1 /* $FreeBSD$ */ 2 /* 3 * Copyright (C) 1984-2015 Mark Nudelman 4 * 5 * You may distribute under the terms of either the GNU General Public 6 * License or the Less License, as specified in the README file. 7 * 8 * For more information, see the README file. 9 */ 10 11 12 /* 13 * Primitives for displaying the file on the screen, 14 * scrolling either forward or backward. 15 */ 16 17 #include "less.h" 18 #include "position.h" 19 20 public int screen_trashed; 21 public int squished; 22 public int no_back_scroll = 0; 23 public int forw_prompt; 24 public int same_pos_bell = 1; 25 26 extern int sigs; 27 extern int top_scroll; 28 extern int quiet; 29 extern int sc_width, sc_height; 30 extern int less_is_more; 31 extern int plusoption; 32 extern int forw_scroll; 33 extern int back_scroll; 34 extern int ignore_eoi; 35 extern int clear_bg; 36 extern int final_attr; 37 extern int oldbot; 38 #if HILITE_SEARCH 39 extern int size_linebuf; 40 extern int hilite_search; 41 extern int status_col; 42 #endif 43 #if TAGS 44 extern char *tagoption; 45 #endif 46 47 /* 48 * Sound the bell to indicate user is trying to move past end of file. 49 */ 50 static void 51 eof_bell(void) 52 { 53 if (quiet == NOT_QUIET) 54 bell(); 55 else 56 vbell(); 57 } 58 59 /* 60 * Check to see if the end of file is currently displayed. 61 */ 62 public int 63 eof_displayed(void) 64 { 65 POSITION pos; 66 67 if (ignore_eoi) 68 return (0); 69 70 if (ch_length() == NULL_POSITION) 71 /* 72 * If the file length is not known, 73 * we can't possibly be displaying EOF. 74 */ 75 return (0); 76 77 /* 78 * If the bottom line is empty, we are at EOF. 79 * If the bottom line ends at the file length, 80 * we must be just at EOF. 81 */ 82 pos = position(BOTTOM_PLUS_ONE); 83 return (pos == NULL_POSITION || pos == ch_length()); 84 } 85 86 /* 87 * Check to see if the entire file is currently displayed. 88 */ 89 public int 90 entire_file_displayed(void) 91 { 92 POSITION pos; 93 94 /* Make sure last line of file is displayed. */ 95 if (!eof_displayed()) 96 return (0); 97 98 /* Make sure first line of file is displayed. */ 99 pos = position(0); 100 return (pos == NULL_POSITION || pos == 0); 101 } 102 103 /* 104 * If the screen is "squished", repaint it. 105 * "Squished" means the first displayed line is not at the top 106 * of the screen; this can happen when we display a short file 107 * for the first time. 108 */ 109 public void 110 squish_check(void) 111 { 112 if (!squished) 113 return; 114 squished = 0; 115 repaint(); 116 } 117 118 /* 119 * Display n lines, scrolling forward, 120 * starting at position pos in the input file. 121 * "force" means display the n lines even if we hit end of file. 122 * "only_last" means display only the last screenful if n > screen size. 123 * "nblank" is the number of blank lines to draw before the first 124 * real line. If nblank > 0, the pos must be NULL_POSITION. 125 * The first real line after the blanks will start at ch_zero(). 126 */ 127 public void 128 forw(int n, POSITION pos, int force, int only_last, int nblank) 129 { 130 int nlines = 0; 131 int do_repaint; 132 static int first_time = 1; 133 134 squish_check(); 135 136 /* 137 * do_repaint tells us not to display anything till the end, 138 * then just repaint the entire screen. 139 * We repaint if we are supposed to display only the last 140 * screenful and the request is for more than a screenful. 141 * Also if the request exceeds the forward scroll limit 142 * (but not if the request is for exactly a screenful, since 143 * repainting itself involves scrolling forward a screenful). 