1:mod:`curses` --- Terminal handling for character-cell displays
2===============================================================
3
4.. module:: curses
5   :synopsis: An interface to the curses library, providing portable
6              terminal handling.
7   :platform: Unix
8
9.. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>
10.. sectionauthor:: Eric Raymond <esr@thyrsus.com>
11
12--------------
13
14The :mod:`curses` module provides an interface to the curses library, the
15de-facto standard for portable advanced terminal handling.
16
17While curses is most widely used in the Unix environment, versions are available
18for Windows, DOS, and possibly other systems as well.  This extension module is
19designed to match the API of ncurses, an open-source curses library hosted on
20Linux and the BSD variants of Unix.
21
22.. note::
23
24   Whenever the documentation mentions a *character* it can be specified
25   as an integer, a one-character Unicode string or a one-byte byte string.
26
27   Whenever the documentation mentions a *character string* it can be specified
28   as a Unicode string or a byte string.
29
30.. note::
31
32   Since version 5.4, the ncurses library decides how to interpret non-ASCII data
33   using the ``nl_langinfo`` function.  That means that you have to call
34   :func:`locale.setlocale` in the application and encode Unicode strings
35   using one of the system's available encodings.  This example uses the
36   system's default encoding::
37
38      import locale
39      locale.setlocale(locale.LC_ALL, '')
40      code = locale.getpreferredencoding()
41
42   Then use *code* as the encoding for :meth:`str.encode` calls.
43
44.. seealso::
45
46   Module :mod:`curses.ascii`
47      Utilities for working with ASCII characters, regardless of your locale settings.
48
49   Module :mod:`curses.panel`
50      A panel stack extension that adds depth to  curses windows.
51
52   Module :mod:`curses.textpad`
53      Editable text widget for curses supporting  :program:`Emacs`\ -like bindings.
54
55   :ref:`curses-howto`
56      Tutorial material on using curses with Python, by Andrew Kuchling and Eric
57      Raymond.
58
59   The :source:`Tools/demo/` directory in the Python source distribution contains
60   some example programs using the curses bindings provided by this module.
61
62
63.. _curses-functions:
64
65Functions
66---------
67
68The module :mod:`curses` defines the following exception:
69
70
71.. exception:: error
72
73   Exception raised when a curses library function returns an error.
74
75.. note::
76
77   Whenever *x* or *y* arguments to a function or a method are optional, they
78   default to the current cursor location. Whenever *attr* is optional, it defaults
79   to :const:`A_NORMAL`.
80
81The module :mod:`curses` defines the following functions:
82
83
84.. function:: baudrate()
85
86   Return the output speed of the terminal in bits per second.  On software
87   terminal emulators it will have a fixed high value. Included for historical
88   reasons; in former times, it was used to  write output loops for time delays and
89   occasionally to change interfaces depending on the line speed.
90
91
92.. function:: beep()
93
94   Emit a short attention sound.
95
96
97.. function:: can_change_color()
98
99   Return ``True`` or ``False``, depending on whether the programmer can change the colors
100   displayed by the terminal.
101
102
103.. function:: cbreak()
104
105   Enter cbreak mode.  In cbreak mode (sometimes called "rare" mode) normal tty
106   line buffering is turned off and characters are available to be read one by one.
107   However, unlike raw mode, special characters (interrupt, quit, suspend, and flow
108   control) retain their effects on the tty driver and calling program.  Calling
109   first :func:`raw` then :func:`cbreak` leaves the terminal in cbreak mode.
110
111
112.. function:: color_content(color_number)
113
114   Return the intensity of the red, green, and blue (RGB) components in the color
115   *color_number*, which must be between ``0`` and ``COLORS - 1``.  Return a 3-tuple,
116   containing the R,G,B values for the given color, which will be between
117   ``0`` (no component) and ``1000`` (maximum amount of component).
118
119
120.. function:: color_pair(pair_number)
121
122   Return the attribute value for displaying text in the specified color pair.
123   Only the first 256 color pairs are supported. This
124   attribute value can be combined with :const:`A_STANDOUT`, :const:`A_REVERSE`,
125   and the other :const:`A_\*` attributes.  :func:`pair_number` is the counterpart
126   to this function.
127
128
129.. function:: curs_set(visibility)
130
131   Set the cursor state.  *visibility* can be set to ``0``, ``1``, or ``2``, for invisible,
132   normal, or very visible.  If the terminal supports the visibility requested, return the
133   previous cursor state; otherwise raise an exception.  On many
134   terminals, the "visible" mode is an underline cursor and the "very visible" mode
135   is a block cursor.
136
137
138.. function:: def_prog_mode()
139
140   Save the current terminal mode as the "program" mode, the mode when the running
141   program is using curses.  (Its counterpart is the "shell" mode, for when the
142   program is not in curses.)  Subsequent calls to :func:`reset_prog_mode` will
143   restore this mode.
144
145
146.. function:: def_shell_mode()
147
148   Save the current terminal mode as the "shell" mode, the mode when the running
149   program is not using curses.  (Its counterpart is the "program" mode, when the
150   program is using curses capabilities.) Subsequent calls to
151   :func:`reset_shell_mode` will restore this mode.
152
153
154.. function:: delay_output(ms)
155
156   Insert an *ms* millisecond pause in output.
157
158
159.. function:: doupdate()
160
161   Update the physical screen.  The curses library keeps two data structures, one
162   representing the current physical screen contents and a virtual screen
163   representing the desired next state.  The :func:`doupdate` ground updates the
164   physical screen to match the virtual screen.
165
166   The virtual screen may be updated by a :meth:`~window.noutrefresh` call after write
167   operations such as :meth:`~window.addstr` have been performed on a window.  The normal
168   :meth:`~window.refresh` call is simply :meth:`!noutrefresh` followed by :func:`!doupdate`;
169   if you have to update multiple windows, you can speed performance and perhaps
170   reduce screen flicker by issuing :meth:`!noutrefresh` calls on all windows,
171   followed by a single :func:`!doupdate`.
172
173
174.. function:: echo()
175
176   Enter echo mode.  In echo mode, each character input is echoed to the screen as
177   it is entered.
178
179
180.. function:: endwin()
181
182   De-initialize the library, and return terminal to normal status.
183
184
185.. function:: erasechar()
186
187   Return the user's current erase character as a one-byte bytes object.  Under Unix operating systems this
188   is a property of the controlling tty of the curses program, and is not set by
189   the curses library itself.
190
191
192.. function:: filter()
193
194   The :func:`.filter` routine, if used, must be called before :func:`initscr` is
195   called.  The effect is that, during those calls, :envvar:`LINES` is set to ``1``; the
196   capabilities ``clear``, ``cup``, ``cud``, ``cud1``, ``cuu1``, ``cuu``, ``vpa`` are disabled; and the ``home``
197   string is set to the value of ``cr``. The effect is that the cursor is confined to
198   the current line, and so are screen updates.  This may be used for enabling
199   character-at-a-time  line editing without touching the rest of the screen.
200
201
202.. function:: flash()
203
204   Flash the screen.  That is, change it to reverse-video and then change it back
205   in a short interval.  Some people prefer such as 'visible bell' to the audible
206   attention signal produced by :func:`beep`.
207
208
209.. function:: flushinp()
210
211   Flush all input buffers.  This throws away any  typeahead  that  has been typed
212   by the user and has not yet been processed by the program.
213
214
215.. function:: getmouse()
216
217   After :meth:`~window.getch` returns :const:`KEY_MOUSE` to signal a mouse event, this
218   method should be called to retrieve the queued mouse event, represented as a
219   5-tuple ``(id, x, y, z, bstate)``. *id* is an ID value used to distinguish
220   multiple devices, and *x*, *y*, *z* are the event's coordinates.  (*z* is
221   currently unused.)  *bstate* is an integer value whose bits will be set to
222   indicate the type of event, and will be the bitwise OR of one or more of the
223   following constants, where *n* is the button number from 1 to 4:
224   :const:`BUTTONn_PRESSED`, :const:`BUTTONn_RELEASED`, :const:`BUTTONn_CLICKED`,
225   :const:`BUTTONn_DOUBLE_CLICKED`, :const:`BUTTONn_TRIPLE_CLICKED`,
226   :const:`BUTTON_SHIFT`, :const:`BUTTON_CTRL`, :const:`BUTTON_ALT`.
227
228
229.. function:: getsyx()
230
231   Return the current coordinates of the virtual screen cursor as a tuple
232   ``(y, x)``.  If :meth:`leaveok <window.leaveok>` is currently ``True``, then return ``(-1, -1)``.
233
234
235.. function:: getwin(file)
236
237   Read window related data stored in the file by an earlier :func:`putwin` call.
238   The routine then creates and initializes a new window using that data, returning
239   the new window object.
240
241
242.. function:: has_colors()
243
244   Return ``True`` if the terminal can display colors; otherwise, return ``False``.
245
246
247.. function:: has_ic()
248
249   Return ``True`` if the terminal has insert- and delete-character capabilities.
250   This function is included for historical reasons only, as all modern software
251   terminal emulators have such capabilities.
