> 2684 2685 <div class="SECT2"> 2686 <hr> 2687 2688 <h3 class="SECT2"><a name="COLORCONTENT" id= 2689 "COLORCONTENT">10.3. Color Content</a></h3> 2690 2691 <p>The functions <tt class="LITERAL">color_content()</tt> 2692 and <tt class="LITERAL">pair_content()</tt> can be used to 2693 find the color content and foreground, background 2694 combination for the pair.</p> 2695 </div> 2696 </div> 2697 2698 <div class="SECT1"> 2699 <hr> 2700 2701 <h2 class="SECT1"><a name="KEYS" id="KEYS">11. Interfacing 2702 with the key board</a></h2> 2703 2704 <div class="SECT2"> 2705 <h3 class="SECT2"><a name="KEYSBASICS" id= 2706 "KEYSBASICS">11.1. The Basics</a></h3> 2707 2708 <p>No GUI is complete without a strong user interface and 2709 to interact with the user, a curses program should be 2710 sensitive to key presses or the mouse actions done by the 2711 user. Let's deal with the keys first.</p> 2712 2713 <p>As you have seen in almost all of the above examples, 2714 it's very easy to get key input from the user. A simple way 2715 of getting key presses is to use <tt class= 2716 "LITERAL">getch()</tt> function. The cbreak mode should be 2717 enabled to read keys when you are interested in reading 2718 individual key hits rather than complete lines of text 2719 (which usually end with a carriage return). keypad should 2720 be enabled to get the Functions keys, arrow keys etc. See 2721 the initialization section for details.</p> 2722 2723 <p><tt class="LITERAL">getch()</tt> returns an integer 2724 corresponding to the key pressed. If it is a normal 2725 character, the integer value will be equivalent to the 2726 character. Otherwise it returns a number which can be 2727 matched with the constants defined in <tt class= 2728 "LITERAL">curses.h</tt>. For example if the user presses 2729 F1, the integer returned is 265. This can be checked using 2730 the macro KEY_F() defined in curses.h. This makes reading 2731 keys portable and easy to manage.</p> 2732 2733 <p>For example, if you call getch() like this</p> 2734 <pre class="PROGRAMLISTING"> 2735 int ch; 2736 2737 ch = getch(); 2738</pre> 2739 2740 <p>getch() will wait for the user to press a key, (unless 2741 you specified a timeout) and when user presses a key, the 2742 corresponding integer is returned. Then you can check the 2743 value returned with the constants defined in curses.h to 2744 match against the keys you want.</p> 2745 2746 <p>The following code piece will do that job.</p> 2747 <pre class="PROGRAMLISTING"> 2748 if(ch == KEY_LEFT) 2749 printw("Left arrow is pressed\n"); 2750</pre> 2751 2752 <p>Let's write a small program which creates a menu which 2753 can be navigated by up and down arrows.</p> 2754 </div> 2755 2756 <div class="SECT2"> 2757 <hr> 2758 2759 <h3 class="SECT2"><a name="SIMPLEKEYEX" id= 2760 "SIMPLEKEYEX">11.2. A Simple Key Usage example</a></h3> 2761 2762 <div class="EXAMPLE"> 2763 <a name="BSIKE" id="BSIKE"></a> 2764 2765 <p><b>Example 10. A Simple Key Usage example</b></p> 2766 <pre class="PROGRAMLISTING"> 2767<span class="INLINEMEDIAOBJECT">#include <stdio.h> 2768#include <ncurses.h> 2769 2770#define WIDTH 30 2771#define HEIGHT 10 2772 2773int startx = 0; 2774int starty = 0; 2775 2776char *choices[] = { 2777 "Choice 1", 2778 "Choice 2", 2779 "Choice 3", 2780 "Choice 4", 2781 "Exit", 2782 }; 2783int n_choices = sizeof(choices) / sizeof(char *); 2784void print_menu(WINDOW *menu_win, int highlight); 2785 2786int main() 2787{ WINDOW *menu_win; 2788 int highlight = 1; 2789 int choice = 0; 2790 int c; 2791 2792 initscr(); 2793 clear(); 2794 noecho(); 2795 cbreak(); /* Line buffering disabled. pass on everything */ 2796 startx = (80 - WIDTH) / 2; 2797 starty = (24 - HEIGHT) / 2; 2798 2799 menu_win = newwin(HEIGHT, WIDTH, starty, startx); 2800 keypad(menu_win, TRUE); 2801 mvprintw(0, 0, "Use arrow keys to go up and down, Press enter to select a choice"); 2802 refresh(); 2803 print_menu(menu_win, highlight); 2804 while(1) 2805 { c = wgetch(menu_win); 2806 switch(c) 2807 { case KEY_UP: 2808 if(highlight == 1) 2809 highlight = n_choices; 2810 else 2811 --highlight; 2812 break; 2813 case KEY_DOWN: 2814 if(highlight == n_choices) 2815 highlight = 1; 2816 else 2817 ++highlight; 2818 break; 2819 case 10: 2820 choice = highlight; 2821 break; 2822 default: 2823 mvprintw(24, 0, "Charcter pressed is = %3d Hopefully it can be printed as '%c'", c, c); 2824 refresh(); 2825 break; 2826 } 2827 print_menu(menu_win, highlight); 2828 if(choice != 0) /* User did a choice come out of the infinite loop */ 2829 break; 2830 } 2831 mvprintw(23, 0, "You chose choice %d with choice string %s\n", choice, choices[choice - 1]); 2832 clrtoeol(); 2833 refresh(); 2834 endwin(); 2835 return 0; 2836} 2837 2838 2839void print_menu(WINDOW *menu_win, int highlight) 2840{ 2841 int x, y, i; 2842 2843 x = 2; 2844 y = 2; 2845 box(menu_win, 0, 0); 2846 for(i = 0; i < n_choices; ++i) 2847 { if(highlight == i + 1) /* High light the present choice */ 2848 { wattron(menu_win, A_REVERSE); 2849 mvwprintw(menu_win, y, x, "%s", choices[i]); 2850 wattroff(menu_win, A_REVERSE); 2851 } 2852 else 2853 mvwprintw(menu_win, y, x, "%s", choices[i]); 2854 ++y; 2855 } 2856 wrefresh(menu_win); 2857} 2858</span> 2859</pre> 2860 </div> 2861 </div> 2862 </div> 2863 2864 <div class="SECT1"> 2865 <hr> 2866 2867 <h2 class="SECT1"><a name="MOUSE" id="MOUSE">12. Interfacing 2868 with the mouse</a></h2> 2869 2870 <p>Now that you have seen how to get keys, lets do the same 2871 thing from mouse. Usually each UI allows the user to interact 2872 with both keyboard and mouse.</p> 2873 2874 <div class="SECT2"> 2875 <hr> 2876 2877 <h3 class="SECT2"><a name="MOUSEBASICS" id= 2878 "MOUSEBASICS">12.1. The Basics</a></h3> 2879 2880 <p>Before you do any thing else, the events you want to 2881 receive have to be enabled with <tt class= 2882 "LITERAL">mousemask()</tt>.</p> 2883 <pre class="PROGRAMLISTING"> 2884 mousemask( mmask_t newmask, /* The events you want to listen to */ 2885 mmask_t *oldmask) /* The old events mask */ 2886</pre> 2887 2888 <p>The first parameter to above function is a bit mask of 2889 events you would like to listen. By default, all the events 2890 are turned off. The bit mask <tt class= 2891 "LITERAL">ALL_MOUSE_EVENTS</tt> can be used to get all the 2892 events.</p> 2893 2894 <p>The following are all the event masks:</p> 2895 <pre class="PROGRAMLISTING"> 2896 Name Description 2897 --------------------------------------------------------------------- 2898 BUTTON1_PRESSED mouse button 1 down 2899 BUTTON1_RELEASED mouse button 1 up 2900 BUTTON1_CLICKED mouse button 1 clicked 2901 BUTTON1_DOUBLE_CLICKED mouse button 1 double clicked 2902 BUTTON1_TRIPLE_CLICKED mouse button 1 triple clicked 2903 BUTTON2_PRESSED mouse button 2 down 2904 BUTTON2_RELEASED mouse button 2 up 2905 BUTTON2_CLICKED mouse button 2 clicked 2906 BUTTON2_DOUBLE_CLICKED mouse button 2 double clicked 2907 BUTTON2_TRIPLE_CLICKED mouse button 2 triple clicked 2908 BUTTON3_PRESSED mouse button 3 down 2909 BUTTON3_RELEASED mouse button 3 up 2910 BUTTON3_CLICKED mouse button 3 clicked 2911 BUTTON3_DOUBLE_CLICKED mouse button 3 double clicked 2912 BUTTON3_TRIPLE_CLICKED mouse button 3 triple clicked 2913 BUTTON4_PRESSED mouse button 4 down 2914 BUTTON4_RELEASED mouse button 4 up 2915 BUTTON4_CLICKED mouse button 4 clicked 2916 BUTTON4_DOUBLE_CLICKED mouse button 4 double clicked 2917 BUTTON4_TRIPLE_CLICKED mouse button 4 triple clicked 2918 BUTTON_SHIFT shift was down during button state change 2919 BUTTON_CTRL control was down during button state change 2920 BUTTON_ALT alt was down during button state change 2921 ALL_MOUSE_EVENTS report all button state changes 2922 REPORT_MOUSE_POSITION report mouse movement 2923</pre> 2924 </div> 2925 2926 <div class="SECT2"> 2927 <hr> 2928 2929 <h3 class="SECT2"><a name="GETTINGEVENTS" id= 2930 "GETTINGEVENTS">12.2. Getting the events</a></h3> 2931 2932 <p>Once a class of mouse events have been enabled, getch() 2933 class of functions return KEY_MOUSE every time some mouse 2934 event happens. Then the mouse event can be retrieved with 2935 <tt class="LITERAL">getmouse()</tt>.</p> 2936 2937 <p>The code approximately looks like this:</p> 2938 <pre class="PROGRAMLISTING"> 2939 MEVENT event; 2940 2941 ch = getch(); 2942 if(ch == KEY_MOUSE) 2943 if(getmouse(&event) == OK) 2944 . /* Do some thing with the event */ 2945 . 2946 . 2947</pre> 2948 2949 <p>getmouse() returns the event into the pointer given to 2950 it. It's a structure which contains</p> 2951 <pre class="PROGRAMLISTING"> 2952 typedef struct 2953 { 2954 short id; /* ID to distinguish multiple devices */ 2955 int x, y, z; /* event coordinates */ 2956 mmask_t bstate; /* button state bits */ 2957 } 2958</pre> 2959 2960 <p>The <tt class="LITERAL">bstate</tt> is the main variable 2961 we are interested in. It tells the button state of the 2962 mouse.</p> 2963 2964 <p>Then with a code snippet like the following, we can find 2965 out what happened.</p> 2966 <pre class="PROGRAMLISTING"> 2967 if(event.bstate & BUTTON1_PRESSED) 2968 printw("Left Button Pressed"); 2969</pre> 2970 </div> 2971 2972 <div class="SECT2"> 2973 <hr> 2974 2975 <h3 class="SECT2"><a name="MOUSETOGETHER" id= 2976 "MOUSETOGETHER">12.3. Putting it all Together</a></h3> 2977 2978 <p>That's pretty much interfacing with mouse. Let's create 2979 the same menu and enable mouse interaction. To make things 2980 simpler, key handling is removed.</p> 2981 2982 <div class="EXAMPLE"> 2983 <a name="BMOME" id="BMOME"></a> 2984 2985 <p><b>Example 11. Access the menu with mouse !!!</b></p> 2986 <pre class="PROGRAMLISTING"> 2987<span class="INLINEMEDIAOBJECT">#include <ncurses.h> 2988 2989#define WIDTH 30 2990#define HEIGHT 10 2991 2992int startx = 0; 2993int starty = 0; 2994 2995char *choices[] = { "Choice 1", 2996 "Choice 2", 2997 "Choice 3", 2998 "Choice 4", 2999 "Exit", 3000 }; 3001 3002int n_choices = sizeof(choices) / sizeof(char *); 3003 3004void print_menu(WINDOW *menu_win, int highlight); 3005void report_choice(int mouse_x, int mouse_y, int *p_choice); 3006 3007int main() 3008{ int c, choice = 0; 3009 WINDOW *menu_win; 3010 MEVENT event; 3011 3012 /* Initialize curses */ 3013 initscr(); 3014 clear(); 3015 noecho(); 3016 cbreak(); //Line buffering disabled. pass on everything 3017 3018 /* Try to put the window in the middle of screen */ 3019 startx = (80 - WIDTH) / 2; 3020 starty = (24 - HEIGHT) / 2; 3021 3022 attron(A_REVERSE); 3023 mvprintw(23, 1, "Click on Exit to quit (Works best in a virtual console)"); 3024 refresh(); 3025 attroff(A_REVERSE); 3026 3027 /* Print the menu for the first time */ 3028 menu_win = newwin(HEIGHT, WIDTH, starty, startx); 3029 print_menu(menu_win, 1); 3030 /* Get all the mouse events */ 3031 mousemask(ALL_MOUSE_EVENTS, NULL); 3032 3033 while(1) 3034 { c = wgetch(menu_win); 3035 switch(c) 3036 { case KEY_MOUSE: 3037 if(getmouse(&event) == OK) 3038 { /* When the user clicks left mouse button */ 3039 if(event.bstate & BUTTON1_PRESSED) 3040 { report_choice(event.x + 1, event.y + 1, &choice); 3041 if(choice == -1) //Exit chosen 3042 goto end; 3043 mvprintw(22, 1, "Choice made is : %d String Chosen is \"%10s\"", choice, choices[choice - 1]); 3044 refresh(); 3045 } 3046 } 3047 print_menu(menu_win, choice); 3048 break; 3049 } 3050 } 3051end: 3052 endwin(); 3053 return 0; 3054} 3055 3056 3057void print_menu(WINDOW *menu_win, int highlight) 3058{ 3059 int x, y, i; 3060 3061 x = 2; 3062 y = 2; 3063 box(menu_win, 0, 0); 3064 for(i = 0; i < n_choices; ++i) 3065 { if(highlight == i + 1) 3066 { wattron(menu_win, A_REVERSE); 3067 mvwprintw(menu_win, y, x, "%s", choices[i]); 3068 wattroff(menu_win, A_REVERSE); 3069 } 3070 else 3071 mvwprintw(menu_win, y, x, "%s", choices[i]); 3072 ++y; 3073 } 3074 wrefresh(menu_win); 3075} 3076 3077/* Report the choice according to mouse position */ 3078void report_choice(int mouse_x, int mouse_y, int *p_choice) 3079{ int i,j, choice; 3080 3081 i = startx + 2; 3082 j = starty + 3; 3083 3084 for(choice = 0; choice < n_choices; ++choice) 3085 if(mouse_y == j + choice && mouse_x >= i && mouse_x <= i + strlen(choices[choice])) 3086 { if(choice == n_choices - 1) 3087 *p_choice = -1; 3088 else 3089 *p_choice = choice + 1; 3090 break; 3091 } 3092}</span> 3093</pre> 3094 </div> 3095 </div> 3096 3097 <div class="SECT2"> 3098 <hr> 3099 3100 <h3 class="SECT2"><a name="MISCMOUSEFUNCS" id= 3101 "MISCMOUSEFUNCS">12.4. Miscellaneous Functions</a></h3> 3102 3103 <p>The functions mouse_trafo() and wmouse_trafo() can be 3104 used to convert to mouse co-ordinates to screen relative 3105 co-ordinates. See curs_mouse(3X) man page for details.</p> 3106 3107 <p>The mouseinterval function sets the maximum time (in 3108 thousands of a second) that can elapse between press and 3109 release events in order for them to be recognized as a 3110 click. This function returns the previous interval value. 3111 The default is one fifth of a second.</p> 3112 </div> 3113 </div> 3114 3115 <div class="SECT1"> 3116 <hr> 3117 3118 <h2 class="SECT1"><a name="SCREEN" id="SCREEN">13. Screen 3119 Manipulation</a></h2> 3120 3121 <p>In this section, we will look into some functions, which 3122 allow us to manage the screen efficiently and to write some 3123 fancy programs. This is especially important in writing 3124 games.</p> 3125 3126 <div class="SECT2"> 3127 <hr> 3128 3129 <h3 class="SECT2"><a name="GETYX" id="GETYX">13.1. getyx() 3130 functions</a></h3> 3131 3132 <p>The function <tt class="LITERAL">getyx()</tt> can be 3133 used to find out the present cursor co-ordinates. It will 3134 fill the values of x and y co-ordinates in the arguments 3135 given to it. Since getyx() is a macro you don't have to 3136 pass the address of the variables. It can be called as</p> 3137 <pre class="PROGRAMLISTING"> 3138 getyx(win, y, x); 3139 /* win: window pointer 3140 * y, x: y, x co-ordinates will be put into this variables 3141 */ 3142</pre> 3143 3144 <p>The function getparyx() gets the beginning co-ordinates 3145 of the sub window relative to the main window. This is some 3146 times useful to update a sub window. When designing fancy 3147 stuff like writing multiple menus, it becomes difficult to 3148 store the menu positions, their first option co-ordinates 3149 etc. A simple solution to this problem, is to create menus 3150 in sub windows and later find the starting co-ordinates of 3151 the menus by using getparyx().</p> 3152 3153 <p>The functions getbegyx() and getmaxyx() store current 3154 window's beginning and maximum co-ordinates. These 3155 functions are useful in the same way as above in managing 3156 the windows and sub windows effectively.</p> 3157 </div> 3158 3159 <div class="SECT2"> 3160 <hr> 3161 3162 <h3 class="SECT2"><a name="SCREENDUMP" id= 3163 "SCREENDUMP">13.2. Screen Dumping</a></h3> 3164 3165 <p>While writing games, some times it becomes necessary to 3166 store the state of the screen and restore it back to the 3167 same state. The function scr_dump() can be used to dump the 3168 screen contents to a file given as an argument. Later it 3169 can be restored by scr_restore function. These two simple 3170 functions can be used effectively to maintain a fast moving 3171 game with changing scenarios.</p> 3172 </div> 3173 3174 <div class="SECT2"> 3175 <hr> 3176 3177 <h3 class="SECT2"><a name="WINDOWDUMP" id= 3178 "WINDOWDUMP">13.3. Window Dumping</a></h3> 3179 3180 <p>To store and restore windows, the functions <tt class= 3181 "LITERAL">putwin()</tt> and <tt class= 3182 "LITERAL">getwin()</tt> can be used. <tt class= 3183 "LITERAL">putwin()</tt> puts the present window state into 3184 a file, which can be later restored by <tt class= 3185 "LITERAL">getwin()</tt>.</p> 3186 3187 <p>The function <tt class="LITERAL">copywin()</tt> can be 3188 used to copy a window completely onto another window. It 3189 takes the source and destination windows as parameters and 3190 according to the rectangle specified, it copies the 3191 rectangular region from source to destination window. It's 3192 last parameter specifies whether to overwrite or just 3193 overlay the contents on to the destination window. If this 3194 argument is true, then the copying is non-destructive.</p> 3195 </div> 3196 </div> 3197 3198 <div class="SECT1"> 3199 <hr> 3200 3201 <h2 class="SECT1"><a name="MISC" id="MISC">14. Miscellaneous 3202 features</a></h2> 3203 3204 <p>Now you know enough features to write a good curses 3205 program, with all bells and whistles. There are some 3206 miscellaneous functions which are useful in various cases. 3207 Let's go headlong into some of those.</p> 3208 3209 <div class="SECT2"> 3210 <hr> 3211 3212 <h3 class="SECT2"><a name="CURSSET" id="CURSSET">14.1. 3213 curs_set()</a></h3> 3214 3215 <p>This function can be used to make the cursor invisible. 3216 The parameter to this function should be</p> 3217 <pre class="PROGRAMLISTING"> 3218 0 : invisible or 3219 1 : normal or 3220 2 : very visible. 3221</pre> 3222 </div> 3223 3224 <div class="SECT2"> 3225 <hr> 3226 3227 <h3 class="SECT2"><a name="TEMPLEAVE" id="TEMPLEAVE">14.2. 3228 Temporarily Leaving Curses mode</a></h3> 3229 3230 <p>Some times you may want to get back to cooked mode 3231 (normal line buffering mode) temporarily. In such a case 3232 you will first need to save the tty modes with a call to 3233 <tt class="LITERAL">def_prog_mode()</tt> and then call 3234 <tt class="LITERAL">endwin()</tt> to end the curses mode. 3235 This will leave you in the original tty mode. To get back 3236 to curses once you are done, call <tt class= 3237 "LITERAL">reset_prog_mode()</tt> . This function returns 3238 the tty to the state stored by <tt class= 3239 "LITERAL">def_prog_mode()</tt>. Then do refresh(), and you 3240 are back to the curses mode. Here is an example showing the 3241 sequence of things to be done.</p> 3242 3243 <div class="EXAMPLE"> 3244 <a name="BTELE" id="BTELE"></a> 3245 3246 <p><b>Example 12. Temporarily Leaving Curses Mode</b></p> 3247 <pre class="PROGRAMLISTING"> 3248<span class="INLINEMEDIAOBJECT">#include <ncurses.h> 3249 3250int main() 3251{ 3252 initscr(); /* Start curses mode */ 3253 printw("Hello World !!!\n"); /* Print Hello World */ 3254 refresh(); /* Print it on to the real screen */ 3255 def_prog_mode(); /* Save the tty modes */ 3256 endwin(); /* End curses mode temporarily */ 3257 system("/bin/sh"); /* Do whatever you like in cooked mode */ 3258 reset_prog_mode(); /* Return to the previous tty mode*/ 3259 /* stored by def_prog_mode() */ 3260 refresh(); /* Do refresh() to restore the */ 3261 /* Screen contents */ 3262 printw("Another String\n"); /* Back to curses use the full */ 3263 refresh(); /* capabilities of curses */ 3264 endwin(); /* End curses mode */ 3265 3266 return 0; 3267}</span> 3268</pre> 3269 </div> 3270 </div> 3271 3272 <div class="SECT2"> 3273 <hr> 3274 3275 <h3 class="SECT2"><a name="ACSVARS" id="ACSVARS">14.3. ACS_ 3276 variables</a></h3> 3277 3278 <p>If you have ever programmed in DOS, you know about those 3279 nifty characters in extended character set. They are 3280 printable only on some terminals. NCURSES functions like 3281 <tt class="LITERAL">box()</tt> use these characters. All 3282 these variables start with ACS meaning alternative 3283 character set. You might have noticed me using these 3284 characters in some of the programs above. Here's an example 3285 showing all the characters.