1 /* 2 * Copyright (C) 1984-2014 Mark Nudelman 3 * 4 * You may distribute under the terms of either the GNU General Public 5 * License or the Less License, as specified in the README file. 6 * 7 * For more information, see the README file. 8 */ 9 10 11 /* 12 * Routines which jump to a new location in the file. 13 */ 14 15 #include "less.h" 16 #include "position.h" 17 18 extern int jump_sline; 19 extern int squished; 20 extern int screen_trashed; 21 extern int sc_width, sc_height; 22 extern int show_attn; 23 extern int top_scroll; 24 25 /* 26 * Jump to the end of the file. 27 */ 28 public void 29 jump_forw() 30 { 31 POSITION pos; 32 POSITION end_pos; 33 34 if (ch_end_seek()) 35 { 36 error("Cannot seek to end of file", NULL_PARG); 37 return; 38 } 39 /* 40 * Note; lastmark will be called later by jump_loc, but it fails 41 * because the position table has been cleared by pos_clear below. 42 * So call it here before calling pos_clear. 43 */ 44 lastmark(); 45 /* 46 * Position the last line in the file at the last screen line. 47 * Go back one line from the end of the file 48 * to get to the beginning of the last line. 49 */ 50 pos_clear(); 51 end_pos = ch_tell(); 52 pos = back_line(end_pos); 53 if (pos == NULL_POSITION) 54 jump_loc((POSITION)0, sc_height-1); 55 else 56 { 57 jump_loc(pos, sc_height-1); 58 if (position(sc_height-1) != end_pos) 59 repaint(); 60 } 61 } 62 63 /* 64 * Jump to the last buffered line in the file. 65 */ 66 public void 67 jump_forw_buffered() 68 { 69 if (ch_end_buffer_seek()) 70 { 71 error("Cannot seek to end of buffers", NULL_PARG); 72 return; 73 } 74 jump_line_loc(ch_tell(), sc_height-1); 75 } 76 77 /* 78 * Jump to line n in the file. 79 */ 80 public void 81 jump_back(linenum) 82 LINENUM linenum; 83 { 84 POSITION pos; 85 PARG parg; 86 87 /* 88 * Find the position of the specified line. 89 * If we can seek there, just jump to it. 90 * If we can't seek, but we're trying to go to line number 1, 91 * use ch_beg_seek() to get as close as we can. 92 */ 93 pos = find_pos(linenum); 94 if (pos != NULL_POSITION && ch_seek(pos) == 0) 95 { 96 if (show_attn) 97 set_attnpos(pos); 98 jump_loc(pos, jump_sline); 99 } else if (linenum <= 1 && ch_beg_seek() == 0) 100 { 101 jump_loc(ch_tell(), jump_sline); 102 error("Cannot seek to beginning of file", NULL_PARG); 103 } else 104 { 105 parg.p_linenum = linenum; 106 error("Cannot seek to line number %n", &parg); 107 } 108 } 109 110 /* 111 * Repaint the screen. 112 */ 113 public void 114 repaint() 115 { 116 struct scrpos scrpos; 117 /* 118 * Start at the line currently at the top of the screen 119 * and redisplay the screen. 120 */ 121 get_scrpos(&scrpos); 122 pos_clear(); 123 jump_loc(scrpos.pos, scrpos.ln); 124 } 125 126 /* 127 * Jump to a specified percentage into the file. 128 */ 129 public void 130 jump_percent(percent, fraction) 131 int percent; 132 long fraction; 133 { 134 POSITION pos, len; 135 136 /* 137 * Determine the position in the file 138 * (the specified percentage of the file's length). 139 */ 140 if ((len = ch_length()) == NULL_POSITION) 141 { 142 ierror("Determining length of file", NULL_PARG); 143 ch_end_seek(); 144 } 145 if ((len = ch_length()) == NULL_POSITION) 146 { 147 error("Don't know length of file", NULL_PARG); 148 return; 149 } 150 pos = percent_pos(len, percent, fraction); 151 if (pos >= len) 152 pos = len-1; 153 154 jump_line_loc(pos, jump_sline); 155 } 156 157 /* 158 * Jump to a specified position in the file. 159 * Like jump_loc, but the position need not be 160 * the first character in a line. 161 */ 162 public