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1.1 ! etheisen 1: /*
! 2: * Copyright (c) 1984,1985,1989,1994,1995 Mark Nudelman
! 3: * All rights reserved.
! 4: *
! 5: * Redistribution and use in source and binary forms, with or without
! 6: * modification, are permitted provided that the following conditions
! 7: * are met:
! 8: * 1. Redistributions of source code must retain the above copyright
! 9: * notice, this list of conditions and the following disclaimer.
! 10: * 2. Redistributions in binary form must reproduce the above copyright
! 11: * notice in the documentation and/or other materials provided with
! 12: * the distribution.
! 13: *
! 14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY
! 15: * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 16: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
! 17: * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE
! 18: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
! 19: * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
! 20: * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
! 21: * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
! 22: * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
! 23: * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
! 24: * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
! 25: */
! 26:
! 27:
! 28: /*
! 29: * Primitives for displaying the file on the screen,
! 30: * scrolling either forward or backward.
! 31: */
! 32:
! 33: #include "less.h"
! 34: #include "position.h"
! 35:
! 36: public int hit_eof; /* Keeps track of how many times we hit end of file */
! 37: public int screen_trashed;
! 38: public int squished;
! 39:
! 40: extern int sigs;
! 41: extern int top_scroll;
! 42: extern int quiet;
! 43: extern int sc_width, sc_height;
! 44: extern int quit_at_eof;
! 45: extern int plusoption;
! 46: extern int forw_scroll;
! 47: extern int back_scroll;
! 48: extern int need_clr;
! 49: extern int ignore_eoi;
! 50: #if TAGS
! 51: extern char *tagoption;
! 52: #endif
! 53:
! 54: /*
! 55: * Sound the bell to indicate user is trying to move past end of file.
! 56: */
! 57: static void
! 58: eof_bell()
! 59: {
! 60: if (quiet == NOT_QUIET)
! 61: bell();
! 62: else
! 63: vbell();
! 64: }
! 65:
! 66: /*
! 67: * Check to see if the end of file is currently "displayed".
! 68: */
! 69: static void
! 70: eof_check()
! 71: {
! 72: POSITION pos;
! 73:
! 74: if (ignore_eoi)
! 75: return;
! 76: if (ABORT_SIGS())
! 77: return;
! 78: /*
! 79: * If the bottom line is empty, we are at EOF.
! 80: * If the bottom line ends at the file length,
! 81: * we must be just at EOF.
! 82: */
! 83: pos = position(BOTTOM_PLUS_ONE);
! 84: if (pos == NULL_POSITION || pos == ch_length())
! 85: hit_eof++;
! 86: }
! 87:
! 88: /*
! 89: * If the screen is "squished", repaint it.
! 90: * "Squished" means the first displayed line is not at the top
! 91: * of the screen; this can happen when we display a short file
! 92: * for the first time.
! 93: */
! 94: static void
! 95: squish_check()
! 96: {
! 97: if (!squished)
! 98: return;
! 99: squished = 0;
! 100: repaint();
! 101: }
! 102:
! 103: /*
! 104: * Display n lines, scrolling forward,
! 105: * starting at position pos in the input file.
! 106: * "force" means display the n lines even if we hit end of file.
! 107: * "only_last" means display only the last screenful if n > screen size.
! 108: * "nblank" is the number of blank lines to draw before the first
! 109: * real line. If nblank > 0, the pos must be NULL_POSITION.
! 110: * The first real line after the blanks will start at ch_zero().
! 111: */
! 112: public void
! 113: forw(n, pos, force, only_last, nblank)
! 114: register int n;
! 115: POSITION pos;
! 116: int force;
! 117: int only_last;
! 118: int nblank;
! 119: {
! 120: int eof = 0;
! 121: int nlines = 0;
! 122: int do_repaint;
! 123: static int first_time = 1;
! 124:
! 125: squish_check();
! 126:
! 127: /*
! 128: * do_repaint tells us not to display anything till the end,
! 129: * then just repaint the entire screen.
! 130: * We repaint if we are supposed to display only the last
! 131: * screenful and the request is for more than a screenful.