</p> 3286 3287 <div class="EXAMPLE"> 3288 <a name="BACSVARS" id="BACSVARS"></a> 3289 3290 <p><b>Example 13. ACS Variables Example</b></p> 3291 <pre class="PROGRAMLISTING"> 3292<span class="INLINEMEDIAOBJECT">#include <ncurses.h> 3293 3294int main() 3295{ 3296 initscr(); 3297 3298 printw("Upper left corner "); addch(ACS_ULCORNER); printw("\n"); 3299 printw("Lower left corner "); addch(ACS_LLCORNER); printw("\n"); 3300 printw("Lower right corner "); addch(ACS_LRCORNER); printw("\n"); 3301 printw("Tee pointing right "); addch(ACS_LTEE); printw("\n"); 3302 printw("Tee pointing left "); addch(ACS_RTEE); printw("\n"); 3303 printw("Tee pointing up "); addch(ACS_BTEE); printw("\n"); 3304 printw("Tee pointing down "); addch(ACS_TTEE); printw("\n"); 3305 printw("Horizontal line "); addch(ACS_HLINE); printw("\n"); 3306 printw("Vertical line "); addch(ACS_VLINE); printw("\n"); 3307 printw("Large Plus or cross over "); addch(ACS_PLUS); printw("\n"); 3308 printw("Scan Line 1 "); addch(ACS_S1); printw("\n"); 3309 printw("Scan Line 3 "); addch(ACS_S3); printw("\n"); 3310 printw("Scan Line 7 "); addch(ACS_S7); printw("\n"); 3311 printw("Scan Line 9 "); addch(ACS_S9); printw("\n"); 3312 printw("Diamond "); addch(ACS_DIAMOND); printw("\n"); 3313 printw("Checker board (stipple) "); addch(ACS_CKBOARD); printw("\n"); 3314 printw("Degree Symbol "); addch(ACS_DEGREE); printw("\n"); 3315 printw("Plus/Minus Symbol "); addch(ACS_PLMINUS); printw("\n"); 3316 printw("Bullet "); addch(ACS_BULLET); printw("\n"); 3317 printw("Arrow Pointing Left "); addch(ACS_LARROW); printw("\n"); 3318 printw("Arrow Pointing Right "); addch(ACS_RARROW); printw("\n"); 3319 printw("Arrow Pointing Down "); addch(ACS_DARROW); printw("\n"); 3320 printw("Arrow Pointing Up "); addch(ACS_UARROW); printw("\n"); 3321 printw("Board of squares "); addch(ACS_BOARD); printw("\n"); 3322 printw("Lantern Symbol "); addch(ACS_LANTERN); printw("\n"); 3323 printw("Solid Square Block "); addch(ACS_BLOCK); printw("\n"); 3324 printw("Less/Equal sign "); addch(ACS_LEQUAL); printw("\n"); 3325 printw("Greater/Equal sign "); addch(ACS_GEQUAL); printw("\n"); 3326 printw("Pi "); addch(ACS_PI); printw("\n"); 3327 printw("Not equal "); addch(ACS_NEQUAL); printw("\n"); 3328 printw("UK pound sign "); addch(ACS_STERLING); printw("\n"); 3329 3330 refresh(); 3331 getch(); 3332 endwin(); 3333 3334 return 0; 3335}</span> 3336</pre> 3337 </div> 3338 </div> 3339 </div> 3340 3341 <div class="SECT1"> 3342 <hr> 3343 3344 <h2 class="SECT1"><a name="OTHERLIB" id="OTHERLIB">15. Other 3345 libraries</a></h2> 3346 3347 <p>Apart from the curses library, there are few text mode 3348 libraries, which provide more functionality and a lot of 3349 features. The following sections explain three standard 3350 libraries which are usually distributed along with 3351 curses.</p> 3352 </div> 3353 3354 <div class="SECT1"> 3355 <hr> 3356 3357 <h2 class="SECT1"><a name="PANELS" id="PANELS">16. Panel 3358 Library</a></h2> 3359 3360 <p>Now that you are proficient in curses, you wanted to do 3361 some thing big. You created a lot of overlapping windows to 3362 give a professional windows-type look. Unfortunately, it soon 3363 becomes difficult to manage these. The multiple refreshes, 3364 updates plunge you into a nightmare. The overlapping windows 3365 create blotches, whenever you forget to refresh the windows 3366 in the proper order.</p> 3367 3368 <p>Don't despair. There's an elegant solution provided in 3369 panels library. In the words of developers of ncurses</p> 3370 3371 <p><span class="emphasis"><i class="EMPHASIS">When your 3372 interface design is such that windows may dive deeper into 3373 the visibility stack or pop to the top at runtime, the 3374 resulting book-keeping can be tedious and difficult to get 3375 right. Hence the panels library.</i></span></p> 3376 3377 <p>If you have lot of overlapping windows, then panels 3378 library is the way to go. It obviates the need of doing 3379 series of wnoutrefresh(), doupdate() and relieves the burden 3380 of doing it correctly(bottom up). The library maintains 3381 information about the order of windows, their overlapping and 3382 update the screen properly. So why wait? Let's take a close 3383 peek into panels.</p> 3384 3385 <div class="SECT2"> 3386 <hr> 3387 3388 <h3 class="SECT2"><a name="PANELBASICS" id= 3389 "PANELBASICS">16.1. The Basics</a></h3> 3390 3391 <p>Panel object is a window that is implicitly treated as 3392 part of a deck including all other panel objects. The deck 3393 is treated as a stack with the top panel being completely 3394 visible and the other panels may or may not be obscured 3395 according to their positions. So the basic idea is to 3396 create a stack of overlapping panels and use panels library 3397 to display them correctly. There is a function similar to 3398 refresh() which, when called , displays panels in the 3399 correct order. Functions are provided to hide or show 3400 panels, move panels, change its size etc.. The overlapping 3401 problem is managed by the panels library during all the 3402 calls to these functions.</p> 3403 3404 <p>The general flow of a panel program goes like this:</p> 3405 3406 <ol type="1"> 3407 <li> 3408 <p>Create the windows (with newwin()) to be attached to 3409 the panels.</p> 3410 </li> 3411 3412 <li> 3413 <p>Create panels with the chosen visibility order. 3414 Stack them up according to the desired visibility. The 3415 function new_panel() is used to created panels.</p> 3416 </li> 3417 3418 <li> 3419 <p>Call update_panels() to write the panels to the 3420 virtual screen in correct visibility order. Do a 3421 doupdate() to show it on the screen.</p> 3422 </li> 3423 3424 <li> 3425 <p>Mainpulate the panels with show_panel(), 3426 hide_panel(), move_panel() etc. Make use of helper 3427 functions like panel_hidden() and panel_window(). Make 3428 use of user pointer to store custom data for a panel. 3429 Use the functions set_panel_userptr() and 3430 panel_userptr() to set and get the user pointer for a 3431 panel.</p> 3432 </li> 3433 3434 <li> 3435 <p>When you are done with the panel use del_panel() to 3436 delete the panel.</p> 3437 </li> 3438 </ol> 3439 3440 <p>Let's make the concepts clear, with some programs. The 3441 following is a simple program which creates 3 overlapping 3442 panels and shows them on the screen.</p> 3443 </div> 3444 3445 <div class="SECT2"> 3446 <hr> 3447 3448 <h3 class="SECT2"><a name="COMPILEPANELS" id= 3449 "COMPILEPANELS">16.2. Compiling With the Panels 3450 Library</a></h3> 3451 3452 <p>To use panels library functions, you have to include 3453 panel.h and to link the program with panels library the 3454 flag -lpanel should be added along with -lncurses in that 3455 order.</p> 3456 <pre class="PROGRAMLISTING"> 3457 #include <panel.h> 3458 . 3459 . 3460 . 3461 3462 compile and link: gcc <program file> -lpanel -lncurses 3463</pre> 3464 3465 <div class="EXAMPLE"> 3466 <a name="PPASI" id="PPASI"></a> 3467 3468 <p><b>Example 14. Panel basics</b></p> 3469 <pre class="PROGRAMLISTING"> 3470<span class="INLINEMEDIAOBJECT">#include <panel.h> 3471 3472int main() 3473{ WINDOW *my_wins[3]; 3474 PANEL *my_panels[3]; 3475 int lines = 10, cols = 40, y = 2, x = 4, i; 3476 3477 initscr(); 3478 cbreak(); 3479 noecho(); 3480 3481 /* Create windows for the panels */ 3482 my_wins[0] = newwin(lines, cols, y, x); 3483 my_wins[1] = newwin(lines, cols, y + 1, x + 5); 3484 my_wins[2] = newwin(lines, cols, y + 2, x + 10); 3485 3486 /* 3487 * Create borders around the windows so that you can see the effect 3488 * of panels 3489 */ 3490 for(i = 0; i < 3; ++i) 3491 box(my_wins[i], 0, 0); 3492 3493 /* Attach a panel to each window */ /* Order is bottom up */ 3494 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ 3495 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ 3496 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ 3497 3498 /* Update the stacking order. 2nd panel will be on top */ 3499 update_panels(); 3500 3501 /* Show it on the screen */ 3502 doupdate(); 3503 3504 getch(); 3505 endwin(); 3506} 3507</span> 3508</pre> 3509 </div> 3510 3511 <p>As you can see, above program follows a simple flow as 3512 explained. The windows are created with newwin() and then 3513 they are attached to panels with new_panel(). As we attach 3514 one panel after another, the stack of panels gets updated. 3515 To put them on screen update_panels() and doupdate() are 3516 called.</p> 3517 </div> 3518 3519 <div class="SECT2"> 3520 <hr> 3521 3522 <h3 class="SECT2"><a name="PANELBROWSING" id= 3523 "PANELBROWSING">16.3. Panel Window Browsing</a></h3> 3524 3525 <p>A slightly complicated example is given below. This 3526 program creates 3 windows which can be cycled through using 3527 tab. Have a look at the code.</p> 3528 3529 <div class="EXAMPLE"> 3530 <a name="PPABR" id="PPABR"></a> 3531 3532 <p><b>Example 15. Panel Window Browsing Example</b></p> 3533 <pre class="PROGRAMLISTING"> 3534<span class="INLINEMEDIAOBJECT">#include <panel.h> 3535 3536#define NLINES 10 3537#define NCOLS 40 3538 3539void init_wins(WINDOW **wins, int n); 3540void win_show(WINDOW *win, char *label, int label_color); 3541void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 3542 3543int main() 3544{ WINDOW *my_wins[3]; 3545 PANEL *my_panels[3]; 3546 PANEL *top; 3547 int ch; 3548 3549 /* Initialize curses */ 3550 initscr(); 3551 start_color(); 3552 cbreak(); 3553 noecho(); 3554 keypad(stdscr, TRUE); 3555 3556 /* Initialize all the colors */ 3557 init_pair(1, COLOR_RED, COLOR_BLACK); 3558 init_pair(2, COLOR_GREEN, COLOR_BLACK); 3559 init_pair(3, COLOR_BLUE, COLOR_BLACK); 3560 init_pair(4, COLOR_CYAN, COLOR_BLACK); 3561 3562 init_wins(my_wins, 3); 3563 3564 /* Attach a panel to each window */ /* Order is bottom up */ 3565 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ 3566 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ 3567 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ 3568 3569 /* Set up the user pointers to the next panel */ 3570 set_panel_userptr(my_panels[0], my_panels[1]); 3571 set_panel_userptr(my_panels[1], my_panels[2]); 3572 set_panel_userptr(my_panels[2], my_panels[0]); 3573 3574 /* Update the stacking order. 2nd panel will be on top */ 3575 update_panels(); 3576 3577 /* Show it on the screen */ 3578 attron(COLOR_PAIR(4)); 3579 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)"); 3580 attroff(COLOR_PAIR(4)); 3581 doupdate(); 3582 3583 top = my_panels[2]; 3584 while((ch = getch()) != KEY_F(1)) 3585 { switch(ch) 3586 { case 9: 3587 top = (PANEL *)panel_userptr(top); 3588 top_panel(top); 3589 break; 3590 } 3591 update_panels(); 3592 doupdate(); 3593 } 3594 endwin(); 3595 return 0; 3596} 3597 3598/* Put all the windows */ 3599void init_wins(WINDOW **wins, int n) 3600{ int x, y, i; 3601 char label[80]; 3602 3603 y = 2; 3604 x = 10; 3605 for(i = 0; i < n; ++i) 3606 { wins[i] = newwin(NLINES, NCOLS, y, x); 3607 sprintf(label, "Window Number %d", i + 1); 3608 win_show(wins[i], label, i + 1); 3609 y += 3; 3610 x += 7; 3611 } 3612} 3613 3614/* Show the window with a border and a label */ 3615void win_show(WINDOW *win, char *label, int label_color) 3616{ int startx, starty, height, width; 3617 3618 getbegyx(win, starty, startx); 3619 getmaxyx(win, height, width); 3620 3621 box(win, 0, 0); 3622 mvwaddch(win, 2, 0, ACS_LTEE); 3623 mvwhline(win, 2, 1, ACS_HLINE, width - 2); 3624 mvwaddch(win, 2, width - 1, ACS_RTEE); 3625 3626 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color)); 3627} 3628 3629void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 3630{ int length, x, y; 3631 float temp; 3632 3633 if(win == NULL) 3634 win = stdscr; 3635 getyx(win, y, x); 3636 if(startx != 0) 3637 x = startx; 3638 if(starty != 0) 3639 y = starty; 3640 if(width == 0) 3641 width = 80; 3642 3643 length = strlen(string); 3644 temp = (width - length)/ 2; 3645 x = startx + (int)temp; 3646 wattron(win, color); 3647 mvwprintw(win, y, x, "%s", string); 3648 wattroff(win, color); 3649 refresh(); 3650}</span> 3651</pre> 3652 </div> 3653 </div> 3654 3655 <div class="SECT2"> 3656 <hr> 3657 3658 <h3 class="SECT2"><a name="USERPTRUSING" id= 3659 "USERPTRUSING">16.4. Using User Pointers</a></h3> 3660 3661 <p>In the above example I used user pointers to find out 3662 the next window in the cycle. We can attach custom 3663 information to the panel by specifying a user pointer, 3664 which can point to any information you want to store. In 3665 this case I stored the pointer to the next panel in the 3666 cycle. User pointer for a panel can be set with the 3667 function <tt class="LITERAL">set_panel_userptr()</tt>. It 3668 can be accessed using the function <tt class= 3669 "LITERAL">panel_userptr()</tt> which will return the user 3670 pointer for the panel given as argument. After finding the 3671 next panel in the cycle It's brought to the top by the 3672 function top_panel(). This function brings the panel given 3673 as argument to the top of the panel stack.</p> 3674 </div> 3675 3676 <div class="SECT2"> 3677 <hr> 3678 3679 <h3 class="SECT2"><a name="PANELMOVERESIZE" id= 3680 "PANELMOVERESIZE">16.5. Moving and Resizing Panels</a></h3> 3681 3682 <p>The function <tt class="LITERAL">move_panel()</tt> can 3683 be used to move a panel to the desired location. It does 3684 not change the position of the panel in the stack. Make 3685 sure that you use move_panel() instead mvwin() on the 3686 window associated with the panel.</p> 3687 3688 <p>Resizing a panel is slightly complex. There is no 3689 straight forward function just to resize the window 3690 associated with a panel. A solution to resize a panel is to 3691 create a new window with the desired sizes, change the 3692 window associated with the panel using replace_panel(). 3693 Don't forget to delete the old window. The window 3694 associated with a panel can be found by using the function 3695 panel_window().</p> 3696 3697 <p>The following program shows these concepts, in 3698 supposedly simple program. You can cycle through the window 3699 with <TAB> as usual. To resize or move the active 3700 panel press 'r' for resize 'm' for moving. Then use arrow 3701 keys to resize or move it to the desired way and press 3702 enter to end your resizing or moving. This example makes 3703 use of user data to get the required data to do the 3704 operations.</p> 3705 3706 <div class="EXAMPLE"> 3707 <a name="PPARE" id="PPARE"></a> 3708 3709 <p><b>Example 16. Panel Moving and Resizing 3710 example</b></p> 3711 <pre class="PROGRAMLISTING"> 3712<span class="INLINEMEDIAOBJECT">#include <panel.h> 3713 3714typedef struct _PANEL_DATA { 3715 int x, y, w, h; 3716 char label[80]; 3717 int label_color; 3718 PANEL *next; 3719}PANEL_DATA; 3720 3721#define NLINES 10 3722#define NCOLS 40 3723 3724void init_wins(WINDOW **wins, int n); 3725void win_show(WINDOW *win, char *label, int label_color); 3726void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 3727void set_user_ptrs(PANEL **panels, int n); 3728 3729int main() 3730{ WINDOW *my_wins[3]; 3731 PANEL *my_panels[3]; 3732 PANEL_DATA *top; 3733 PANEL *stack_top; 3734 WINDOW *temp_win, *old_win; 3735 int ch; 3736 int newx, newy, neww, newh; 3737 int size = FALSE, move = FALSE; 3738 3739 /* Initialize curses */ 3740 initscr(); 3741 start_color(); 3742 cbreak(); 3743 noecho(); 3744 keypad(stdscr, TRUE); 3745 3746 /* Initialize all the colors */ 3747 init_pair(1, COLOR_RED, COLOR_BLACK); 3748 init_pair(2, COLOR_GREEN, COLOR_BLACK); 3749 init_pair(3, COLOR_BLUE, COLOR_BLACK); 3750 init_pair(4, COLOR_CYAN, COLOR_BLACK); 3751 3752 init_wins(my_wins, 3); 3753 3754 /* Attach a panel to each window */ /* Order is bottom up */ 3755 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ 3756 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ 3757 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ 3758 3759 set_user_ptrs(my_panels, 3); 3760 /* Update the stacking order. 2nd panel will be on top */ 3761 update_panels(); 3762 3763 /* Show it on the screen */ 3764 attron(COLOR_PAIR(4)); 3765 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing"); 3766 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)"); 3767 attroff(COLOR_PAIR(4)); 3768 doupdate(); 3769 3770 stack_top = my_panels[2]; 3771 top = (PANEL_DATA *)panel_userptr(stack_top); 3772 newx = top->x; 3773 newy = top->y; 3774 neww = top->w; 3775 newh = top->h; 3776 while((ch = getch()) != KEY_F(1)) 3777 { switch(ch) 3778 { case 9: /* Tab */ 3779 top = (PANEL_DATA *)panel_userptr(stack_top); 3780 top_panel(top->next); 3781 stack_top = top->next; 3782 top = (PANEL_DATA *)panel_userptr(stack_top); 3783 newx = top->x; 3784 newy = top->y; 3785 neww = top->w; 3786 newh = top->h; 3787 break; 3788 case 'r': /* Re-Size*/ 3789 size = TRUE; 3790 attron(COLOR_PAIR(4)); 3791 mvprintw(LINES - 4, 0, "Entered Resizing :Use Arrow Keys to resize and press <ENTER> to end resizing"); 3792 refresh(); 3793 attroff(COLOR_PAIR(4)); 3794 break; 3795 case 'm': /* Move */ 3796 attron(COLOR_PAIR(4)); 3797 mvprintw(LINES - 4, 0, "Entered Moving: Use Arrow Keys to Move and press <ENTER> to end moving"); 3798 refresh(); 3799 attroff(COLOR_PAIR(4)); 3800 move = TRUE; 3801 break; 3802 case KEY_LEFT: 3803 if(size == TRUE) 3804 { --newx; 3805 ++neww; 3806 } 3807 if(move == TRUE) 3808 --newx; 3809 break; 3810 case KEY_RIGHT: 3811 if(size == TRUE) 3812 { ++newx; 3813 --neww; 3814 } 3815 if(move == TRUE) 3816 ++newx; 3817 break; 3818 case KEY_UP: 3819 if(size == TRUE) 3820 { --newy; 3821 ++newh; 3822 } 3823 if(move == TRUE) 3824 --newy; 3825 break; 3826 case KEY_DOWN: 3827 if(size == TRUE) 3828 { ++newy; 3829 --newh; 3830 } 3831 if(move == TRUE) 3832 ++newy; 3833 break; 3834 case 10: /* Enter */ 3835 move(LINES - 4, 0); 3836 clrtoeol(); 3837 refresh(); 3838 if(size == TRUE) 3839 { old_win = panel_window(stack_top); 3840 temp_win = newwin(newh, neww, newy, newx); 3841 replace_panel(stack_top, temp_win); 3842 win_show(temp_win, top->label, top->label_color); 3843 delwin(old_win); 3844 size = FALSE; 3845 } 3846 if(move == TRUE) 3847 { move_panel(stack_top, newy, newx); 3848 move = FALSE; 3849 } 3850 break; 3851 3852 } 3853 attron(COLOR_PAIR(4)); 3854 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing"); 3855 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)"); 3856 attroff(COLOR_PAIR(4)); 3857 refresh(); 3858 update_panels(); 3859 doupdate(); 3860 } 3861 endwin(); 3862 return 0; 3863} 3864 3865/* Put all the windows */ 3866void init_wins(WINDOW **wins, int n) 3867{ int x, y, i; 3868 char label[80]; 3869 3870 y = 2; 3871 x = 10; 3872 for(i = 0; i < n; ++i) 3873 { wins[i] = newwin(NLINES, NCOLS, y, x); 3874 sprintf(label, "Window Number %d", i + 1); 3875 win_show(wins[i], label, i + 1); 3876 y += 3; 3877 x += 7; 3878 } 3879} 3880 3881/* Set the PANEL_DATA structures for individual panels */ 3882void set_user_ptrs(PANEL **panels, int n) 3883{ PANEL_DATA *ptrs; 3884 WINDOW *win; 3885 int x, y, w, h, i; 3886 char temp[80]; 3887 3888 ptrs = (PANEL_DATA *)calloc(n, sizeof(PANEL_DATA)); 3889 3890 for(i = 0;i < n; ++i) 3891 { win = panel_window(panels[i]); 3892 getbegyx(win, y, x); 3893 getmaxyx(win, h, w); 3894 ptrs[i].x = x; 3895 ptrs[i].y = y; 3896 ptrs[i].w = w; 3897 ptrs[i].h = h; 3898 sprintf(temp, "Window Number %d", i + 1); 3899 strcpy(ptrs[i].label, temp); 3900 ptrs[i].label_color = i + 1; 3901 if(i + 1 == n) 3902 ptrs[i].next = panels[0]; 3903 else 3904 ptrs[i].next = panels[i + 1]; 3905 set_panel_userptr(panels[i], &ptrs[i]); 3906 } 3907} 3908 3909/* Show the window with a border and a label */ 3910void win_show(WINDOW *win, char *label, int label_color) 3911{ int startx, starty, height, width; 3912 3913 getbegyx(win, starty, startx); 3914 getmaxyx(win, height, width); 3915 3916 box(win, 0, 0); 3917 mvwaddch(win, 2, 0, ACS_LTEE); 3918 mvwhline(win, 2, 1, ACS_HLINE, width - 2); 3919 mvwaddch(win, 2, width - 1, ACS_RTEE); 3920 3921 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color)); 3922} 3923 3924void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 3925{ int length, x, y; 3926 float temp; 3927 3928 if(win == NULL) 3929 win = stdscr; 3930 getyx(win, y, x); 3931 if(startx != 0) 3932 x = startx; 3933 if(starty != 0) 3934 y = starty; 3935 if(width == 0) 3936 width = 80; 3937 3938 length = strlen(string); 3939 temp = (width - length)/ 2; 3940 x = startx + (int)temp; 3941 wattron(win, color); 3942 mvwprintw(win, y, x, "%s", string); 3943 wattroff(win, color); 3944 refresh(); 3945}</span> 3946</pre> 3947 </div> 3948 3949 <p>Concentrate on the main while loop. Once it finds out 3950 the type of key pressed, it takes appropriate action. If 3951 'r' is pressed resizing mode is started. After this the new 3952 sizes are updated as the user presses the arrow keys. When 3953 the user presses <ENTER> present selection ends and 3954 panel is resized by using the concept explained. While in 3955 resizing mode the program doesn't show how the window is 3956 getting resized. It's left as an exercise to the reader to 3957 print a dotted border while it gets resized to a new 3958 position.