Re: Display problems with 'before-string in overlay

[Lennart Borgman (gmail)]

Kim F. Storm wrote:
> "Lennart Borgman (gmail)" <address@hidden> writes:
>
> > Just another note if someone else is trying this. Having coming back
> > to this several times today I am starting to believe that the way to
> > fix this is to change cursor_row_p. This was the original way that Kim
> > tried to solve it. Maybe Kim's solution with an added test of if the
> > "string" has the 'display property will solve the problem for now.
> >
> > I am unable to test this now, since I do not understand how to check
> > for the 'display property in cursor_row_p. If someone can tell that I
> > will test.
>
> That is _not_ easy.  
>
> You have to record that during redisplay (by display_line in the glyph
> row) if you need that information later.


Here is a version that I believe works. It just does local changes to 
cursor_row_p. I seems to me that is sufficient. I have not seen any 
problems with the display of 'display property parts, only with cursor 
positioning.

If this way works (my test works) then as I said before this seems 
rather safe as far as the return value from cursor_row_p is concerned.

However I think the actual code I added in cursor_row_p must be checked 
carefully and perhaps rewritten. I have tried to use the ideas from 
set_cursor_from_row, but I may easily have misunderstood things. I am 
not good at C and the code in xdisp.c is complicated.

Here is the patch:


Index: xdisp.c
===================================================================
RCS file: /sources/emacs/emacs/src/xdisp.c,v
retrieving revision 1.1146
diff -c -r1.1146 xdisp.c
*** xdisp.c     10 Apr 2007 15:57:25 -0000      1.1146
--- xdisp.c     15 Apr 2007 14:31:07 -0000
***************
*** 15858,15865 ****
         string if the string starts in this row.
         If the row is continued it doesn't end in a newline.  */
        if (CHARPOS (row->end.string_pos) >= 0)
!       cursor_row_p = (row->continued_p
!                       || PT >= MATRIX_ROW_START_CHARPOS (row));
        else if (MATRIX_ROW_ENDS_IN_MIDDLE_OF_CHAR_P (row))
        {
          /* If the row ends in middle of a real character,
--- 15858,15880 ----
         string if the string starts in this row.
         If the row is continued it doesn't end in a newline.  */
        if (CHARPOS (row->end.string_pos) >= 0)
!         {
!           /* Check for 'display property: */
!           int end = row->end.pos.charpos;
!           struct glyph *text_glyphs = row->glyphs[TEXT_AREA];
!           struct glyph *end_glyph = text_glyphs + row->used[TEXT_AREA];
!           struct glyph *glyph = end_glyph;
!           int q2 = -1;
!           while (-1 == q2 && glyph > text_glyphs) {
!             int gend2 = -1;
!             if (STRINGP (glyph->object))
!               gend2 = string_buffer_position(w, glyph->object, end);
!             if (gend2 > 0)
!               q2 = Fget_char_property (make_number (gend2), Qdisplay, 
Qnil);
!             --glyph;
!           }
!           cursor_row_p = (row->continued_p || (q2 != -1) );
!         }
        else if (MATRIX_ROW_ENDS_IN_MIDDLE_OF_CHAR_P (row))
        {
          /* If the row ends in middle of a real character,