xdisp.c 75 KB
Newer Older
Jim Blandy's avatar
Jim Blandy committed
1
/* Display generation from window structure and buffer text.
2
   Copyright (C) 1985, 1986, 1987, 1988, 1993 Free Software Foundation, Inc.
Jim Blandy's avatar
Jim Blandy committed
3 4 5 6 7

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
8
the Free Software Foundation; either version 2, or (at your option)
Jim Blandy's avatar
Jim Blandy committed
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


#include "config.h"
#include <stdio.h>
/*#include <ctype.h>*/
#undef NULL
#include "lisp.h"
Jim Blandy's avatar
Jim Blandy committed
26
#include "frame.h"
Jim Blandy's avatar
Jim Blandy committed
27 28 29 30 31 32 33 34
#include "window.h"
#include "termchar.h"
#include "dispextern.h"
#include "buffer.h"
#include "indent.h"
#include "commands.h"
#include "macros.h"
#include "disptab.h"
35
#include "termhooks.h"
Jim Blandy's avatar
Jim Blandy committed
36 37 38 39 40 41 42 43 44 45 46 47

extern int interrupt_input;
extern int command_loop_level;

/* Nonzero means print newline before next minibuffer message.  */

int noninteractive_need_newline;

#define min(a, b) ((a) < (b) ? (a) : (b))
#define max(a, b) ((a) > (b) ? (a) : (b))

/* The buffer position of the first character appearing
Jim Blandy's avatar
Jim Blandy committed
48 49
 entirely or partially on the current frame line.
 Or zero, which disables the optimization for the current frame line. */
Jim Blandy's avatar
Jim Blandy committed
50 51 52 53 54 55
static int this_line_bufpos;

/* Number of characters past the end of this line,
   including the terminating newline */
static int this_line_endpos;

Jim Blandy's avatar
Jim Blandy committed
56
/* The vertical position of this frame line. */
Jim Blandy's avatar
Jim Blandy committed
57 58
static int this_line_vpos;

Jim Blandy's avatar
Jim Blandy committed
59
/* Hpos value for start of display on this frame line.
Jim Blandy's avatar
Jim Blandy committed
60 61 62 63 64 65 66 67
   Usually zero, but negative if first character really began
   on previous line */
static int this_line_start_hpos;

/* Buffer that this_line variables are describing. */
static struct buffer *this_line_buffer;

/* Set by try_window_id to the vpos of first of any lines
Jim Blandy's avatar
Jim Blandy committed
68
   scrolled on to the bottom of the frame.  These lines should
Jim Blandy's avatar
Jim Blandy committed
69 70 71 72
   not be included in any general scroll computation.  */
static int scroll_bottom_vpos;

/* Value of echo_area_glyphs when it was last acted on.
Jim Blandy's avatar
Jim Blandy committed
73
  If this is nonzero, there is a message on the frame
Jim Blandy's avatar
Jim Blandy committed
74 75 76 77
  in the minibuffer and it should be erased as soon
  as it is no longer requested to appear. */
char *previous_echo_glyphs;

Jim Blandy's avatar
Jim Blandy committed
78
/* Nonzero means truncate lines in all windows less wide than the frame */
Jim Blandy's avatar
Jim Blandy committed
79 80 81 82 83 84 85 86 87 88 89
int truncate_partial_width_windows;

Lisp_Object Vglobal_mode_string;

/* Marker for where to display an arrow on top of the buffer text.  */
Lisp_Object Voverlay_arrow_position;

/* String to display for the arrow.  */
Lisp_Object Voverlay_arrow_string;

/* Values of those variables at last redisplay.  */
90
static Lisp_Object last_arrow_position, last_arrow_string;
Jim Blandy's avatar
Jim Blandy committed
91 92 93 94

/* Nonzero if overlay arrow has been displayed once in this window.  */
static int overlay_arrow_seen;

Jim Blandy's avatar
Jim Blandy committed
95
/* If cursor motion alone moves point off frame,
Jim Blandy's avatar
Jim Blandy committed
96 97 98 99 100 101 102 103 104 105 106
   Try scrolling this many lines up or down if that will bring it back.  */
int scroll_step;

/* Nonzero if try_window_id has made blank lines at window bottom
 since the last redisplay that paused */
static int blank_end_of_window;

/* Number of windows showing the buffer of the selected window.
   keyboard.c refers to this.  */
int buffer_shared;

Jim Blandy's avatar
Jim Blandy committed
107
/* display_text_line sets these to the frame position (origin 0) of point,
Jim Blandy's avatar
Jim Blandy committed
108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130
   whether the window is selected or not.
   Set one to -1 first to determine whether point was found afterwards.  */

static int cursor_vpos;
static int cursor_hpos;

int debug_end_pos;

/* Nonzero means display mode line highlighted */
int mode_line_inverse_video;

static void echo_area_display ();
void mark_window_display_accurate ();
static void redisplay_windows ();
static void redisplay_window ();
static void try_window ();
static int try_window_id ();
static struct position *display_text_line ();
static void display_mode_line ();
static int display_mode_element ();
static char *fmodetrunc ();
static char *decode_mode_spec ();
static int display_string ();
131
static void display_menu_bar ();
132
static int display_count_lines ();
Jim Blandy's avatar
Jim Blandy committed
133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171

/* Prompt to display in front of the minibuffer contents */
char *minibuf_prompt;

/* Width in columns of current minibuffer prompt.  */
int minibuf_prompt_width;

/* Message to display instead of minibuffer contents
   This is what the functions error and message make,
   and command echoing uses it as well.
   It overrides the minibuf_prompt as well as the buffer.  */
char *echo_area_glyphs;

/* true iff we should redraw the mode lines on the next redisplay */
int update_mode_lines;

/* Smallest number of characters before the gap
   at any time since last redisplay that finished.
   Valid for current buffer when try_window_id can be called.  */
int beg_unchanged;

/* Smallest number of characters after the gap
   at any time since last redisplay that finished.
   Valid for current buffer when try_window_id can be called.  */
int end_unchanged;

/* MODIFF as of last redisplay that finished;
   if it matches MODIFF, beg_unchanged and end_unchanged
   contain no useful information */
int unchanged_modified;

/* Nonzero if head_clip or tail_clip of current buffer has changed
   since last redisplay that finished */
int clip_changed;

/* Nonzero if window sizes or contents have changed
   since last redisplay that finished */
int windows_or_buffers_changed;

172 173 174 175 176 177
/* Nonzero after display_mode_line if %l was used
   and it displayed a line number.  */
int line_number_displayed;

/* Maximum buffer size for which to display line numbers.  */
int line_number_display_limit;
Jim Blandy's avatar
Jim Blandy committed
178