</p> 3959 3960 <p>When the user presses 'm' the move mode starts. This is 3961 a bit simpler than resizing. As the arrow keys are pressed 3962 the new position is updated and pressing of <ENTER> 3963 causes the panel to be moved by calling the function 3964 move_panel().</p> 3965 3966 <p>In this program the user data which is represented as 3967 PANEL_DATA, plays very important role in finding the 3968 associated information with a panel. As written in the 3969 comments, the PANEL_DATA stores the panel sizes, label, 3970 label color and a pointer to the next panel in the 3971 cycle.</p> 3972 </div> 3973 3974 <div class="SECT2"> 3975 <hr> 3976 3977 <h3 class="SECT2"><a name="PANELSHOWHIDE" id= 3978 "PANELSHOWHIDE">16.6. Hiding and Showing Panels</a></h3> 3979 3980 <p>A Panel can be hidden by using the function 3981 hide_panel(). This function merely removes it form the 3982 stack of panels, thus hiding it on the screen once you do 3983 update_panels() and doupdate(). It doesn't destroy the 3984 PANEL structure associated with the hidden panel. It can be 3985 shown again by using the show_panel() function.</p> 3986 3987 <p>The following program shows the hiding of panels. Press 3988 'a' or 'b' or 'c' to show or hide first, second and third 3989 windows respectively. It uses a user data with a small 3990 variable hide, which keeps track of whether the window is 3991 hidden or not. For some reason the function <tt class= 3992 "LITERAL">panel_hidden()</tt> which tells whether a panel 3993 is hidden or not is not working. A bug report was also 3994 presented by Michael Andres <a href= 3995 "http://www.geocrawler.com/archives/3/344/1999/9/0/2643549/" 3996 target="_top">here</a></p> 3997 3998 <div class="EXAMPLE"> 3999 <a name="PPAHI" id="PPAHI"></a> 4000 4001 <p><b>Example 17. Panel Hiding and Showing 4002 example</b></p> 4003 <pre class="PROGRAMLISTING"> 4004<span class="INLINEMEDIAOBJECT">#include <panel.h> 4005 4006typedef struct _PANEL_DATA { 4007 int hide; /* TRUE if panel is hidden */ 4008}PANEL_DATA; 4009 4010#define NLINES 10 4011#define NCOLS 40 4012 4013void init_wins(WINDOW **wins, int n); 4014void win_show(WINDOW *win, char *label, int label_color); 4015void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 4016 4017int main() 4018{ WINDOW *my_wins[3]; 4019 PANEL *my_panels[3]; 4020 PANEL_DATA panel_datas[3]; 4021 PANEL_DATA *temp; 4022 int ch; 4023 4024 /* Initialize curses */ 4025 initscr(); 4026 start_color(); 4027 cbreak(); 4028 noecho(); 4029 keypad(stdscr, TRUE); 4030 4031 /* Initialize all the colors */ 4032 init_pair(1, COLOR_RED, COLOR_BLACK); 4033 init_pair(2, COLOR_GREEN, COLOR_BLACK); 4034 init_pair(3, COLOR_BLUE, COLOR_BLACK); 4035 init_pair(4, COLOR_CYAN, COLOR_BLACK); 4036 4037 init_wins(my_wins, 3); 4038 4039 /* Attach a panel to each window */ /* Order is bottom up */ 4040 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ 4041 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ 4042 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ 4043 4044 /* Initialize panel datas saying that nothing is hidden */ 4045 panel_datas[0].hide = FALSE; 4046 panel_datas[1].hide = FALSE; 4047 panel_datas[2].hide = FALSE; 4048 4049 set_panel_userptr(my_panels[0], &panel_datas[0]); 4050 set_panel_userptr(my_panels[1], &panel_datas[1]); 4051 set_panel_userptr(my_panels[2], &panel_datas[2]); 4052 4053 /* Update the stacking order. 2nd panel will be on top */ 4054 update_panels(); 4055 4056 /* Show it on the screen */ 4057 attron(COLOR_PAIR(4)); 4058 mvprintw(LINES - 3, 0, "Show or Hide a window with 'a'(first window) 'b'(Second Window) 'c'(Third Window)"); 4059 mvprintw(LINES - 2, 0, "F1 to Exit"); 4060 4061 attroff(COLOR_PAIR(4)); 4062 doupdate(); 4063 4064 while((ch = getch()) != KEY_F(1)) 4065 { switch(ch) 4066 { case 'a': 4067 temp = (PANEL_DATA *)panel_userptr(my_panels[0]); 4068 if(temp->hide == FALSE) 4069 { hide_panel(my_panels[0]); 4070 temp->hide = TRUE; 4071 } 4072 else 4073 { show_panel(my_panels[0]); 4074 temp->hide = FALSE; 4075 } 4076 break; 4077 case 'b': 4078 temp = (PANEL_DATA *)panel_userptr(my_panels[1]); 4079 if(temp->hide == FALSE) 4080 { hide_panel(my_panels[1]); 4081 temp->hide = TRUE; 4082 } 4083 else 4084 { show_panel(my_panels[1]); 4085 temp->hide = FALSE; 4086 } 4087 break; 4088 case 'c': 4089 temp = (PANEL_DATA *)panel_userptr(my_panels[2]); 4090 if(temp->hide == FALSE) 4091 { hide_panel(my_panels[2]); 4092 temp->hide = TRUE; 4093 } 4094 else 4095 { show_panel(my_panels[2]); 4096 temp->hide = FALSE; 4097 } 4098 break; 4099 } 4100 update_panels(); 4101 doupdate(); 4102 } 4103 endwin(); 4104 return 0; 4105} 4106 4107/* Put all the windows */ 4108void init_wins(WINDOW **wins, int n) 4109{ int x, y, i; 4110 char label[80]; 4111 4112 y = 2; 4113 x = 10; 4114 for(i = 0; i < n; ++i) 4115 { wins[i] = newwin(NLINES, NCOLS, y, x); 4116 sprintf(label, "Window Number %d", i + 1); 4117 win_show(wins[i], label, i + 1); 4118 y += 3; 4119 x += 7; 4120 } 4121} 4122 4123/* Show the window with a border and a label */ 4124void win_show(WINDOW *win, char *label, int label_color) 4125{ int startx, starty, height, width; 4126 4127 getbegyx(win, starty, startx); 4128 getmaxyx(win, height, width); 4129 4130 box(win, 0, 0); 4131 mvwaddch(win, 2, 0, ACS_LTEE); 4132 mvwhline(win, 2, 1, ACS_HLINE, width - 2); 4133 mvwaddch(win, 2, width - 1, ACS_RTEE); 4134 4135 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color)); 4136} 4137 4138void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 4139{ int length, x, y; 4140 float temp; 4141 4142 if(win == NULL) 4143 win = stdscr; 4144 getyx(win, y, x); 4145 if(startx != 0) 4146 x = startx; 4147 if(starty != 0) 4148 y = starty; 4149 if(width == 0) 4150 width = 80; 4151 4152 length = strlen(string); 4153 temp = (width - length)/ 2; 4154 x = startx + (int)temp; 4155 wattron(win, color); 4156 mvwprintw(win, y, x, "%s", string); 4157 wattroff(win, color); 4158 refresh(); 4159}</span> 4160</pre> 4161 </div> 4162 </div> 4163 4164 <div class="SECT2"> 4165 <hr> 4166 4167 <h3 class="SECT2"><a name="PANELABOVE" id= 4168 "PANELABOVE">16.7. panel_above() and panel_below() 4169 Functions</a></h3> 4170 4171 <p>The functions <tt class="LITERAL">panel_above()</tt> and 4172 <tt class="LITERAL">panel_below()</tt> can be used to find 4173 out the panel above and below a panel. If the argument to 4174 these functions is NULL, then they return a pointer to 4175 bottom panel and top panel respectively.</p> 4176 </div> 4177 </div> 4178 4179 <div class="SECT1"> 4180 <hr> 4181 4182 <h2 class="SECT1"><a name="MENUS" id="MENUS">17. Menus 4183 Library</a></h2> 4184 4185 <p>The menus library provides a nice extension to basic 4186 curses, through which you can create menus. It provides a set 4187 of functions to create menus. But they have to be customized 4188 to give a nicer look, with colors etc. Let's get into the 4189 details.</p> 4190 4191 <p>A menu is a screen display that assists the user to choose 4192 some subset of a given set of items. To put it simple, a menu 4193 is a collection of items from which one or more items can be 4194 chosen. Some readers might not be aware of multiple item 4195 selection capability. Menu library provides functionality to 4196 write menus from which the user can chose more than one item 4197 as the preferred choice. This is dealt with in a later 4198 section. Now it is time for some rudiments.</p> 4199 4200 <div class="SECT2"> 4201 <hr> 4202 4203 <h3 class="SECT2"><a name="MENUBASICS" id= 4204 "MENUBASICS">17.1. The Basics</a></h3> 4205 4206 <p>To create menus, you first create items, and then post 4207 the menu to the display. After that, all the processing of 4208 user responses is done in an elegant function menu_driver() 4209 which is the work horse of any menu program.</p> 4210 4211 <p>The general flow of control of a menu program looks like 4212 this.</p> 4213 4214 <ol type="1"> 4215 <li> 4216 <p>Initialize curses</p> 4217 </li> 4218 4219 <li> 4220 <p>Create items using new_item(). You can specify a 4221 name and description for the items.</p> 4222 </li> 4223 4224 <li> 4225 <p>Create the menu with new_menu() by specifying the 4226 items to be attached with.</p> 4227 </li> 4228 4229 <li> 4230 <p>Post the menu with menu_post() and refresh the 4231 screen.</p> 4232 </li> 4233 4234 <li> 4235 <p>Process the user requests with a loop and do 4236 necessary updates to menu with menu_driver.</p> 4237 </li> 4238 4239 <li> 4240 <p>Unpost the menu with menu_unpost()</p> 4241 </li> 4242 4243 <li> 4244 <p>Free the memory allocated to menu by free_menu()</p> 4245 </li> 4246 4247 <li> 4248 <p>Free the memory allocated to the items with 4249 free_item()</p> 4250 </li> 4251 4252 <li> 4253 <p>End curses</p> 4254 </li> 4255 </ol> 4256 4257 <p>Let's see a program which prints a simple menu and 4258 updates the current selection with up, down arrows.</p> 4259 </div> 4260 4261 <div class="SECT2"> 4262 <hr> 4263 4264 <h3 class="SECT2"><a name="COMPILEMENUS" id= 4265 "COMPILEMENUS">17.2. Compiling With the Menu 4266 Library</a></h3> 4267 4268 <p>To use menu library functions, you have to include 4269 menu.h and to link the program with menu library the flag 4270 -lmenu should be added along with -lncurses in that 4271 order.</p> 4272 <pre class="PROGRAMLISTING"> 4273 #include <menu.h> 4274 . 4275 . 4276 . 4277 4278 compile and link: gcc <program file> -lmenu -lncurses 4279</pre> 4280 4281 <div class="EXAMPLE"> 4282 <a name="MMESI" id="MMESI"></a> 4283 4284 <p><b>Example 18. Menu Basics</b></p> 4285 <pre class="PROGRAMLISTING"> 4286<span class="INLINEMEDIAOBJECT">#include <curses.h> 4287#include <menu.h> 4288 4289#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 4290#define CTRLD 4 4291 4292char *choices[] = { 4293 "Choice 1", 4294 "Choice 2", 4295 "Choice 3", 4296 "Choice 4", 4297 "Exit", 4298 }; 4299 4300int main() 4301{ ITEM **my_items; 4302 int c; 4303 MENU *my_menu; 4304 int n_choices, i; 4305 ITEM *cur_item; 4306 4307 4308 initscr(); 4309 cbreak(); 4310 noecho(); 4311 keypad(stdscr, TRUE); 4312 4313 n_choices = ARRAY_SIZE(choices); 4314 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); 4315 4316 for(i = 0; i < n_choices; ++i) 4317 my_items[i] = new_item(choices[i], choices[i]); 4318 my_items[n_choices] = (ITEM *)NULL; 4319 4320 my_menu = new_menu((ITEM **)my_items); 4321 mvprintw(LINES - 2, 0, "F1 to Exit"); 4322 post_menu(my_menu); 4323 refresh(); 4324 4325 while((c = getch()) != KEY_F(1)) 4326 { switch(c) 4327 { case KEY_DOWN: 4328 menu_driver(my_menu, REQ_DOWN_ITEM); 4329 break; 4330 case KEY_UP: 4331 menu_driver(my_menu, REQ_UP_ITEM); 4332 break; 4333 } 4334 } 4335 4336 free_item(my_items[0]); 4337 free_item(my_items[1]); 4338 free_menu(my_menu); 4339 endwin(); 4340} 4341 </span> 4342</pre> 4343 </div> 4344 4345 <p>This program demonstrates the basic concepts involved in 4346 creating a menu using menus library. First we create the 4347 items using new_item() and then attach them to the menu 4348 with new_menu() function. After posting the menu and 4349 refreshing the screen, the main processing loop starts. It 4350 reads user input and takes corresponding action. The 4351 function menu_driver() is the main work horse of the menu 4352 system. The second parameter to this function tells what's 4353 to be done with the menu. According to the parameter, 4354 menu_driver() does the corresponding task. The value can be 4355 either a menu navigational request, an ascii character, or 4356 a KEY_MOUSE special key associated with a mouse event.</p> 4357 4358 <p>The menu_driver accepts following navigational 4359 requests.</p> 4360 <pre class="PROGRAMLISTING"> 4361 REQ_LEFT_ITEM Move left to an item. 4362 REQ_RIGHT_ITEM Move right to an item. 4363 REQ_UP_ITEM Move up to an item. 4364 REQ_DOWN_ITEM Move down to an item. 4365 REQ_SCR_ULINE Scroll up a line. 4366 REQ_SCR_DLINE Scroll down a line. 4367 REQ_SCR_DPAGE Scroll down a page. 4368 REQ_SCR_UPAGE Scroll up a page. 4369 REQ_FIRST_ITEM Move to the first item. 4370 REQ_LAST_ITEM Move to the last item. 4371 REQ_NEXT_ITEM Move to the next item. 4372 REQ_PREV_ITEM Move to the previous item. 4373 REQ_TOGGLE_ITEM Select/deselect an item. 4374 REQ_CLEAR_PATTERN Clear the menu pattern buffer. 4375 REQ_BACK_PATTERN Delete the previous character from the pattern buffer. 4376 REQ_NEXT_MATCH Move to the next item matching the pattern match. 4377 REQ_PREV_MATCH Move to the previous item matching the pattern match. 4378</pre> 4379 4380 <p>Don't get overwhelmed by the number of options. We will 4381 see them slowly one after another. The options of interest 4382 in this example are REQ_UP_ITEM and REQ_DOWN_ITEM. These 4383 two options when passed to menu_driver, menu driver updates 4384 the current item to one item up or down respectively.</p> 4385 </div> 4386 4387 <div class="SECT2"> 4388 <hr> 4389 4390 <h3 class="SECT2"><a name="MENUDRIVER" id= 4391 "MENUDRIVER">17.3. Menu Driver: The work horse of the menu 4392 system</a></h3> 4393 4394 <p>As you have seen in the above example, menu_driver plays 4395 an important role in updating the menu. It is very 4396 important to understand various options it takes and what 4397 they do. As explained above, the second parameter to 4398 menu_driver() can be either a navigational request, a 4399 printable character or a KEY_MOUSE key. Let's dissect the 4400 different navigational requests.</p> 4401 4402 <ul> 4403 <li> 4404 <p><span class="emphasis"><i class= 4405 "EMPHASIS">REQ_LEFT_ITEM and 4406 REQ_RIGHT_ITEM</i></span></p> 4407 4408 <p>A Menu can be displayed with multiple columns for 4409 more than one item. This can be done by using the 4410 <tt class="LITERAL">menu_format()</tt>function. When a 4411 multi columnar menu is displayed these requests cause 4412 the menu driver to move the current selection to left 4413 or right.</p> 4414 </li> 4415 4416 <li> 4417 <p><span class="emphasis"><i class= 4418 "EMPHASIS">REQ_UP_ITEM and REQ_DOWN_ITEM</i></span></p> 4419 4420 <p>These two options you have seen in the above 4421 example. These options when given, makes the 4422 menu_driver to move the current selection to an item up 4423 or down.</p> 4424 </li> 4425 4426 <li> 4427 <p><span class="emphasis"><i class="EMPHASIS">REQ_SCR_* 4428 options</i></span></p> 4429 4430 <p>The four options REQ_SCR_ULINE, REQ_SCR_DLINE, 4431 REQ_SCR_DPAGE, REQ_SCR_UPAGE are related to scrolling. 4432 If all the items in the menu cannot be displayed in the 4433 menu sub window, then the menu is scrollable. These 4434 requests can be given to the menu_driver to do the 4435 scrolling either one line up, down or one page down or 4436 up respectively.</p> 4437 </li> 4438 4439 <li> 4440 <p><span class="emphasis"><i class= 4441 "EMPHASIS">REQ_FIRST_ITEM, REQ_LAST_ITEM, REQ_NEXT_ITEM 4442 and REQ_PREV_ITEM</i></span></p> 4443 4444 <p>These requests are self explanatory.</p> 4445 </li> 4446 4447 <li> 4448 <p><span class="emphasis"><i class= 4449 "EMPHASIS">REQ_TOGGLE_ITEM</i></span></p> 4450 4451 <p>This request when given, toggles the present 4452 selection. This option is to be used only in a multi 4453 valued menu. So to use this request the option 4454 O_ONEVALUE must be off. This option can be made off or 4455 on with set_menu_opts().</p> 4456 </li> 4457 4458 <li> 4459 <p><span class="emphasis"><i class="EMPHASIS">Pattern 4460 Requests</i></span></p> 4461 4462 <p>Every menu has an associated pattern buffer, which 4463 is used to find the nearest match to the ascii 4464 characters entered by the user. Whenever ascii 4465 characters are given to menu_driver, it puts in to the 4466 pattern buffer. It also tries to find the nearest match 4467 to the pattern in the items list and moves current 4468 selection to that item. The request REQ_CLEAR_PATTERN 4469 clears the pattern buffer. The request REQ_BACK_PATTERN 4470 deletes the previous character in the pattern buffer. 4471 In case the pattern matches more than one item then the 4472 matched items can be cycled through REQ_NEXT_MATCH and 4473 REQ_PREV_MATCH which move the current selection to the 4474 next and previous matches respectively.