252
253
254.. function:: has_il()
255
256   Return ``True`` if the terminal has insert- and delete-line capabilities, or can
257   simulate  them  using scrolling regions. This function is included for
258   historical reasons only, as all modern software terminal emulators have such
259   capabilities.
260
261
262.. function:: has_key(ch)
263
264   Take a key value *ch*, and return ``True`` if the current terminal type recognizes
265   a key with that value.
266
267
268.. function:: halfdelay(tenths)
269
270   Used for half-delay mode, which is similar to cbreak mode in that characters
271   typed by the user are immediately available to the program. However, after
272   blocking for *tenths* tenths of seconds, raise an exception if nothing has
273   been typed.  The value of *tenths* must be a number between ``1`` and ``255``.  Use
274   :func:`nocbreak` to leave half-delay mode.
275
276
277.. function:: init_color(color_number, r, g, b)
278
279   Change the definition of a color, taking the number of the color to be changed
280   followed by three RGB values (for the amounts of red, green, and blue
281   components).  The value of *color_number* must be between ``0`` and
282   `COLORS - 1`.  Each of *r*, *g*, *b*, must be a value between ``0`` and
283   ``1000``.  When :func:`init_color` is used, all occurrences of that color on the
284   screen immediately change to the new definition.  This function is a no-op on
285   most terminals; it is active only if :func:`can_change_color` returns ``True``.
286
287
288.. function:: init_pair(pair_number, fg, bg)
289
290   Change the definition of a color-pair.  It takes three arguments: the number of
291   the color-pair to be changed, the foreground color number, and the background
292   color number.  The value of *pair_number* must be between ``1`` and
293   ``COLOR_PAIRS - 1`` (the ``0`` color pair is wired to white on black and cannot
294   be changed).  The value of *fg* and *bg* arguments must be between ``0`` and
295   ``COLORS - 1``, or, after calling :func:`use_default_colors`, ``-1``.
296   If the color-pair was previously initialized, the screen is
297   refreshed and all occurrences of that color-pair are changed to the new
298   definition.
299
300
301.. function:: initscr()
302
303   Initialize the library. Return a :ref:`window <curses-window-objects>` object
304   which represents the whole screen.
305
306   .. note::
307
308      If there is an error opening the terminal, the underlying curses library may
309      cause the interpreter to exit.
310
311
312.. function:: is_term_resized(nlines, ncols)
313
314   Return ``True`` if :func:`resize_term` would modify the window structure,
315   ``False`` otherwise.
316
317
318.. function:: isendwin()
319
320   Return ``True`` if :func:`endwin` has been called (that is, the  curses library has
321   been deinitialized).
322
323
324.. function:: keyname(k)
325
326   Return the name of the key numbered *k* as a bytes object.  The name of a key generating printable
327   ASCII character is the key's character.  The name of a control-key combination
328   is a two-byte bytes object consisting of a caret (``b'^'``) followed by the corresponding
329   printable ASCII character.  The name of an alt-key combination (128--255) is a
330   bytes object consisting of the prefix ``b'M-'`` followed by the name of the corresponding
331   ASCII character.
332
333
334.. function:: killchar()
335
336   Return the user's current line kill character as a one-byte bytes object. Under Unix operating systems
337   this is a property of the controlling tty of the curses program, and is not set
338   by the curses library itself.
339
340
341.. function:: longname()
342
343   Return a bytes object containing the terminfo long name field describing the current
344   terminal.  The maximum length of a verbose description is 128 characters.  It is
345   defined only after the call to :func:`initscr`.
346
347
348.. function:: meta(flag)
349
350   If *flag* is ``True``, allow 8-bit characters to be input.  If
351   *flag* is ``False``,  allow only 7-bit chars.
352
353
354.. function:: mouseinterval(interval)
355
356   Set the maximum time in milliseconds that can elapse between press and release
357   events in order for them to be recognized as a click, and return the previous
358   interval value.  The default value is 200 msec, or one fifth of a second.
359
360
361.. function:: mousemask(mousemask)
362
363   Set the mouse events to be reported, and return a tuple ``(availmask,
364   oldmask)``.   *availmask* indicates which of the specified mouse events can be
365   reported; on complete failure it returns ``0``.  *oldmask* is the previous value of
366   the given window's mouse event mask.  If this function is never called, no mouse
367   events are ever reported.
368
369
370.. function:: napms(ms)
371
372   Sleep for *ms* milliseconds.
373
374
375.. function:: newpad(nlines, ncols)
376
377   Create and return a pointer to a new pad data structure with the given number
378   of lines and columns.  Return a pad as a window object.
379
380   A pad is like a window, except that it is not restricted by the screen size, and
381   is not necessarily associated with a particular part of the screen.  Pads can be
382   used when a large window is needed, and only a part of the window will be on the
383   screen at one time.  Automatic refreshes of pads (such as from scrolling or
384   echoing of input) do not occur.  The :meth:`~window.refresh` and :meth:`~window.noutrefresh`
385   methods of a pad require 6 arguments to specify the part of the pad to be
386   displayed and the location on the screen to be used for the display. The
387   arguments are *pminrow*, *pmincol*, *sminrow*, *smincol*, *smaxrow*, *smaxcol*; the *p*
388   arguments refer to the upper left corner of the pad region to be displayed and
389   the *s* arguments define a clipping box on the screen within which the pad region
390   is to be displayed.
391
392
393.. function:: newwin(nlines, ncols)
394              newwin(nlines, ncols, begin_y, begin_x)
395
396   Return a new :ref:`window <curses-window-objects>`, whose left-upper corner
397   is at  ``(begin_y, begin_x)``, and whose height/width is  *nlines*/*ncols*.
398
399   By default, the window will extend from the  specified position to the lower
400   right corner of the screen.
401
402
403.. function:: nl()
404
405   Enter newline mode.  This mode translates the return key into newline on input,
406   and translates newline into return and line-feed on output. Newline mode is
407   initially on.
408
409
410.. function:: nocbreak()
411
412   Leave cbreak mode.  Return to normal "cooked" mode with line buffering.
413
414
415.. function:: noecho()
416
417   Leave echo mode.  Echoing of input characters is turned off.
418
419
420.. function:: nonl()
421
422   Leave newline mode.  Disable translation of return into newline on input, and
423   disable low-level translation of newline into newline/return on output (but this
424   does not change the behavior of ``addch('\n')``, which always does the
425   equivalent of return and line feed on the virtual screen).  With translation
426   off, curses can sometimes speed up vertical motion a little; also, it will be
427   able to detect the return key on input.
428
429
430.. function:: noqiflush()
431
432   When the :func:`!noqiflush` routine is used, normal flush of input and output queues
433   associated with the ``INTR``, ``QUIT`` and ``SUSP`` characters will not be done.  You may
434   want to call :func:`!noqiflush` in a signal handler if you want output to
435   continue as though the interrupt had not occurred, after the handler exits.
436
437
438.. function:: noraw()
439
440   Leave raw mode. Return to normal "cooked" mode with line buffering.
441
442
443.. function:: pair_content(pair_number)
444
445   Return a tuple ``(fg, bg)`` containing the colors for the requested color pair.
446   The value of *pair_number* must be between ``0`` and ``COLOR_PAIRS - 1``.
447
448
449.. function:: pair_number(attr)
450
451   Return the number of the color-pair set by the attribute value *attr*.
452   :func:`color_pair` is the counterpart to this function.
453
454
455.. function:: putp(str)
456
457   Equivalent to ``tputs(str, 1, putchar)``; emit the value of a specified
458   terminfo capability for the current terminal.  Note that the output of :func:`putp`
459   always goes to standard output.
460
461
462.. function:: qiflush([flag])
463
464   If *flag* is ``False``, the effect is the same as calling :func:`noqiflush`. If
465   *flag* is ``True``, or no argument is provided, the queues will be flushed when
466   these control characters are read.
467
468
469.. function:: raw()
470
471   Enter raw mode.  In raw mode, normal line buffering and  processing of
472   interrupt, quit, suspend, and flow control keys are turned off; characters are
473   presented to curses input functions one by one.
474
475
476.. function:: reset_prog_mode()
477
478   Restore the  terminal  to "program" mode, as previously saved  by
479   :func:`def_prog_mode`.
480
481
482.. function:: reset_shell_mode()
483
484   Restore the  terminal  to "shell" mode, as previously saved  by
485   :func:`def_shell_mode`.
486
487
488.. function:: resetty()
489
490   Restore the state of the terminal modes to what it was at the last call to
491   :func:`savetty`.
492
493
494.. function:: resize_term(nlines, ncols)
495
496   Backend function used by :func:`resizeterm`, performing most of the work;
497   when resizing the windows, :func:`resize_term` blank-fills the areas that are
498   extended.  The calling application should fill in these areas with
499   appropriate data.  The :func:`!resize_term` function attempts to resize all
500   windows.  However, due to the calling convention of pads, it is not possible
501   to resize these without additional interaction with the application.
502
503
504.. function:: resizeterm(nlines, ncols)
505
506   Resize the standard and current windows to the specified dimensions, and
507   adjusts other bookkeeping data used by the curses library that record the
508   window dimensions (in particular the SIGWINCH handler).