! 132: * Also if the request exceeds the forward scroll limit
! 133: * (but not if the request is for exactly a screenful, since
! 134: * repainting itself involves scrolling forward a screenful).
! 135: */
! 136: do_repaint = (only_last && n > sc_height-1) ||
! 137: (forw_scroll >= 0 && n > forw_scroll && n != sc_height-1);
! 138:
! 139: if (!do_repaint)
! 140: {
! 141: if (top_scroll && n >= sc_height - 1 && pos != ch_length())
! 142: {
! 143: /*
! 144: * Start a new screen.
! 145: * {{ This is not really desirable if we happen
! 146: * to hit eof in the middle of this screen,
! 147: * but we don't yet know if that will happen. }}
! 148: */
! 149: if (top_scroll == OPT_ONPLUS || first_time)
! 150: clear();
! 151: home();
! 152: force = 1;
! 153: } else
! 154: {
! 155: clear_bot();
! 156: }
! 157:
! 158: if (pos != position(BOTTOM_PLUS_ONE) || empty_screen())
! 159: {
! 160: /*
! 161: * This is not contiguous with what is
! 162: * currently displayed. Clear the screen image
! 163: * (position table) and start a new screen.
! 164: */
! 165: pos_clear();
! 166: add_forw_pos(pos);
! 167: force = 1;
! 168: if (top_scroll)
! 169: {
! 170: if (top_scroll == OPT_ONPLUS)
! 171: clear();
! 172: home();
! 173: } else if (!first_time)
! 174: {
! 175: putstr("...skipping...\n");
! 176: }
! 177: }
! 178: }
! 179:
! 180: while (--n >= 0)
! 181: {
! 182: /*
! 183: * Read the next line of input.
! 184: */
! 185: if (nblank > 0)
! 186: {
! 187: /*
! 188: * Still drawing blanks; don't get a line
! 189: * from the file yet.
! 190: * If this is the last blank line, get ready to
! 191: * read a line starting at ch_zero() next time.
! 192: */
! 193: if (--nblank == 0)
! 194: pos = ch_zero();
! 195: } else
! 196: {
! 197: /*
! 198: * Get the next line from the file.
! 199: */
! 200: pos = forw_line(pos);
! 201: if (pos == NULL_POSITION)
! 202: {
! 203: /*
! 204: * End of file: stop here unless the top line
! 205: * is still empty, or "force" is true.
! 206: */
! 207: eof = 1;
! 208: if (!force && position(TOP) != NULL_POSITION)
! 209: break;
! 210: }
! 211: }
! 212: /*
! 213: * Add the position of the next line to the position table.
! 214: * Display the current line on the screen.
! 215: */
! 216: add_forw_pos(pos);
! 217: nlines++;
! 218: if (do_repaint)
! 219: continue;
! 220: /*
! 221: * If this is the first screen displayed and
! 222: * we hit an early EOF (i.e. before the requested
! 223: * number of lines), we "squish" the display down
! 224: * at the bottom of the screen.
! 225: * But don't do this if a + option or a -t option
! 226: * was given. These options can cause us to
! 227: * start the display after the beginning of the file,
! 228: * and it is not appropriate to squish in that case.
! 229: */
! 230: if (first_time && pos == NULL_POSITION && !top_scroll &&
! 231: #if TAGS
! 232: tagoption == NULL &&
! 233: #endif
! 234: !plusoption)
! 235: {
! 236: squished = 1;
! 237: continue;
! 238: }
! 239: if (top_scroll == 1)
! 240: clear_eol();
! 241: put_line();
! 242: }
! 243:
! 244: if (ignore_eoi)
! 245: hit_eof = 0;
! 246: else if (eof && !ABORT_SIGS())
! 247: hit_eof++;
! 248: else
! 249: eof_check();
! 250: if (nlines == 0)
! 251: eof_bell();
! 252: else if (do_repaint)
! 253: repaint();
! 254: first_time = 0;
! 255: (void) currline(BOTTOM);
! 256: }
! 257:
! 258: /*
! 259: * Display n lines, scrolling backward.