179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202
/* Specify m, a string, as a message in the minibuf.  If m is 0, clear out
   any existing message, and let the minibuffer text show through.  */
void
message1 (m)
     char *m;
{
  if (noninteractive)
    {
      if (noninteractive_need_newline)
	putc ('\n', stderr);
      noninteractive_need_newline = 0;
      fprintf (stderr, "%s\n", m);
      fflush (stderr);
    }
  /* A null message buffer means that the frame hasn't really been
     initialized yet.  Error messages get reported properly by
     cmd_error, so this must be just an informative message; toss it.  */
  else if (INTERACTIVE && FRAME_MESSAGE_BUF (selected_frame))
    {
#ifdef MULTI_FRAME
      Lisp_Object minibuf_frame;

      choose_minibuf_frame ();
      minibuf_frame = WINDOW_FRAME (XWINDOW (minibuf_window));
203
      FRAME_SAMPLE_VISIBILITY (XFRAME (minibuf_frame));
204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220
      if (FRAME_VISIBLE_P (selected_frame)
	  && ! FRAME_VISIBLE_P (XFRAME (minibuf_frame)))
	Fmake_frame_visible (WINDOW_FRAME (XWINDOW (minibuf_window)));
#endif

      if (m)
	echo_area_glyphs = m;
      else
	echo_area_glyphs = previous_echo_glyphs = 0;

      do_pending_window_change ();
      echo_area_display ();
      update_frame (XFRAME (XWINDOW (minibuf_window)->frame), 1, 1);
      do_pending_window_change ();
    }
}

Jim Blandy's avatar
Jim Blandy committed
221
/* Nonzero if FRAME_MESSAGE_BUF (selected_frame) is being used by print;
Jim Blandy's avatar
Jim Blandy committed
222 223 224
   zero if being used by message.  */
int message_buf_print;

225 226
/* Dump an informative message to the minibuf.  If m is 0, clear out
   any existing message, and let the minibuffer text show through.  */
Jim Blandy's avatar
Jim Blandy committed
227 228 229 230 231 232 233
/* VARARGS 1 */
void
message (m, a1, a2, a3)
     char *m;
{
  if (noninteractive)
    {
234 235 236 237 238 239 240 241 242
      if (m)
	{
	  if (noninteractive_need_newline)
	    putc ('\n', stderr);
	  noninteractive_need_newline = 0;
	  fprintf (stderr, m, a1, a2, a3);
	  fprintf (stderr, "\n");
	  fflush (stderr);
	}
Jim Blandy's avatar
Jim Blandy committed
243
    }
244
  else if (INTERACTIVE)
Jim Blandy's avatar
Jim Blandy committed
245
    {
246 247 248 249 250 251 252 253 254 255 256 257 258 259 260
      /* The frame whose minibuffer we're going to display the message on.
	 It may be larger than the selected frame, so we need
	 to use its buffer, not the selected frame's buffer.  */
      FRAME_PTR echo_frame;
#ifdef MULTI_FRAME
      choose_minibuf_frame ();
      echo_frame = XFRAME (WINDOW_FRAME (XWINDOW (minibuf_window)));
#else
      echo_frame = selected_frame;
#endif

      /* A null message buffer means that the frame hasn't really been
	 initialized yet.  Error messages get reported properly by
	 cmd_error, so this must be just an informative message; toss it.  */
      if (FRAME_MESSAGE_BUF (echo_frame))
261
	{
262 263 264
	  if (m)
	    {
	      {
Jim Blandy's avatar
Jim Blandy committed
265
#ifdef NO_ARG_ARRAY
266 267 268 269
		int a[3];
		a[0] = a1;
		a[1] = a2;
		a[2] = a3;
Jim Blandy's avatar
Jim Blandy committed
270

271 272
		doprnt (FRAME_MESSAGE_BUF (echo_frame),
			FRAME_WIDTH (echo_frame), m, 0, 3, a);
Jim Blandy's avatar
Jim Blandy committed
273
#else
274 275 276 277 278 279 280 281 282 283 284 285 286
		doprnt (FRAME_MESSAGE_BUF (echo_frame),
			FRAME_WIDTH (echo_frame), m, 0, 3, &a1);
#endif /* NO_ARG_ARRAY */
	      }

	      message1 (FRAME_MESSAGE_BUF (echo_frame));
	    }
	  else
	    message1 (0);

	  /* Print should start at the beginning of the message
	     buffer next time.  */
	  message_buf_print = 0;
287
	}
Jim Blandy's avatar
Jim Blandy committed
288 289 290 291 292 293 294
    }
}

static void
echo_area_display ()
{
  register int vpos;
Jim Blandy's avatar
Jim Blandy committed
295
  FRAME_PTR f;
Jim Blandy's avatar
Jim Blandy committed
296

Jim Blandy's avatar
Jim Blandy committed
297 298
#ifdef MULTI_FRAME
  choose_minibuf_frame ();
299 300
#endif

Jim Blandy's avatar
Jim Blandy committed
301
  f = XFRAME (WINDOW_FRAME (XWINDOW (minibuf_window)));
Jim Blandy's avatar
Jim Blandy committed
302

Jim Blandy's avatar
Jim Blandy committed
303
  if (! FRAME_VISIBLE_P (f))
Jim Blandy's avatar
Jim Blandy committed
304 305
    return;

Jim Blandy's avatar
Jim Blandy committed
306
  if (frame_garbaged)
Jim Blandy's avatar
Jim Blandy committed
307 308
    {
      Fredraw_display ();
Jim Blandy's avatar
Jim Blandy committed
309
      frame_garbaged = 0;
Jim Blandy's avatar
Jim Blandy committed
310 311 312 313 314
    }

  if (echo_area_glyphs || minibuf_level == 0)
    {
      vpos = XFASTINT (XWINDOW (minibuf_window)->top);
Jim Blandy's avatar
Jim Blandy committed
315
      get_display_line (f, vpos, 0);
Jim Blandy's avatar
Jim Blandy committed
316 317
      display_string (XWINDOW (minibuf_window), vpos,
		      echo_area_glyphs ? echo_area_glyphs : "",
Jim Blandy's avatar
Jim Blandy committed
318
		      0, 0, 0, FRAME_WIDTH (f));
Jim Blandy's avatar
Jim Blandy committed
319 320

      /* If desired cursor location is on this line, put it at end of text */
Jim Blandy's avatar
Jim Blandy committed
321 322
      if (FRAME_CURSOR_Y (f) == vpos)
	FRAME_CURSOR_X (f) = FRAME_DESIRED_GLYPHS (f)->used[vpos];
Jim Blandy's avatar
Jim Blandy committed
323 324 325 326 327 328 329

      /* Fill the rest of the minibuffer window with blank lines.  */
      {
	int i;

	for (i = vpos + 1; i < vpos + XWINDOW (minibuf_window)->height; i++)
	  {
Jim Blandy's avatar
Jim Blandy committed
330
	    get_display_line (f, i, 0);
Jim Blandy's avatar
Jim Blandy committed
331
	    display_string (XWINDOW (minibuf_window), vpos,
Jim Blandy's avatar
Jim Blandy committed
332
			    "", 0, 0, 0, FRAME_WIDTH (f));
Jim Blandy's avatar
Jim Blandy committed
333 334
	  }
      }
Jim Blandy's avatar
Jim Blandy committed
335 336 337 338 339 340 341 342 343 344
    }
  else if (!EQ (minibuf_window, selected_window))
    windows_or_buffers_changed++;

  if (EQ (minibuf_window, selected_window))
    this_line_bufpos = 0;

  previous_echo_glyphs = echo_area_glyphs;
}

Jim Blandy's avatar
Jim Blandy committed
345
/* Do a frame update, taking possible shortcuts into account.
Jim Blandy's avatar
Jim Blandy committed
346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373
   This is the main external entry point for redisplay.