509
510
511.. function:: savetty()
512
513   Save the current state of the terminal modes in a buffer, usable by
514   :func:`resetty`.
515
516
517.. function:: setsyx(y, x)
518
519   Set the virtual screen cursor to *y*, *x*. If *y* and *x* are both ``-1``, then
520   :meth:`leaveok <window.leaveok>` is set ``True``.
521
522
523.. function:: setupterm(term=None, fd=-1)
524
525   Initialize the terminal.  *term* is a string giving
526   the terminal name, or ``None``; if omitted or ``None``, the value of the
527   :envvar:`TERM` environment variable will be used.  *fd* is the
528   file descriptor to which any initialization sequences will be sent; if not
529   supplied or ``-1``, the file descriptor for ``sys.stdout`` will be used.
530
531
532.. function:: start_color()
533
534   Must be called if the programmer wants to use colors, and before any other color
535   manipulation routine is called.  It is good practice to call this routine right
536   after :func:`initscr`.
537
538   :func:`start_color` initializes eight basic colors (black, red,  green, yellow,
539   blue, magenta, cyan, and white), and two global variables in the :mod:`curses`
540   module, :const:`COLORS` and :const:`COLOR_PAIRS`, containing the maximum number
541   of colors and color-pairs the terminal can support.  It also restores the colors
542   on the terminal to the values they had when the terminal was just turned on.
543
544
545.. function:: termattrs()
546
547   Return a logical OR of all video attributes supported by the terminal.  This
548   information is useful when a curses program needs complete control over the
549   appearance of the screen.
550
551
552.. function:: termname()
553
554   Return the value of the environment variable :envvar:`TERM`, as a bytes object,
555   truncated to 14 characters.
556
557
558.. function:: tigetflag(capname)
559
560   Return the value of the Boolean capability corresponding to the terminfo
561   capability name *capname* as an integer.  Return the value ``-1`` if *capname* is not a
562   Boolean capability, or ``0`` if it is canceled or absent from the terminal
563   description.
564
565
566.. function:: tigetnum(capname)
567
568   Return the value of the numeric capability corresponding to the terminfo
569   capability name *capname* as an integer.  Return the value ``-2`` if *capname* is not a
570   numeric capability, or ``-1`` if it is canceled or absent from the terminal
571   description.
572
573
574.. function:: tigetstr(capname)
575
576   Return the value of the string capability corresponding to the terminfo
577   capability name *capname* as a bytes object.  Return ``None`` if *capname*
578   is not a terminfo "string capability", or is canceled or absent from the
579   terminal description.
580
581
582.. function:: tparm(str[, ...])
583
584   Instantiate the bytes object *str* with the supplied parameters, where *str* should
585   be a parameterized string obtained from the terminfo database.  E.g.
586   ``tparm(tigetstr("cup"), 5, 3)`` could result in ``b'\033[6;4H'``, the exact
587   result depending on terminal type.
588
589
590.. function:: typeahead(fd)
591
592   Specify that the file descriptor *fd* be used for typeahead checking.  If *fd*
593   is ``-1``, then no typeahead checking is done.
594
595   The curses library does "line-breakout optimization" by looking for typeahead
596   periodically while updating the screen.  If input is found, and it is coming
597   from a tty, the current update is postponed until refresh or doupdate is called
598   again, allowing faster response to commands typed in advance. This function
599   allows specifying a different file descriptor for typeahead checking.
600
601
602.. function:: unctrl(ch)
603
604   Return a bytes object which is a printable representation of the character *ch*.
605   Control characters are represented as a caret followed by the character, for
606   example as ``b'^C'``. Printing characters are left as they are.
607
608
609.. function:: ungetch(ch)
610
611   Push *ch* so the next :meth:`~window.getch` will return it.
612
613   .. note::
614
615      Only one *ch* can be pushed before :meth:`!getch` is called.
616
617
618.. function:: update_lines_cols()
619
620   Update :envvar:`LINES` and :envvar:`COLS`. Useful for detecting manual screen resize.
621
622   .. versionadded:: 3.5
623
624
625.. function:: unget_wch(ch)
626
627   Push *ch* so the next :meth:`~window.get_wch` will return it.
628
629   .. note::
630
631      Only one *ch* can be pushed before :meth:`!get_wch` is called.
632
633   .. versionadded:: 3.3
634
635
636.. function:: ungetmouse(id, x, y, z, bstate)
637
638   Push a :const:`KEY_MOUSE` event onto the input queue, associating the given
639   state data with it.
640
641
642.. function:: use_env(flag)
643
644   If used, this function should be called before :func:`initscr` or newterm are
645   called.  When *flag* is ``False``, the values of lines and columns specified in the
646   terminfo database will be used, even if environment variables :envvar:`LINES`
647   and :envvar:`COLUMNS` (used by default) are set, or if curses is running in a
648   window (in which case default behavior would be to use the window size if
649   :envvar:`LINES` and :envvar:`COLUMNS` are not set).
650
651
652.. function:: use_default_colors()
653
654   Allow use of default values for colors on terminals supporting this feature. Use
655   this to support transparency in your application.  The default color is assigned
656   to the color number ``-1``. After calling this function,  ``init_pair(x,
657   curses.COLOR_RED, -1)`` initializes, for instance, color pair *x* to a red
658   foreground color on the default background.
659
660
661.. function:: wrapper(func, ...)
662
663   Initialize curses and call another callable object, *func*, which should be the
664   rest of your curses-using application.  If the application raises an exception,
665   this function will restore the terminal to a sane state before re-raising the
666   exception and generating a traceback.  The callable object *func* is then passed
667   the main window 'stdscr' as its first argument, followed by any other arguments
668   passed to :func:`!wrapper`.  Before calling *func*, :func:`!wrapper` turns on
669   cbreak mode, turns off echo, enables the terminal keypad, and initializes colors
670   if the terminal has color support.  On exit (whether normally or by exception)
671   it restores cooked mode, turns on echo, and disables the terminal keypad.
672
673
674.. _curses-window-objects:
675
676Window Objects
677--------------
678
679Window objects, as returned by :func:`initscr` and :func:`newwin` above, have
680the following methods and attributes:
681
682
683.. method:: window.addch(ch[, attr])
684            window.addch(y, x, ch[, attr])
685
686   Paint character *ch* at ``(y, x)`` with attributes *attr*, overwriting any
687   character previously painted at that location.  By default, the character
688   position and attributes are the current settings for the window object.
689
690   .. note::
691
692      Writing outside the window, subwindow, or pad raises a :exc:`curses.error`.
693      Attempting to write to the lower right corner of a window, subwindow,
694      or pad will cause an exception to be raised after the character is printed.
695
696
697.. method:: window.addnstr(str, n[, attr])
698            window.addnstr(y, x, str, n[, attr])
699
700   Paint at most *n* characters of the character string *str* at
701   ``(y, x)`` with attributes
702   *attr*, overwriting anything previously on the display.
703
704
705.. method:: window.addstr(str[, attr])
706            window.addstr(y, x, str[, attr])
707
708   Paint the character string *str* at ``(y, x)`` with attributes
709   *attr*, overwriting anything previously on the display.
710
711   .. note::
712
713      * Writing outside the window, subwindow, or pad raises :exc:`curses.error`.
714        Attempting to write to the lower right corner of a window, subwindow,
715        or pad will cause an exception to be raised after the string is printed.
716
717      * A `bug in ncurses <https://bugs.python.org/issue35924>`_, the backend
718        for this Python module, can cause SegFaults when resizing windows. This
719        is fixed in ncurses-6.1-20190511.  If you are stuck with an earlier
720        ncurses, you can avoid triggering this if you do not call :func:`addstr`
721        with a *str* that has embedded newlines.  Instead, call :func:`addstr`
722        separately for each line.
723
724
725.. method:: window.attroff(attr)
726
727   Remove attribute *attr* from the "background" set applied to all writes to the
728   current window.
729
730
731.. method:: window.attron(attr)
732
733   Add attribute *attr* from the "background" set applied to all writes to the
734   current window.
735
736
737.. method:: window.attrset(attr)
738
739   Set the "background" set of attributes to *attr*.  This set is initially
740   ``0`` (no attributes).
741
742
743.. method:: window.bkgd(ch[, attr])
744
745   Set the background property of the window to the character *ch*, with
746   attributes *attr*.  The change is then applied to every character position in
747   that window:
748
749   * The attribute of every character in the window  is changed to the new
750     background attribute.
751
752   * Wherever  the  former background character appears, it is changed to the new
753     background character.
754
755
756.. method:: window.bkgdset(ch[, attr])
757
758   Set the window's background.  A window's background consists of a character and
759   any combination of attributes.  The attribute part of the background is combined
760   (OR'ed) with all non-blank characters that are written into the window.  Both
761   the character and attribute parts of the background are combined with the blank
762   characters.  The background becomes a property of the character and moves with
763   the character through any scrolling and insert/delete line/character operations.
764
765
766.. method:: window.border([ls[, rs[, ts[, bs[, tl[, tr[, bl[, br]]]]]]]])
767
768   Draw a border around the edges of the window. Each parameter specifies  the
769   character to use for a specific part of the border; see the table below for more
770   details.