144 */ 145 do_repaint = (only_last && n > sc_height-1) || 146 (forw_scroll >= 0 && n > forw_scroll && n != sc_height-1); 147 148 #if HILITE_SEARCH 149 if (hilite_search == OPT_ONPLUS || is_filtering() || status_col) { 150 prep_hilite(pos, pos + 4*size_linebuf, ignore_eoi ? 1 : -1); 151 pos = next_unfiltered(pos); 152 } 153 #endif 154 155 if (!do_repaint) 156 { 157 if (top_scroll && n >= sc_height - 1 && pos != ch_length()) 158 { 159 /* 160 * Start a new screen. 161 * {{ This is not really desirable if we happen 162 * to hit eof in the middle of this screen, 163 * but we don't yet know if that will happen. }} 164 */ 165 pos_clear(); 166 add_forw_pos(pos); 167 force = 1; 168 if (less_is_more == 0) { 169 clear(); 170 home(); 171 } 172 } 173 174 if (pos != position(BOTTOM_PLUS_ONE) || empty_screen()) 175 { 176 /* 177 * This is not contiguous with what is 178 * currently displayed. Clear the screen image 179 * (position table) and start a new screen. 180 */ 181 pos_clear(); 182 add_forw_pos(pos); 183 force = 1; 184 if (top_scroll) 185 { 186 clear(); 187 home(); 188 } else if (!first_time) 189 { 190 putstr("...skipping...\n"); 191 } 192 } 193 } 194 195 while (--n >= 0) 196 { 197 /* 198 * Read the next line of input. 199 */ 200 if (nblank > 0) 201 { 202 /* 203 * Still drawing blanks; don't get a line 204 * from the file yet. 205 * If this is the last blank line, get ready to 206 * read a line starting at ch_zero() next time. 207 */ 208 if (--nblank == 0) 209 pos = ch_zero(); 210 } else 211 { 212 /* 213 * Get the next line from the file. 214 */ 215 pos = forw_line(pos); 216 #if HILITE_SEARCH 217 pos = next_unfiltered(pos); 218 #endif 219 if (pos == NULL_POSITION) 220 { 221 /* 222 * End of file: stop here unless the top line 223 * is still empty, or "force" is true. 224 * Even if force is true, stop when the last 225 * line in the file reaches the top of screen. 226 */ 227 if (!force && position(TOP) != NULL_POSITION) 228 break; 229 if (!empty_lines(0, 0) && 230 !empty_lines(1, 1) && 231 empty_lines(2, sc_height-1)) 232 break; 233 } 234 } 235 /* 236 * Add the position of the next line to the position table. 237 * Display the current line on the screen. 238 */ 239 add_forw_pos(pos); 240 nlines++; 241 if (do_repaint) 242 continue; 243 /* 244 * If this is the first screen displayed and 245 * we hit an early EOF (i.e. before the requested 246 * number of lines), we "squish" the display down 247 * at the bottom of the screen. 248 * But don't do this if a + option or a -t option 249 * was given. These options can cause us to 250 * start the display after the beginning of the file, 251 * and it is not appropriate to squish in that case. 252 */ 253 if ((first_time || less_is_more) && 254 pos == NULL_POSITION && !top_scroll && 255 #if TAGS 256 tagoption == NULL && 257 #endif 258 !plusoption) 259 { 260 squished = 1; 261 continue; 262 } 263 put_line(); 264 #if 0 265 /* {{ 266 * Can't call clear_eol here. The cursor might be at end of line 267 * on an ignaw terminal, so clear_eol would clear the last char 268 * of the current line instead of all of the next line. 269 * If we really need to do this on clear_bg terminals, we need 270 * to find a better way. 271 * }} 272 */ 273 if (clear_bg && apply_at_specials(final_attr) != AT_NORMAL) 274 { 275 /* 276 * Writing the last character on the last line 277 * of the display may have scrolled the screen. 