</p> 4475 </li> 4476 4477 <li> 4478 <p><span class="emphasis"><i class="EMPHASIS">Mouse 4479 Requests</i></span></p> 4480 4481 <p>In case of KEY_MOUSE requests, according to the 4482 mouse position an action is taken accordingly. The 4483 action to be taken is explained in the man page as,</p> 4484 <pre class="PROGRAMLISTING"> 4485<span class="emphasis"><i class= 4486"EMPHASIS"> If the second argument is the KEY_MOUSE special key, the 4487 associated mouse event is translated into one of the above 4488 pre-defined requests. Currently only clicks in the user 4489 window (e.g. inside the menu display area or the decora­ 4490 tion window) are handled. If you click above the display 4491 region of the menu, a REQ_SCR_ULINE is generated, if you 4492 doubleclick a REQ_SCR_UPAGE is generated and if you 4493 tripleclick a REQ_FIRST_ITEM is generated. If you click 4494 below the display region of the menu, a REQ_SCR_DLINE is 4495 generated, if you doubleclick a REQ_SCR_DPAGE is generated 4496 and if you tripleclick a REQ_LAST_ITEM is generated. If 4497 you click at an item inside the display area of the menu, 4498 the menu cursor is positioned to that item.</i></span> 4499</pre> 4500 </li> 4501 </ul> 4502 4503 <p>Each of the above requests will be explained in the 4504 following lines with several examples whenever 4505 appropriate.</p> 4506 </div> 4507 4508 <div class="SECT2"> 4509 <hr> 4510 4511 <h3 class="SECT2"><a name="MENUWINDOWS" id= 4512 "MENUWINDOWS">17.4. Menu Windows</a></h3> 4513 4514 <p>Every menu created is associated with a window and a sub 4515 window. The menu window displays any title or border 4516 associated with the menu. The menu sub window displays the 4517 menu items currently available for selection. But we didn't 4518 specify any window or sub window in the simple example. 4519 When a window is not specified, stdscr is taken as the main 4520 window, and then menu system calculates the sub window size 4521 required for the display of items. Then items are displayed 4522 in the calculated sub window. So let's play with these 4523 windows and display a menu with a border and a title.</p> 4524 4525 <div class="EXAMPLE"> 4526 <a name="MMEWI" id="MMEWI"></a> 4527 4528 <p><b>Example 19. Menu Windows Usage example</b></p> 4529 <pre class="PROGRAMLISTING"> 4530<span class="INLINEMEDIAOBJECT">#include <menu.h> 4531 4532#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 4533#define CTRLD 4 4534 4535char *choices[] = { 4536 "Choice 1", 4537 "Choice 2", 4538 "Choice 3", 4539 "Choice 4", 4540 "Exit", 4541 (char *)NULL, 4542 }; 4543void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 4544 4545int main() 4546{ ITEM **my_items; 4547 int c; 4548 MENU *my_menu; 4549 WINDOW *my_menu_win; 4550 int n_choices, i; 4551 4552 /* Initialize curses */ 4553 initscr(); 4554 start_color(); 4555 cbreak(); 4556 noecho(); 4557 keypad(stdscr, TRUE); 4558 init_pair(1, COLOR_RED, COLOR_BLACK); 4559 4560 /* Create items */ 4561 n_choices = ARRAY_SIZE(choices); 4562 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *)); 4563 for(i = 0; i < n_choices; ++i) 4564 my_items[i] = new_item(choices[i], choices[i]); 4565 4566 /* Crate menu */ 4567 my_menu = new_menu((ITEM **)my_items); 4568 4569 /* Create the window to be associated with the menu */ 4570 my_menu_win = newwin(10, 40, 4, 4); 4571 keypad(my_menu_win, TRUE); 4572 4573 /* Set main window and sub window */ 4574 set_menu_win(my_menu, my_menu_win); 4575 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1)); 4576 4577 /* Set menu mark to the string " * " */ 4578 set_menu_mark(my_menu, " * "); 4579 4580 /* Print a border around the main window and print a title */ 4581 box(my_menu_win, 0, 0); 4582 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1)); 4583 mvwaddch(my_menu_win, 2, 0, ACS_LTEE); 4584 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38); 4585 mvwaddch(my_menu_win, 2, 39, ACS_RTEE); 4586 mvprintw(LINES - 2, 0, "F1 to exit"); 4587 refresh(); 4588 4589 /* Post the menu */ 4590 post_menu(my_menu); 4591 wrefresh(my_menu_win); 4592 4593 while((c = wgetch(my_menu_win)) != KEY_F(1)) 4594 { switch(c) 4595 { case KEY_DOWN: 4596 menu_driver(my_menu, REQ_DOWN_ITEM); 4597 break; 4598 case KEY_UP: 4599 menu_driver(my_menu, REQ_UP_ITEM); 4600 break; 4601 } 4602 wrefresh(my_menu_win); 4603 } 4604 4605 /* Unpost and free all the memory taken up */ 4606 unpost_menu(my_menu); 4607 free_menu(my_menu); 4608 for(i = 0; i < n_choices; ++i) 4609 free_item(my_items[i]); 4610 endwin(); 4611} 4612 4613void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 4614{ int length, x, y; 4615 float temp; 4616 4617 if(win == NULL) 4618 win = stdscr; 4619 getyx(win, y, x); 4620 if(startx != 0) 4621 x = startx; 4622 if(starty != 0) 4623 y = starty; 4624 if(width == 0) 4625 width = 80; 4626 4627 length = strlen(string); 4628 temp = (width - length)/ 2; 4629 x = startx + (int)temp; 4630 wattron(win, color); 4631 mvwprintw(win, y, x, "%s", string); 4632 wattroff(win, color); 4633 refresh(); 4634}</span> 4635</pre> 4636 </div> 4637 4638 <p>This example creates a menu with a title, border, a 4639 fancy line separating title and the items. As you can see, 4640 in order to attach a window to a menu the function 4641 set_menu_win() has to be used. Then we attach the sub 4642 window also. This displays the items in the sub window. You 4643 can also set the mark string which gets displayed to the 4644 left of the selected item with set_menu_mark().</p> 4645 </div> 4646 4647 <div class="SECT2"> 4648 <hr> 4649 4650 <h3 class="SECT2"><a name="SCROLLMENUS" id= 4651 "SCROLLMENUS">17.5. Scrolling Menus</a></h3> 4652 4653 <p>If the sub window given for a window is not big enough 4654 to show all the items, then the menu will be scrollable. 4655 When you are on the last item in the present list, if you 4656 send REQ_DOWN_ITEM, it gets translated into REQ_SCR_DLINE 4657 and the menu scrolls by one item. You can manually give 4658 REQ_SCR_ operations to do scrolling. Let's see how it can 4659 be done.</p> 4660 4661 <div class="EXAMPLE"> 4662 <a name="MMESC" id="MMESC"></a> 4663 4664 <p><b>Example 20. Scrolling Menus example</b></p> 4665 <pre class="PROGRAMLISTING"> 4666<span class="INLINEMEDIAOBJECT">#include <curses.h> 4667#include <menu.h> 4668 4669#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 4670#define CTRLD 4 4671 4672char *choices[] = { 4673 "Choice 1", 4674 "Choice 2", 4675 "Choice 3", 4676 "Choice 4", 4677 "Choice 5", 4678 "Choice 6", 4679 "Choice 7", 4680 "Choice 8", 4681 "Choice 9", 4682 "Choice 10", 4683 "Exit", 4684 (char *)NULL, 4685 }; 4686void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 4687 4688int main() 4689{ ITEM **my_items; 4690 int c; 4691 MENU *my_menu; 4692 WINDOW *my_menu_win; 4693 int n_choices, i; 4694 4695 /* Initialize curses */ 4696 initscr(); 4697 start_color(); 4698 cbreak(); 4699 noecho(); 4700 keypad(stdscr, TRUE); 4701 init_pair(1, COLOR_RED, COLOR_BLACK); 4702 init_pair(2, COLOR_CYAN, COLOR_BLACK); 4703 4704 /* Create items */ 4705 n_choices = ARRAY_SIZE(choices); 4706 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *)); 4707 for(i = 0; i < n_choices; ++i) 4708 my_items[i] = new_item(choices[i], choices[i]); 4709 4710 /* Crate menu */ 4711 my_menu = new_menu((ITEM **)my_items); 4712 4713 /* Create the window to be associated with the menu */ 4714 my_menu_win = newwin(10, 40, 4, 4); 4715 keypad(my_menu_win, TRUE); 4716 4717 /* Set main window and sub window */ 4718 set_menu_win(my_menu, my_menu_win); 4719 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1)); 4720 set_menu_format(my_menu, 5, 1); 4721 4722 /* Set menu mark to the string " * " */ 4723 set_menu_mark(my_menu, " * "); 4724 4725 /* Print a border around the main window and print a title */ 4726 box(my_menu_win, 0, 0); 4727 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1)); 4728 mvwaddch(my_menu_win, 2, 0, ACS_LTEE); 4729 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38); 4730 mvwaddch(my_menu_win, 2, 39, ACS_RTEE); 4731 4732 /* Post the menu */ 4733 post_menu(my_menu); 4734 wrefresh(my_menu_win); 4735 4736 attron(COLOR_PAIR(2)); 4737 mvprintw(LINES - 2, 0, "Use PageUp and PageDown to scoll down or up a page of items"); 4738 mvprintw(LINES - 1, 0, "Arrow Keys to navigate (F1 to Exit)"); 4739 attroff(COLOR_PAIR(2)); 4740 refresh(); 4741 4742 while((c = wgetch(my_menu_win)) != KEY_F(1)) 4743 { switch(c) 4744 { case KEY_DOWN: 4745 menu_driver(my_menu, REQ_DOWN_ITEM); 4746 break; 4747 case KEY_UP: 4748 menu_driver(my_menu, REQ_UP_ITEM); 4749 break; 4750 case KEY_NPAGE: 4751 menu_driver(my_menu, REQ_SCR_DPAGE); 4752 break; 4753 case KEY_PPAGE: 4754 menu_driver(my_menu, REQ_SCR_UPAGE); 4755 break; 4756 } 4757 wrefresh(my_menu_win); 4758 } 4759 4760 /* Unpost and free all the memory taken up */ 4761 unpost_menu(my_menu); 4762 free_menu(my_menu); 4763 for(i = 0; i < n_choices; ++i) 4764 free_item(my_items[i]); 4765 endwin(); 4766} 4767 4768void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 4769{ int length, x, y; 4770 float temp; 4771 4772 if(win == NULL) 4773 win = stdscr; 4774 getyx(win, y, x); 4775 if(startx != 0) 4776 x = startx; 4777 if(starty != 0) 4778 y = starty; 4779 if(width == 0) 4780 width = 80; 4781 4782 length = strlen(string); 4783 temp = (width - length)/ 2; 4784 x = startx + (int)temp; 4785 wattron(win, color); 4786 mvwprintw(win, y, x, "%s", string); 4787 wattroff(win, color); 4788 refresh(); 4789}</span> 4790</pre> 4791 </div> 4792 4793 <p>This program is self-explanatory. In this example the 4794 number of choices has been increased to ten, which is 4795 larger than our sub window size which can hold 6 items. 4796 This message has to be explicitly conveyed to the menu 4797 system with the function set_menu_format(). In here we 4798 specify the number of rows and columns we want to be 4799 displayed for a single page. We can specify any number of 4800 items to be shown, in the rows variables, if it is less 4801 than the height of the sub window. If the key pressed by 4802 the user is a PAGE UP or PAGE DOWN, the menu is scrolled a 4803 page due to the requests (REQ_SCR_DPAGE and REQ_SCR_UPAGE) 4804 given to menu_driver().</p> 4805 </div> 4806 4807 <div class="SECT2"> 4808 <hr> 4809 4810 <h3 class="SECT2"><a name="MULTICOLUMN" id= 4811 "MULTICOLUMN">17.6. Multi Columnar Menus</a></h3> 4812 4813 <p>In the above example you have seen how to use the 4814 function set_menu_format(). I didn't mention what the cols 4815 variable (third parameter) does. Well, If your sub window 4816 is wide enough, you can opt to display more than one item 4817 per row. This can be specified in the cols variable. To 4818 make things simpler, the following example doesn't show 4819 descriptions for the items.</p> 4820 4821 <div class="EXAMPLE"> 4822 <a name="MMEMUCO" id="MMEMUCO"></a> 4823 4824 <p><b>Example 21. Milt Columnar Menus Example</b></p> 4825 <pre class="PROGRAMLISTING"> 4826<span class="INLINEMEDIAOBJECT">#include <curses.h> 4827#include <menu.h> 4828 4829#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 4830#define CTRLD 4 4831 4832char *choices[] = { 4833 "Choice 1", "Choice 2", "Choice 3", "Choice 4", "Choice 5", 4834 "Choice 6", "Choice 7", "Choice 8", "Choice 9", "Choice 10", 4835 "Choice 11", "Choice 12", "Choice 13", "Choice 14", "Choice 15", 4836 "Choice 16", "Choice 17", "Choice 18", "Choice 19", "Choice 20", 4837 "Exit", 4838 (char *)NULL, 4839 }; 4840 4841int main() 4842{ ITEM **my_items; 4843 int c; 4844 MENU *my_menu; 4845 WINDOW *my_menu_win; 4846 int n_choices, i; 4847 4848 /* Initialize curses */ 4849 initscr(); 4850 start_color(); 4851 cbreak(); 4852 noecho(); 4853 keypad(stdscr, TRUE); 4854 init_pair(1, COLOR_RED, COLOR_BLACK); 4855 init_pair(2, COLOR_CYAN, COLOR_BLACK); 4856 4857 /* Create items */ 4858 n_choices = ARRAY_SIZE(choices); 4859 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *)); 4860 for(i = 0; i < n_choices; ++i) 4861 my_items[i] = new_item(choices[i], choices[i]); 4862 4863 /* Crate menu */ 4864 my_menu = new_menu((ITEM **)my_items); 4865 4866 /* Set menu option not to show the description */ 4867 menu_opts_off(my_menu, O_SHOWDESC); 4868 4869 /* Create the window to be associated with the menu */ 4870 my_menu_win = newwin(10, 70, 4, 4); 4871 keypad(my_menu_win, TRUE); 4872 4873 /* Set main window and sub window */ 4874 set_menu_win(my_menu, my_menu_win); 4875 set_menu_sub(my_menu, derwin(my_menu_win, 6, 68, 3, 1)); 4876 set_menu_format(my_menu, 5, 3); 4877 set_menu_mark(my_menu, " * "); 4878 4879 /* Print a border around the main window and print a title */ 4880 box(my_menu_win, 0, 0); 4881 4882 attron(COLOR_PAIR(2)); 4883 mvprintw(LINES - 3, 0, "Use PageUp and PageDown to scroll"); 4884 mvprintw(LINES - 2, 0, "Use Arrow Keys to navigate (F1 to Exit)"); 4885 attroff(COLOR_PAIR(2)); 4886 refresh(); 4887 4888 /* Post the menu */ 4889 post_menu(my_menu); 4890 wrefresh(my_menu_win); 4891 4892 while((c = wgetch(my_menu_win)) != KEY_F(1)) 4893 { switch(c) 4894 { case KEY_DOWN: 4895 menu_driver(my_menu, REQ_DOWN_ITEM); 4896 break; 4897 case KEY_UP: 4898 menu_driver(my_menu, REQ_UP_ITEM); 4899 break; 4900 case KEY_LEFT: 4901 menu_driver(my_menu, REQ_LEFT_ITEM); 4902 break; 4903 case KEY_RIGHT: 4904 menu_driver(my_menu, REQ_RIGHT_ITEM); 4905 break; 4906 case KEY_NPAGE: 4907 menu_driver(my_menu, REQ_SCR_DPAGE); 4908 break; 4909 case KEY_PPAGE: 4910 menu_driver(my_menu, REQ_SCR_UPAGE); 4911 break; 4912 } 4913 wrefresh(my_menu_win); 4914 } 4915 4916 /* Unpost and free all the memory taken up */ 4917 unpost_menu(my_menu); 4918 free_menu(my_menu); 4919 for(i = 0; i < n_choices; ++i) 4920 free_item(my_items[i]); 4921 endwin(); 4922}</span> 4923</pre> 4924 </div> 4925 4926 <p>Watch the function call to set_menu_format(). It 4927 specifies the number of columns to be 3, thus displaying 3 4928 items per row. We have also switched off the showing 4929 descriptions with the function menu_opts_off(). There are 4930 couple of functions set_menu_opts(), menu_opts_on() and 4931 menu_opts() which can be used to manipulate menu options. 4932 The following menu options can be specified.</p> 4933 <pre class="PROGRAMLISTING"> 4934 O_ONEVALUE 4935 Only one item can be selected for this menu. 4936 4937 O_SHOWDESC 4938 Display the item descriptions when the menu is 4939 posted. 4940 4941 O_ROWMAJOR 4942 Display the menu in row-major order. 4943 4944 O_IGNORECASE 4945 Ignore the case when pattern-matching. 4946 4947 O_SHOWMATCH 4948 Move the cursor to within the item name while pat­ 4949 tern-matching. 4950 4951 O_NONCYCLIC 4952 Don't wrap around next-item and previous-item, 4953 requests to the other end of the menu. 4954</pre> 4955 4956 <p>All options are on by default. You can switch specific 4957 attributes on or off with menu_opts_on() and 4958 menu_opts_off() functions. You can also use set_menu_opts() 4959 to directly specify the options. The argument to this 4960 function should be a OR ed value of some of those above 4961 constants. The function menu_opts() can be used to find out 4962 a menu's present options.</p> 4963 </div> 4964 4965 <div class="SECT2"> 4966 <hr> 4967 4968 <h3 class="SECT2"><a name="MULTIVALUEMENUS" id= 4969 "MULTIVALUEMENUS">17.7. Multi Valued Menus</a></h3> 4970 4971 <p>You might be wondering what if you switch off the option 4972 O_ONEVALUE. Then the menu becomes multi-valued. That means 4973 you can select more than one item. This brings us to the 4974 request REQ_TOGGLE_ITEM. Let's see it in action.</p> 4975 4976 <div class="EXAMPLE"> 4977 <a name="MMETO" id="MMETO"></a> 4978 4979 <p><b>Example 22. Multi Valued Menus example</b></p> 4980 <pre class="PROGRAMLISTING"> 4981<span class="INLINEMEDIAOBJECT">#include <curses.h> 4982#include <menu.h> 4983 4984#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 4985#define CTRLD 4 4986 4987char *choices[] = { 4988 "Choice 1", 4989 "Choice 2", 4990 "Choice 3", 4991 "Choice 4", 4992 "Choice 5", 4993 "Choice 6", 4994 "Choice 7", 4995 "Exit", 4996 }; 4997 4998int main() 4999{ ITEM **my_items; 5000 int c; 5001 MENU *my_menu; 5002 int n_choices, i; 5003 ITEM *cur_item; 5004 5005 /* Initialize curses */ 5006 initscr(); 5007 cbreak(); 5008 noecho(); 5009 keypad(stdscr, TRUE); 5010 5011 /* Initialize items */ 5012 n_choices = ARRAY_SIZE(choices); 5013 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); 5014 for(i = 0; i < n_choices; ++i) 5015 my_items[i] = new_item(choices[i], choices[i]); 5016 my_items[n_choices] = (ITEM *)NULL; 5017 5018 my_menu = new_menu((ITEM **)my_items); 5019 5020 /* Make the menu multi valued */ 5021 menu_opts_off(my_menu, O_ONEVALUE); 5022 5023 mvprintw(LINES - 3, 0, "Use <SPACE> to select or unselect an item."); 5024 mvprintw(LINES - 2, 0, "<ENTER> to see presently selected items(F1 to Exit)"); 5025 post_menu(my_menu); 5026 refresh(); 5027 5028 while((c = getch()) != KEY_F(1)) 5029 { switch(c) 5030 { case KEY_DOWN: 5031 menu_driver(my_menu, REQ_DOWN_ITEM); 5032 break; 5033 case KEY_UP: 5034 menu_driver(my_menu, REQ_UP_ITEM); 5035 break; 5036 case ' ': 5037 menu_driver(my_menu, REQ_TOGGLE_ITEM); 5038 break; 5039 case 10: /* Enter */ 5040 { char temp[200]; 5041 ITEM **items; 5042 5043 items = menu_items(my_menu); 5044 temp[0] = '\0'; 5045 for(i = 0; i < item_count(my_menu); ++i) 5046 if(item_value(items[i]) == TRUE) 5047 { strcat(temp, item_name(items[i])); 5048 strcat(temp, " "); 5049 } 5050 move(20, 0); 5051 clrtoeol(); 5052 mvprintw(20, 0, temp); 5053 refresh(); 5054 } 5055 break; 5056 } 5057 } 5058 5059 free_item(my_items[0]); 5060 free_item(my_items[1]); 5061 free_menu(my_menu); 5062 endwin(); 5063} 5064 </span> 5065</pre> 5066 </div> 5067 5068 <p>Whew, A lot of new functions. Let's take them one after 5069 another. Firstly, the REQ_TOGGLE_ITEM. In a multi-valued 5070 menu, the user should be allowed to select or un select 5071 more than one item. The request REQ_TOGGLE_ITEM toggles the 5072 present selection. In this case when space is pressed 5073 REQ_TOGGLE_ITEM request is sent to menu_driver to achieve 5074 the result.</p> 5075 5076 <p>Now when the user presses <ENTER> we show the 5077 items he presently selected. First we find out the items 5078 associated with the menu using the function menu_items(). 5079 Then we loop through the items to find out if the item is 5080 selected or not. The function item_value() returns TRUE if 5081 an item is selected. The function item_count() returns the 5082 number of items in the menu. The item name can be found 5083 with item_name(). You can also find the description 5084 associated with an item using item_description().</p> 5085 </div> 5086 5087 <div class="SECT2"> 5088 <hr> 5089 5090 <h3 class="SECT2"><a name="MENUOPT" id="MENUOPT">17.8. Menu 5091 Options</a></h3> 5092 5093 <p>Well, by this time you must be itching for some 5094 difference in your menu, with lots of functionality. I 5095 know. You want Colors !!!. You want to create nice menus 5096 similar to those text mode <a href= 5097 "http://www.jersey.net/~debinjoe/games/" target="_top">dos 5098 games</a>. The functions set_menu_fore() and 5099 set_menu_back() can be used to change the attribute of the 5100 selected item and unselected item. The names are 5101 misleading. They don't change menu's foreground or 5102 background which would have been useless.