[Emacs-diffs] Changes to emacs/src/xdisp.c,v

[Chong Yidong]

CVSROOT:        /sources/emacs
Module name:    emacs
Changes by:     Chong Yidong <cyd>      08/08/06 18:26:48

Index: xdisp.c
===================================================================
RCS file: /sources/emacs/emacs/src/xdisp.c,v
retrieving revision 1.1242
retrieving revision 1.1243
diff -u -b -r1.1242 -r1.1243
--- xdisp.c     5 Aug 2008 22:45:50 -0000       1.1242
+++ xdisp.c     6 Aug 2008 18:26:47 -0000       1.1243
@@ -12655,19 +12655,12 @@
 {
   struct window *w = XWINDOW (window);
   struct frame *f = XFRAME (w->frame);
-  struct text_pos scroll_margin_pos;
-  struct text_pos pos;
-  struct text_pos startp;
+  struct text_pos pos, startp;
   struct it it;
-  Lisp_Object window_end;
-  int this_scroll_margin;
-  int dy = 0;
-  int scroll_max;
-  int rc;
-  int amount_to_scroll = 0;
-  Lisp_Object aggressive;
-  int height;
+  int this_scroll_margin, scroll_max, rc, height;
+  int dy = 0, amount_to_scroll = 0, scroll_down_p = 0;
   int extra_scroll_margin_lines = last_line_misfit ? 1 : 0;
+  Lisp_Object aggressive;
 
 #if GLYPH_DEBUG
   debug_method_add (w, "try_scrolling");
@@ -12706,48 +12699,44 @@
     scroll_max = 0;
   scroll_max *= FRAME_LINE_HEIGHT (f);
 
-  /* Decide whether we have to scroll down.  Start at the window end
-     and move this_scroll_margin up to find the position of the scroll
-     margin.  */
-  window_end = Fwindow_end (window, Qt);
-
  too_near_end:
 
-  CHARPOS (scroll_margin_pos) = XINT (window_end);
-  BYTEPOS (scroll_margin_pos) = CHAR_TO_BYTE (CHARPOS (scroll_margin_pos));
-
-  if (this_scroll_margin || extra_scroll_margin_lines)
-    {
-      start_display (&it, w, scroll_margin_pos);
-      if (this_scroll_margin)
-       move_it_vertically_backward (&it, this_scroll_margin);
-      if (extra_scroll_margin_lines)
-       move_it_by_lines (&it, - extra_scroll_margin_lines, 0);
-      scroll_margin_pos = it.current.pos;
-    }
-
-  if (PT >= CHARPOS (scroll_margin_pos))
+  /* Decide whether we have to scroll down.  */
+  if (PT > CHARPOS (startp))
     {
-      int y0;
+      int scroll_margin_y;
 
-      /* Point is in the scroll margin at the bottom of the window, or
-        below.  Compute a new window start that makes point visible.  */
-
-      /* Compute the distance from the scroll margin to PT.
-        Give up if the distance is greater than scroll_max.  */
-      start_display (&it, w, scroll_margin_pos);
-      y0 = it.current_y;
-      move_it_to (&it, PT, 0, it.last_visible_y, -1,
-                 MOVE_TO_POS | MOVE_TO_X | MOVE_TO_Y);
+      /* Compute the pixel ypos of the scroll margin, then move it to
+        either that ypos or PT, whichever comes first.  */
+      start_display (&it, w, startp);
+      scroll_margin_y = it.last_visible_y - this_scroll_margin
+       - FRAME_LINE_HEIGHT (f) * extra_scroll_margin_lines;
+      move_it_to (&it, PT, -1, scroll_margin_y - 1, -1,
+                 (MOVE_TO_POS | MOVE_TO_Y));
+
+      if (PT > CHARPOS (it.current.pos))
+       {
+         /* Point is in the scroll margin at the bottom of the
+            window, or below.  Compute the distance from the scroll
+            margin to PT, and give up if the distance is greater than
+            scroll_max.  */
+         move_it_to (&it, PT, -1, it.last_visible_y - 1, -1,
+                     MOVE_TO_POS | MOVE_TO_Y);
 
-      /* To make point visible, we have to move the window start
-        down so that the line the cursor is in is visible, which
-        means we have to add in the height of the cursor line.  */
-      dy = line_bottom_y (&it) - y0;
+         /* To make point visible, we must move the window start down
+            so that the cursor line is visible, which means we have
+            to add in the height of the cursor line.  */
+         dy = line_bottom_y (&it) - scroll_margin_y;
 
       if (dy > scroll_max)
        return SCROLLING_FAILED;
 
+         scroll_down_p = 1;
+       }
+    }
+
+  if (scroll_down_p)
+    {
       /* Move the window start down.  If scrolling conservatively,
         move it just enough down to make point visible.  If
         scroll_step is set, move it down by scroll_step.  */
@@ -12787,9 +12776,10 @@
     }
   else
     {
+      struct text_pos scroll_margin_pos = startp;
+
       /* See if point is inside the scroll margin at the top of the
          window.  */
-      scroll_margin_pos = startp;
       if (this_scroll_margin)
        {
          start_display (&it, w, startp);
@@ -13038,9 +13028,13 @@
 
       /* Scroll if point within this distance from the top or bottom
         of the window.  This is a pixel value.  */
-      this_scroll_margin = max (0, scroll_margin);
-      this_scroll_margin = min (this_scroll_margin, WINDOW_TOTAL_LINES (w) / 
4);
+      if (scroll_margin > 0)
+       {
+         this_scroll_margin = min (scroll_margin, WINDOW_TOTAL_LINES (w) / 4);
       this_scroll_margin *= FRAME_LINE_HEIGHT (f);
+       }
+      else
+       this_scroll_margin = 0;
 
       top_scroll_margin = this_scroll_margin;
       if (WINDOW_WANTS_HEADER_LINE_P (w))
@@ -13674,6 +13668,11 @@
       debug_method_add (w, "same window start");
 #endif
 
+      /* If there's a scroll margin, we must try to scroll, in case
+        point is now in the scroll margin.  */
+      if (scroll_margin > 0)
+       goto try_to_scroll;
+
       /* Try to redisplay starting at same place as before.
          If point has not moved off frame, accept the results.  */
       if (!current_matrix_up_to_date_p