   If the last redisplay displayed an echo area message and that
   message is no longer requested, we clear the echo area
   or bring back the minibuffer if that is in use.

   Everyone would like to have a hook here to call eval,
   but that cannot be done safely without a lot of changes elsewhere.
   This can be called from signal handlers; with alarms set up;
   or with synchronous processes running.
   See the function `echo' in keyboard.c.
   See Fcall_process; if you called it from here, it could be
   entered recursively.  */

void
redisplay ()
{
  register struct window *w = XWINDOW (selected_window);
  register int pause;
  int must_finish = 0;
  int all_windows;
  register int tlbufpos, tlendpos;
  struct position pos;
  extern int input_pending;

  if (noninteractive)
    return;

374 375 376 377 378
  /* Set the visible flags for all frames.
     Do this before checking for resized or garbaged frames; they want
     to know if their frames are visible.
     See the comment in frame.h for FRAME_SAMPLE_VISIBILITY.  */
  {
379
    Lisp_Object tail, frame;
380

381 382
    FOR_EACH_FRAME (tail, frame)
      FRAME_SAMPLE_VISIBILITY (XFRAME (frame));
383 384
  }

Jim Blandy's avatar
Jim Blandy committed
385
  /* Notice any pending interrupt request to change frame size.  */
Jim Blandy's avatar
Jim Blandy committed
386 387
  do_pending_window_change ();

Jim Blandy's avatar
Jim Blandy committed
388
  if (frame_garbaged)
Jim Blandy's avatar
Jim Blandy committed
389 390
    {
      Fredraw_display ();
Jim Blandy's avatar
Jim Blandy committed
391
      frame_garbaged = 0;
Jim Blandy's avatar
Jim Blandy committed
392 393
    }

Jim Blandy's avatar
Jim Blandy committed
394
  /* Normally the message* functions will have already displayed and
Jim Blandy's avatar
Jim Blandy committed
395
     updated the echo area, but the frame may have been trashed, or
Jim Blandy's avatar
Jim Blandy committed
396 397
     the update may have been preempted, so display the echo area
     again here.  */
Jim Blandy's avatar
Jim Blandy committed
398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415
  if (echo_area_glyphs || previous_echo_glyphs)
    {
      echo_area_display ();
      must_finish = 1;
    }

  if (clip_changed || windows_or_buffers_changed)
    update_mode_lines++;

  /* Detect case that we need to write a star in the mode line.  */
  if (XFASTINT (w->last_modified) < MODIFF
      && XFASTINT (w->last_modified) <= current_buffer->save_modified)
    {
      w->update_mode_line = Qt;
      if (buffer_shared > 1)
	update_mode_lines++;
    }

Jim Blandy's avatar
Jim Blandy committed
416
  FRAME_SCROLL_BOTTOM_VPOS (XFRAME (w->frame)) = -1;
Jim Blandy's avatar
Jim Blandy committed
417 418 419 420 421

  all_windows = update_mode_lines || buffer_shared > 1;

  /* If specs for an arrow have changed, do thorough redisplay
     to ensure we remove any arrow that should no longer exist.  */
422 423
  if (! EQ (Voverlay_arrow_position, last_arrow_position)
      || ! EQ (Voverlay_arrow_string, last_arrow_string))
Jim Blandy's avatar
Jim Blandy committed
424 425 426 427
    all_windows = 1, clip_changed = 1;

  tlbufpos = this_line_bufpos;
  tlendpos = this_line_endpos;
Jim Blandy's avatar
Jim Blandy committed
428
  if (!all_windows && tlbufpos > 0 && NILP (w->update_mode_line)
Jim Blandy's avatar
Jim Blandy committed
429
      && FRAME_VISIBLE_P (XFRAME (w->frame))
Jim Blandy's avatar
Jim Blandy committed
430 431 432
      /* Make sure recorded data applies to current buffer, etc */
      && this_line_buffer == current_buffer
      && current_buffer == XBUFFER (w->buffer)
Jim Blandy's avatar
Jim Blandy committed
433
      && NILP (w->force_start)
Jim Blandy's avatar
Jim Blandy committed
434 435 436 437 438 439 440 441
      /* Point must be on the line that we have info recorded about */
      && point >= tlbufpos
      && point <= Z - tlendpos
      /* All text outside that line, including its final newline,
	 must be unchanged */
      && (XFASTINT (w->last_modified) >= MODIFF
	  || (beg_unchanged >= tlbufpos - 1
	      && GPT >= tlbufpos
Jim Blandy's avatar
Jim Blandy committed
442 443 444 445 446 447 448
	      /* If selective display, can't optimize
		 if the changes start at the beginning of the line.  */
	      && ((XTYPE (current_buffer->selective_display) == Lisp_Int
		   && XINT (current_buffer->selective_display) > 0
		   ? (beg_unchanged >= tlbufpos
		      && GPT > tlbufpos)
		   : 1))
Jim Blandy's avatar
Jim Blandy committed
449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468
	      && end_unchanged >= tlendpos
	      && Z - GPT >= tlendpos)))
    {
      if (tlbufpos > BEGV && FETCH_CHAR (tlbufpos - 1) != '\n'
	  && (tlbufpos == ZV
	      || FETCH_CHAR (tlbufpos) == '\n'))
	/* Former continuation line has disappeared by becoming empty */
	goto cancel;
      else if (XFASTINT (w->last_modified) < MODIFF
	       || MINI_WINDOW_P (w))
	{
	  cursor_vpos = -1;
	  overlay_arrow_seen = 0;
	  display_text_line (w, tlbufpos, this_line_vpos, this_line_start_hpos,
			     pos_tab_offset (w, tlbufpos));
	  /* If line contains point, is not continued,
		 and ends at same distance from eob as before, we win */
	  if (cursor_vpos >= 0 && this_line_bufpos
	      && this_line_endpos == tlendpos)
	    {
Jim Blandy's avatar
Jim Blandy committed
469
	      if (XFASTINT (w->width) != FRAME_WIDTH (XFRAME (WINDOW_FRAME (w))))
Jim Blandy's avatar
Jim Blandy committed
470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489
		preserve_other_columns (w);
	      goto update;
	    }
	  else
	    goto cancel;
	}
      else if (point == XFASTINT (w->last_point))
	{
	  if (!must_finish)
	    {
	      do_pending_window_change ();
	      return;
	    }
	  goto update;
	}
      else
	{
	  pos = *compute_motion (tlbufpos, 0,
				 XINT (w->hscroll) ? 1 - XINT (w->hscroll) : 0,
				 point, 2, - (1 << (SHORTBITS - 1)),
490
				 window_internal_width (w) - 1,
Jim Blandy's avatar
Jim Blandy committed
491 492
				 XINT (w->hscroll),
				 pos_tab_offset (w, tlbufpos));
Jim Blandy's avatar
Jim Blandy committed
493 494
	  if (pos.vpos < 1)
	    {
Jim Blandy's avatar
Jim Blandy committed
495
	      FRAME_CURSOR_X (selected_frame)
Jim Blandy's avatar
Jim Blandy committed
496
		= XFASTINT (w->left) + max (pos.hpos, 0);
Jim Blandy's avatar
Jim Blandy committed
497
	      FRAME_CURSOR_Y (selected_frame) = this_line_vpos;
Jim Blandy's avatar
Jim Blandy committed
498 499 500 501 502 503 504
	      goto update;
	    }
	  else
	    goto cancel;
	}
    cancel:
      /* Text changed drastically or point moved off of line */
Jim Blandy's avatar
Jim Blandy committed
505
      cancel_line (this_line_vpos, selected_frame);
Jim Blandy's avatar
Jim Blandy committed
506 507 508 509 510 511 512
    }