</p> 5103 5104 <p>The function set_menu_grey() can be used to set the 5105 display attribute for the non-selectable items in the menu. 5106 This brings us to the interesting option for an item the 5107 one and only O_SELECTABLE. We can turn it off by the 5108 function item_opts_off() and after that that item is not 5109 selectable. It's like a grayed item in those fancy windows 5110 menus. Let's put these concepts in practice with this 5111 example</p> 5112 5113 <div class="EXAMPLE"> 5114 <a name="MMEAT" id="MMEAT"></a> 5115 5116 <p><b>Example 23. Menu Options example</b></p> 5117 <pre class="PROGRAMLISTING"> 5118<span class="INLINEMEDIAOBJECT">#include <menu.h> 5119 5120#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 5121#define CTRLD 4 5122 5123char *choices[] = { 5124 "Choice 1", 5125 "Choice 2", 5126 "Choice 3", 5127 "Choice 4", 5128 "Choice 5", 5129 "Choice 6", 5130 "Choice 7", 5131 "Exit", 5132 }; 5133 5134int main() 5135{ ITEM **my_items; 5136 int c; 5137 MENU *my_menu; 5138 int n_choices, i; 5139 ITEM *cur_item; 5140 5141 /* Initialize curses */ 5142 initscr(); 5143 start_color(); 5144 cbreak(); 5145 noecho(); 5146 keypad(stdscr, TRUE); 5147 init_pair(1, COLOR_RED, COLOR_BLACK); 5148 init_pair(2, COLOR_GREEN, COLOR_BLACK); 5149 init_pair(3, COLOR_MAGENTA, COLOR_BLACK); 5150 5151 /* Initialize items */ 5152 n_choices = ARRAY_SIZE(choices); 5153 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); 5154 for(i = 0; i < n_choices; ++i) 5155 my_items[i] = new_item(choices[i], choices[i]); 5156 my_items[n_choices] = (ITEM *)NULL; 5157 item_opts_off(my_items[3], O_SELECTABLE); 5158 item_opts_off(my_items[6], O_SELECTABLE); 5159 5160 /* Create menu */ 5161 my_menu = new_menu((ITEM **)my_items); 5162 5163 /* Set fore ground and back ground of the menu */ 5164 set_menu_fore(my_menu, COLOR_PAIR(1) | A_REVERSE); 5165 set_menu_back(my_menu, COLOR_PAIR(2)); 5166 set_menu_grey(my_menu, COLOR_PAIR(3)); 5167 5168 /* Post the menu */ 5169 mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected"); 5170 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)"); 5171 post_menu(my_menu); 5172 refresh(); 5173 5174 while((c = getch()) != KEY_F(1)) 5175 { switch(c) 5176 { case KEY_DOWN: 5177 menu_driver(my_menu, REQ_DOWN_ITEM); 5178 break; 5179 case KEY_UP: 5180 menu_driver(my_menu, REQ_UP_ITEM); 5181 break; 5182 case 10: /* Enter */ 5183 move(20, 0); 5184 clrtoeol(); 5185 mvprintw(20, 0, "Item selected is : %s", 5186 item_name(current_item(my_menu))); 5187 pos_menu_cursor(my_menu); 5188 break; 5189 } 5190 } 5191 unpost_menu(my_menu); 5192 for(i = 0; i < n_choices; ++i) 5193 free_item(my_items[i]); 5194 free_menu(my_menu); 5195 endwin(); 5196} 5197 </span> 5198</pre> 5199 </div> 5200 </div> 5201 5202 <div class="SECT2"> 5203 <hr> 5204 5205 <h3 class="SECT2"><a name="MENUUSERPTR" id= 5206 "MENUUSERPTR">17.9. The useful User Pointer</a></h3> 5207 5208 <p>We can associate a user pointer with each item in the 5209 menu. It works the same way as user pointer in panels. It's 5210 not touched by menu system. You can store any thing you 5211 like in that. I usually use it to store the function to be 5212 executed when the menu option is chosen (It's selected and 5213 may be the user pressed <ENTER>);</p> 5214 5215 <div class="EXAMPLE"> 5216 <a name="MMEUS" id="MMEUS"></a> 5217 5218 <p><b>Example 24. Menu User Pointer Usage</b></p> 5219 <pre class="PROGRAMLISTING"> 5220<span class="INLINEMEDIAOBJECT">#include <curses.h> 5221#include <menu.h> 5222 5223#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 5224#define CTRLD 4 5225 5226char *choices[] = { 5227 "Choice 1", 5228 "Choice 2", 5229 "Choice 3", 5230 "Choice 4", 5231 "Choice 5", 5232 "Choice 6", 5233 "Choice 7", 5234 "Exit", 5235 }; 5236void func(char *name); 5237 5238int main() 5239{ ITEM **my_items; 5240 int c; 5241 MENU *my_menu; 5242 int n_choices, i; 5243 ITEM *cur_item; 5244 5245 /* Initialize curses */ 5246 initscr(); 5247 start_color(); 5248 cbreak(); 5249 noecho(); 5250 keypad(stdscr, TRUE); 5251 init_pair(1, COLOR_RED, COLOR_BLACK); 5252 init_pair(2, COLOR_GREEN, COLOR_BLACK); 5253 init_pair(3, COLOR_MAGENTA, COLOR_BLACK); 5254 5255 /* Initialize items */ 5256 n_choices = ARRAY_SIZE(choices); 5257 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); 5258 for(i = 0; i < n_choices; ++i) 5259 { my_items[i] = new_item(choices[i], choices[i]); 5260 /* Set the user pointer */ 5261 set_item_userptr(my_items[i], func); 5262 } 5263 my_items[n_choices] = (ITEM *)NULL; 5264 5265 /* Create menu */ 5266 my_menu = new_menu((ITEM **)my_items); 5267 5268 /* Post the menu */ 5269 mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected"); 5270 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)"); 5271 post_menu(my_menu); 5272 refresh(); 5273 5274 while((c = getch()) != KEY_F(1)) 5275 { switch(c) 5276 { case KEY_DOWN: 5277 menu_driver(my_menu, REQ_DOWN_ITEM); 5278 break; 5279 case KEY_UP: 5280 menu_driver(my_menu, REQ_UP_ITEM); 5281 break; 5282 case 10: /* Enter */ 5283 { ITEM *cur; 5284 void (*p)(char *); 5285 5286 cur = current_item(my_menu); 5287 p = item_userptr(cur); 5288 p((char *)item_name(cur)); 5289 pos_menu_cursor(my_menu); 5290 break; 5291 } 5292 break; 5293 } 5294 } 5295 unpost_menu(my_menu); 5296 for(i = 0; i < n_choices; ++i) 5297 free_item(my_items[i]); 5298 free_menu(my_menu); 5299 endwin(); 5300} 5301 5302void func(char *name) 5303{ move(20, 0); 5304 clrtoeol(); 5305 mvprintw(20, 0, "Item selected is : %s", name); 5306} </span> 5307</pre> 5308 </div> 5309 </div> 5310 </div> 5311 5312 <div class="SECT1"> 5313 <hr> 5314 5315 <h2 class="SECT1"><a name="FORMS" id="FORMS">18. Forms 5316 Library</a></h2> 5317 5318 <p>Well. If you have seen those forms on web pages which take 5319 input from users and do various kinds of things, you might be 5320 wondering how would any one create such forms in text mode 5321 display. It's quite difficult to write those nifty forms in 5322 plain ncurses. Forms library tries to provide a basic frame 5323 work to build and maintain forms with ease. It has lot of 5324 features(functions) which manage validation, dynamic 5325 expansion of fields etc.. Let's see it in full flow.</p> 5326 5327 <p>A form is a collection of fields; each field can be either 5328 a label(static text) or a data-entry location. The forms also 5329 library provides functions to divide forms into multiple 5330 pages.</p> 5331 5332 <div class="SECT2"> 5333 <hr> 5334 5335 <h3 class="SECT2"><a name="FORMBASICS" id= 5336 "FORMBASICS">18.1. The Basics</a></h3> 5337 5338 <p>Forms are created in much the same way as menus. First 5339 the fields related to the form are created with 5340 new_field(). You can set options for the fields, so that 5341 they can be displayed with some fancy attributes, validated 5342 before the field looses focus etc.. Then the fields are 5343 attached to form. After this, the form can be posted to 5344 display and is ready to receive inputs. On the similar 5345 lines to menu_driver(), the form is manipulated with 5346 form_driver(). We can send requests to form_driver to move 5347 focus to a certain field, move cursor to end of the field 5348 etc.. After the user enters values in the fields and 5349 validation done, form can be unposted and memory allocated 5350 can be freed.</p> 5351 5352 <p>The general flow of control of a forms program looks 5353 like this.</p> 5354 5355 <ol type="1"> 5356 <li> 5357 <p>Initialize curses</p> 5358 </li> 5359 5360 <li> 5361 <p>Create fields using new_field(). You can specify the 5362 height and width of the field, and its position on the 5363 form.</p> 5364 </li> 5365 5366 <li> 5367 <p>Create the forms with new_form() by specifying the 5368 fields to be attached with.</p> 5369 </li> 5370 5371 <li> 5372 <p>Post the form with form_post() and refresh the 5373 screen.</p> 5374 </li> 5375 5376 <li> 5377 <p>Process the user requests with a loop and do 5378 necessary updates to form with form_driver.</p> 5379 </li> 5380 5381 <li> 5382 <p>Unpost the menu with form_unpost()</p> 5383 </li> 5384 5385 <li> 5386 <p>Free the memory allocated to menu by free_form()</p> 5387 </li> 5388 5389 <li> 5390 <p>Free the memory allocated to the items with 5391 free_field()</p> 5392 </li> 5393 5394 <li> 5395 <p>End curses</p> 5396 </li> 5397 </ol> 5398 5399 <p>As you can see, working with forms library is much 5400 similar to handling menu library. The following examples 5401 will explore various aspects of form processing. Let's 5402 start the journey with a simple example. first.</p> 5403 </div> 5404 5405 <div class="SECT2"> 5406 <hr> 5407 5408 <h3 class="SECT2"><a name="COMPILEFORMS" id= 5409 "COMPILEFORMS">18.2. Compiling With the Forms 5410 Library</a></h3> 5411 5412 <p>To use forms library functions, you have to include 5413 form.h and to link the program with forms library the flag 5414 -lform should be added along with -lncurses in that 5415 order.</p> 5416 <pre class="PROGRAMLISTING"> 5417 #include <form.h> 5418 . 5419 . 5420 . 5421 5422 compile and link: gcc <program file> -lform -lncurses 5423</pre> 5424 5425 <div class="EXAMPLE"> 5426 <a name="FFOSI" id="FFOSI"></a> 5427 5428 <p><b>Example 25. Forms Basics</b></p> 5429 <pre class="PROGRAMLISTING"> 5430<span class="INLINEMEDIAOBJECT">#include <form.h> 5431 5432int main() 5433{ FIELD *field[3]; 5434 FORM *my_form; 5435 int ch; 5436 5437 /* Initialize curses */ 5438 initscr(); 5439 cbreak(); 5440 noecho(); 5441 keypad(stdscr, TRUE); 5442 5443 /* Initialize the fields */ 5444 field[0] = new_field(1, 10, 4, 18, 0, 0); 5445 field[1] = new_field(1, 10, 6, 18, 0, 0); 5446 field[2] = NULL; 5447 5448 /* Set field options */ 5449 set_field_back(field[0], A_UNDERLINE); /* Print a line for the option */ 5450 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */ 5451 /* Field is filled up */ 5452 set_field_back(field[1], A_UNDERLINE); 5453 field_opts_off(field[1], O_AUTOSKIP); 5454 5455 /* Create the form and post it */ 5456 my_form = new_form(field); 5457 post_form(my_form); 5458 refresh(); 5459 5460 mvprintw(4, 10, "Value 1:"); 5461 mvprintw(6, 10, "Value 2:"); 5462 refresh(); 5463 5464 /* Loop through to get user requests */ 5465 while((ch = getch()) != KEY_F(1)) 5466 { switch(ch) 5467 { case KEY_DOWN: 5468 /* Go to next field */ 5469 form_driver(my_form, REQ_NEXT_FIELD); 5470 /* Go to the end of the present buffer */ 5471 /* Leaves nicely at the last character */ 5472 form_driver(my_form, REQ_END_LINE); 5473 break; 5474 case KEY_UP: 5475 /* Go to previous field */ 5476 form_driver(my_form, REQ_PREV_FIELD); 5477 form_driver(my_form, REQ_END_LINE); 5478 break; 5479 default: 5480 /* If this is a normal character, it gets */ 5481 /* Printed */ 5482 form_driver(my_form, ch); 5483 break; 5484 } 5485 } 5486 5487 /* Un post form and free the memory */ 5488 unpost_form(my_form); 5489 free_form(my_form); 5490 free_field(field[0]); 5491 free_field(field[1]); 5492 5493 endwin(); 5494 return 0; 5495}</span> 5496</pre> 5497 </div> 5498 5499 <p>Above example is pretty straight forward. It creates two 5500 fields with <tt class="LITERAL">new_field()</tt>. 5501 new_field() takes height, width, starty, startx, number of 5502 offscreen rows and number of additional working buffers. 5503 The fifth argument number of offscreen rows specifies how 5504 much of the field to be shown. If it is zero, the entire 5505 field is always displayed otherwise the form will be 5506 scrollable when the user accesses not displayed parts of 5507 the field. The forms library allocates one buffer per field 5508 to store the data user enters. Using the last parameter to 5509 new_field() we can specify it to allocate some additional 5510 buffers. These can be used for any purpose you like.</p> 5511 5512 <p>After creating the fields, back ground attribute of both 5513 of them is set to an underscore with set_field_back(). The 5514 AUTOSKIP option is turned off using field_opts_off(). If 5515 this option is turned on, focus will move to the next field 5516 in the form once the active field is filled up 5517 completely.</p> 5518 5519 <p>After attaching the fields to the form, it is posted. 5520 Here on, user inputs are processed in the while loop, by 5521 making corresponding requests to form_driver. The details 5522 of all the requests to the form_driver() are explained 5523 later.</p> 5524 </div> 5525 5526 <div class="SECT2"> 5527 <hr> 5528 5529 <h3 class="SECT2"><a name="PLAYFIELDS" id= 5530 "PLAYFIELDS">18.3. Playing with Fields</a></h3> 5531 5532 <p>Each form field is associated with a lot of attributes. 5533 They can be manipulated to get the required effect and to 5534 have fun !!!. So why wait?</p> 5535 5536 <div class="SECT3"> 5537 <hr> 5538 5539 <h4 class="SECT3"><a name="FETCHINFO" id= 5540 "FETCHINFO">18.3.1. Fetching Size and Location of 5541 Field</a></h4> 5542 5543 <p>The parameters we have given at the time of creation 5544 of a field can be retrieved with field_info(). It returns 5545 height, width, starty, startx, number of offscreen rows, 5546 and number of additional buffers into the parameters 5547 given to it. It is a sort of inverse of new_field().</p> 5548 <pre class="PROGRAMLISTING"> 5549int field_info( FIELD *field, /* field from which to fetch */ 5550 int *height, *int width, /* field size */ 5551 int *top, int *left, /* upper left corner */ 5552 int *offscreen, /* number of offscreen rows */ 5553 int *nbuf); /* number of working buffers */ 5554</pre> 5555 </div> 5556 5557 <div class="SECT3"> 5558 <hr> 5559 5560 <h4 class="SECT3"><a name="MOVEFIELD" id= 5561 "MOVEFIELD">18.3.2. Moving the field</a></h4> 5562 5563 <p>The location of the field can be moved to a different 5564 position with move_field().</p> 5565 <pre class="PROGRAMLISTING"> 5566int move_field( FIELD *field, /* field to alter */ 5567 int top, int left); /* new upper-left corner */ 5568</pre> 5569 5570 <p>As usual, the changed position can be queried with 5571 field_infor().</p> 5572 </div> 5573 5574 <div class="SECT3"> 5575 <hr> 5576 5577 <h4 class="SECT3"><a name="JUSTIFYFIELD" id= 5578 "JUSTIFYFIELD">18.3.3. Field Justification</a></h4> 5579 5580 <p>The justification to be done for the field can be 5581 fixed using the function set_field_just().</p> 5582 <pre class="PROGRAMLISTING"> 5583 int set_field_just(FIELD *field, /* field to alter */ 5584 int justmode); /* mode to set */ 5585 int field_just(FIELD *field); /* fetch justify mode of field */ 5586</pre> 5587 5588 <p>The justification mode valued accepted and returned by 5589 these functions are NO_JUSTIFICATION, JUSTIFY_RIGHT, 5590 JUSTIFY_LEFT, or JUSTIFY_CENTER.</p> 5591 </div> 5592 5593 <div class="SECT3"> 5594 <hr> 5595 5596 <h4 class="SECT3"><a name="FIELDDISPATTRIB" id= 5597 "FIELDDISPATTRIB">18.3.4. Field Display 5598 Attributes</a></h4> 5599 5600 <p>As you have seen, in the above example, display 5601 attribute for the fields can be set with set_field_fore() 5602 and setfield_back(). These functions set foreground and 5603 background attribute of the fields. You can also specify 5604 a pad character which will be filled in the unfilled 5605 portion of the field. The pad character is set with a 5606 call to set_field_pad(). Default pad value is a space. 5607 The functions field_fore(), field_back, field_pad() can 5608 be used to query the present foreground, background 5609 attributes and pad character for the field. The following 5610 list gives the usage of functions.</p> 5611 <pre class="PROGRAMLISTING"> 5612 int set_field_fore(FIELD *field, /* field to alter */ 5613 chtype attr); /* attribute to set */ 5614 5615chtype field_fore(FIELD *field); /* field to query */ 5616 /* returns foreground attribute */ 5617 5618int set_field_back(FIELD *field, /* field to alter */ 5619 chtype attr); /* attribute to set */ 5620 5621chtype field_back(FIELD *field); /* field to query */ 5622 /* returns background attribute */ 5623 5624int set_field_pad(FIELD *field, /* field to alter */ 5625 int pad); /* pad character to set */ 5626 5627chtype field_pad(FIELD *field); /* field to query */ 5628 /* returns present pad character */ 5629</pre> 5630 5631 <p>Though above functions seem quite simple, using colors 5632 with set_field_fore() may be frustrating in the 5633 beginning. Let me first explain about foreground and 5634 background attributes of a field. The foreground 5635 attribute is associated with the character. That means a 5636 character in the field is printed with the attribute you 5637 have set with set_field_fore(). Background attribute is 5638 the attribute used to fill background of field, whether 5639 any character is there or not. So what about colors? 5640 Since colors are always defined in pairs, what is the 5641 right way to display colored fields? Here's an example 5642 clarifying color attributes.</p> 5643 5644 <div class="EXAMPLE"> 5645 <a name="FFOAT" id="FFOAT"></a> 5646 5647 <p><b>Example 26. Form Attributes example</b></p> 5648 <pre class="PROGRAMLISTING"> 5649<span class="INLINEMEDIAOBJECT">#include <form.h> 5650 5651int main() 5652{ FIELD *field[3]; 5653 FORM *my_form; 5654 int ch; 5655 5656 /* Initialize curses */ 5657 initscr(); 5658 start_color(); 5659 cbreak(); 5660 noecho(); 5661 keypad(stdscr, TRUE); 5662 5663 /* Initialize few color pairs */ 5664 init_pair(1, COLOR_WHITE, COLOR_BLUE); 5665 init_pair(2, COLOR_WHITE, COLOR_BLUE); 5666 5667 /* Initialize the fields */ 5668 field[0] = new_field(1, 10, 4, 18, 0, 0); 5669 field[1] = new_field(1, 10, 6, 18, 0, 0); 5670 field[2] = NULL; 5671 5672 /* Set field options */ 5673 set_field_fore(field[0], COLOR_PAIR(1));/* Put the field with blue background */ 5674 set_field_back(field[0], COLOR_PAIR(2));/* and white foreground (characters */ 5675 /* are printed in white */ 5676 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */ 5677 /* Field is filled up */ 5678 set_field_back(field[1], A_UNDERLINE); 5679 field_opts_off(field[1], O_AUTOSKIP); 5680 5681 /* Create the form and post it */ 5682 my_form = new_form(field); 5683 post_form(my_form); 5684 refresh(); 5685 5686 set_current_field(my_form, field[0]); /* Set focus to the colored field */ 5687 mvprintw(4, 10, "Value 1:"); 5688 mvprintw(6, 10, "Value 2:"); 5689 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields"); 5690 refresh(); 5691 5692 /* Loop through to get user requests */ 5693 while((ch = getch()) != KEY_F(1)) 5694 { switch(ch) 5695 { case KEY_DOWN: 5696 /* Go to next field */ 5697 form_driver(my_form, REQ_NEXT_FIELD); 5698 /* Go to the end of the present buffer */ 5699 /* Leaves nicely at the last character */ 5700 form_driver(my_form, REQ_END_LINE); 5701 break; 5702 case KEY_UP: 5703 /* Go to previous field */ 5704 form_driver(my_form, REQ_PREV_FIELD); 5705 form_driver(my_form, REQ_END_LINE); 5706 break; 5707 default: 5708 /* If this is a normal character, it gets */ 5709 /* Printed */ 5710 form_driver(my_form, ch); 5711 break; 5712 } 5713 } 5714 5715 /* Un post form and free the memory */ 5716 unpost_form(my_form); 5717 free_form(my_form); 5718 free_field(field[0]); 5719 free_field(field[1]); 5720 5721 endwin(); 5722 return 0; 5723}</span> 5724</pre> 5725 </div> 5726 5727 <p>Play with the color pairs and try to understand the 5728 foreground and background attributes. In my programs 5729 using color attributes, I usually set only the background 5730 with set_field_back(). Curses simply doesn't allow 5731 defining individual color attributes.