void 163 jump_line_loc(pos, sline) 164 POSITION pos; 165 int sline; 166 { 167 int c; 168 169 if (ch_seek(pos) == 0) 170 { 171 /* 172 * Back up to the beginning of the line. 173 */ 174 while ((c = ch_back_get()) != '\n' && c != EOI) 175 ; 176 if (c == '\n') 177 (void) ch_forw_get(); 178 pos = ch_tell(); 179 } 180 if (show_attn) 181 set_attnpos(pos); 182 jump_loc(pos, sline); 183 } 184 185 /* 186 * Jump to a specified position in the file. 187 * The position must be the first character in a line. 188 * Place the target line on a specified line on the screen. 189 */ 190 public void 191 jump_loc(pos, sline) 192 POSITION pos; 193 int sline; 194 { 195 register int nline; 196 POSITION tpos; 197 POSITION bpos; 198 199 /* 200 * Normalize sline. 201 */ 202 sline = adjsline(sline); 203 204 if ((nline = onscreen(pos)) >= 0) 205 { 206 /* 207 * The line is currently displayed. 208 * Just scroll there. 209 */ 210 nline -= sline; 211 if (nline > 0) 212 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0); 213 else 214 back(-nline, position(TOP), 1, 0); 215 #if HILITE_SEARCH 216 if (show_attn) 217 repaint_hilite(1); 218 #endif 219 return; 220 } 221 222 /* 223 * Line is not on screen. 224 * Seek to the desired location. 225 */ 226 if (ch_seek(pos)) 227 { 228 error("Cannot seek to that file position", NULL_PARG); 229 return; 230 } 231 232 /* 233 * See if the desired line is before or after 234 * the currently displayed screen. 235 */ 236 tpos = position(TOP); 237 bpos = position(BOTTOM_PLUS_ONE); 238 if (tpos == NULL_POSITION || pos >= tpos) 239 { 240 /* 241 * The desired line is after the current screen. 242 * Move back in the file far enough so that we can 243 * call forw() and put the desired line at the 244 * sline-th line on the screen. 245 */ 246 for (nline = 0; nline < sline; nline++) 247 { 248 if (bpos != NULL_POSITION && pos <= bpos) 249 { 250 /* 251 * Surprise! The desired line is 252 * close enough to the current screen 253 * that we can just scroll there after all. 254 */ 255 forw(sc_height-sline+nline-1, bpos, 1, 0, 0); 256 #if HILITE_SEARCH 257 if (show_attn) 258 repaint_hilite(1); 259 #endif 260 return; 261 } 262 pos = back_line(pos); 263 if (pos == NULL_POSITION) 264 { 265 /* 266 * Oops. Ran into the beginning of the file. 267 * Exit the loop here and rely on forw() 268 * below to draw the required number of 269 * blank lines at the top of the screen. 270 */ 271 break; 272 } 273 } 274 lastmark(); 275 squished = 0; 276 screen_trashed = 0; 277 forw(sc_height-1, pos, 1, 0, sline-nline); 278 } else 279 { 280 /* 281 * The desired line is before the current screen. 282 * Move forward in the file far enough so that we 283 * can call back() and put the desired line at the 284 * sline-th line on the screen. 285 */ 286 for (nline = sline; nline < sc_height - 1; nline++) 287 { 288 pos = forw_line(pos); 289 if (pos == NULL_POSITION) 290 { 291 /* 292 * Ran into end of file. 293 * This shouldn't normally happen, 294 * but may if there is some kind of read error. 295 */ 296 break; 297 } 298 #if HILITE_SEARCH 299 pos = next_unfiltered(pos); 300 #endif 301 if (pos >= tpos) 302 { 303 /* 304 * Surprise! The desired line is 305 * close enough to the current screen 306 * that we can just scroll there after all. 307 */ 308 back(nline+1, tpos, 1, 0); 309 #if HILITE_SEARCH 310 if (show_attn) 311 repaint_hilite(1); 312 #endif 313 return; 314 } 315 } 316 lastmark(); 317 if (!top_scroll) 318 clear(); 319 else 320 home(); 321 screen_trashed = 0; 322 add_back_pos(pos); 323 back(sc_height-1, pos, 1, 0); 324 } 325 } 326