  this_line_bufpos = 0;
  all_windows |= buffer_shared > 1;

  if (all_windows)
    {
513
      Lisp_Object tail, frame;
Jim Blandy's avatar
Jim Blandy committed
514 515

      /* Recompute # windows showing selected buffer.
Jim Blandy's avatar
Jim Blandy committed
516
	 This will be incremented each time such a window is displayed.  */
Jim Blandy's avatar
Jim Blandy committed
517 518
      buffer_shared = 0;

519
      FOR_EACH_FRAME (tail, frame)
520
	{
521 522
	  FRAME_PTR f = XFRAME (frame);

523
	  /* Mark all the scroll bars to be removed; we'll redeem the ones
524
	     we want when we redisplay their windows.  */
525 526
	  if (condemn_scroll_bars_hook)
	    (*condemn_scroll_bars_hook) (f);
527 528 529 530

	  if (FRAME_VISIBLE_P (f))
	    redisplay_windows (FRAME_ROOT_WINDOW (f));

531
	  /* Any scroll bars which redisplay_windows should have nuked
532
	     should now go away.  */
533 534
	  if (judge_scroll_bars_hook)
	    (*judge_scroll_bars_hook) (f);
535
	}
Jim Blandy's avatar
Jim Blandy committed
536
    }
Jim Blandy's avatar
Jim Blandy committed
537
  else if (FRAME_VISIBLE_P (selected_frame))
Jim Blandy's avatar
Jim Blandy committed
538 539
    {
      redisplay_window (selected_window, 1);
Jim Blandy's avatar
Jim Blandy committed
540
      if (XFASTINT (w->width) != FRAME_WIDTH (selected_frame))
Jim Blandy's avatar
Jim Blandy committed
541 542 543 544 545 546 547 548 549 550 551
	preserve_other_columns (w);
    }

update: 
  /* Prevent various kinds of signals during display update.
     stdio is not robust about handling signals,
     which can cause an apparent I/O error.  */
  if (interrupt_input)
    unrequest_sigio ();
  stop_polling ();

Jim Blandy's avatar
Jim Blandy committed
552
#ifdef MULTI_FRAME
Jim Blandy's avatar
Jim Blandy committed
553 554 555 556 557 558
  if (all_windows)
    {
      Lisp_Object tail;

      pause = 0;

Jim Blandy's avatar
Jim Blandy committed
559
      for (tail = Vframe_list; CONSP (tail); tail = XCONS (tail)->cdr)
Jim Blandy's avatar
Jim Blandy committed
560
	{
Jim Blandy's avatar
Jim Blandy committed
561
	  FRAME_PTR f;
Jim Blandy's avatar
Jim Blandy committed
562

Jim Blandy's avatar
Jim Blandy committed
563
	  if (XTYPE (XCONS (tail)->car) != Lisp_Frame)
Jim Blandy's avatar
Jim Blandy committed
564 565
	    continue;

Jim Blandy's avatar
Jim Blandy committed
566
	  f = XFRAME (XCONS (tail)->car);
567
	  if (FRAME_VISIBLE_P (f))
Jim Blandy's avatar
Jim Blandy committed
568
	    {
Jim Blandy's avatar
Jim Blandy committed
569
	      pause |= update_frame (f, 0, 0);
Jim Blandy's avatar
Jim Blandy committed
570
	      if (!pause)
Jim Blandy's avatar
Jim Blandy committed
571
		mark_window_display_accurate (f->root_window, 1);
Jim Blandy's avatar
Jim Blandy committed
572 573 574 575
	    }
	}
    }
  else
Jim Blandy's avatar
Jim Blandy committed
576
#endif /* MULTI_FRAME */
Jim Blandy's avatar
Jim Blandy committed
577
    {
Jim Blandy's avatar
Jim Blandy committed
578 579
      if (FRAME_VISIBLE_P (selected_frame))
	pause = update_frame (selected_frame, 0, 0);
580

Jim Blandy's avatar
Jim Blandy committed
581
      /* We may have called echo_area_display at the top of this
Jim Blandy's avatar
Jim Blandy committed
582 583 584
	 function.  If the echo area is on another frame, that may
	 have put text on a frame other than the selected one, so the
	 above call to update_frame would not have caught it.  Catch
Jim Blandy's avatar
Jim Blandy committed
585 586
	 it here.  */
      {
Jim Blandy's avatar
Jim Blandy committed
587 588
	FRAME_PTR mini_frame =
	  XFRAME (WINDOW_FRAME (XWINDOW (minibuf_window)));
Jim Blandy's avatar
Jim Blandy committed
589
	
Jim Blandy's avatar
Jim Blandy committed
590 591
	if (mini_frame != selected_frame)
	  pause |= update_frame (mini_frame, 0, 0);
Jim Blandy's avatar
Jim Blandy committed
592
      }
Jim Blandy's avatar
Jim Blandy committed
593
    }
Jim Blandy's avatar
Jim Blandy committed
594

Jim Blandy's avatar
Jim Blandy committed
595
  /* If frame does not match, prevent doing single-line-update next time.
Jim Blandy's avatar
Jim Blandy committed
596 597 598 599
     Also, don't forget to check every line to update the arrow.  */
  if (pause)
    {
      this_line_bufpos = 0;
Jim Blandy's avatar
Jim Blandy committed
600
      if (!NILP (last_arrow_position))
Jim Blandy's avatar
Jim Blandy committed
601 602 603 604
	{
	  last_arrow_position = Qt;
	  last_arrow_string = Qt;
	}
Jim Blandy's avatar
Jim Blandy committed
605
      /* If we pause after scrolling, some lines in current_frame
Jim Blandy's avatar
Jim Blandy committed
606 607 608
	 may be null, so preserve_other_columns won't be able to
	 preserve all the vertical-bar separators.  So, avoid using it
	 in that case.  */
Jim Blandy's avatar
Jim Blandy committed
609
      if (XFASTINT (w->width) != FRAME_WIDTH (selected_frame))
Jim Blandy's avatar
Jim Blandy committed
610 611 612
	update_mode_lines = 1;
    }