</p> 5732 </div> 5733 5734 <div class="SECT3"> 5735 <hr> 5736 5737 <h4 class="SECT3"><a name="FIELDOPTIONBITS" id= 5738 "FIELDOPTIONBITS">18.3.5. Field Option Bits</a></h4> 5739 5740 <p>There is also a large collection of field option bits 5741 you can set to control various aspects of forms 5742 processing. You can manipulate them with these 5743 functions:</p> 5744 <pre class="PROGRAMLISTING"> 5745int set_field_opts(FIELD *field, /* field to alter */ 5746 int attr); /* attribute to set */ 5747 5748int field_opts_on(FIELD *field, /* field to alter */ 5749 int attr); /* attributes to turn on */ 5750 5751int field_opts_off(FIELD *field, /* field to alter */ 5752 int attr); /* attributes to turn off */ 5753 5754int field_opts(FIELD *field); /* field to query */ 5755</pre> 5756 5757 <p>The function set_field_opts() can be used to directly 5758 set attributes of a field or you can choose to switch a 5759 few attributes on and off with field_opts_on() and 5760 field_opts_off() selectively. Anytime you can query the 5761 attributes of a field with field_opts(). The following is 5762 the list of available options. By default, all options 5763 are on.</p> 5764 5765 <div class="VARIABLELIST"> 5766 <dl> 5767 <dt>O_VISIBLE</dt> 5768 5769 <dd> 5770 <p>Controls whether the field is visible on the 5771 screen. Can be used during form processing to hide 5772 or pop up fields depending on the value of parent 5773 fields.</p> 5774 </dd> 5775 5776 <dt>O_ACTIVE</dt> 5777 5778 <dd> 5779 <p>Controls whether the field is active during 5780 forms processing (i.e. visited by form navigation 5781 keys). Can be used to make labels or derived fields 5782 with buffer values alterable by the forms 5783 application, not the user.</p> 5784 </dd> 5785 5786 <dt>O_PUBLIC</dt> 5787 5788 <dd> 5789 <p>Controls whether data is displayed during field 5790 entry. If this option is turned off on a field, the 5791 library will accept and edit data in that field, 5792 but it will not be displayed and the visible field 5793 cursor will not move. You can turn off the O_PUBLIC 5794 bit to define password fields.</p> 5795 </dd> 5796 5797 <dt>O_EDIT</dt> 5798 5799 <dd> 5800 <p>Controls whether the field's data can be 5801 modified. When this option is off, all editing 5802 requests except <tt class= 5803 "LITERAL">REQ_PREV_CHOICE</tt> and <tt class= 5804 "LITERAL">REQ_NEXT_CHOICE</tt>will fail. Such 5805 read-only fields may be useful for help 5806 messages.</p> 5807 </dd> 5808 5809 <dt>O_WRAP</dt> 5810 5811 <dd> 5812 <p>Controls word-wrapping in multi-line fields. 5813 Normally, when any character of a (blank-separated) 5814 word reaches the end of the current line, the 5815 entire word is wrapped to the next line (assuming 5816 there is one). When this option is off, the word 5817 will be split across the line break.</p> 5818 </dd> 5819 5820 <dt>O_BLANK</dt> 5821 5822 <dd> 5823 <p>Controls field blanking. When this option is on, 5824 entering a character at the first field position 5825 erases the entire field (except for the 5826 just-entered character).</p> 5827 </dd> 5828 5829 <dt>O_AUTOSKIP</dt> 5830 5831 <dd> 5832 <p>Controls automatic skip to next field when this 5833 one fills. Normally, when the forms user tries to 5834 type more data into a field than will fit, the 5835 editing location jumps to next field. When this 5836 option is off, the user's cursor will hang at the 5837 end of the field. This option is ignored in dynamic 5838 fields that have not reached their size limit.</p> 5839 </dd> 5840 5841 <dt>O_NULLOK</dt> 5842 5843 <dd> 5844 <p>Controls whether validation is applied to blank 5845 fields. Normally, it is not; the user can leave a 5846 field blank without invoking the usual validation 5847 check on exit. If this option is off on a field, 5848 exit from it will invoke a validation check.</p> 5849 </dd> 5850 5851 <dt>O_PASSOK</dt> 5852 5853 <dd> 5854 <p>Controls whether validation occurs on every 5855 exit, or only after the field is modified. Normally 5856 the latter is true. Setting O_PASSOK may be useful 5857 if your field's validation function may change 5858 during forms processing.</p> 5859 </dd> 5860 5861 <dt>O_STATIC</dt> 5862 5863 <dd> 5864 <p>Controls whether the field is fixed to its 5865 initial dimensions. If you turn this off, the field 5866 becomes dynamic and will stretch to fit entered 5867 data.</p> 5868 </dd> 5869 </dl> 5870 </div> 5871 5872 <p>A field's options cannot be changed while the field is 5873 currently selected. However, options may be changed on 5874 posted fields that are not current.</p> 5875 5876 <p>The option values are bit-masks and can be composed 5877 with logical-or in the obvious way. You have seen the 5878 usage of switching off O_AUTOSKIP option. The following 5879 example clarifies usage of some more options. Other 5880 options are explained where appropriate.</p> 5881 5882 <div class="EXAMPLE"> 5883 <a name="FFOOP" id="FFOOP"></a> 5884 5885 <p><b>Example 27. Field Options Usage example</b></p> 5886 <pre class="PROGRAMLISTING"> 5887<span class="INLINEMEDIAOBJECT">#include <form.h> 5888 5889#define STARTX 15 5890#define STARTY 4 5891#define WIDTH 25 5892 5893#define N_FIELDS 3 5894 5895int main() 5896{ FIELD *field[N_FIELDS]; 5897 FORM *my_form; 5898 int ch, i; 5899 5900 /* Initialize curses */ 5901 initscr(); 5902 cbreak(); 5903 noecho(); 5904 keypad(stdscr, TRUE); 5905 5906 /* Initialize the fields */ 5907 for(i = 0; i < N_FIELDS - 1; ++i) 5908 field[i] = new_field(1, WIDTH, STARTY + i * 2, STARTX, 0, 0); 5909 field[N_FIELDS - 1] = NULL; 5910 5911 /* Set field options */ 5912 set_field_back(field[1], A_UNDERLINE); /* Print a line for the option */ 5913 5914 field_opts_off(field[0], O_ACTIVE); /* This field is a static label */ 5915 field_opts_off(field[1], O_PUBLIC); /* This filed is like a password field*/ 5916 field_opts_off(field[1], O_AUTOSKIP); /* To avoid entering the same field */ 5917 /* after last character is entered */ 5918 5919 /* Create the form and post it */ 5920 my_form = new_form(field); 5921 post_form(my_form); 5922 refresh(); 5923 5924 set_field_just(field[0], JUSTIFY_CENTER); /* Center Justification */ 5925 set_field_buffer(field[0], 0, "This is a static Field"); 5926 /* Initialize the field */ 5927 mvprintw(STARTY, STARTX - 10, "Field 1:"); 5928 mvprintw(STARTY + 2, STARTX - 10, "Field 2:"); 5929 refresh(); 5930 5931 /* Loop through to get user requests */ 5932 while((ch = getch()) != KEY_F(1)) 5933 { switch(ch) 5934 { case KEY_DOWN: 5935 /* Go to next field */ 5936 form_driver(my_form, REQ_NEXT_FIELD); 5937 /* Go to the end of the present buffer */ 5938 /* Leaves nicely at the last character */ 5939 form_driver(my_form, REQ_END_LINE); 5940 break; 5941 case KEY_UP: 5942 /* Go to previous field */ 5943 form_driver(my_form, REQ_PREV_FIELD); 5944 form_driver(my_form, REQ_END_LINE); 5945 break; 5946 default: 5947 /* If this is a normal character, it gets */ 5948 /* Printed */ 5949 form_driver(my_form, ch); 5950 break; 5951 } 5952 } 5953 5954 /* Un post form and free the memory */ 5955 unpost_form(my_form); 5956 free_form(my_form); 5957 free_field(field[0]); 5958 free_field(field[1]); 5959 5960 endwin(); 5961 return 0; 5962}</span> 5963</pre> 5964 </div> 5965 5966 <p>This example, though useless, shows the usage of 5967 options. If used properly, they can present information 5968 very effectively in a form. The second field being not 5969 O_PUBLIC, does not show the characters you are 5970 typing.</p> 5971 </div> 5972 5973 <div class="SECT3"> 5974 <hr> 5975 5976 <h4 class="SECT3"><a name="FIELDSTATUS" id= 5977 "FIELDSTATUS">18.3.6. Field Status</a></h4> 5978 5979 <p>The field status specifies whether the field has got 5980 edited or not. It is initially set to FALSE and when user 5981 enters something and the data buffer gets modified it 5982 becomes TRUE. So a field's status can be queried to find 5983 out whether it has been modified or not. The following 5984 functions can assist in those operations.</p> 5985 <pre class="PROGRAMLISTING"> 5986int set_field_status(FIELD *field, /* field to alter */ 5987 int status); /* status to set */ 5988 5989int field_status(FIELD *field); /* fetch status of field */ 5990</pre> 5991 5992 <p>It's better to check the field's status only after 5993 after leaving the field, as data buffer might not have 5994 been updated yet as the validation is still due. To 5995 guarantee that right status is returned, call 5996 field_status() either (1) in the field's exit validation 5997 check routine, (2) from the field's or form's 5998 initialization or termination hooks, or (3) just after a 5999 REQ_VALIDATION request has been processed by the forms 6000 driver</p> 6001 </div> 6002 6003 <div class="SECT3"> 6004 <hr> 6005 6006 <h4 class="SECT3"><a name="FIELDUSERPTR" id= 6007 "FIELDUSERPTR">18.3.7. Field User Pointer</a></h4> 6008 6009 <p>Every field structure contains one pointer that can be 6010 used by the user for various purposes. It is not touched 6011 by forms library and can be used for any purpose by the 6012 user. The following functions set and fetch user 6013 pointer.</p> 6014 <pre class="PROGRAMLISTING"> 6015int set_field_userptr(FIELD *field, 6016 char *userptr); /* the user pointer you wish to associate */ 6017 /* with the field */ 6018 6019char *field_userptr(FIELD *field); /* fetch user pointer of the field */ 6020</pre> 6021 </div> 6022 6023 <div class="SECT3"> 6024 <hr> 6025 6026 <h4 class="SECT3"><a name="VARIABLESIZEFIELDS" id= 6027 "VARIABLESIZEFIELDS">18.3.8. Variable-Sized 6028 Fields</a></h4> 6029 6030 <p>If you want a dynamically changing field with variable 6031 width, this is the feature you want to put to full use. 6032 This will allow the user to enter more data than the 6033 original size of the field and let the field grow. 6034 According to the field orientation it will scroll 6035 horizontally or vertically to incorporate the new 6036 data.</p> 6037 6038 <p>To make a field dynamically growable, the option 6039 O_STATIC should be turned off. This can be done with 6040 a</p> 6041 <pre class="PROGRAMLISTING"> 6042 field_opts_off(field_pointer, O_STATIC); 6043</pre> 6044 6045 <p>But it's usually not advisable to allow a field to 6046 grow infinitely. You can set a maximum limit to the 6047 growth of the field with</p> 6048 <pre class="PROGRAMLISTING"> 6049int set_max_field(FIELD *field, /* Field on which to operate */ 6050 int max_growth); /* maximum growth allowed for the field */ 6051</pre> 6052 6053 <p>The field info for a dynamically growable field can be 6054 retrieved by</p> 6055 <pre class="PROGRAMLISTING"> 6056int dynamic_field_info( FIELD *field, /* Field on which to operate */ 6057 int *prows, /* number of rows will be filled in this */ 6058 int *pcols, /* number of columns will be filled in this*/ 6059 int *pmax) /* maximum allowable growth will be filled */ 6060 /* in this */ 6061</pre>Though field_info work as usual, it is advisable to use this 6062function to get the proper attributes of a dynamically growable 6063field. 6064 6065 <p>Recall the library routine new_field; a new field 6066 created with height set to one will be defined to be a 6067 one line field. A new field created with height greater 6068 than one will be defined to be a multi line field.</p> 6069 6070 <p>A one line field with O_STATIC turned off (dynamically 6071 growable field) will contain a single fixed row, but the 6072 number of columns can increase if the user enters more 6073 data than the initial field will hold. The number of 6074 columns displayed will remain fixed and the additional 6075 data will scroll horizontally.</p> 6076 6077 <p>A multi line field with O_STATIC turned off 6078 (dynamically growable field) will contain a fixed number 6079 of columns, but the number of rows can increase if the 6080 user enters more data than the initial field will hold. 6081 The number of rows displayed will remain fixed and the 6082 additional data will scroll vertically.</p> 6083 6084 <p>The above two paragraphs pretty much describe a 6085 dynamically growable field's behavior. The way other 6086 parts of forms library behaves is described below:</p> 6087 6088 <ol type="1"> 6089 <li> 6090 <p>The field option O_AUTOSKIP will be ignored if the 6091 option O_STATIC is off and there is no maximum growth 6092 specified for the field. Currently, O_AUTOSKIP 6093 generates an automatic REQ_NEXT_FIELD form driver 6094 request when the user types in the last character 6095 position of a field. On a growable field with no 6096 maximum growth specified, there is no last character 6097 position. If a maximum growth is specified, the 6098 O_AUTOSKIP option will work as normal if the field 6099 has grown to its maximum size.</p> 6100 </li> 6101 6102 <li> 6103 <p>The field justification will be ignored if the 6104 option O_STATIC is off. Currently, set_field_just can 6105 be used to JUSTIFY_LEFT, JUSTIFY_RIGHT, 6106 JUSTIFY_CENTER the contents of a one line field. A 6107 growable one line field will, by definition, grow and 6108 scroll horizontally and may contain more data than 6109 can be justified. The return from field_just will be 6110 unchanged.</p> 6111 </li> 6112 6113 <li> 6114 <p>The overloaded form driver request REQ_NEW_LINE 6115 will operate the same way regardless of the 6116 O_NL_OVERLOAD form option if the field option 6117 O_STATIC is off and there is no maximum growth 6118 specified for the field. Currently, if the form 6119 option O_NL_OVERLOAD is on, REQ_NEW_LINE implicitly 6120 generates a REQ_NEXT_FIELD if called from the last 6121 line of a field. If a field can grow without bound, 6122 there is no last line, so REQ_NEW_LINE will never 6123 implicitly generate a REQ_NEXT_FIELD. If a maximum 6124 growth limit is specified and the O_NL_OVERLOAD form 6125 option is on, REQ_NEW_LINE will only implicitly 6126 generate REQ_NEXT_FIELD if the field has grown to its 6127 maximum size and the user is on the last line.</p> 6128 </li> 6129 6130 <li> 6131 <p>The library call dup_field will work as usual; it 6132 will duplicate the field, including the current 6133 buffer size and contents of the field being 6134 duplicated. Any specified maximum growth will also be 6135 duplicated.</p> 6136 </li> 6137 6138 <li> 6139 <p>The library call link_field will work as usual; it 6140 will duplicate all field attributes and share buffers 6141 with the field being linked. If the O_STATIC field 6142 option is subsequently changed by a field sharing 6143 buffers, how the system reacts to an attempt to enter 6144 more data into the field than the buffer will 6145 currently hold will depend on the setting of the 6146 option in the current field.</p> 6147 </li> 6148 6149 <li> 6150 <p>The library call field_info will work as usual; 6151 the variable nrow will contain the value of the 6152 original call to new_field. The user should use 6153 dynamic_field_info, described above, to query the 6154 current size of the buffer.</p> 6155 </li> 6156 </ol> 6157 6158 <p>Some of the above points make sense only after 6159 explaining form driver. We will be looking into that in 6160 next few sections.</p> 6161 </div> 6162 </div> 6163 6164 <div class="SECT2"> 6165 <hr> 6166 6167 <h3 class="SECT2"><a name="FORMWINDOWS" id= 6168 "FORMWINDOWS">18.4. Form Windows</a></h3> 6169 6170 <p>The form windows concept is pretty much similar to menu 6171 windows. Every form is associated with a main window and a 6172 sub window. The form main window displays any title or 6173 border associated or whatever the user wishes. Then the sub 6174 window contains all the fields and displays them according 6175 to their position. This gives the flexibility of 6176 manipulating fancy form displaying very easily.</p> 6177 6178 <p>Since this is pretty much similar to menu windows, I am 6179 providing an example with out much explanation. The 6180 functions are similar and they work the same way.</p> 6181 6182 <div class="EXAMPLE"> 6183 <a name="FFOWI" id="FFOWI"></a> 6184 6185 <p><b>Example 28. Form Windows Example</b></p> 6186 <pre class="PROGRAMLISTING"> 6187<span class="INLINEMEDIAOBJECT">#include <form.h> 6188 6189void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 6190 6191int main() 6192{ 6193 FIELD *field[3]; 6194 FORM *my_form; 6195 WINDOW *my_form_win; 6196 int ch, rows, cols; 6197 6198 /* Initialize curses */ 6199 initscr(); 6200 start_color(); 6201 cbreak(); 6202 noecho(); 6203 keypad(stdscr, TRUE); 6204 6205 /* Initialize few color pairs */ 6206 init_pair(1, COLOR_RED, COLOR_BLACK); 6207 6208 /* Initialize the fields */ 6209 field[0] = new_field(1, 10, 6, 1, 0, 0); 6210 field[1] = new_field(1, 10, 8, 1, 0, 0); 6211 field[2] = NULL; 6212 6213 /* Set field options */ 6214 set_field_back(field[0], A_UNDERLINE); 6215 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */ 6216 /* Field is filled up */ 6217 set_field_back(field[1], A_UNDERLINE); 6218 field_opts_off(field[1], O_AUTOSKIP); 6219 6220 /* Create the form and post it */ 6221 my_form = new_form(field); 6222 6223 /* Calculate the area required for the form */ 6224 scale_form(my_form, &rows, &cols); 6225 6226 /* Create the window to be associated with the form */ 6227 my_form_win = newwin(rows + 4, cols + 4, 4, 4); 6228 keypad(my_form_win, TRUE); 6229 6230 /* Set main window and sub window */ 6231 set_form_win(my_form, my_form_win); 6232 set_form_sub(my_form, derwin(my_form_win, rows, cols, 2, 2)); 6233 6234 /* Print a border around the main window and print a title */ 6235 box(my_form_win, 0, 0); 6236 print_in_middle(my_form_win, 1, 0, cols + 4, "My Form", COLOR_PAIR(1)); 6237 6238 post_form(my_form); 6239 wrefresh(my_form_win); 6240 6241 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields"); 6242 refresh(); 6243 6244 /* Loop through to get user requests */ 6245 while((ch = wgetch(my_form_win)) != KEY_F(1)) 6246 { switch(ch) 6247 { case KEY_DOWN: 6248 /* Go to next field */ 6249 form_driver(my_form, REQ_NEXT_FIELD); 6250 /* Go to the end of the present buffer */ 6251 /* Leaves nicely at the last character */ 6252 form_driver(my_form, REQ_END_LINE); 6253 break; 6254 case KEY_UP: 6255 /* Go to previous field */ 6256 form_driver(my_form, REQ_PREV_FIELD); 6257 form_driver(my_form, REQ_END_LINE); 6258 break; 6259 default: 6260 /* If this is a normal character, it gets */ 6261 /* Printed */ 6262 form_driver(my_form, ch); 6263 break; 6264 } 6265 } 6266 6267 /* Un post form and free the memory */ 6268 unpost_form(my_form); 6269 free_form(my_form); 6270 free_field(field[0]); 6271 free_field(field[1]); 6272 6273 endwin(); 6274 return 0; 6275} 6276 6277void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 6278{ int length, x, y; 6279 float temp; 6280 6281 if(win == NULL) 6282 win = stdscr; 6283 getyx(win, y, x); 6284 if(startx != 0) 6285 x = startx; 6286 if(starty != 0) 6287 y = starty; 6288 if(width == 0) 6289 width = 80; 6290 6291 length = strlen(string); 6292 temp = (width - length)/ 2; 6293 x = startx + (int)temp; 6294 wattron(win, color); 6295 mvwprintw(win, y, x, "%s", string); 6296 wattroff(win, color); 6297 refresh(); 6298}</span> 6299</pre> 6300 </div> 6301 </div> 6302 6303 <div class="SECT2"> 6304 <hr> 6305 6306 <h3 class="SECT2"><a name="FILEDVALIDATE" id= 6307 "FILEDVALIDATE">18.5. Field Validation</a></h3> 6308 6309 <p>By default, a field will accept any data input by the 6310 user. It is possible to attach validation to the field. 