771
772   .. note::
773
774      A ``0`` value for any parameter will cause the default character to be used for
775      that parameter.  Keyword parameters can *not* be used.  The defaults are listed
776      in this table:
777
778   +-----------+---------------------+-----------------------+
779   | Parameter | Description         | Default value         |
780   +===========+=====================+=======================+
781   | *ls*      | Left side           | :const:`ACS_VLINE`    |
782   +-----------+---------------------+-----------------------+
783   | *rs*      | Right side          | :const:`ACS_VLINE`    |
784   +-----------+---------------------+-----------------------+
785   | *ts*      | Top                 | :const:`ACS_HLINE`    |
786   +-----------+---------------------+-----------------------+
787   | *bs*      | Bottom              | :const:`ACS_HLINE`    |
788   +-----------+---------------------+-----------------------+
789   | *tl*      | Upper-left corner   | :const:`ACS_ULCORNER` |
790   +-----------+---------------------+-----------------------+
791   | *tr*      | Upper-right corner  | :const:`ACS_URCORNER` |
792   +-----------+---------------------+-----------------------+
793   | *bl*      | Bottom-left corner  | :const:`ACS_LLCORNER` |
794   +-----------+---------------------+-----------------------+
795   | *br*      | Bottom-right corner | :const:`ACS_LRCORNER` |
796   +-----------+---------------------+-----------------------+
797
798
799.. method:: window.box([vertch, horch])
800
801   Similar to :meth:`border`, but both *ls* and *rs* are *vertch* and both *ts* and
802   *bs* are *horch*.  The default corner characters are always used by this function.
803
804
805.. method:: window.chgat(attr)
806            window.chgat(num, attr)
807            window.chgat(y, x, attr)
808            window.chgat(y, x, num, attr)
809
810   Set the attributes of *num* characters at the current cursor position, or at
811   position ``(y, x)`` if supplied. If *num* is not given or is ``-1``,
812   the attribute will be set on all the characters to the end of the line.  This
813   function moves cursor to position ``(y, x)`` if supplied. The changed line
814   will be touched using the :meth:`touchline` method so that the contents will
815   be redisplayed by the next window refresh.
816
817
818.. method:: window.clear()
819
820   Like :meth:`erase`, but also cause the whole window to be repainted upon next
821   call to :meth:`refresh`.
822
823
824.. method:: window.clearok(flag)
825
826   If *flag* is ``True``, the next call to :meth:`refresh` will clear the window
827   completely.
828
829
830.. method:: window.clrtobot()
831
832   Erase from cursor to the end of the window: all lines below the cursor are
833   deleted, and then the equivalent of :meth:`clrtoeol` is performed.
834
835
836.. method:: window.clrtoeol()
837
838   Erase from cursor to the end of the line.
839
840
841.. method:: window.cursyncup()
842
843   Update the current cursor position of all the ancestors of the window to
844   reflect the current cursor position of the window.
845
846
847.. method:: window.delch([y, x])
848
849   Delete any character at ``(y, x)``.
850
851
852.. method:: window.deleteln()
853
854   Delete the line under the cursor. All following lines are moved up by one line.
855
856
857.. method:: window.derwin(begin_y, begin_x)
858            window.derwin(nlines, ncols, begin_y, begin_x)
859
860   An abbreviation for "derive window", :meth:`derwin` is the same as calling
861   :meth:`subwin`, except that *begin_y* and *begin_x* are relative to the origin
862   of the window, rather than relative to the entire screen.  Return a window
863   object for the derived window.
864
865
866.. method:: window.echochar(ch[, attr])
867
868   Add character *ch* with attribute *attr*, and immediately  call :meth:`refresh`
869   on the window.
870
871
872.. method:: window.enclose(y, x)
873
874   Test whether the given pair of screen-relative character-cell coordinates are
875   enclosed by the given window, returning ``True`` or ``False``.  It is useful for
876   determining what subset of the screen windows enclose the location of a mouse
877   event.
878
879
880.. attribute:: window.encoding
881
882   Encoding used to encode method arguments (Unicode strings and characters).
883   The encoding attribute is inherited from the parent window when a subwindow
884   is created, for example with :meth:`window.subwin`. By default, the locale
885   encoding is used (see :func:`locale.getpreferredencoding`).
886
887   .. versionadded:: 3.3
888
889
890.. method:: window.erase()
891
892   Clear the window.
893
894
895.. method:: window.getbegyx()
896
897   Return a tuple ``(y, x)`` of co-ordinates of upper-left corner.
898
899
900.. method:: window.getbkgd()
901
902   Return the given window's current background character/attribute pair.
903
904
905.. method:: window.getch([y, x])
906
907   Get a character. Note that the integer returned does *not* have to be in ASCII
908   range: function keys, keypad keys and so on are represented by numbers higher
909   than 255.  In no-delay mode, return ``-1`` if there is no input, otherwise
910   wait until a key is pressed.
911
912
913.. method:: window.get_wch([y, x])
914
915   Get a wide character. Return a character for most keys, or an integer for
916   function keys, keypad keys, and other special keys.
917   In no-delay mode, raise an exception if there is no input.
918
919   .. versionadded:: 3.3
920
921
922.. method:: window.getkey([y, x])
923
924   Get a character, returning a string instead of an integer, as :meth:`getch`
925   does. Function keys, keypad keys and other special keys return a multibyte
926   string containing the key name.  In no-delay mode, raise an exception if
927   there is no input.
928
929
930.. method:: window.getmaxyx()
931
932   Return a tuple ``(y, x)`` of the height and width of the window.
933
934
935.. method:: window.getparyx()
936
937   Return the beginning coordinates of this window relative to its parent window
938   as a tuple ``(y, x)``.  Return ``(-1, -1)`` if this window has no
939   parent.
940
941
942.. method:: window.getstr()
943            window.getstr(n)
944            window.getstr(y, x)
945            window.getstr(y, x, n)
946
947   Read a bytes object from the user, with primitive line editing capacity.
948
949
950.. method:: window.getyx()
951
952   Return a tuple ``(y, x)`` of current cursor position  relative to the window's
953   upper-left corner.
954
955
956.. method:: window.hline(ch, n)
957            window.hline(y, x, ch, n)
958
959   Display a horizontal line starting at ``(y, x)`` with length *n* consisting of
960   the character *ch*.
961
962
963.. method:: window.idcok(flag)
964
965   If *flag* is ``False``, curses no longer considers using the hardware insert/delete
966   character feature of the terminal; if *flag* is ``True``, use of character insertion
967   and deletion is enabled.  When curses is first initialized, use of character
968   insert/delete is enabled by default.
969
970
971.. method:: window.idlok(flag)
972
973   If *flag* is ``True``, :mod:`curses` will try and use hardware line
974   editing facilities. Otherwise, line insertion/deletion are disabled.
975
976
977.. method:: window.immedok(flag)
978
979   If *flag* is ``True``, any change in the window image automatically causes the
980   window to be refreshed; you no longer have to call :meth:`refresh` yourself.
981   However, it may degrade performance considerably, due to repeated calls to
982   wrefresh.  This option is disabled by default.
983
984
985.. method:: window.inch([y, x])
986
987   Return the character at the given position in the window. The bottom 8 bits are
988   the character proper, and upper bits are the attributes.
989
990
991.. method:: window.insch(ch[, attr])
992            window.insch(y, x, ch[, attr])
993
994   Paint character *ch* at ``(y, x)`` with attributes *attr*, moving the line from
995   position *x* right by one character.
996
997
998.. method:: window.insdelln(nlines)
999
1000   Insert *nlines* lines into the specified window above the current line.  The
1001   *nlines* bottom lines are lost.  For negative *nlines*, delete *nlines* lines
1002   starting with the one under the cursor, and move the remaining lines up.  The
1003   bottom *nlines* lines are cleared.  The current cursor position remains the
1004   same.
1005
1006
1007.. method:: window.insertln()
1008
1009   Insert a blank line under the cursor. All following lines are moved down by one
1010   line.
1011
1012
1013.. method:: window.insnstr(str, n[, attr])
1014            window.insnstr(y, x, str, n[, attr])
1015
1016   Insert a character string (as many characters as will fit on the line) before
1017   the character under the cursor, up to *n* characters.   If *n* is zero or
1018   negative, the entire string is inserted. All characters to the right of the
1019   cursor are shifted right, with the rightmost characters on the line being lost.
1020   The cursor position does not change (after moving to *y*, *x*, if specified).
1021
1022
1023.. method:: window.insstr(str[, attr])
1024            window.insstr(y, x, str[, attr])
1025
1026   Insert a character string (as many characters as will fit on the line) before
1027   the character under the cursor.  All characters to the right of the cursor are
1028   shifted right, with the rightmost characters on the line being lost.  The cursor
1029   position does not change (after moving to *y*, *x*, if specified).
1030
1031
1032.. method:: window.instr([n])
1033            window.instr(y, x[, n])
1034
1035   Return a bytes object of characters, extracted from the window starting at the
1036   current cursor position, or at *y*, *x* if specified. Attributes are stripped
1037   from the characters.  If *n* is specified, :meth:`instr` returns a string
1038   at most *n* characters long (exclusive of the trailing NUL).