Jim Blandy's avatar
Jim Blandy committed
613
  /* Now text on frame agrees with windows, so
Jim Blandy's avatar
Jim Blandy committed
614 615 616 617 618 619 620 621 622 623 624 625 626
     put info into the windows for partial redisplay to follow */

  if (!pause)
    {
      register struct buffer *b = XBUFFER (w->buffer);

      blank_end_of_window = 0;
      clip_changed = 0;
      unchanged_modified = BUF_MODIFF (b);
      beg_unchanged = BUF_GPT (b) - BUF_BEG (b);
      end_unchanged = BUF_Z (b) - BUF_GPT (b);

      XFASTINT (w->last_point) = BUF_PT (b);
Jim Blandy's avatar
Jim Blandy committed
627 628
      XFASTINT (w->last_point_x) = FRAME_CURSOR_X (selected_frame);
      XFASTINT (w->last_point_y) = FRAME_CURSOR_Y (selected_frame);
Jim Blandy's avatar
Jim Blandy committed
629 630

      if (all_windows)
631
	mark_window_display_accurate (FRAME_ROOT_WINDOW (selected_frame), 1);
Jim Blandy's avatar
Jim Blandy committed
632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654
      else
	{
	  w->update_mode_line = Qnil;
	  XFASTINT (w->last_modified) = BUF_MODIFF (b);
	  w->window_end_valid = Qt;
	  last_arrow_position = Voverlay_arrow_position;
	  last_arrow_string = Voverlay_arrow_string;
	}
      update_mode_lines = 0;
      windows_or_buffers_changed = 0;
    }

  /* Start SIGIO interrupts coming again.
     Having them off during the code above
     makes it less likely one will discard output,
     but not impossible, since there might be stuff
     in the system buffer here.
     But it is much hairier to try to do anything about that.  */

  if (interrupt_input)
    request_sigio ();
  start_polling ();

Jim Blandy's avatar
Jim Blandy committed
655
  /* Change frame size now if a change is pending.  */
Jim Blandy's avatar
Jim Blandy committed
656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685
  do_pending_window_change ();
}

/* Redisplay, but leave alone any recent echo area message
   unless another message has been requested in its place.

   This is useful in situations where you need to redisplay but no
   user action has occurred, making it inappropriate for the message
   area to be cleared.  See tracking_off and
   wait_reading_process_input for examples of these situations.  */

redisplay_preserve_echo_area ()
{
  if (echo_area_glyphs == 0 && previous_echo_glyphs != 0)
    {
      echo_area_glyphs = previous_echo_glyphs;
      redisplay ();
      echo_area_glyphs = 0;
    }
  else
    redisplay ();
}

void
mark_window_display_accurate (window, flag)
     Lisp_Object window;
     int flag;
{
  register struct window *w;

Jim Blandy's avatar
Jim Blandy committed
686
  for (;!NILP (window); window = w->next)
Jim Blandy's avatar
Jim Blandy committed
687
    {
688
      if (XTYPE (window) != Lisp_Window) abort ();
Jim Blandy's avatar
Jim Blandy committed
689 690
      w = XWINDOW (window);

Jim Blandy's avatar
Jim Blandy committed
691
      if (!NILP (w->buffer))
Jim Blandy's avatar
Jim Blandy committed
692 693 694 695 696 697 698
	XFASTINT (w->last_modified)
	  = !flag ? 0
	    : XBUFFER (w->buffer) == current_buffer
	      ? MODIFF : BUF_MODIFF (XBUFFER (w->buffer));
      w->window_end_valid = Qt;
      w->update_mode_line = Qnil;

Jim Blandy's avatar
Jim Blandy committed
699
      if (!NILP (w->vchild))
Jim Blandy's avatar
Jim Blandy committed
700
	mark_window_display_accurate (w->vchild, flag);
Jim Blandy's avatar
Jim Blandy committed
701
      if (!NILP (w->hchild))
Jim Blandy's avatar
Jim Blandy committed
702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723
	mark_window_display_accurate (w->hchild, flag);
    }

  if (flag)
    {
      last_arrow_position = Voverlay_arrow_position;
      last_arrow_string = Voverlay_arrow_string;
    }
  else
    {
      /* t is unequal to any useful value of Voverlay_arrow_... */
      last_arrow_position = Qt;
      last_arrow_string = Qt;
    }
}

int do_id = 1;

static void
redisplay_windows (window)
     Lisp_Object window;
{
Jim Blandy's avatar
Jim Blandy committed
724
  for (; !NILP (window); window = XWINDOW (window)->next)
Jim Blandy's avatar
Jim Blandy committed
725 726 727 728 729 730 731 732 733
    redisplay_window (window, 0);
}

static void
redisplay_window (window, just_this_one)
     Lisp_Object window;
     int just_this_one;
{
  register struct window *w = XWINDOW (window);
734
  FRAME_PTR f = XFRAME (WINDOW_FRAME (w));
Jim Blandy's avatar
Jim Blandy committed
735 736 737
  int height;
  register int lpoint = point;
  struct buffer *old = current_buffer;
738
  register int width = window_internal_width (w) - 1;
Jim Blandy's avatar
Jim Blandy committed
739 740 741
  register int startp;
  register int hscroll = XINT (w->hscroll);
  struct position pos;
742
  int opoint = point;
Jim Blandy's avatar
Jim Blandy committed
743 744 745
  int tem;
  int window_needs_modeline;

Jim Blandy's avatar
Jim Blandy committed
746
  if (FRAME_HEIGHT (f) == 0) abort (); /* Some bug zeros some core */
Jim Blandy's avatar
Jim Blandy committed
747 748 749

  /* If this is a combination window, do its children; that's all.  */

Jim Blandy's avatar
Jim Blandy committed
750
  if (!NILP (w->vchild))
Jim Blandy's avatar
Jim Blandy committed
751 752 753 754
    {
      redisplay_windows (w->vchild);
      return;
    }
Jim Blandy's avatar
Jim Blandy committed
755
  if (!NILP (w->hchild))
Jim Blandy's avatar
Jim Blandy committed
756 757 758 759
    {
      redisplay_windows (w->hchild);
      return;
    }
Jim Blandy's avatar
Jim Blandy committed
760
  if (NILP (w->buffer))
Jim Blandy's avatar
Jim Blandy committed
761
    abort ();
Jim Blandy's avatar
Jim Blandy committed
762 763 764 765 766 767 768 769 770
  
  height = window_internal_height (w);

  if (MINI_WINDOW_P (w))
    {
      if (w == XWINDOW (minibuf_window))
	{
	  if (echo_area_glyphs)
	    /* We've already displayed the echo area glyphs, if any.  */
771
	    goto finish_scroll_bars;
Jim Blandy's avatar
Jim Blandy committed
772 773 774 775 776
	}
      else
	{
	  /* This is a minibuffer, but it's not the currently active one, so
	     clear it.  */
Jim Blandy's avatar
Jim Blandy committed
777
	  int vpos = XFASTINT (XWINDOW (FRAME_MINIBUF_WINDOW (f))->top);
Jim Blandy's avatar
Jim Blandy committed
778 779 780 781
	  int i;

	  for (i = 0; i < height; i++)
	    {
Jim Blandy's avatar
Jim Blandy committed
782
	      get_display_line (f, vpos + i, 0);
Jim Blandy's avatar
Jim Blandy committed
783 784 785
	      display_string (w, vpos + i, "", 0, 0, 0, width);
	    }
	  