6311 Then any attempt by the user to leave the field, while it 6312 contains data that doesn't match the validation type will 6313 fail. Some validation types also have a character-validity 6314 check for each time a character is entered in the 6315 field.</p> 6316 6317 <p>Validation can be attached to a field with the following 6318 function.</p> 6319 <pre class="PROGRAMLISTING"> 6320int set_field_type(FIELD *field, /* field to alter */ 6321 FIELDTYPE *ftype, /* type to associate */ 6322 ...); /* additional arguments*/ 6323</pre>Once set, the validation type for a field can be queried with 6324 <pre class="PROGRAMLISTING"> 6325FIELDTYPE *field_type(FIELD *field); /* field to query */ 6326</pre> 6327 6328 <p>The form driver validates the data in a field only when 6329 data is entered by the end-user. Validation does not occur 6330 when</p> 6331 6332 <ul> 6333 <li> 6334 <p>the application program changes the field value by 6335 calling set_field_buffer.</p> 6336 </li> 6337 6338 <li> 6339 <p>linked field values are changed indirectly -- by 6340 changing the field to which they are linked</p> 6341 </li> 6342 </ul> 6343 6344 <p>The following are the pre-defined validation types. You 6345 can also specify custom validation, though it's a bit 6346 tricky and cumbersome.</p> 6347 6348 <h1 class="BRIDGEHEAD"><a name="AEN1069" id= 6349 "AEN1069"></a>TYPE_ALPHA</h1> 6350 6351 <p>This field type accepts alphabetic data; no blanks, no 6352 digits, no special characters (this is checked at 6353 character-entry time). It is set up with:</p> 6354 <pre class="PROGRAMLISTING"> 6355int set_field_type(FIELD *field, /* field to alter */ 6356 TYPE_ALPHA, /* type to associate */ 6357 int width); /* minimum width of field */ 6358</pre> 6359 6360 <p>The width argument sets a minimum width of data. The 6361 user has to enter at-least width number of characters 6362 before he can leave the field. Typically you'll want to set 6363 this to the field width; if it's greater than the field 6364 width, the validation check will always fail. A minimum 6365 width of zero makes field completion optional.</p> 6366 6367 <h1 class="BRIDGEHEAD"><a name="AEN1073" id= 6368 "AEN1073"></a>TYPE_ALNUM</h1> 6369 6370 <p>This field type accepts alphabetic data and digits; no 6371 blanks, no special characters (this is checked at 6372 character-entry time). It is set up with:</p> 6373 <pre class="PROGRAMLISTING"> 6374int set_field_type(FIELD *field, /* field to alter */ 6375 TYPE_ALNUM, /* type to associate */ 6376 int width); /* minimum width of field */ 6377</pre> 6378 6379 <p>The width argument sets a minimum width of data. As with 6380 TYPE_ALPHA, typically you'll want to set this to the field 6381 width; if it's greater than the field width, the validation 6382 check will always fail. A minimum width of zero makes field 6383 completion optional.</p> 6384 6385 <h1 class="BRIDGEHEAD"><a name="AEN1077" id= 6386 "AEN1077"></a>TYPE_ENUM</h1> 6387 6388 <p>This type allows you to restrict a field's values to be 6389 among a specified set of string values (for example, the 6390 two-letter postal codes for U.S. states). It is set up 6391 with:</p> 6392 <pre class="PROGRAMLISTING"> 6393int set_field_type(FIELD *field, /* field to alter */ 6394 TYPE_ENUM, /* type to associate */ 6395 char **valuelist; /* list of possible values */ 6396 int checkcase; /* case-sensitive? */ 6397 int checkunique); /* must specify uniquely? */ 6398</pre> 6399 6400 <p>The valuelist parameter must point at a NULL-terminated 6401 list of valid strings. The checkcase argument, if true, 6402 makes comparison with the string case-sensitive.</p> 6403 6404 <p>When the user exits a TYPE_ENUM field, the validation 6405 procedure tries to complete the data in the buffer to a 6406 valid entry. If a complete choice string has been entered, 6407 it is of course valid. But it is also possible to enter a 6408 prefix of a valid string and have it completed for you.</p> 6409 6410 <p>By default, if you enter such a prefix and it matches 6411 more than one value in the string list, the prefix will be 6412 completed to the first matching value. But the checkunique 6413 argument, if true, requires prefix matches to be unique in 6414 order to be valid.</p> 6415 6416 <p>The REQ_NEXT_CHOICE and REQ_PREV_CHOICE input requests 6417 can be particularly useful with these fields.</p> 6418 6419 <h1 class="BRIDGEHEAD"><a name="AEN1084" id= 6420 "AEN1084"></a>TYPE_INTEGER</h1> 6421 6422 <p>This field type accepts an integer. It is set up as 6423 follows:</p> 6424 <pre class="PROGRAMLISTING"> 6425int set_field_type(FIELD *field, /* field to alter */ 6426 TYPE_INTEGER, /* type to associate */ 6427 int padding, /* # places to zero-pad to */ 6428 int vmin, int vmax); /* valid range */ 6429</pre> 6430 6431 <p>Valid characters consist of an optional leading minus 6432 and digits. The range check is performed on exit. If the 6433 range maximum is less than or equal to the minimum, the 6434 range is ignored.</p> 6435 6436 <p>If the value passes its range check, it is padded with 6437 as many leading zero digits as necessary to meet the 6438 padding argument.</p> 6439 6440 <p>A TYPE_INTEGER value buffer can conveniently be 6441 interpreted with the C library function atoi(3).</p> 6442 6443 <h1 class="BRIDGEHEAD"><a name="AEN1090" id= 6444 "AEN1090"></a>TYPE_NUMERIC</h1> 6445 6446 <p>This field type accepts a decimal number. It is set up 6447 as follows:</p> 6448 <pre class="PROGRAMLISTING"> 6449int set_field_type(FIELD *field, /* field to alter */ 6450 TYPE_NUMERIC, /* type to associate */ 6451 int padding, /* # places of precision */ 6452 int vmin, int vmax); /* valid range */ 6453</pre> 6454 6455 <p>Valid characters consist of an optional leading minus 6456 and digits. possibly including a decimal point. The range 6457 check is performed on exit. If the range maximum is less 6458 than or equal to the minimum, the range is ignored.</p> 6459 6460 <p>If the value passes its range check, it is padded with 6461 as many trailing zero digits as necessary to meet the 6462 padding argument.</p> 6463 6464 <p>A TYPE_NUMERIC value buffer can conveniently be 6465 interpreted with the C library function atof(3).</p> 6466 6467 <h1 class="BRIDGEHEAD"><a name="AEN1096" id= 6468 "AEN1096"></a>TYPE_REGEXP</h1> 6469 6470 <p>This field type accepts data matching a regular 6471 expression. It is set up as follows:</p> 6472 <pre class="PROGRAMLISTING"> 6473int set_field_type(FIELD *field, /* field to alter */ 6474 TYPE_REGEXP, /* type to associate */ 6475 char *regexp); /* expression to match */ 6476</pre> 6477 6478 <p>The syntax for regular expressions is that of 6479 regcomp(3). The check for regular-expression match is 6480 performed on exit.</p> 6481 </div> 6482 6483 <div class="SECT2"> 6484 <hr> 6485 6486 <h3 class="SECT2"><a name="FORMDRIVER" id= 6487 "FORMDRIVER">18.6. Form Driver: The work horse of the forms 6488 system</a></h3> 6489 6490 <p>As in the menu system, form_driver() plays a very 6491 important role in forms system. All types of requests to 6492 forms system should be funneled through form_driver().</p> 6493 <pre class="PROGRAMLISTING"> 6494int form_driver(FORM *form, /* form on which to operate */ 6495 int request) /* form request code */ 6496</pre> 6497 6498 <p>As you have seen some of the examples above, you have to 6499 be in a loop looking for user input and then decide whether 6500 it's a field data or a form request. The form requests are 6501 then passed to form_driver() to do the work.</p> 6502 6503 <p>The requests roughly can be divided into following 6504 categories. Different requests and their usage is explained 6505 below:</p> 6506 6507 <div class="SECT3"> 6508 <hr> 6509 6510 <h4 class="SECT3"><a name="PAGENAVREQ" id= 6511 "PAGENAVREQ">18.6.1. Page Navigation Requests</a></h4> 6512 6513 <p>These requests cause page-level moves through the 6514 form, triggering display of a new form screen. A form can 6515 be made of multiple pages. If you have a big form with 6516 lot of fields and logical sections, then you can divide 6517 the form into pages. The function set_new_page() to set a 6518 new page at the field specified.</p> 6519 <pre class="PROGRAMLISTING"> 6520int set_new_page(FIELD *field,/* Field at which page break to be set or unset */ 6521 bool new_page_flag); /* should be TRUE to put a break */ 6522</pre> 6523 6524 <p>The following requests allow you to move to different 6525 pages</p> 6526 6527 <ul> 6528 <li> 6529 <p><span class="emphasis"><i class= 6530 "EMPHASIS">REQ_NEXT_PAGE</i></span> Move to the next 6531 form page.</p> 6532 </li> 6533 6534 <li> 6535 <p><span class="emphasis"><i class= 6536 "EMPHASIS">REQ_PREV_PAGE</i></span> Move to the 6537 previous form page.</p> 6538 </li> 6539 6540 <li> 6541 <p><span class="emphasis"><i class= 6542 "EMPHASIS">REQ_FIRST_PAGE</i></span> Move to the 6543 first form page.</p> 6544 </li> 6545 6546 <li> 6547 <p><span class="emphasis"><i class= 6548 "EMPHASIS">REQ_LAST_PAGE</i></span> Move to the last 6549 form page.</p> 6550 </li> 6551 </ul> 6552 6553 <p>These requests treat the list as cyclic; that is, 6554 REQ_NEXT_PAGE from the last page goes to the first, and 6555 REQ_PREV_PAGE from the first page goes to the last.</p> 6556 </div> 6557 6558 <div class="SECT3"> 6559 <hr> 6560 6561 <h4 class="SECT3"><a name="INTERFIELDNAVREQ" id= 6562 "INTERFIELDNAVREQ">18.6.2. Inter-Field Navigation 6563 Requests</a></h4> 6564 6565 <p>These requests handle navigation between fields on the 6566 same page.</p> 6567 6568 <ul> 6569 <li> 6570 <p><span class="emphasis"><i class= 6571 "EMPHASIS">REQ_NEXT_FIELD</i></span> Move to next 6572 field.</p> 6573 </li> 6574 6575 <li> 6576 <p><span class="emphasis"><i class= 6577 "EMPHASIS">REQ_PREV_FIELD</i></span> Move to previous 6578 field.</p> 6579 </li> 6580 6581 <li> 6582 <p><span class="emphasis"><i class= 6583 "EMPHASIS">REQ_FIRST_FIELD</i></span> Move to the 6584 first field.</p> 6585 </li> 6586 6587 <li> 6588 <p><span class="emphasis"><i class= 6589 "EMPHASIS">REQ_LAST_FIELD</i></span> Move to the last 6590 field.</p> 6591 </li> 6592 6593 <li> 6594 <p><span class="emphasis"><i class= 6595 "EMPHASIS">REQ_SNEXT_FIELD</i></span> Move to sorted 6596 next field.</p> 6597 </li> 6598 6599 <li> 6600 <p><span class="emphasis"><i class= 6601 "EMPHASIS">REQ_SPREV_FIELD</i></span> Move to sorted 6602 previous field.</p> 6603 </li> 6604 6605 <li> 6606 <p><span class="emphasis"><i class= 6607 "EMPHASIS">REQ_SFIRST_FIELD</i></span> Move to the 6608 sorted first field.</p> 6609 </li> 6610 6611 <li> 6612 <p><span class="emphasis"><i class= 6613 "EMPHASIS">REQ_SLAST_FIELD</i></span> Move to the 6614 sorted last field.</p> 6615 </li> 6616 6617 <li> 6618 <p><span class="emphasis"><i class= 6619 "EMPHASIS">REQ_LEFT_FIELD</i></span> Move left to 6620 field.</p> 6621 </li> 6622 6623 <li> 6624 <p><span class="emphasis"><i class= 6625 "EMPHASIS">REQ_RIGHT_FIELD</i></span> Move right to 6626 field.</p> 6627 </li> 6628 6629 <li> 6630 <p><span class="emphasis"><i class= 6631 "EMPHASIS">REQ_UP_FIELD</i></span> Move up to 6632 field.</p> 6633 </li> 6634 6635 <li> 6636 <p><span class="emphasis"><i class= 6637 "EMPHASIS">REQ_DOWN_FIELD</i></span> Move down to 6638 field.</p> 6639 </li> 6640 </ul> 6641 6642 <p>These requests treat the list of fields on a page as 6643 cyclic; that is, REQ_NEXT_FIELD from the last field goes 6644 to the first, and REQ_PREV_FIELD from the first field 6645 goes to the last. The order of the fields for these (and 6646 the REQ_FIRST_FIELD and REQ_LAST_FIELD requests) is 6647 simply the order of the field pointers in the form array 6648 (as set up by new_form() or set_form_fields()</p> 6649 6650 <p>It is also possible to traverse the fields as if they 6651 had been sorted in screen-position order, so the sequence 6652 goes left-to-right and top-to-bottom. To do this, use the 6653 second group of four sorted-movement requests.</p> 6654 6655 <p>Finally, it is possible to move between fields using 6656 visual directions up, down, right, and left. To 6657 accomplish this, use the third group of four requests. 6658 Note, however, that the position of a form for purposes 6659 of these requests is its upper-left corner.</p> 6660 6661 <p>For example, suppose you have a multi-line field B, 6662 and two single-line fields A and C on the same line with 6663 B, with A to the left of B and C to the right of B. A 6664 REQ_MOVE_RIGHT from A will go to B only if A, B, and C 6665 all share the same first line; otherwise it will skip 6666 over B to C.</p> 6667 </div> 6668 6669 <div class="SECT3"> 6670 <hr> 6671 6672 <h4 class="SECT3"><a name="INTRAFIELDNAVREQ" id= 6673 "INTRAFIELDNAVREQ">18.6.3. Intra-Field Navigation 6674 Requests</a></h4> 6675 6676 <p>These requests drive movement of the edit cursor 6677 within the currently selected field.</p> 6678 6679 <ul> 6680 <li> 6681 <p><span class="emphasis"><i class= 6682 "EMPHASIS">REQ_NEXT_CHAR</i></span> Move to next 6683 character.</p> 6684 </li> 6685 6686 <li> 6687 <p><span class="emphasis"><i class= 6688 "EMPHASIS">REQ_PREV_CHAR</i></span> Move to previous 6689 character.</p> 6690 </li> 6691 6692 <li> 6693 <p><span class="emphasis"><i class= 6694 "EMPHASIS">REQ_NEXT_LINE</i></span> Move to next 6695 line.</p> 6696 </li> 6697 6698 <li> 6699 <p><span class="emphasis"><i class= 6700 "EMPHASIS">REQ_PREV_LINE</i></span> Move to previous 6701 line.</p> 6702 </li> 6703 6704 <li> 6705 <p><span class="emphasis"><i class= 6706 "EMPHASIS">REQ_NEXT_WORD</i></span> Move to next 6707 word.</p> 6708 </li> 6709 6710 <li> 6711 <p><span class="emphasis"><i class= 6712 "EMPHASIS">REQ_PREV_WORD</i></span> Move to previous 6713 word.</p> 6714 </li> 6715 6716 <li> 6717 <p><span class="emphasis"><i class= 6718 "EMPHASIS">REQ_BEG_FIELD</i></span> Move to beginning 6719 of field.</p> 6720 </li> 6721 6722 <li> 6723 <p><span class="emphasis"><i class= 6724 "EMPHASIS">REQ_END_FIELD</i></span> Move to end of 6725 field.</p> 6726 </li> 6727 6728 <li> 6729 <p><span class="emphasis"><i class= 6730 "EMPHASIS">REQ_BEG_LINE</i></span> Move to beginning 6731 of line.</p> 6732 </li> 6733 6734 <li> 6735 <p><span class="emphasis"><i class= 6736 "EMPHASIS">REQ_END_LINE</i></span> Move to end of 6737 line.</p> 6738 </li> 6739 6740 <li> 6741 <p><span class="emphasis"><i class= 6742 "EMPHASIS">REQ_LEFT_CHAR</i></span> Move left in 6743 field.</p> 6744 </li> 6745 6746 <li> 6747 <p><span class="emphasis"><i class= 6748 "EMPHASIS">REQ_RIGHT_CHAR</i></span> Move right in 6749 field.</p> 6750 </li> 6751 6752 <li> 6753 <p><span class="emphasis"><i class= 6754 "EMPHASIS">REQ_UP_CHAR</i></span> Move up in 6755 field.</p> 6756 </li> 6757 6758 <li> 6759 <p><span class="emphasis"><i class= 6760 "EMPHASIS">REQ_DOWN_CHAR</i></span> Move down in 6761 field.</p> 6762 </li> 6763 </ul> 6764 6765 <p>Each word is separated from the previous and next 6766 characters by whitespace. The commands to move to 6767 beginning and end of line or field look for the first or 6768 last non-pad character in their ranges.</p> 6769 </div> 6770 6771 <div class="SECT3"> 6772 <hr> 6773 6774 <h4 class="SECT3"><a name="SCROLLREQ" id= 6775 "SCROLLREQ">18.6.4. Scrolling Requests</a></h4> 6776 6777 <p>Fields that are dynamic and have grown and fields 6778 explicitly created with offscreen rows are scrollable. 6779 One-line fields scroll horizontally; multi-line fields 6780 scroll vertically. Most scrolling is triggered by editing 6781 and intra-field movement (the library scrolls the field 6782 to keep the cursor visible). It is possible to explicitly 6783 request scrolling with the following requests:</p> 6784 6785 <ul> 6786 <li> 6787 <p><span class="emphasis"><i class= 6788 "EMPHASIS">REQ_SCR_FLINE</i></span> Scroll vertically 6789 forward a line.</p> 6790 </li> 6791 6792 <li> 6793 <p><span class="emphasis"><i class= 6794 "EMPHASIS">REQ_SCR_BLINE</i></span> Scroll vertically 6795 backward a line.</p> 6796 </li> 6797 6798 <li> 6799 <p><span class="emphasis"><i class= 6800 "EMPHASIS">REQ_SCR_FPAGE</i></span> Scroll vertically 6801 forward a page.</p> 6802 </li> 6803 6804 <li> 6805 <p><span class="emphasis"><i class= 6806 "EMPHASIS">REQ_SCR_BPAGE</i></span> Scroll vertically 6807 backward a page.</p> 6808 </li> 6809 6810 <li> 6811 <p><span class="emphasis"><i class= 6812 "EMPHASIS">REQ_SCR_FHPAGE</i></span> Scroll 6813 vertically forward half a page.</p> 6814 </li> 6815 6816 <li> 6817 <p><span class="emphasis"><i class= 6818 "EMPHASIS">REQ_SCR_BHPAGE</i></span> Scroll 6819 vertically backward half a page.</p> 6820 </li> 6821 6822 <li> 6823 <p><span class="emphasis"><i class= 6824 "EMPHASIS">REQ_SCR_FCHAR</i></span> Scroll 6825 horizontally forward a character.</p> 6826 </li> 6827 6828 <li> 6829 <p><span class="emphasis"><i class= 6830 "EMPHASIS">REQ_SCR_BCHAR</i></span> Scroll 6831 horizontally backward a character.</p> 6832 </li> 6833 6834 <li> 6835 <p><span class="emphasis"><i class= 6836 "EMPHASIS">REQ_SCR_HFLINE</i></span> Scroll 6837 horizontally one field width forward.</p> 6838 </li> 6839 6840 <li> 6841 <p><span class="emphasis"><i class= 6842 "EMPHASIS">REQ_SCR_HBLINE</i></span> Scroll 6843 horizontally one field width backward.</p> 6844 </li> 6845 6846 <li> 6847 <p><span class="emphasis"><i class= 6848 "EMPHASIS">REQ_SCR_HFHALF</i></span> Scroll 6849 horizontally one half field width forward.</p> 6850 </li> 6851 6852 <li> 6853 <p><span class="emphasis"><i class= 6854 "EMPHASIS">REQ_SCR_HBHALF</i></span> Scroll 6855 horizontally one half field width backward.</p> 6856 </li> 6857 </ul> 6858 6859 <p>For scrolling purposes, a page of a field is the 6860 height of its visible part.</p> 6861 </div> 6862 6863 <div class="SECT3"> 6864 <hr> 6865 6866 <h4 class="SECT3"><a name="EDITREQ" id="EDITREQ">18.6.5. 6867 Editing Requests</a></h4> 6868 6869 <p>When you pass the forms driver an ASCII character, it 6870 is treated as a request to add the character to the 6871 field's data buffer. Whether this is an insertion or a 6872 replacement depends on the field's edit mode (insertion 6873 is the default.</p> 6874 6875 <p>The following requests support editing the field and 6876 changing the edit mode:</p> 6877 6878 <ul> 6879 <li> 6880 <p><span class="emphasis"><i class= 6881 "EMPHASIS">REQ_INS_MODE</i></span> Set insertion 6882 mode.</p> 6883 </li> 6884 6885 <li> 6886 <p><span class="emphasis"><i class= 6887 "EMPHASIS">REQ_OVL_MODE</i></span> Set overlay 6888 mode.</p> 6889 </li> 6890 6891 <li> 6892 <p><span class="emphasis"><i class= 6893 "EMPHASIS">REQ_NEW_LINE</i></span> New line request 6894 (see below for explanation).