278 * If we were in standout mode, clear_bg terminals 279 * will fill the new line with the standout color. 280 * Now we're in normal mode again, so clear the line. 281 */ 282 clear_eol(); 283 } 284 #endif 285 forw_prompt = 1; 286 } 287 288 if (nlines == 0 && same_pos_bell) 289 eof_bell(); 290 else if (do_repaint) 291 repaint(); 292 first_time = 0; 293 (void) currline(BOTTOM); 294 } 295 296 /* 297 * Display n lines, scrolling backward. 298 */ 299 public void 300 back(int n, POSITION pos, int force, int only_last) 301 { 302 int nlines = 0; 303 int do_repaint; 304 305 squish_check(); 306 do_repaint = (n > get_back_scroll() || (only_last && n > sc_height-1)); 307 #if HILITE_SEARCH 308 if (hilite_search == OPT_ONPLUS || is_filtering() || status_col) { 309 prep_hilite((pos < 3*size_linebuf) ? 0 : pos - 3*size_linebuf, pos, -1); 310 } 311 #endif 312 while (--n >= 0) 313 { 314 /* 315 * Get the previous line of input. 316 */ 317 #if HILITE_SEARCH 318 pos = prev_unfiltered(pos); 319 #endif 320 321 pos = back_line(pos); 322 if (pos == NULL_POSITION) 323 { 324 /* 325 * Beginning of file: stop here unless "force" is true. 326 */ 327 if (!force) 328 break; 329 } 330 /* 331 * Add the position of the previous line to the position table. 332 * Display the line on the screen. 333 */ 334 add_back_pos(pos); 335 nlines++; 336 if (!do_repaint) 337 { 338 home(); 339 add_line(); 340 put_line(); 341 } 342 } 343 344 if (nlines == 0 && same_pos_bell) 345 eof_bell(); 346 else if (do_repaint) 347 repaint(); 348 else if (!oldbot) 349 lower_left(); 350 (void) currline(BOTTOM); 351 } 352 353 /* 354 * Display n more lines, forward. 355 * Start just after the line currently displayed at the bottom of the screen. 356 */ 357 public void 358 forward(int n, int force, int only_last) 359 { 360 POSITION pos; 361 362 if (get_quit_at_eof() && eof_displayed() && !(ch_getflags() & CH_HELPFILE)) 363 { 364 /* 365 * If the -e flag is set and we're trying to go 366 * forward from end-of-file, go on to the next file. 367 */ 368 if (edit_next(1)) 369 quit(QUIT_OK); 370 return; 371 } 372 373 pos = position(BOTTOM_PLUS_ONE); 374 if (pos == NULL_POSITION && (!force || empty_lines(2, sc_height-1))) 375 { 376 if (ignore_eoi) 377 { 378 /* 379 * ignore_eoi is to support A_F_FOREVER. 380 * Back up until there is a line at the bottom 381 * of the screen. 382 */ 383 if (empty_screen()) 384 pos = ch_zero(); 385 else 386 { 387 do 388 { 389 back(1, position(TOP), 1, 0); 390 pos = position(BOTTOM_PLUS_ONE); 391 } while (pos == NULL_POSITION); 392 } 393 } else 394 { 395 eof_bell(); 396 return; 397 } 398 } 399 forw(n, pos, force, only_last, 0); 400 } 401 402 /* 403 * Display n more lines, backward. 404 * Start just before the line currently displayed at the top of the screen. 405 */ 406 public void 407 backward(int n, int force, int only_last) 408 { 409 POSITION pos; 410 411 pos = position(TOP); 412 if (pos == NULL_POSITION && (!force || position(BOTTOM) == 0)) 413 { 414 eof_bell(); 415 return; 416 } 417 back(n, pos, force, only_last); 418 } 419 420 /* 421 * Get the backwards scroll limit. 422 * Must call this function instead of just using the value of 423 * back_scroll, because the default case depends on sc_height and 424 * top_scroll, as well as back_scroll. 425 */ 426 public int 427 get_back_scroll(void) 428 { 429 if (no_back_scroll) 430 return (0); 431 if (back_scroll >= 0) 432 return (back_scroll); 433 if (top_scroll) 434 return (sc_height - 2); 435 return (10000); /* infinity */ 436 } 437