Support bidi-reordered text in mouse-highlighted mode- and header-lines.

Note: Not tested with actually bidi-reordered strings.

 xdisp.c (note_mode_line_or_margin_highlight): Support
 bidi-reordered strings and R2L glyph rows.  Fix more comments.

2 files changed, 79 insertions, 47 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 0f7d39e4d8a..5f6fed12620 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,10 @@
 2010-10-16  Eli Zaretskii  <eliz@gnu.org>
 
+        * xdisp.c (note_mode_line_or_margin_highlight): Support
+        bidi-reordered strings and R2L glyph rows.  Fix more comments.
+
+2010-10-16  Eli Zaretskii  <eliz@gnu.org>
+
         * xdisp.c (rows_from_pos_range, mouse_face_from_buffer_pos)
         (note_mode_line_or_margin_highlight): Fix comments.
 
diff --git a/src/xdisp.c b/src/xdisp.c
index 4a7cc275c47..41be01c407f 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -24602,6 +24602,8 @@ note_mode_line_or_margin_highlight (Lisp_Object window, int x, int y,
       int x0;
       struct glyph *end;
 
+      /* Kludge alert: mode_line_string takes X/Y in pixels, but
+         returns them in row/column units!  */
       string = mode_line_string (w, area, &x, &y, &charpos,
                                  &object, &dx, &dy, &width, &height);
 
@@ -24627,6 +24629,8 @@ note_mode_line_or_margin_highlight (Lisp_Object window, int x, int y,
   else
     {
       x -= WINDOW_LEFT_SCROLL_BAR_AREA_WIDTH (w);
+      /* Kludge alert: marginal_area_string takes X/Y in pixels, but
+         returns them in row/column units!  */
       string = marginal_area_string (w, area, &x, &y, &charpos,
                                      &object, &dx, &dy, &width, &height);
     }
@@ -24715,21 +24719,26 @@ note_mode_line_or_margin_highlight (Lisp_Object window, int x, int y,
           int gpos;
           int gseq_length;
           int total_pixel_width;
-          EMACS_INT ignore;
+          EMACS_INT begpos, endpos, ignore;
 
           int vpos, hpos;
 
           b = Fprevious_single_property_change (make_number (charpos + 1),
                                                 Qmouse_face, string, Qnil);
           if (NILP (b))
-            b = make_number (0);
+            begpos = 0;
+          else
+            begpos = XINT (b);
 
           e = Fnext_single_property_change (pos, Qmouse_face, string, Qnil);
           if (NILP (e))
-            e = make_number (SCHARS (string));
+            endpos = SCHARS (string);
+          else
+            endpos = XINT (e);
 
           /* Calculate the glyph position GPOS of GLYPH in the
-             displayed string.
+             displayed string, relative to the beginning of the
+             highlighted part of the string.
 
              Note: GPOS is different from CHARPOS.  CHARPOS is the
              position of GLYPH in the internal string object.  A mode
@@ -24737,71 +24746,89 @@ note_mode_line_or_margin_highlight (Lisp_Object window, int x, int y,
              a flattened string by the Emacs Lisp interpreter.  The
              internal string is an element of those structures.  The
              displayed string is the flattened string.  */
-          gpos = 0;
-          if (glyph > row_start_glyph)
-            {
-              tmp_glyph = glyph - 1;
-              while (tmp_glyph >= row_start_glyph
-                     && tmp_glyph->charpos >= XINT (b)
-                     && EQ (tmp_glyph->object, glyph->object))
-                {
-                  tmp_glyph--;
-                  gpos++;
-                }
-            }
-
-          /* Calculate the glyph sequence length GSEQ_LENGTH of the
-             displayed string to which GLYPH belongs.  Note:
-             GSEQ_LENGTH is different from SCHARS (STRING), because
-             the latter returns the length of the internal string.  */
-          for (tmp_glyph = glyph, gseq_length = gpos;
-               tmp_glyph->charpos < XINT (e);
-               tmp_glyph++, gseq_length++)
-              {
-                if (!EQ (tmp_glyph->object, glyph->object))
-                  break;
-              }
+          tmp_glyph = row_start_glyph;
+          while (tmp_glyph < glyph
+                 && (!(EQ (tmp_glyph->object, glyph->object)
+                       && begpos <= tmp_glyph->charpos
+                       && tmp_glyph->charpos < endpos)))
+            tmp_glyph++;
+          gpos = glyph - tmp_glyph;
+
+          /* Calculate the length GSEQ_LENGTH of the glyph sequence of
+             the highlighted part of the displayed string to which
+             GLYPH belongs.  Note: GSEQ_LENGTH is different from
+             SCHARS (STRING), because the latter returns the length of
+             the internal string.  */
+          for (tmp_glyph = row->glyphs[TEXT_AREA] + row->used[TEXT_AREA] - 1;
+               tmp_glyph > glyph
+                 && (!(EQ (tmp_glyph->object, glyph->object)
+                       && begpos <= tmp_glyph->charpos
+                       && tmp_glyph->charpos < endpos));
+               tmp_glyph--)
+            ;
+          gseq_length = gpos + (tmp_glyph - glyph) + 1;
 