786
	  goto finish_scroll_bars;
Jim Blandy's avatar
Jim Blandy committed
787 788
	}
    }
Jim Blandy's avatar
Jim Blandy committed
789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811

  if (update_mode_lines)
    w->update_mode_line = Qt;

  /* Otherwise set up data on this window; select its buffer and point value */

  current_buffer = XBUFFER (w->buffer);
  opoint = point;

  /* Count number of windows showing the selected buffer.  */

  if (!just_this_one
      && current_buffer == XBUFFER (XWINDOW (selected_window)->buffer))
    buffer_shared++;

  /* POINT refers normally to the selected window.
     For any other window, set up appropriate value.  */

  if (!EQ (window, selected_window))
    {
      SET_PT (marker_position (w->pointm));
      if (point < BEGV)
	{
Jim Blandy's avatar
Jim Blandy committed
812
	  SET_PT (BEGV);
Jim Blandy's avatar
Jim Blandy committed
813 814 815 816
	  Fset_marker (w->pointm, make_number (point), Qnil);
	}
      else if (point > (ZV - 1))
	{
Jim Blandy's avatar
Jim Blandy committed
817
	  SET_PT (ZV);
Jim Blandy's avatar
Jim Blandy committed
818 819 820 821 822 823 824 825 826 827
	  Fset_marker (w->pointm, make_number (point), Qnil);
	}
    }

  /* If window-start is screwed up, choose a new one.  */
  if (XMARKER (w->start)->buffer != current_buffer)
    goto recenter;

  startp = marker_position (w->start);

Jim Blandy's avatar
Jim Blandy committed
828
  /* Handle case where place to start displaying has been specified,
829
     unless the specified location is outside the accessible range.  */
Jim Blandy's avatar
Jim Blandy committed
830
  if (!NILP (w->force_start))
Jim Blandy's avatar
Jim Blandy committed
831
    {
832 833
      /* Forget any recorded base line for line number display.  */
      w->base_line_number = Qnil;
Jim Blandy's avatar
Jim Blandy committed
834 835 836
      w->update_mode_line = Qt;
      w->force_start = Qnil;
      XFASTINT (w->last_modified) = 0;
Jim Blandy's avatar
Jim Blandy committed
837 838
      if (startp < BEGV) startp = BEGV;
      if (startp > ZV)   startp = ZV;
Jim Blandy's avatar
Jim Blandy committed
839 840 841 842 843 844 845 846 847 848 849 850 851
      try_window (window, startp);
      if (cursor_vpos < 0)
	{
	  /* If point does not appear, move point so it does appear */
	  pos = *compute_motion (startp, 0,
				((EQ (window, minibuf_window) && startp == 1)
				 ? minibuf_prompt_width : 0)
				+
				(hscroll ? 1 - hscroll : 0),
				ZV, height / 2,
				- (1 << (SHORTBITS - 1)),
				width, hscroll, pos_tab_offset (w, startp));
	  SET_PT (pos.bufpos);
Jim Blandy's avatar
Jim Blandy committed
852
	  if (w != XWINDOW (FRAME_SELECTED_WINDOW (f)))
Jim Blandy's avatar
Jim Blandy committed
853 854 855 856
	    Fset_marker (w->pointm, make_number (point), Qnil);
	  else
	    {
	      lpoint = point;
Jim Blandy's avatar
Jim Blandy committed
857 858
	      FRAME_CURSOR_X (f) = max (0, pos.hpos) + XFASTINT (w->left);
	      FRAME_CURSOR_Y (f) = pos.vpos + XFASTINT (w->top);
Jim Blandy's avatar
Jim Blandy committed
859 860 861 862 863 864
	    }
	}
      goto done;
    }

  /* Handle case where text has not changed, only point,
Jim Blandy's avatar
Jim Blandy committed
865
     and it has not moved off the frame */
Jim Blandy's avatar
Jim Blandy committed
866 867 868 869 870 871 872 873 874 875

  /* This code is not used for minibuffer for the sake of
     the case of redisplaying to replace an echo area message;
     since in that case the minibuffer contents per se are usually unchanged.
     This code is of no real use in the minibuffer since
     the handling of this_line_bufpos, etc.,
     in redisplay handles the same cases.  */

  if (XFASTINT (w->last_modified) >= MODIFF
      && point >= startp && !clip_changed
Jim Blandy's avatar
Jim Blandy committed
876
      && (just_this_one || XFASTINT (w->width) == FRAME_WIDTH (f))
Jim Blandy's avatar
Jim Blandy committed
877 878 879 880 881 882 883 884
      && !EQ (window, minibuf_window))
    {
      pos = *compute_motion (startp, 0, (hscroll ? 1 - hscroll : 0),
			    point, height + 1, 10000, width, hscroll,
			    pos_tab_offset (w, startp));