</p> 6895 </li> 6896 6897 <li> 6898 <p><span class="emphasis"><i class= 6899 "EMPHASIS">REQ_INS_CHAR</i></span> Insert space at 6900 character location.</p> 6901 </li> 6902 6903 <li> 6904 <p><span class="emphasis"><i class= 6905 "EMPHASIS">REQ_INS_LINE</i></span> Insert blank line 6906 at character location.</p> 6907 </li> 6908 6909 <li> 6910 <p><span class="emphasis"><i class= 6911 "EMPHASIS">REQ_DEL_CHAR</i></span> Delete character 6912 at cursor.</p> 6913 </li> 6914 6915 <li> 6916 <p><span class="emphasis"><i class= 6917 "EMPHASIS">REQ_DEL_PREV</i></span> Delete previous 6918 word at cursor.</p> 6919 </li> 6920 6921 <li> 6922 <p><span class="emphasis"><i class= 6923 "EMPHASIS">REQ_DEL_LINE</i></span> Delete line at 6924 cursor.</p> 6925 </li> 6926 6927 <li> 6928 <p><span class="emphasis"><i class= 6929 "EMPHASIS">REQ_DEL_WORD</i></span> Delete word at 6930 cursor.</p> 6931 </li> 6932 6933 <li> 6934 <p><span class="emphasis"><i class= 6935 "EMPHASIS">REQ_CLR_EOL</i></span> Clear to end of 6936 line.</p> 6937 </li> 6938 6939 <li> 6940 <p><span class="emphasis"><i class= 6941 "EMPHASIS">REQ_CLR_EOF</i></span> Clear to end of 6942 field.</p> 6943 </li> 6944 6945 <li> 6946 <p><span class="emphasis"><i class= 6947 "EMPHASIS">REQ_CLR_FIELD</i></span> Clear entire 6948 field.</p> 6949 </li> 6950 </ul> 6951 6952 <p>The behavior of the REQ_NEW_LINE and REQ_DEL_PREV 6953 requests is complicated and partly controlled by a pair 6954 of forms options. The special cases are triggered when 6955 the cursor is at the beginning of a field, or on the last 6956 line of the field.</p> 6957 6958 <p>First, we consider REQ_NEW_LINE:</p> 6959 6960 <p>The normal behavior of REQ_NEW_LINE in insert mode is 6961 to break the current line at the position of the edit 6962 cursor, inserting the portion of the current line after 6963 the cursor as a new line following the current and moving 6964 the cursor to the beginning of that new line (you may 6965 think of this as inserting a newline in the field 6966 buffer).</p> 6967 6968 <p>The normal behavior of REQ_NEW_LINE in overlay mode is 6969 to clear the current line from the position of the edit 6970 cursor to end of line. The cursor is then moved to the 6971 beginning of the next line.</p> 6972 6973 <p>However, REQ_NEW_LINE at the beginning of a field, or 6974 on the last line of a field, instead does a 6975 REQ_NEXT_FIELD. O_NL_OVERLOAD option is off, this special 6976 action is disabled.</p> 6977 6978 <p>Now, let us consider REQ_DEL_PREV:</p> 6979 6980 <p>The normal behavior of REQ_DEL_PREV is to delete the 6981 previous character. If insert mode is on, and the cursor 6982 is at the start of a line, and the text on that line will 6983 fit on the previous one, it instead appends the contents 6984 of the current line to the previous one and deletes the 6985 current line (you may think of this as deleting a newline 6986 from the field buffer).</p> 6987 6988 <p>However, REQ_DEL_PREV at the beginning of a field is 6989 instead treated as a REQ_PREV_FIELD.</p> 6990 6991 <p>If the O_BS_OVERLOAD option is off, this special 6992 action is disabled and the forms driver just returns 6993 E_REQUEST_DENIED.</p> 6994 </div> 6995 6996 <div class="SECT3"> 6997 <hr> 6998 6999 <h4 class="SECT3"><a name="ORDERREQ" id= 7000 "ORDERREQ">18.6.6. Order Requests</a></h4> 7001 7002 <p>If the type of your field is ordered, and has 7003 associated functions for getting the next and previous 7004 values of the type from a given value, there are requests 7005 that can fetch that value into the field buffer:</p> 7006 7007 <ul> 7008 <li> 7009 <p><span class="emphasis"><i class= 7010 "EMPHASIS">REQ_NEXT_CHOICE</i></span> Place the 7011 successor value of the current value in the 7012 buffer.</p> 7013 </li> 7014 7015 <li> 7016 <p><span class="emphasis"><i class= 7017 "EMPHASIS">REQ_PREV_CHOICE</i></span> Place the 7018 predecessor value of the current value in the 7019 buffer.</p> 7020 </li> 7021 </ul> 7022 7023 <p>Of the built-in field types, only TYPE_ENUM has 7024 built-in successor and predecessor functions. When you 7025 define a field type of your own (see Custom Validation 7026 Types), you can associate our own ordering functions.</p> 7027 </div> 7028 7029 <div class="SECT3"> 7030 <hr> 7031 7032 <h4 class="SECT3"><a name="APPLICCOMMANDS" id= 7033 "APPLICCOMMANDS">18.6.7. Application Commands</a></h4> 7034 7035 <p>Form requests are represented as integers above the 7036 curses value greater than KEY_MAX and less than or equal 7037 to the constant MAX_COMMAND. A value within this range 7038 gets ignored by form_driver(). So this can be used for 7039 any purpose by the application. It can be treated as an 7040 application specific action and take corresponding 7041 action.</p> 7042 </div> 7043 </div> 7044 </div> 7045 7046 <div class="SECT1"> 7047 <hr> 7048 7049 <h2 class="SECT1"><a name="TOOLS" id="TOOLS">19. Tools and 7050 Widget Libraries</a></h2> 7051 7052 <p>Now that you have seen the capabilities of ncurses and its 7053 sister libraries, you are rolling your sleeves up and gearing 7054 for a project that heavily manipulates screen. But wait.. It 7055 can be pretty difficult to write and maintain complex GUI 7056 widgets in plain ncurses or even with the additional 7057 libraries. There are some ready-to-use tools and widget 7058 libraries that can be used instead of writing your own 7059 widgets. You can use some of them, get ideas from the code, 7060 or even extend them.</p> 7061 7062 <div class="SECT2"> 7063 <hr> 7064 7065 <h3 class="SECT2"><a name="CDK" id="CDK">19.1. CDK (Curses 7066 Development Kit)</a></h3> 7067 7068 <p>In the author's words</p> 7069 7070 <p><span class="emphasis"><i class="EMPHASIS">CDK stands 7071 for 'Curses Development Kit' and it currently contains 21 7072 ready to use widgets which facilitate the speedy 7073 development of full screen curses programs.</i></span></p> 7074 7075 <p>The kit provides some useful widgets, which can be used 7076 in your programs directly. It's pretty well written and the 7077 documentation is very good. The examples in the examples 7078 directory can be a good place to start for beginners. The 7079 CDK can be downloaded from <a href= 7080 "https://invisible-island.net/cdk/" target= 7081 "_top">https://invisible-island.net/cdk/</a> . Follow the 7082 instructions in README file to install it.</p> 7083 7084 <div class="SECT3"> 7085 <hr> 7086 7087 <h4 class="SECT3"><a name="WIDGETLIST" id= 7088 "WIDGETLIST">19.1.1. Widget List</a></h4> 7089 7090 <p>The following is the list of widgets provided with cdk 7091 and their description.</p> 7092 <pre class="PROGRAMLISTING"> 7093Widget Type Quick Description 7094=========================================================================== 7095Alphalist Allows a user to select from a list of words, with 7096 the ability to narrow the search list by typing in a 7097 few characters of the desired word. 7098Buttonbox This creates a multiple button widget. 7099Calendar Creates a little simple calendar widget. 7100Dialog Prompts the user with a message, and the user 7101 can pick an answer from the buttons provided. 7102Entry Allows the user to enter various types of information. 7103File Selector A file selector built from Cdk base widgets. This 7104 example shows how to create more complicated widgets 7105 using the Cdk widget library. 7106Graph Draws a graph. 7107Histogram Draws a histogram. 7108Item List Creates a pop up field which allows the user to select 7109 one of several choices in a small field. Very useful 7110 for things like days of the week or month names. 7111Label Displays messages in a pop up box, or the label can be 7112 considered part of the screen. 7113Marquee Displays a message in a scrolling marquee. 7114Matrix Creates a complex matrix with lots of options. 7115Menu Creates a pull-down menu interface. 7116Multiple Line Entry A multiple line entry field. Very useful 7117 for long fields. (like a description 7118 field) 7119Radio List Creates a radio button list. 7120Scale Creates a numeric scale. Used for allowing a user to 7121 pick a numeric value and restrict them to a range of 7122 values. 7123Scrolling List Creates a scrolling list/menu list. 7124Scrolling Window Creates a scrolling log file viewer. Can add 7125 information into the window while its running. 7126 A good widget for displaying the progress of 7127 something. (akin to a console window) 7128Selection List Creates a multiple option selection list. 7129Slider Akin to the scale widget, this widget provides a 7130 visual slide bar to represent the numeric value. 7131Template Creates a entry field with character sensitive 7132 positions. Used for pre-formatted fields like 7133 dates and phone numbers. 7134Viewer This is a file/information viewer. Very useful 7135 when you need to display loads of information. 7136=========================================================================== 7137</pre> 7138 7139 <p>A few of the widgets are modified by Thomas Dickey in 7140 recent versions.</p> 7141 </div> 7142 7143 <div class="SECT3"> 7144 <hr> 7145 7146 <h4 class="SECT3"><a name="CDKATTRACT" id= 7147 "CDKATTRACT">19.1.2. Some Attractive Features</a></h4> 7148 7149 <p>Apart from making our life easier with readily usable 7150 widgets, cdk solves one frustrating problem with printing 7151 multi colored strings, justified strings elegantly. 7152 Special formatting tags can be embedded in the strings 7153 which are passed to CDK functions. For Example</p> 7154 7155 <p>If the string</p> 7156 <pre class="PROGRAMLISTING"> 7157"</B/1>This line should have a yellow foreground and a blue 7158background.<!1>" 7159</pre> 7160 7161 <p>given as a parameter to newCDKLabel(), it prints the 7162 line with yellow foreground and blue background. There 7163 are other tags available for justifying string, embedding 7164 special drawing characters etc.. Please refer to the man 7165 page cdk_display(3X) for details. The man page explains 7166 the usage with nice examples.</p> 7167 </div> 7168 7169 <div class="SECT3"> 7170 <hr> 7171 7172 <h4 class="SECT3"><a name="CDKCONCLUSION" id= 7173 "CDKCONCLUSION">19.1.3. Conclusion</a></h4> 7174 7175 <p>All in all, CDK is a well-written package of widgets, 7176 which if used properly can form a strong frame work for 7177 developing complex GUI.</p> 7178 </div> 7179 </div> 7180 7181 <div class="SECT2"> 7182 <hr> 7183 7184 <h3 class="SECT2"><a name="DIALOG" id="DIALOG">19.2. The 7185 dialog</a></h3> 7186 7187 <p>Long long ago, in September 1994, when few people knew 7188 linux, Jeff Tranter wrote an <a href= 7189 "http://www2.linuxjournal.com/lj-issues/issue5/2807.html" 7190 target="_top">article</a> on dialog in Linux Journal. He 7191 starts the article with these words..</p> 7192 7193 <p><span class="emphasis"><i class="EMPHASIS">Linux is 7194 based on the Unix operating system, but also features a 7195 number of unique and useful kernel features and application 7196 programs that often go beyond what is available under Unix. 7197 One little-known gem is "dialog", a utility for creating 7198 professional-looking dialog boxes from within shell 7199 scripts. This article presents a tutorial introduction to 7200 the dialog utility, and shows examples of how and where it 7201 can be used</i></span></p> 7202 7203 <p>As he explains, dialog is a real gem in making 7204 professional-looking dialog boxes with ease. It creates a 7205 variety of dialog boxes, menus, check lists etc.. It is 7206 usually installed by default. If not, you can download it 7207 from <a href="https://invisible-island.net/dialog/" target= 7208 "_top">Thomas Dickey</a>'s site.</p> 7209 7210 <p>The above-mentioned article gives a very good overview 7211 of its uses and capabilites. The man page has more details. 7212 It can be used in variety of situations. One good example 7213 is building of linux kernel in text mode. Linux kernel uses 7214 a modified version of dialog tailored for its needs.</p> 7215 7216 <p>dialog was initially designed to be used with shell 7217 scripts. If you want to use its functionality in a c 7218 program, then you can use libdialog. The documentation 7219 regarding this is sparse. Definitive reference is the 7220 dialog.h header file which comes with the library. You may 7221 need to hack here and there to get the required output. The 7222 source is easily customizable. I have used it on a number 7223 of occasions by modifying the code.</p> 7224 </div> 7225 7226 <div class="SECT2"> 7227 <hr> 7228 7229 <h3 class="SECT2"><a name="PERLCURSES" id= 7230 "PERLCURSES">19.3. Perl Curses Modules CURSES::FORM and 7231 CURSES::WIDGETS</a></h3> 7232 7233 <p>The perl module Curses, Curses::Form and Curses::Widgets 7234 give access to curses from perl. If you have curses and 7235 basic perl is installed, you can get these modules from 7236 <a href="http://www.cpan.org/modules/01modules.index.html" 7237 target="_top">CPAN All Modules page</a>. Get the three 7238 zipped modules in the Curses category. Once installed you 7239 can use these modules from perl scripts like any other 7240 module. For more information on perl modules see perlmod 7241 man page. The above modules come with good documentation 7242 and they have some demo scripts to test the functionality. 7243 Though the widgets provided are very rudimentary, these 7244 modules provide good access to curses library from 7245 perl.</p> 7246 7247 <p>Some of my code examples are converted to perl by 7248 Anuradha Ratnaweera and they are available in the 7249 <tt class="LITERAL">perl</tt> directory.</p> 7250 7251 <p>For more information see man pages Curses(3) , 7252 Curses::Form(3) and Curses::Widgets(3). These pages are 7253 installed only when the above modules are acquired and 7254 installed.</p> 7255 </div> 7256 </div> 7257 7258 <div class="SECT1"> 7259 <hr> 7260 7261 <h2 class="SECT1"><a name="JUSTFORFUN" id="JUSTFORFUN">20. 7262 Just For Fun !!!</a></h2> 7263 7264 <p>This section contains few programs written by me just for 7265 fun. They don't signify a better programming practice or the 7266 best way of using ncurses. They are provided here so as to 7267 allow beginners to get ideas and add more programs to this 7268 section. If you have written a couple of nice, simple 7269 programs in curses and want them to included here, contact 7270 <a href="mailto:ppadala@gmail.com" target="_top">me</a>.</p> 7271 7272 <div class="SECT2"> 7273 <hr> 7274 7275 <h3 class="SECT2"><a name="GAMEOFLIFE" id= 7276 "GAMEOFLIFE">20.1. The Game of Life</a></h3> 7277 7278 <p>Game of life is a wonder of math. In <a href= 7279 "http://www.math.com/students/wonders/life/life.html" 7280 target="_top">Paul Callahan</a>'s words</p> 7281 <pre class="PROGRAMLISTING"> 7282<span class="emphasis"><i class= 7283"EMPHASIS">The Game of Life (or simply Life) is not a game in the conventional sense. There 7284are no players, and no winning or losing. Once the "pieces" are placed in the 7285starting position, the rules determine everything that happens later. 7286Nevertheless, Life is full of surprises! In most cases, it is impossible to look 7287at a starting position (or pattern) and see what will happen in the future. The 7288only way to find out is to follow the rules of the game.</i></span> 7289</pre> 7290 7291 <p>This program starts with a simple inverted U pattern and 7292 shows how wonderful life works. There is a lot of room for 7293 improvement in the program. You can let the user enter 7294 pattern of his choice or even take input from a file. You 7295 can also change rules and play with a lot of variations. 7296 Search on <a href="http://www.google.com" target= 7297 "_top">google</a> for interesting information on game of 7298 life.</p> 7299 7300 <p><span class="emphasis"><i class="EMPHASIS">File Path: 7301 JustForFun/life.c</i></span></p> 7302 </div> 7303 7304 <div class="SECT2"> 7305 <hr> 7306 7307 <h3 class="SECT2"><a name="MAGIC" id="MAGIC">20.2. Magic 7308 Square</a></h3> 7309 7310 <p>Magic Square, another wonder of math, is very simple to 7311 understand but very difficult to make. In a magic square 7312 sum of the numbers in each row, each column is equal. Even 7313 diagnol sum can be equal. There are many variations which 7314 have special properties.</p> 7315 7316 <p>This program creates a simple magic square of odd 7317 order.</p> 7318 7319 <p><span class="emphasis"><i class="EMPHASIS">File Path: 7320 JustForFun/magic.c</i></span></p> 7321 </div> 7322 7323 <div class="SECT2"> 7324 <hr> 7325 7326 <h3 class="SECT2"><a name="HANOI" id="HANOI">20.3. Towers 7327 of Hanoi</a></h3> 7328 7329 <p>The famous towers of hanoi solver. The aim of the game 7330 is to move the disks on the first peg to last peg, using 7331 middle peg as a temporary stay. The catch is not to place a 7332 larger disk over a small disk at any time.</p> 7333 7334 <p><span class="emphasis"><i class="EMPHASIS">File Path: 7335 JustForFun/hanoi.c</i></span></p> 7336 </div> 7337 7338 <div class="SECT2"> 7339 <hr> 7340 7341 <h3 class="SECT2"><a name="QUEENS" id="QUEENS">20.4. Queens 7342 Puzzle</a></h3> 7343 7344 <p>The objective of the famous N-Queen puzzle is to put N 7345 queens on a N X N chess board without attacking each 7346 other.</p> 7347 7348 <p>This program solves it with a simple backtracking 7349 technique.</p> 7350 7351 <p><span class="emphasis"><i class="EMPHASIS">File Path: 7352 JustForFun/queens.c</i></span></p> 7353 </div> 7354 7355 <div class="SECT2"> 7356 <hr> 7357 7358 <h3 class="SECT2"><a name="SHUFFLE" id="SHUFFLE">20.5. 7359 Shuffle</a></h3> 7360 7361 <p>A fun game, if you have time to kill.</p> 7362 7363 <p><span class="emphasis"><i class="EMPHASIS">File Path: 7364 JustForFun/shuffle.c</i></span></p> 7365 </div> 7366 7367 <div class="SECT2"> 7368 <hr> 7369 7370 <h3 class="SECT2"><a name="TT" id="TT">20.6. Typing 7371 Tutor</a></h3> 7372 7373 <p>A simple typing tutor, I created more out of need than 7374 for ease of use. If you know how to put your fingers 7375 correctly on the keyboard, but lack practice, this can be 7376 helpful.</p> 7377 7378 <p><span class="emphasis"><i class="EMPHASIS">File Path: 7379 JustForFun/tt.c</i></span></p> 7380 </div> 7381 </div> 7382 7383 <div class="SECT1"> 7384 <hr> 7385 7386 <h2 class="SECT1"><a name="REF" id="REF">21. 7387 References</a></h2> 7388 7389 <ul> 7390 <li> 7391 <p>NCURSES man pages</p> 7392 </li> 7393 7394 <li> 7395 <p>NCURSES FAQ at <a href= 7396 "https://invisible-island.net/ncurses/ncurses.faq.html" 7397 target= 7398 "_top">https://invisible-island.net/ncurses/ncurses.faq.html</a></p> 7399 </li> 7400 7401 <li> 7402 <p>Writing programs with NCURSES by Eric Raymond and Zeyd 7403 M. Ben-Halim at <a href= 7404 "https://invisible-island.net/ncurses/ncurses-intro.html" 7405 target= 7406 "_top">https://invisible-island.net/ncurses/ncurses-intro.html</a> 7407 - somewhat obsolete. I was inspired by this document and 7408 the structure of this HOWTO follows from the original 7409 document</p> 7410 </li> 7411 </ul> 7412 </div> 7413 </div> 7414</body> 7415</html> 7416