[Emacs-diffs] emacs-24 r116842: Fix bug #17047 with cursor motion when invisible text starts a line.

[Eli Zaretskii]

------------------------------------------------------------
revno: 116842
revision-id: address@hidden
parent: address@hidden
fixes bug: http://debbugs.gnu.org/17047
committer: Eli Zaretskii <address@hidden>
branch nick: emacs-24
timestamp: Sun 2014-03-23 17:57:25 +0200
message:
  Fix bug #17047 with cursor motion when invisible text starts a line.
  
   src/xdisp.c (redisplay_window): If all previous attempts to find the
   cursor row failed, try a few alternatives before falling back to
   the top-most row of the window.  Use row_containing_pos.
modified:
  src/ChangeLog                  changelog-20091113204419-o5vbwnq5f7feedwu-1438
  src/xdisp.c                    xdisp.c-20091113204419-o5vbwnq5f7feedwu-240

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2014-03-23 06:07:54 +0000
+++ b/src/ChangeLog     2014-03-23 15:57:25 +0000
@@ -1,3 +1,9 @@
+2014-03-23  Eli Zaretskii  <address@hidden>
+
+       * xdisp.c (redisplay_window): If all previous attempts to find the
+       cursor row failed, try a few alternatives before falling back to
+       the top-most row of the window.  (Bug#17047)
+
 2014-03-22  Daniel Colascione  <address@hidden>
 
        * process.c (conv_sockaddr_to_lisp): When extracting the string

=== modified file 'src/xdisp.c'
--- a/src/xdisp.c       2014-03-20 14:09:37 +0000
+++ b/src/xdisp.c       2014-03-23 15:57:25 +0000
@@ -16400,12 +16400,50 @@
   /* Consider the following case: Window starts at BEGV, there is
      invisible, intangible text at BEGV, so that display starts at
      some point START > BEGV.  It can happen that we are called with
-     PT somewhere between BEGV and START.  Try to handle that case.  */
+     PT somewhere between BEGV and START.  Try to handle that case,
+     and similar ones.  */
   if (w->cursor.vpos < 0)
     {
-      struct glyph_row *row = w->current_matrix->rows;
-      if (row->mode_line_p)
-       ++row;
+      /* First, try locating the proper glyph row for PT.  */
+      struct glyph_row *row =
+       row_containing_pos (w, PT, w->current_matrix->rows, NULL, 0);
+
+      /* Sometimes point is at the beginning of invisible text that is
+        before the 1st character displayed in the row.  In that case,
+        row_containing_pos fails to find the row, because no glyphs
+        with appropriate buffer positions are present in the row.
+        Therefore, we next try to find the row which shows the 1st
+        position after the invisible text.  */
+      if (!row)
+       {
+         Lisp_Object val =
+           get_char_property_and_overlay (make_number (PT), Qinvisible,
+                                          Qnil, NULL);
+
+         if (TEXT_PROP_MEANS_INVISIBLE (val))
+           {
+             ptrdiff_t alt_pos;
+             Lisp_Object invis_end =
+               Fnext_single_char_property_change (make_number (PT), Qinvisible,
+                                                  Qnil, Qnil);
+
+             if (NATNUMP (invis_end))
+               alt_pos = XFASTINT (invis_end);
+             else
+               alt_pos = ZV;
+             row = row_containing_pos (w, alt_pos, w->current_matrix->rows,
+                                       NULL, 0);
+           }
+       }
+      /* Finally, fall back on the first row of the window after the
+        header line (if any).  This is slightly better than not
+        displaying the cursor at all.  */
+      if (!row)
+       {
+         row = w->current_matrix->rows;
+         if (row->mode_line_p)
+           ++row;
+       }
       set_cursor_from_row (w, row, w->current_matrix, 0, 0, 0, 0);
     }