(try_window_id): Stop the compute_motion at ZV, not Z,

when checking if all changes are below the window.

(Qredisplay_end_trigger_hook): New variable.
(syms_of_xdisp): Set up Lisp variable.
(display_text_line): Run the hook when appropriate.

1 files changed, 33 insertions, 3 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 0978787947d..7014219d59c 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -50,6 +50,7 @@ extern Lisp_Object Voverriding_local_map_menu_flag;
 
 Lisp_Object Qoverriding_local_map, Qoverriding_terminal_local_map;
 Lisp_Object Qwindow_scroll_functions, Vwindow_scroll_functions;
+Lisp_Object Qredisplay_end_trigger_hook;
 
 /* Nonzero means print newline to stdout before next minibuffer message.  */
 
@@ -1911,12 +1912,12 @@ try_window_id (window)
     {
       if (PT < bp.bufpos)
         {
-          /* All changes are below the frame, and point is on the frame.
-             We don't need to change the frame at all.
+          /* All changes are beyond the window end, and point is on the screen.
+             We don't need to change the text at all.
              But we need to update window_end_pos to account for
              any change in buffer size.  */
           bp = *compute_motion (start, 0, lmargin, 0,
-                                Z, height, 0,
+                                ZV, height, 0,
                                 width, hscroll, pos_tab_offset (w, start), w);
           XSETFASTINT (w->window_end_vpos, height);
           XSETFASTINT (w->window_end_pos, Z - bp.bufpos);
@@ -2616,6 +2617,8 @@ display_text_line (w, start, vpos, hpos, taboffset)
     {
       if (pos >= pause)
         {
+          int e_t_h;
+
           while (pos == next_boundary)
             {
               Lisp_Object position, limit, prop, ww;
@@ -2707,6 +2710,27 @@ display_text_line (w, start, vpos, hpos, taboffset)
                                               &next_face_change, pos + 50, 0);
 #endif
 
+          /* Figure out where (if at all) the
+             redisplay_end_trigger-hook should run.  */
+          if (MARKERP (current_buffer->redisplay_end_trigger))
+            e_t_h = marker_position (current_buffer->redisplay_end_trigger);
+          else if (INTEGERP (current_buffer->redisplay_end_trigger))
+            e_t_h = XINT (current_buffer->redisplay_end_trigger);
+          else
+            e_t_h = ZV;
+
+          /* If we've gone past the place to run a hook,
+             run the hook.  */
+          if (pos >= e_t_h && e_t_h != ZV)
+            {
+              call1 (Vrun_hooks, Qredisplay_end_trigger_hook);
+              current_buffer->redisplay_end_trigger = Qnil;
+              e_t_h = ZV;
+            }
+
+          /* Compute the next place we need to stop
+             and do something special; set PAUSE.  */
+
           pause = ZV;
 
           if (pos < next_boundary && next_boundary < pause)
@@ -2714,6 +2738,9 @@ display_text_line (w, start, vpos, hpos, taboffset)
           if (pos < next_face_change && next_face_change < pause)
             pause = next_face_change;
 
+          if (e_t_h < pause)
+            pause = e_t_h;
+
           /* Wouldn't you hate to read the next line to someone over
              the phone?  */
           if (pos < PT && PT < pause)
@@ -4202,6 +4229,9 @@ syms_of_xdisp ()
   staticpro (&Qwindow_scroll_functions);
   Qwindow_scroll_functions = intern ("window-scroll-functions");
 
+  staticpro (&Qredisplay_end_trigger_hook);
+  Qredisplay_end_trigger_hook = intern ("redisplay-end-trigger-hook");
+
   staticpro (&last_arrow_position);
   staticpro (&last_arrow_string);
   last_arrow_position = Qnil;