1039
1040
1041.. method:: window.is_linetouched(line)
1042
1043   Return ``True`` if the specified line was modified since the last call to
1044   :meth:`refresh`; otherwise return ``False``.  Raise a :exc:`curses.error`
1045   exception if *line* is not valid for the given window.
1046
1047
1048.. method:: window.is_wintouched()
1049
1050   Return ``True`` if the specified window was modified since the last call to
1051   :meth:`refresh`; otherwise return ``False``.
1052
1053
1054.. method:: window.keypad(flag)
1055
1056   If *flag* is ``True``, escape sequences generated by some keys (keypad,  function keys)
1057   will be interpreted by :mod:`curses`. If *flag* is ``False``, escape sequences will be
1058   left as is in the input stream.
1059
1060
1061.. method:: window.leaveok(flag)
1062
1063   If *flag* is ``True``, cursor is left where it is on update, instead of being at "cursor
1064   position."  This reduces cursor movement where possible. If possible the cursor
1065   will be made invisible.
1066
1067   If *flag* is ``False``, cursor will always be at "cursor position" after an update.
1068
1069
1070.. method:: window.move(new_y, new_x)
1071
1072   Move cursor to ``(new_y, new_x)``.
1073
1074
1075.. method:: window.mvderwin(y, x)
1076
1077   Move the window inside its parent window.  The screen-relative parameters of
1078   the window are not changed.  This routine is used to display different parts of
1079   the parent window at the same physical position on the screen.
1080
1081
1082.. method:: window.mvwin(new_y, new_x)
1083
1084   Move the window so its upper-left corner is at ``(new_y, new_x)``.
1085
1086
1087.. method:: window.nodelay(flag)
1088
1089   If *flag* is ``True``, :meth:`getch` will be non-blocking.
1090
1091
1092.. method:: window.notimeout(flag)
1093
1094   If *flag* is ``True``, escape sequences will not be timed out.
1095
1096   If *flag* is ``False``, after a few milliseconds, an escape sequence will not be
1097   interpreted, and will be left in the input stream as is.
1098
1099
1100.. method:: window.noutrefresh()
1101
1102   Mark for refresh but wait.  This function updates the data structure
1103   representing the desired state of the window, but does not force an update of
1104   the physical screen.  To accomplish that, call  :func:`doupdate`.
1105
1106
1107.. method:: window.overlay(destwin[, sminrow, smincol, dminrow, dmincol, dmaxrow, dmaxcol])
1108
1109   Overlay the window on top of *destwin*. The windows need not be the same size,
1110   only the overlapping region is copied. This copy is non-destructive, which means
1111   that the current background character does not overwrite the old contents of
1112   *destwin*.
1113
1114   To get fine-grained control over the copied region, the second form of
1115   :meth:`overlay` can be used. *sminrow* and *smincol* are the upper-left
1116   coordinates of the source window, and the other variables mark a rectangle in
1117   the destination window.
1118
1119
1120.. method:: window.overwrite(destwin[, sminrow, smincol, dminrow, dmincol, dmaxrow, dmaxcol])
1121
1122   Overwrite the window on top of *destwin*. The windows need not be the same size,
1123   in which case only the overlapping region is copied. This copy is destructive,
1124   which means that the current background character overwrites the old contents of
1125   *destwin*.
1126
1127   To get fine-grained control over the copied region, the second form of
1128   :meth:`overwrite` can be used. *sminrow* and *smincol* are the upper-left
1129   coordinates of the source window, the other variables mark a rectangle in the
1130   destination window.
1131
1132
1133.. method:: window.putwin(file)
1134
1135   Write all data associated with the window into the provided file object.  This
1136   information can be later retrieved using the :func:`getwin` function.
1137
1138
1139.. method:: window.redrawln(beg, num)
1140
1141   Indicate that the *num* screen lines, starting at line *beg*, are corrupted and
1142   should be completely redrawn on the next :meth:`refresh` call.
1143
1144
1145.. method:: window.redrawwin()
1146
1147   Touch the entire window, causing it to be completely redrawn on the next
1148   :meth:`refresh` call.
1149
1150
1151.. method:: window.refresh([pminrow, pmincol, sminrow, smincol, smaxrow, smaxcol])
1152
1153   Update the display immediately (sync actual screen with previous
1154   drawing/deleting methods).
1155
1156   The 6 optional arguments can only be specified when the window is a pad created
1157   with :func:`newpad`.  The additional parameters are needed to indicate what part
1158   of the pad and screen are involved. *pminrow* and *pmincol* specify the upper
1159   left-hand corner of the rectangle to be displayed in the pad.  *sminrow*,
1160   *smincol*, *smaxrow*, and *smaxcol* specify the edges of the rectangle to be
1161   displayed on the screen.  The lower right-hand corner of the rectangle to be
1162   displayed in the pad is calculated from the screen coordinates, since the
1163   rectangles must be the same size.  Both rectangles must be entirely contained
1164   within their respective structures.  Negative values of *pminrow*, *pmincol*,
1165   *sminrow*, or *smincol* are treated as if they were zero.
1166
1167
1168.. method:: window.resize(nlines, ncols)
1169
1170   Reallocate storage for a curses window to adjust its dimensions to the
1171   specified values.  If either dimension is larger than the current values, the
1172   window's data is filled with blanks that have the current background
1173   rendition (as set by :meth:`bkgdset`) merged into them.
1174
1175
1176.. method:: window.scroll([lines=1])
1177
1178   Scroll the screen or scrolling region upward by *lines* lines.
1179
1180
1181.. method:: window.scrollok(flag)
1182
1183   Control what happens when the cursor of a window is moved off the edge of the
1184   window or scrolling region, either as a result of a newline action on the bottom
1185   line, or typing the last character of the last line.  If *flag* is ``False``, the
1186   cursor is left on the bottom line.  If *flag* is ``True``, the window is scrolled up
1187   one line.  Note that in order to get the physical scrolling effect on the
1188   terminal, it is also necessary to call :meth:`idlok`.
1189
1190
1191.. method:: window.setscrreg(top, bottom)
1192
1193   Set the scrolling region from line *top* to line *bottom*. All scrolling actions
1194   will take place in this region.
1195
1196
1197.. method:: window.standend()
1198
1199   Turn off the standout attribute.  On some terminals this has the side effect of
1200   turning off all attributes.
1201
1202
1203.. method:: window.standout()
1204
1205   Turn on attribute *A_STANDOUT*.
1206
1207
1208.. method:: window.subpad(begin_y, begin_x)
1209            window.subpad(nlines, ncols, begin_y, begin_x)
1210
1211   Return a sub-window, whose upper-left corner is at ``(begin_y, begin_x)``, and
1212   whose width/height is *ncols*/*nlines*.
1213
1214
1215.. method:: window.subwin(begin_y, begin_x)
1216            window.subwin(nlines, ncols, begin_y, begin_x)
1217
1218   Return a sub-window, whose upper-left corner is at ``(begin_y, begin_x)``, and
1219   whose width/height is *ncols*/*nlines*.
1220
1221   By default, the sub-window will extend from the specified position to the lower
1222   right corner of the window.
1223
1224
1225.. method:: window.syncdown()
1226
1227   Touch each location in the window that has been touched in any of its ancestor
1228   windows.  This routine is called by :meth:`refresh`, so it should almost never
1229   be necessary to call it manually.
1230
1231
1232.. method:: window.syncok(flag)
1233
1234   If *flag* is ``True``, then :meth:`syncup` is called automatically
1235   whenever there is a change in the window.
1236
1237
1238.. method:: window.syncup()
1239
1240   Touch all locations in ancestors of the window that have been changed in  the
1241   window.
1242
1243
1244.. method:: window.timeout(delay)
1245
1246   Set blocking or non-blocking read behavior for the window.  If *delay* is
1247   negative, blocking read is used (which will wait indefinitely for input).  If
1248   *delay* is zero, then non-blocking read is used, and :meth:`getch` will
1249   return ``-1`` if no input is waiting.  If *delay* is positive, then
1250   :meth:`getch` will block for *delay* milliseconds, and return ``-1`` if there is
1251   still no input at the end of that time.
1252
1253
1254.. method:: window.touchline(start, count[, changed])
1255
1256   Pretend *count* lines have been changed, starting with line *start*.  If
1257   *changed* is supplied, it specifies whether the affected lines are marked as
1258   having been changed (*changed*\ ``=True``) or unchanged (*changed*\ ``=False``).
1259
1260
1261.. method:: window.touchwin()
1262
1263   Pretend the whole window has been changed, for purposes of drawing
1264   optimizations.
1265
1266
1267.. method:: window.untouchwin()
1268
1269   Mark all lines in  the  window  as unchanged since the last call to
1270   :meth:`refresh`.
1271
1272
1273.. method:: window.vline(ch, n)
1274            window.vline(y, x, ch, n)
1275
1276   Display a vertical line starting at ``(y, x)`` with length *n* consisting of the
1277   character *ch*.
1278
1279
1280Constants
1281---------
1282
1283The :mod:`curses` module defines the following data members:
1284
1285
1286.. data:: ERR
1287
1288   Some curses routines  that  return  an integer, such as :meth:`~window.getch`, return
1289   :const:`ERR` upon failure.