      if (pos.vpos < height)
	{
Jim Blandy's avatar
Jim Blandy committed
885 886
	  /* Ok, point is still on frame */
	  if (w == XWINDOW (FRAME_SELECTED_WINDOW (f)))
Jim Blandy's avatar
Jim Blandy committed
887 888
	    {
	      /* These variables are supposed to be origin 1 */
Jim Blandy's avatar
Jim Blandy committed
889 890
	      FRAME_CURSOR_X (f) = max (0, pos.hpos) + XFASTINT (w->left);
	      FRAME_CURSOR_Y (f) = pos.vpos + XFASTINT (w->top);
Jim Blandy's avatar
Jim Blandy committed
891 892 893
	    }
	  /* This doesn't do the trick, because if a window to the right of
	     this one must be redisplayed, this does nothing because there
Jim Blandy's avatar
Jim Blandy committed
894
	     is nothing in DesiredFrame yet, and then the other window is
Jim Blandy's avatar
Jim Blandy committed
895
	     redisplayed, making likes that are empty in this window's columns.
Jim Blandy's avatar
Jim Blandy committed
896
	     if (XFASTINT (w->width) != FRAME_WIDTH (f))
Jim Blandy's avatar
Jim Blandy committed
897 898 899 900 901 902 903 904 905
	     preserve_my_columns (w);
	     */
	  goto done;
	}
      /* Don't bother trying redisplay with same start;
	we already know it will lose */
    }
  /* If current starting point was originally the beginning of a line
     but no longer is, find a new starting point.  */
Jim Blandy's avatar
Jim Blandy committed
906
  else if (!NILP (w->start_at_line_beg)
Jim Blandy's avatar
Jim Blandy committed
907 908 909 910 911 912 913 914 915 916 917
	   && !(startp == BEGV
		|| FETCH_CHAR (startp - 1) == '\n'))
    {
      goto recenter;
    }
  else if (just_this_one && !MINI_WINDOW_P (w)
	   && point >= startp
	   && XFASTINT (w->last_modified)
	   && ! EQ (w->window_end_valid, Qnil)
	   && do_id && !clip_changed
	   && !blank_end_of_window
Jim Blandy's avatar
Jim Blandy committed
918
	   && XFASTINT (w->width) == FRAME_WIDTH (f)
Jim Blandy's avatar
Jim Blandy committed
919 920
	   && EQ (last_arrow_position, Voverlay_arrow_position)
	   && EQ (last_arrow_string, Voverlay_arrow_string)
Jim Blandy's avatar
Jim Blandy committed
921
	   && (tem = try_window_id (FRAME_SELECTED_WINDOW (f)))
Jim Blandy's avatar
Jim Blandy committed
922 923 924 925 926 927 928 929 930 931 932
	   && tem != -2)
    {
      /* tem > 0 means success.  tem == -1 means choose new start.
	 tem == -2 means try again with same start,
	  and nothing but whitespace follows the changed stuff.
	 tem == 0 means try again with same start.  */
      if (tem > 0)
	goto done;
    }
  else if (startp >= BEGV && startp <= ZV
	   /* Avoid starting display at end of buffer! */
Jim Blandy's avatar
Jim Blandy committed
933
	   && (startp < ZV || startp == BEGV
Jim Blandy's avatar
Jim Blandy committed
934 935 936
	       || (XFASTINT (w->last_modified) >= MODIFF)))
    {
      /* Try to redisplay starting at same place as before */
Jim Blandy's avatar
Jim Blandy committed
937
      /* If point has not moved off frame, accept the results */
Jim Blandy's avatar
Jim Blandy committed
938 939
      try_window (window, startp);
      if (cursor_vpos >= 0)
940 941 942 943 944 945
	{
	  if (!just_this_one || clip_changed || beg_unchanged < startp)
	    /* Forget any recorded base line for line number display.  */
	    w->base_line_number = Qnil;
	  goto done;
	}
Jim Blandy's avatar
Jim Blandy committed
946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971
      else
	cancel_my_columns (w);
    }

  XFASTINT (w->last_modified) = 0;
  w->update_mode_line = Qt;

  /* Try to scroll by specified few lines */

  if (scroll_step && !clip_changed)
    {
      if (point > startp)
	{
	  pos = *vmotion (Z - XFASTINT (w->window_end_pos),
			  scroll_step, width, hscroll, window);
	  if (pos.vpos >= height)
	    goto scroll_fail;
	}

      pos = *vmotion (startp, point < startp ? - scroll_step : scroll_step,
		      width, hscroll, window);

      if (point >= pos.bufpos)
	{
	  try_window (window, pos.bufpos);
	  if (cursor_vpos >= 0)
972 973 974 975 976 977
	    {
	      if (!just_this_one || clip_changed || beg_unchanged < startp)
		/* Forget any recorded base line for line number display.  */
		w->base_line_number = Qnil;
	      goto done;
	    }
Jim Blandy's avatar
Jim Blandy committed
978 979 980 981 982 983 984 985 986
	  else
	    cancel_my_columns (w);
	}
    scroll_fail: ;
    }

  /* Finally, just choose place to start which centers point */

recenter:
987 988 989
  /* Forget any previously recorded base line for line number display.  */
  w->base_line_number = Qnil;

Jim Blandy's avatar
Jim Blandy committed
990 991 992 993 994 995 996 997
  pos = *vmotion (point, - height / 2, width, hscroll, window);
  try_window (window, pos.bufpos);

  startp = marker_position (w->start);
  w->start_at_line_beg = 
    (startp == BEGV || FETCH_CHAR (startp - 1) == '\n') ? Qt : Qnil;

done:
Jim Blandy's avatar
Jim Blandy committed
998
  if ((!NILP (w->update_mode_line)
999 1000 1001 1002
       /* If window not full width, must redo its mode line
	  if the window to its side is being redone */
       || (!just_this_one && width < FRAME_WIDTH (f) - 1)
       || INTEGERP (w->base_line_pos))
Jim Blandy's avatar
Jim Blandy committed
1003 1004
      && height != XFASTINT (w->height))
    display_mode_line (w);
1005 1006 1007 1008 1009 1010
  if (! line_number_displayed
      && ! BUFFERP (w->base_line_pos))
    {
      w->base_line_pos = Qnil;
      w->base_line_number = Qnil;
    }
Jim Blandy's avatar
Jim Blandy committed
1011

1012 1013 1014 1015 1016 1017
  /* When we reach a frame's selected window, redo the frame's menu bar.  */
  if (!NILP (w->update_mode_line)
      && FRAME_MENU_BAR_LINES (f) > 0
      && EQ (FRAME_SELECTED_WINDOW (f), window))
    display_menu_bar (w);

1018 1019
 finish_scroll_bars:
  if (FRAME_HAS_VERTICAL_SCROLL_BARS (f))
1020
    {
1021
      int start, end, whole;
1022

1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035
      /* Calculate the start and end positions for the current window.
	 Note that minibuffers sometimes aren't displaying any text.  */
      if (! MINI_WINDOW_P (w)
	  || (w == XWINDOW (minibuf_window) && ! echo_area_glyphs))
	{
	  start = startp;
	  /* I don't think this is guaranteed to be right.  For the
	     moment, we'll pretend it is.  */
	  end = Z - XINT (w->window_end_pos);
	  whole = Z - BEG;
	}
      else
	start = end = whole = 0;
1036

1037 1038
      /* Indicate what this scroll bar ought to be displaying now.  */
      (*set_vertical_scroll_bar_hook) (w, end - start, whole, start - 1);
1039

1040
      /* Note that we actually used the scroll bar attached to this window,
1041
	 so it shouldn't be deleted at the end of redisplay.  */
1042
      (*redeem_scroll_bar_hook) (w);
1043
    }
1044 1045 1046 1047

  SET_PT (opoint);
  current_buffer = old;
  SET_PT (lpoint);
Jim Blandy's avatar
Jim Blandy committed
1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061
}

/* Do full redisplay on one window, starting at position `pos'. */

static void
try_window (window, pos)
     Lisp_Object window;
     register int pos;
{
  register struct window *w = XWINDOW (window);
  register int height = window_internal_height (w);
  register int vpos = XFASTINT (w->top);
  register int last_text_vpos = vpos;
  int tab_offset = pos_tab_offset (w, pos);
Jim Blandy's avatar
Jim Blandy committed
1062
  FRAME_PTR f = XFRAME (w->frame);
1063
  int width = window_internal_width (w) - 1;
Jim Blandy's avatar
Jim Blandy committed
1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084
  struct position val;