+          /* Calculate the total pixel width of all the glyphs between
+             the beginning of the highlighted area and GLYPH.  */
           total_pixel_width = 0;
           for (tmp_glyph = glyph - gpos; tmp_glyph != glyph; tmp_glyph++)
             total_pixel_width += tmp_glyph->pixel_width;
 
-          /* Pre calculation of re-rendering position.  */
+          /* Pre calculation of re-rendering position.  Note: X is in
+             column units here, after the call to mode_line_string or
+             marginal_area_string.  */
           hpos = x - gpos;
           vpos = (area == ON_MODE_LINE
                   ? (w->current_matrix)->nrows - 1
                   : 0);
 
-          /* If the re-rendering position is included in the last
-             re-rendering area, we should do nothing.  */
+          /* If GLYPH's position is included in the region that is
+             already drawn in mouse face, we have nothing to do.  */
           if ( EQ (window, dpyinfo->mouse_face_window)
-               && dpyinfo->mouse_face_beg_col <= hpos
-               && hpos < dpyinfo->mouse_face_end_col
+               && (!row->reversed_p
+                   ? (dpyinfo->mouse_face_beg_col <= hpos
+                      && hpos < dpyinfo->mouse_face_end_col)
+                   /* In R2L rows we swap BEG and END, see below.  */
+                   : (dpyinfo->mouse_face_end_col <= hpos
+                      && hpos < dpyinfo->mouse_face_beg_col))
                && dpyinfo->mouse_face_beg_row == vpos )
             return;
 
           if (clear_mouse_face (dpyinfo))
             cursor = No_Cursor;
 
-          dpyinfo->mouse_face_beg_col = hpos;
-          dpyinfo->mouse_face_beg_row = vpos;
-
-          dpyinfo->mouse_face_beg_x   = original_x_pixel - (total_pixel_width + dx);
-          dpyinfo->mouse_face_beg_y   = 0;
-
-          dpyinfo->mouse_face_end_col = hpos + gseq_length;
-          dpyinfo->mouse_face_end_row = dpyinfo->mouse_face_beg_row;
-
-          dpyinfo->mouse_face_end_x   = 0;
-          dpyinfo->mouse_face_end_y   = 0;
+          if (!row->reversed_p)
+            {
+              dpyinfo->mouse_face_beg_col = hpos;
+              dpyinfo->mouse_face_beg_x   = original_x_pixel
+                                            - (total_pixel_width + dx);
+              dpyinfo->mouse_face_end_col = hpos + gseq_length;
+              dpyinfo->mouse_face_end_x   = 0;
+            }
+          else
+            {
+              /* In R2L rows, show_mouse_face expects BEG and END
+                 coordinates to be swapped.  */
+              dpyinfo->mouse_face_end_col = hpos;
+              dpyinfo->mouse_face_end_x   = original_x_pixel
+                                            - (total_pixel_width + dx);
+              dpyinfo->mouse_face_beg_col = hpos + gseq_length;
+              dpyinfo->mouse_face_beg_x   = 0;
+            }
 
+          dpyinfo->mouse_face_beg_row  = vpos;
+          dpyinfo->mouse_face_end_row  = dpyinfo->mouse_face_beg_row;
+          dpyinfo->mouse_face_beg_y    = 0;
+          dpyinfo->mouse_face_end_y    = 0;
           dpyinfo->mouse_face_past_end = 0;
-          dpyinfo->mouse_face_window  = window;
+          dpyinfo->mouse_face_window   = window;
 
           dpyinfo->mouse_face_face_id = face_at_string_position (w, string,
                                                                  charpos,
-                                                                 0, 0, 0, &ignore,
-                                                                 glyph->face_id, 1);
+                                                                 0, 0, 0,
+                                                                 &ignore,
+                                                                 glyph->face_id,
+                                                                 1);
           show_mouse_face (dpyinfo, DRAW_MOUSE_FACE);
 
           if (NILP (pointer))