Fix bug #17905 with display of point in partially visible line at end of window.

 src/xdisp.c (redisplay_window): If redisplay of a window ends up
 with point in a partially visible line at end of the window, make
 sure the amended position of point actually has smaller Y
 coordinate; if not, give up and scroll the display.
 src/window.c (window_scroll_pixel_based): When point ends up at the
 last fully visible line, don't let move_it_to stop at the left
 edge of the line and dupe us into thinking point is inside the
 scroll margin.

diff --git a/src/ChangeLog b/src/ChangeLog
index 24343faa4072dbc29bee11c4c60f75f2c0567b1e..a88c6caacfd31655ffeef8174f00259cf9f1e301 100644 (file)
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,15 @@
 2014-07-04  Eli Zaretskii  <eliz@gnu.org>
 
+       * xdisp.c (redisplay_window): If redisplay of a window ends up
+       with point in a partially visible line at end of the window, make
+       sure the amended position of point actually has smaller Y
+       coordinate; if not, give up and scroll the display.  (Bug#17905)
+
+       * window.c (window_scroll_pixel_based): When point ends up at the
+       last fully visible line, don't let move_it_to stop at the left
+       edge of the line and dupe us into thinking point is inside the
+       scroll margin.
+
        * w32.c (network_interface_info): Make sure the argument is a
        Lisp string.
 

diff --git a/src/window.c b/src/window.c
index 8e8252d3b76534bcc88e5d7e50312ce0fe5dc9b6..5e9dd0ec718cc51011359d5270a724d3c83d1f53 100644 (file)
--- a/src/window.c
+++ b/src/window.c
@@ -5167,6 +5167,32 @@ window_scroll_pixel_based (Lisp_Object window, int n, bool whole, int noerror)
       charpos = IT_CHARPOS (it);
       bytepos = IT_BYTEPOS (it);
 
+      /* If PT is in the screen line at the last fully visible line,
+        move_it_to will stop at X = 0 in that line, because the
+        required Y coordinate is reached there.  See if we can get to
+        PT without descending lower in Y, and if we can, it means we
+        reached PT before the scroll margin.  */
+      if (charpos != PT)
+       {
+         struct it it2;
+         void *it_data;
+
+         it2 = it;
+         it_data = bidi_shelve_cache ();
+         move_it_to (&it, PT, -1, -1, -1, MOVE_TO_POS);
+         if (IT_CHARPOS (it) == PT && it.current_y == it2.current_y)
+           {
+             charpos = IT_CHARPOS (it);
+             bytepos = IT_BYTEPOS (it);
+             bidi_unshelve_cache (it_data, 1);
+           }
+         else
+           {
+             it = it2;
+             bidi_unshelve_cache (it_data, 0);
+           }
+       }
+
       /* See if point is on a partially visible line at the end.  */
       if (it.what == IT_EOB)
        partial_p = it.current_y + it.ascent + it.descent > it.last_visible_y;

diff --git a/src/xdisp.c b/src/xdisp.c
index 459edf4367fc7ef42003afab9aeef6a25a36863c..fe5d0f579d827496742b395f8bde1b6ef9cc216d 100644 (file)
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -16106,6 +16106,18 @@ redisplay_window (Lisp_Object window, bool just_this_one_p)
          /* Point does appear, but on a line partly visible at end of window.
             Move it back to a fully-visible line.  */
          new_vpos = window_box_height (w);
+         /* But if window_box_height suggests a Y coordinate that is
+            not less than we already have, that line will clearly not
+            be fully visible, so give up and scroll the display.
+            This can happen when the default face uses a font whose
+            dimensions are different from the frame's default
+            font.  */
+         if (new_vpos >= w->cursor.y)
+           {
+             w->cursor.vpos = -1;
+             clear_glyph_matrix (w->desired_matrix);
+             goto try_to_scroll;
+           }
        }
       else if (w->cursor.vpos >= 0)
        {