  Fset_marker (w->start, make_number (pos), Qnil);
  cursor_vpos = -1;
  overlay_arrow_seen = 0;
  val.hpos = XINT (w->hscroll) ? 1 - XINT (w->hscroll) : 0;

  while (--height >= 0)
    {
      val = *display_text_line (w, pos, vpos, val.hpos, tab_offset);
      tab_offset += width;
      if (val.vpos) tab_offset = 0;
      vpos++;
      if (pos != val.bufpos)
	last_text_vpos
	  /* Next line, unless prev line ended in end of buffer with no cr */
	  = vpos - (val.vpos && FETCH_CHAR (val.bufpos - 1) != '\n');
      pos = val.bufpos;
    }

  /* If last line is continued in middle of character,
Jim Blandy's avatar
Jim Blandy committed
1085
     include the split character in the text considered on the frame */
Jim Blandy's avatar
Jim Blandy committed
1086 1087 1088
  if (val.hpos < (XINT (w->hscroll) ? 1 - XINT (w->hscroll) : 0))
    pos++;

Jim Blandy's avatar
Jim Blandy committed
1089
  /* If bottom just moved off end of frame, change mode line percentage.  */
Jim Blandy's avatar
Jim Blandy committed
1090 1091 1092 1093
  if (XFASTINT (w->window_end_pos) == 0
      && Z != pos)
    w->update_mode_line = Qt;

Jim Blandy's avatar
Jim Blandy committed
1094
  /* Say where last char on frame will be, once redisplay is finished.  */
Jim Blandy's avatar
Jim Blandy committed
1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114
  XFASTINT (w->window_end_pos) = Z - pos;
  XFASTINT (w->window_end_vpos) = last_text_vpos - XFASTINT (w->top);
  /* But that is not valid info until redisplay finishes.  */
  w->window_end_valid = Qnil;
}

/* Try to redisplay when buffer is modified locally,
 computing insert/delete line to preserve text outside
 the bounds of the changes.
 Return 1 if successful, 0 if if cannot tell what to do,
 or -1 to tell caller to find a new window start,
 or -2 to tell caller to do normal redisplay with same window start.  */

static int
try_window_id (window)
     Lisp_Object window;
{
  int pos;
  register struct window *w = XWINDOW (window);
  register int height = window_internal_height (w);
Jim Blandy's avatar
Jim Blandy committed
1115
  FRAME_PTR f = XFRAME (w->frame);
Jim Blandy's avatar
Jim Blandy committed
1116 1117
  int top = XFASTINT (w->top);
  int start = marker_position (w->start);
1118
  int width = window_internal_width (w) - 1;
Jim Blandy's avatar
Jim Blandy committed
1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140
  int hscroll = XINT (w->hscroll);
  int lmargin = hscroll > 0 ? 1 - hscroll : 0;
  register int vpos;
  register int i, tem;
  int last_text_vpos = 0;
  int stop_vpos;

  struct position val, bp, ep, xp, pp;
  int scroll_amount = 0;
  int delta;
  int tab_offset, epto;

  if (GPT - BEG < beg_unchanged)
    beg_unchanged = GPT - BEG;
  if (Z - GPT < end_unchanged)
    end_unchanged = Z - GPT;

  if (beg_unchanged + 1 < start)
    return 0;			/* Give up if changes go above top of window */

  /* Find position before which nothing is changed.  */
  bp = *compute_motion (start, 0, lmargin,
Jim Blandy's avatar
Jim Blandy committed
1141
			beg_unchanged + 1, height + 1, 0, width, hscroll,
Jim Blandy's avatar
Jim Blandy committed
1142 1143
			pos_tab_offset (w, start));
  if (bp.vpos >= height)
Jim Blandy's avatar
Jim Blandy committed
1144 1145 1146
    {
      if (point < bp.bufpos && !bp.contin)
	{
Jim Blandy's avatar
Jim Blandy committed
1147 1148
	  /* All changes are below the frame, and point is on the frame.
	     We don't need to change the frame at all.
Jim Blandy's avatar
Jim Blandy committed
1149 1150
	     But we need to update window_end_pos to account for
	     any change in buffer size.  */
Jim Blandy's avatar
Jim Blandy committed
1151 1152 1153
	  bp = *compute_motion (start, 0, lmargin,
				Z, height, 0,
				width, hscroll, pos_tab_offset (w, start));
Jim Blandy's avatar
Jim Blandy committed
1154 1155 1156 1157 1158 1159
	  XFASTINT (w->window_end_vpos) = height;
	  XFASTINT (w->window_end_pos) = Z - bp.bufpos;
	  return 1;
	}
      return 0;
    }
Jim Blandy's avatar
Jim Blandy committed
1160 1161 1162

  vpos = bp.vpos;

Jim Blandy's avatar
Jim Blandy committed
1163
  /* Find beginning of that frame line.  Must display from there.  */
Jim Blandy's avatar
Jim Blandy committed
1164 1165 1166 1167 1168 1169 1170 1171
  bp = *vmotion (bp.bufpos, 0, width, hscroll, window);

  pos = bp.bufpos;
  val.hpos = lmargin;
  if (pos < start)
    return -1;

  /* If about to start displaying at the beginning of a continuation line,
Jim Blandy's avatar
Jim Blandy committed
1172
     really start with previous frame line, in case it was not
Jim Blandy's avatar
Jim Blandy committed
1173
     continued when last redisplayed */
Jim Blandy's avatar
Jim Blandy committed
1174 1175 1176 1177 1178 1179
  if ((bp.contin && bp.bufpos - 1 == beg_unchanged && vpos > 0)
      ||
      /* Likewise if we have to worry about selective display.  */
      (XTYPE (current_buffer->selective_display) == Lisp_Int
       && XINT (current_buffer->selective_display) > 0
       && bp.bufpos - 1 == beg_unchanged && vpos > 0))
Jim Blandy's avatar
Jim Blandy committed
1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207
    {
      bp = *vmotion (bp.bufpos, -1, width, hscroll, window);
      --vpos;
      pos = bp.bufpos;
    }

  if (bp.contin && bp.hpos != lmargin)
    {
      val.hpos = bp.prevhpos - width + lmargin;
      pos--;
    }

  bp.vpos = vpos;

  /* Find first visible newline after which no more is changed.  */
  tem = find_next_newline (Z - max (end_unchanged, Z - ZV), 1);
  if (XTYPE (current_buffer->selective_display) == Lisp_Int
      && XINT (current_buffer->selective_display) > 0)
    while (tem < ZV - 1
	   && (position_indentation (tem)
	       >= XINT (current_buffer->selective_display)))
      tem = find_next_newline (tem, 1);

  /* Compute the cursor position after that newline.  */
  ep = *compute_motion (pos, vpos, val.hpos, tem,
			height, - (1 << (SHORTBITS - 1)),
			width, hscroll, pos_tab_offset (w, bp.bufpos));

Jim Blandy's avatar
Jim Blandy committed
1208 1209
  /* If changes reach past the text available on the frame,
     just display rest of frame.  */
Jim Blandy's avatar
Jim Blandy committed
1210 1211 1212 1213