! 260: */
! 261: public void
! 262: back(n, pos, force, only_last)
! 263: register int n;
! 264: POSITION pos;
! 265: int force;
! 266: int only_last;
! 267: {
! 268: int nlines = 0;
! 269: int do_repaint;
! 270:
! 271: squish_check();
! 272: do_repaint = (n > get_back_scroll() || (only_last && n > sc_height-1));
! 273: hit_eof = 0;
! 274: while (--n >= 0)
! 275: {
! 276: /*
! 277: * Get the previous line of input.
! 278: */
! 279: pos = back_line(pos);
! 280: if (pos == NULL_POSITION)
! 281: {
! 282: /*
! 283: * Beginning of file: stop here unless "force" is true.
! 284: */
! 285: if (!force)
! 286: break;
! 287: }
! 288: /*
! 289: * Add the position of the previous line to the position table.
! 290: * Display the line on the screen.
! 291: */
! 292: add_back_pos(pos);
! 293: nlines++;
! 294: if (!do_repaint)
! 295: {
! 296: home();
! 297: add_line();
! 298: put_line();
! 299: }
! 300: }
! 301:
! 302: eof_check();
! 303: if (nlines == 0)
! 304: eof_bell();
! 305: else if (do_repaint)
! 306: repaint();
! 307: (void) currline(BOTTOM);
! 308: }
! 309:
! 310: /*
! 311: * Display n more lines, forward.
! 312: * Start just after the line currently displayed at the bottom of the screen.
! 313: */
! 314: public void
! 315: forward(n, force, only_last)
! 316: int n;
! 317: int force;
! 318: int only_last;
! 319: {
! 320: POSITION pos;
! 321:
! 322: if (quit_at_eof && hit_eof)
! 323: {
! 324: /*
! 325: * If the -e flag is set and we're trying to go
! 326: * forward from end-of-file, go on to the next file.
! 327: */
! 328: if (edit_next(1))
! 329: quit(QUIT_OK);
! 330: return;
! 331: }
! 332:
! 333: pos = position(BOTTOM_PLUS_ONE);
! 334: if (pos == NULL_POSITION && (!force || empty_lines(2, sc_height-1)))
! 335: {
! 336: if (ignore_eoi)
! 337: {
! 338: /*
! 339: * ignore_eoi is to support A_F_FOREVER.
! 340: * Back up until there is a line at the bottom
! 341: * of the screen.
! 342: */
! 343: if (empty_screen())
! 344: pos = ch_zero();
! 345: else
! 346: {
! 347: do
! 348: {
! 349: back(1, position(TOP), 1, 0);
! 350: pos = position(BOTTOM_PLUS_ONE);
! 351: } while (pos == NULL_POSITION);
! 352: }
! 353: } else
! 354: {
! 355: eof_bell();
! 356: hit_eof++;
! 357: return;
! 358: }
! 359: }
! 360: forw(n, pos, force, only_last, 0);
! 361: }
! 362:
! 363: /*
! 364: * Display n more lines, backward.
! 365: * Start just before the line currently displayed at the top of the screen.
! 366: */
! 367: public void
! 368: backward(n, force, only_last)
! 369: int n;
! 370: int force;
! 371: int only_last;
! 372: {
! 373: POSITION pos;
! 374:
! 375: pos = position(TOP);
! 376: if (pos == NULL_POSITION && (!force || position(BOTTOM) == 0))
! 377: {
! 378: eof_bell();
! 379: return;
! 380: }
! 381: back(n, pos, force, only_last);
! 382: }
! 383:
! 384: /*
! 385: * Get the backwards scroll limit.
! 386: * Must call this function instead of just using the value of
! 387: * back_scroll, because the default case depends on sc_height and
! 388: * top_scroll, as well as back_scroll.
! 389: */
! 390: public int
! 391: get_back_scroll()
! 392: {
! 393: if (back_scroll >= 0)
! 394: return (back_scroll);
! 395: if (top_scroll)
! 396: return (sc_height - 2);
! 397: return (10000); /* infinity */
! 398: }