1290
1291
1292.. data:: OK
1293
1294   Some curses routines  that  return  an integer, such as  :func:`napms`, return
1295   :const:`OK` upon success.
1296
1297
1298.. data:: version
1299
1300   A bytes object representing the current version of the module.  Also available as
1301   :const:`__version__`.
1302
1303
1304.. data:: ncurses_version
1305
1306   A named tuple containing the three components of the ncurses library
1307   version: *major*, *minor*, and *patch*.  All values are integers.  The
1308   components can also be accessed by name,  so ``curses.ncurses_version[0]``
1309   is equivalent to ``curses.ncurses_version.major`` and so on.
1310
1311   Availability: if the ncurses library is used.
1312
1313   .. versionadded:: 3.8
1314
1315
1316Some constants are available to specify character cell attributes.
1317The exact constants available are system dependent.
1318
1319+------------------+-------------------------------+
1320| Attribute        | Meaning                       |
1321+==================+===============================+
1322| ``A_ALTCHARSET`` | Alternate character set mode  |
1323+------------------+-------------------------------+
1324| ``A_BLINK``      | Blink mode                    |
1325+------------------+-------------------------------+
1326| ``A_BOLD``       | Bold mode                     |
1327+------------------+-------------------------------+
1328| ``A_DIM``        | Dim mode                      |
1329+------------------+-------------------------------+
1330| ``A_INVIS``      | Invisible or blank mode       |
1331+------------------+-------------------------------+
1332| ``A_ITALIC``     | Italic mode                   |
1333+------------------+-------------------------------+
1334| ``A_NORMAL``     | Normal attribute              |
1335+------------------+-------------------------------+
1336| ``A_PROTECT``    | Protected mode                |
1337+------------------+-------------------------------+
1338| ``A_REVERSE``    | Reverse background and        |
1339|                  | foreground colors             |
1340+------------------+-------------------------------+
1341| ``A_STANDOUT``   | Standout mode                 |
1342+------------------+-------------------------------+
1343| ``A_UNDERLINE``  | Underline mode                |
1344+------------------+-------------------------------+
1345| ``A_HORIZONTAL`` | Horizontal highlight          |
1346+------------------+-------------------------------+
1347| ``A_LEFT``       | Left highlight                |
1348+------------------+-------------------------------+
1349| ``A_LOW``        | Low highlight                 |
1350+------------------+-------------------------------+
1351| ``A_RIGHT``      | Right highlight               |
1352+------------------+-------------------------------+
1353| ``A_TOP``        | Top highlight                 |
1354+------------------+-------------------------------+
1355| ``A_VERTICAL``   | Vertical highlight            |
1356+------------------+-------------------------------+
1357| ``A_CHARTEXT``   | Bit-mask to extract a         |
1358|                  | character                     |
1359+------------------+-------------------------------+
1360
1361.. versionadded:: 3.7
1362   ``A_ITALIC`` was added.
1363
1364Several constants are available to extract corresponding attributes returned
1365by some methods.
1366
1367+------------------+-------------------------------+
1368| Bit-mask         | Meaning                       |
1369+==================+===============================+
1370| ``A_ATTRIBUTES`` | Bit-mask to extract           |
1371|                  | attributes                    |
1372+------------------+-------------------------------+
1373| ``A_CHARTEXT``   | Bit-mask to extract a         |
1374|                  | character                     |
1375+------------------+-------------------------------+
1376| ``A_COLOR``      | Bit-mask to extract           |
1377|                  | color-pair field information  |
1378+------------------+-------------------------------+
1379
1380Keys are referred to by integer constants with names starting with  ``KEY_``.
1381The exact keycaps available are system dependent.
1382
1383.. XXX this table is far too large! should it be alphabetized?
1384
1385+-------------------+--------------------------------------------+
1386| Key constant      | Key                                        |
1387+===================+============================================+
1388| ``KEY_MIN``       | Minimum key value                          |
1389+-------------------+--------------------------------------------+
1390| ``KEY_BREAK``     | Break key (unreliable)                     |
1391+-------------------+--------------------------------------------+
1392| ``KEY_DOWN``      | Down-arrow                                 |
1393+-------------------+--------------------------------------------+
1394| ``KEY_UP``        | Up-arrow                                   |
1395+-------------------+--------------------------------------------+
1396| ``KEY_LEFT``      | Left-arrow                                 |
1397+-------------------+--------------------------------------------+
1398| ``KEY_RIGHT``     | Right-arrow                                |
1399+-------------------+--------------------------------------------+
1400| ``KEY_HOME``      | Home key (upward+left arrow)               |
1401+-------------------+--------------------------------------------+
1402| ``KEY_BACKSPACE`` | Backspace (unreliable)                     |
1403+-------------------+--------------------------------------------+
1404| ``KEY_F0``        | Function keys.  Up to 64 function keys are |
1405|                   | supported.                                 |
1406+-------------------+--------------------------------------------+
1407| ``KEY_Fn``        | Value of function key *n*                  |
1408+-------------------+--------------------------------------------+
1409| ``KEY_DL``        | Delete line                                |
1410+-------------------+--------------------------------------------+
1411| ``KEY_IL``        | Insert line                                |
1412+-------------------+--------------------------------------------+
1413| ``KEY_DC``        | Delete character                           |
1414+-------------------+--------------------------------------------+
1415| ``KEY_IC``        | Insert char or enter insert mode           |
1416+-------------------+--------------------------------------------+
1417| ``KEY_EIC``       | Exit insert char mode                      |
1418+-------------------+--------------------------------------------+
1419| ``KEY_CLEAR``     | Clear screen                               |
1420+-------------------+--------------------------------------------+
1421| ``KEY_EOS``       | Clear to end of screen                     |
1422+-------------------+--------------------------------------------+
1423| ``KEY_EOL``       | Clear to end of line                       |
1424+-------------------+--------------------------------------------+
1425| ``KEY_SF``        | Scroll 1 line forward                      |
1426+-------------------+--------------------------------------------+
1427| ``KEY_SR``        | Scroll 1 line backward (reverse)           |
1428+-------------------+--------------------------------------------+
1429| ``KEY_NPAGE``     | Next page                                  |
1430+-------------------+--------------------------------------------+
1431| ``KEY_PPAGE``     | Previous page                              |
1432+-------------------+--------------------------------------------+
1433| ``KEY_STAB``      | Set tab                                    |
1434+-------------------+--------------------------------------------+
1435| ``KEY_CTAB``      | Clear tab                                  |
1436+-------------------+--------------------------------------------+
1437| ``KEY_CATAB``     | Clear all tabs                             |
1438+-------------------+--------------------------------------------+
1439| ``KEY_ENTER``     | Enter or send (unreliable)                 |
1440+-------------------+--------------------------------------------+
1441| ``KEY_SRESET``    | Soft (partial) reset (unreliable)          |
1442+-------------------+--------------------------------------------+
1443| ``KEY_RESET``     | Reset or hard reset (unreliable)           |
1444+-------------------+--------------------------------------------+
1445| ``KEY_PRINT``     | Print                                      |
1446+-------------------+--------------------------------------------+
1447| ``KEY_LL``        | Home down or bottom (lower left)           |
1448+-------------------+--------------------------------------------+
1449| ``KEY_A1``        | Upper left of keypad                       |
1450+-------------------+--------------------------------------------+
1451| ``KEY_A3``        | Upper right of keypad                      |
1452+-------------------+--------------------------------------------+
1453| ``KEY_B2``        | Center of keypad                           |
1454+-------------------+--------------------------------------------+
1455| ``KEY_C1``        | Lower left of keypad                       |
1456+-------------------+--------------------------------------------+
1457| ``KEY_C3``        | Lower right of keypad                      |
1458+-------------------+--------------------------------------------+
1459| ``KEY_BTAB``      | Back tab                                   |
1460+-------------------+--------------------------------------------+
1461| ``KEY_BEG``       | Beg (beginning)                            |
1462+-------------------+--------------------------------------------+
1463| ``KEY_CANCEL``    | Cancel                                     |
1464+-------------------+--------------------------------------------+
1465| ``KEY_CLOSE``     | Close                                      |
1466+-------------------+--------------------------------------------+
1467| ``KEY_COMMAND``   | Cmd (command)                              |
1468+-------------------+--------------------------------------------+
1469| ``KEY_COPY``      | Copy                                       |
1470+-------------------+--------------------------------------------+
1471| ``KEY_CREATE``    | Create                                     |
1472+-------------------+--------------------------------------------+
1473| ``KEY_END``       | End                                        |
1474+-------------------+--------------------------------------------+
1475| ``KEY_EXIT``      | Exit                                       |
1476+-------------------+--------------------------------------------+
1477| ``KEY_FIND``      | Find                                       |
1478+-------------------+--------------------------------------------+
1479| ``KEY_HELP``      | Help                                       |
1480+-------------------+--------------------------------------------+
1481| ``KEY_MARK``      | Mark                                       |
1482+-------------------+--------------------------------------------+
1483| ``KEY_MESSAGE``   | Message                                    |
1484+-------------------+--------------------------------------------+
1485| ``KEY_MOVE``      | Move                                       |
1486+-------------------+--------------------------------------------+
1487| ``KEY_NEXT``      | Next                                       |
1488+-------------------+--------------------------------------------+
1489| ``KEY_OPEN``      | Open                                       |
1490+-------------------+--------------------------------------------+
1491| ``KEY_OPTIONS``   | Options                                    |
1492+-------------------+--------------------------------------------+
1493| ``KEY_PREVIOUS``  | Prev (previous)                            |
1494+-------------------+--------------------------------------------+
1495| ``KEY_REDO``      | Redo                                       |
1496+-------------------+--------------------------------------------+
1497| ``KEY_REFERENCE`` | Ref (reference)                            |
1498+-------------------+--------------------------------------------+
1499| ``KEY_REFRESH``   | Refresh                                    |
1500+-------------------+--------------------------------------------+
1501| ``KEY_REPLACE``   | Replace                                    |
1502+-------------------+--------------------------------------------+
1503| ``KEY_RESTART``   | Restart                                    |
1504+-------------------+--------------------------------------------+
1505| ``KEY_RESUME``    | Resume                                     |
1506+-------------------+--------------------------------------------+
1507| ``KEY_SAVE``      | Save                                       |
1508+-------------------+--------------------------------------------+
1509| ``KEY_SBEG``      | Shifted Beg (beginning)                    |
1510+-------------------+--------------------------------------------+
1511| ``KEY_SCANCEL``   | Shifted Cancel                             |
1512+-------------------+--------------------------------------------+
1513| ``KEY_SCOMMAND``  | Shifted Command                            |
1514+-------------------+--------------------------------------------+
1515| ``KEY_SCOPY``     | Shifted Copy                               |
1516+-------------------+--------------------------------------------+
1517| ``KEY_SCREATE``   | Shifted Create                             |
1518+-------------------+--------------------------------------------+
1519| ``KEY_SDC``       | Shifted Delete char                        |
1520+-------------------+--------------------------------------------+
1521| ``KEY_SDL``       | Shifted Delete line                        |
1522+-------------------+--------------------------------------------+
1523| ``KEY_SELECT``    | Select                                     |
1524+-------------------+--------------------------------------------+
1525| ``KEY_SEND``      | Shifted End                                |
1526+-------------------+--------------------------------------------+
1527| ``KEY_SEOL``      | Shifted Clear line                         |
1528+-------------------+--------------------------------------------+
1529| ``KEY_SEXIT``     | Shifted Exit                               |
1530+-------------------+--------------------------------------------+
1531| ``KEY_SFIND``     | Shifted Find                               |
1532+-------------------+--------------------------------------------+
1533| ``KEY_SHELP``     | Shifted Help                               |
1534+-------------------+--------------------------------------------+
1535| ``KEY_SHOME``     | Shifted Home                               |
1536+-------------------+--------------------------------------------+
1537| ``KEY_SIC``       | Shifted Input                              |
1538+-------------------+--------------------------------------------+
1539| ``KEY_SLEFT``     | Shifted Left arrow                         |
1540+-------------------+--------------------------------------------+
1541| ``KEY_SMESSAGE``  | Shifted Message                            |
1542+-------------------+--------------------------------------------+
1543| ``KEY_SMOVE``     | Shifted Move                               |
1544+-------------------+--------------------------------------------+
1545| ``KEY_SNEXT``     | Shifted Next                               |
1546+-------------------+--------------------------------------------+
1547| ``KEY_SOPTIONS``  | Shifted Options                            |
1548+-------------------+--------------------------------------------+
1549| ``KEY_SPREVIOUS`` | Shifted Prev                               |
1550+-------------------+--------------------------------------------+
1551| ``KEY_SPRINT``    | Shifted Print                              |
1552+-------------------+--------------------------------------------+
1553| ``KEY_SREDO``     | Shifted Redo                               |
1554+-------------------+--------------------------------------------+
1555| ``KEY_SREPLACE``  | Shifted Replace                            |
1556+-------------------+--------------------------------------------+
1557| ``KEY_SRIGHT``    | Shifted Right arrow                        |
1558+-------------------+--------------------------------------------+
1559| ``KEY_SRSUME``    | Shifted Resume                             |
1560+-------------------+--------------------------------------------+
1561| ``KEY_SSAVE``     | Shifted Save                               |
1562+-------------------+--------------------------------------------+
1563| ``KEY_SSUSPEND``  | Shifted Suspend                            |
1564+-------------------+--------------------------------------------+
1565| ``KEY_SUNDO``     | Shifted Undo                               |
1566+-------------------+--------------------------------------------+
1567| ``KEY_SUSPEND``   | Suspend                                    |
1568+-------------------+--------------------------------------------+
1569| ``KEY_UNDO``      | Undo                                       |
1570+-------------------+--------------------------------------------+
1571| ``KEY_MOUSE``     | Mouse event has occurred                   |
1572+-------------------+--------------------------------------------+
1573| ``KEY_RESIZE``    | Terminal resize event                      |
1574+-------------------+--------------------------------------------+
1575| ``KEY_MAX``       | Maximum key value                          |
1576+-------------------+--------------------------------------------+
1577
1578On VT100s and their software emulations, such as X terminal emulators, there are
1579normally at least four function keys (:const:`KEY_F1`, :const:`KEY_F2`,
1580:const:`KEY_F3`, :const:`KEY_F4`) available, and the arrow keys mapped to
1581:const:`KEY_UP`, :const:`KEY_DOWN`, :const:`KEY_LEFT` and :const:`KEY_RIGHT` in
1582the obvious way.  If your machine has a PC keyboard, it is safe to expect arrow
1583keys and twelve function keys (older PC keyboards may have only ten function
1584keys); also, the following keypad mappings are standard:
1585
1586+------------------+-----------+
1587| Keycap           | Constant  |
1588+==================+===========+
1589| :kbd:`Insert`    | KEY_IC    |
1590+------------------+-----------+
1591| :kbd:`Delete`    | KEY_DC    |
1592+------------------+-----------+
1593| :kbd:`Home`      | KEY_HOME  |
1594+------------------+-----------+
1595| :kbd:`End`       | KEY_END   |
1596+------------------+-----------+
1597| :kbd:`Page Up`   | KEY_PPAGE |
1598+------------------+-----------+
1599| :kbd:`Page Down` | KEY_NPAGE |
1600+------------------+-----------+
1601
1602The following table lists characters from the alternate character set. These are
1603inherited from the VT100 terminal, and will generally be  available on software
1604emulations such as X terminals.  When there is no graphic available, curses
1605falls back on a crude printable ASCII approximation.
1606
1607.. note::
1608
1609   These are available only after :func:`initscr` has  been called.
1610
1611+------------------+------------------------------------------+
1612| ACS code         | Meaning                                  |
1613+==================+==========================================+
1614| ``ACS_BBSS``     | alternate name for upper right corner    |
1615+------------------+------------------------------------------+
1616| ``ACS_BLOCK``    | solid square block                       |
1617+------------------+------------------------------------------+
1618| ``ACS_BOARD``    | board of squares                         |
1619+------------------+------------------------------------------+
1620| ``ACS_BSBS``     | alternate name for horizontal line       |
1621+------------------+------------------------------------------+
1622| ``ACS_BSSB``     | alternate name for upper left corner     |
1623+------------------+------------------------------------------+
1624| ``ACS_BSSS``     | alternate name for top tee               |
1625+------------------+------------------------------------------+
1626| ``ACS_BTEE``     | bottom tee                               |
1627+------------------+------------------------------------------+
1628| ``ACS_BULLET``   | bullet                                   |
1629+------------------+------------------------------------------+
1630| ``ACS_CKBOARD``  | checker board (stipple)                  |
1631+------------------+------------------------------------------+
1632| ``ACS_DARROW``   | arrow pointing down                      |
1633+------------------+------------------------------------------+
1634| ``ACS_DEGREE``   | degree symbol                            |
1635+------------------+------------------------------------------+
1636| ``ACS_DIAMOND``  | diamond                                  |
1637+------------------+------------------------------------------+
1638| ``ACS_GEQUAL``   | greater-than-or-equal-to                 |
1639+------------------+------------------------------------------+
1640| ``ACS_HLINE``    | horizontal line                          |
1641+------------------+------------------------------------------+
1642| ``ACS_LANTERN``  | lantern symbol                           |
1643+------------------+------------------------------------------+
1644| ``ACS_LARROW``   | left arrow                               |
1645+------------------+------------------------------------------+
1646| ``ACS_LEQUAL``   | less-than-or-equal-to                    |
1647+------------------+------------------------------------------+
1648| ``ACS_LLCORNER`` | lower left-hand corner                   |
1649+------------------+------------------------------------------+
1650| ``ACS_LRCORNER`` | lower right-hand corner                  |
1651+------------------+------------------------------------------+
1652| ``ACS_LTEE``     | left tee                                 |
1653+------------------+------------------------------------------+
1654| ``ACS_NEQUAL``   | not-equal sign                           |
1655+------------------+------------------------------------------+
1656| ``ACS_PI``       | letter pi                                |
1657+------------------+------------------------------------------+
1658| ``ACS_PLMINUS``  | plus-or-minus sign                       |
1659+------------------+------------------------------------------+
1660| ``ACS_PLUS``     | big plus sign                            |
1661+------------------+------------------------------------------+
1662| ``ACS_RARROW``   | right arrow                              |
1663+------------------+------------------------------------------+
1664| ``ACS_RTEE``     | right tee                                |
1665+------------------+------------------------------------------+
1666| ``ACS_S1``       | scan line 1                              |
1667+------------------+------------------------------------------+
1668| ``ACS_S3``       | scan line 3                              |
1669+------------------+------------------------------------------+
1670| ``ACS_S7``       | scan line 7                              |
1671+------------------+------------------------------------------+
1672| ``ACS_S9``       | scan line 9                              |
1673+------------------+------------------------------------------+
1674| ``ACS_SBBS``     | alternate name for lower right corner    |
1675+------------------+------------------------------------------+
1676| ``ACS_SBSB``     | alternate name for vertical line         |
1677+------------------+------------------------------------------+
1678| ``ACS_SBSS``     | alternate name for right tee             |
1679+------------------+------------------------------------------+
1680| ``ACS_SSBB``     | alternate name for lower left corner     |
1681+------------------+------------------------------------------+
1682| ``ACS_SSBS``     | alternate name for bottom tee            |
1683+------------------+------------------------------------------+
1684| ``ACS_SSSB``     | alternate name for left tee              |
1685+------------------+------------------------------------------+
1686| ``ACS_SSSS``     | alternate name for crossover or big plus |
1687+------------------+------------------------------------------+
1688| ``ACS_STERLING`` | pound sterling                           |
1689+------------------+------------------------------------------+
1690| ``ACS_TTEE``     | top tee                                  |
1691+------------------+------------------------------------------+
1692| ``ACS_UARROW``   | up arrow                                 |
1693+------------------+------------------------------------------+
1694| ``ACS_ULCORNER`` | upper left corner                        |
1695+------------------+------------------------------------------+
1696| ``ACS_URCORNER`` | upper right corner                       |
1697+------------------+------------------------------------------+
1698| ``ACS_VLINE``    | vertical line                            |
1699+------------------+------------------------------------------+
1700
1701The following table lists the predefined colors:
1702
1703+-------------------+----------------------------+
1704| Constant          | Color                      |
1705+===================+============================+
1706| ``COLOR_BLACK``   | Black                      |
1707+-------------------+----------------------------+
1708| ``COLOR_BLUE``    | Blue                       |
1709+-------------------+----------------------------+
1710| ``COLOR_CYAN``    | Cyan (light greenish blue) |
1711+-------------------+----------------------------+
1712| ``COLOR_GREEN``   | Green                      |
1713+-------------------+----------------------------+
1714| ``COLOR_MAGENTA`` | Magenta (purplish red)     |
1715+-------------------+----------------------------+
1716| ``COLOR_RED``     | Red                        |
1717+-------------------+----------------------------+
1718| ``COLOR_WHITE``   | White                      |
1719+-------------------+----------------------------+
1720| ``COLOR_YELLOW``  | Yellow                     |
1721+-------------------+----------------------------+
1722
1723
1724:mod:`curses.textpad` --- Text input widget for curses programs
1725===============================================================
1726
1727.. module:: curses.textpad
1728   :synopsis: Emacs-like input editing in a curses window.
1729.. moduleauthor:: Eric Raymond <esr@thyrsus.com>
1730.. sectionauthor:: Eric Raymond <esr@thyrsus.com>
1731
1732
1733The :mod:`curses.textpad` module provides a :class:`Textbox` class that handles
1734elementary text editing in a curses window, supporting a set of keybindings
1735resembling those of Emacs (thus, also of Netscape Navigator, BBedit 6.x,
1736FrameMaker, and many other programs).  The module also provides a
1737rectangle-drawing function useful for framing text boxes or for other purposes.
1738
1739The module :mod:`curses.textpad` defines the following function:
1740
1741
1742.. function:: rectangle(win, uly, ulx, lry, lrx)
1743
1744   Draw a rectangle.  The first argument must be a window object; the remaining
1745   arguments are coordinates relative to that window.  The second and third
1746   arguments are the y and x coordinates of the upper left hand corner of the
1747   rectangle to be drawn; the fourth and fifth arguments are the y and x
1748   coordinates of the lower right hand corner. The rectangle will be drawn using
1749   VT100/IBM PC forms characters on terminals that make this possible (including
1750   xterm and most other software terminal emulators).  Otherwise it will be drawn
1751   with ASCII  dashes, vertical bars, and plus signs.
1752
1753
1754.. _curses-textpad-objects:
1755
1756Textbox objects
1757---------------
1758
1759You can instantiate a :class:`Textbox` object as follows:
1760
1761
1762.. class:: Textbox(win)
1763
1764   Return a textbox widget object.  The *win* argument should be a curses
1765   :ref:`window <curses-window-objects>` object in which the textbox is to
1766   be contained. The edit cursor of the textbox is initially located at the
1767   upper left hand corner of the containing window, with coordinates ``(0, 0)``.
1768   The instance's :attr:`stripspaces` flag is initially on.
1769
1770   :class:`Textbox` objects have the following methods:
1771
1772
1773   .. method:: edit([validator])
1774
1775      This is the entry point you will normally use.  It accepts editing
1776      keystrokes until one of the termination keystrokes is entered.  If
1777      *validator* is supplied, it must be a function.  It will be called for
1778      each keystroke entered with the keystroke as a parameter; command dispatch
1779      is done on the result. This method returns the window contents as a
1780      string; whether blanks in the window are included is affected by the
1781      :attr:`stripspaces` attribute.
1782
1783
1784   .. method:: do_command(ch)
1785
1786      Process a single command keystroke.  Here are the supported special
1787      keystrokes:
1788
1789      +------------------+-------------------------------------------+
1790      | Keystroke        | Action                                    |
1791      +==================+===========================================+
1792      | :kbd:`Control-A` | Go to left edge of window.                |
1793      +------------------+-------------------------------------------+
1794      | :kbd:`Control-B` | Cursor left, wrapping to previous line if |
1795      |                  | appropriate.                              |
1796      +------------------+-------------------------------------------+
1797      | :kbd:`Control-D` | Delete character under cursor.            |
1798      +------------------+-------------------------------------------+
1799      | :kbd:`Control-E` | Go to right edge (stripspaces off) or end |
1800      |                  | of line (stripspaces on).                 |
1801      +------------------+-------------------------------------------+
1802      | :kbd:`Control-F` | Cursor right, wrapping to next line when  |
1803      |                  | appropriate.                              |
1804      +------------------+-------------------------------------------+
1805      | :kbd:`Control-G` | Terminate, returning the window contents. |
1806      +------------------+-------------------------------------------+
1807      | :kbd:`Control-H` | Delete character backward.                |
1808      +------------------+-------------------------------------------+
1809      | :kbd:`Control-J` | Terminate if the window is 1 line,        |
1810      |                  | otherwise insert newline.                 |
1811      +------------------+-------------------------------------------+
1812      | :kbd:`Control-K` | If line is blank, delete it, otherwise    |
1813      |                  | clear to end of line.                     |
1814      +------------------+-------------------------------------------+
1815      | :kbd:`Control-L` | Refresh screen.                           |
1816      +------------------+-------------------------------------------+
1817      | :kbd:`Control-N` | Cursor down; move down one line.          |
1818      +------------------+-------------------------------------------+
1819      | :kbd:`Control-O` | Insert a blank line at cursor location.   |
1820      +------------------+-------------------------------------------+
1821      | :kbd:`Control-P` | Cursor up; move up one line.              |
1822      +------------------+-------------------------------------------+
1823
1824      Move operations do nothing if the cursor is at an edge where the movement
1825      is not possible.  The following synonyms are supported where possible:
1826
1827      +------------------------+------------------+
1828      | Constant               | Keystroke        |
1829      +========================+==================+
1830      | :const:`KEY_LEFT`      | :kbd:`Control-B` |
1831      +------------------------+------------------+
1832      | :const:`KEY_RIGHT`     | :kbd:`Control-F` |
1833      +------------------------+------------------+
1834      | :const:`KEY_UP`        | :kbd:`Control-P` |
1835      +------------------------+------------------+
1836      | :const:`KEY_DOWN`      | :kbd:`Control-N` |
1837      +------------------------+------------------+
1838      | :const:`KEY_BACKSPACE` | :kbd:`Control-h` |
1839      +------------------------+------------------+
1840
1841      All other keystrokes are treated as a command to insert the given
1842      character and move right (with line wrapping).
1843
1844
1845   .. method:: gather()
1846
1847      Return the window contents as a string; whether blanks in the
1848      window are included is affected by the :attr:`stripspaces` member.
1849
1850
1851   .. attribute:: stripspaces
1852
1853      This attribute is a flag which controls the interpretation of blanks in
1854      the window.  When it is on, trailing blanks on each line are ignored; any
1855      cursor motion that would land the cursor on a trailing blank goes to the
1856      end of that line instead, and trailing blanks are stripped when the window
1857      contents are gathered.
1858