Implement cursor on the left fringe for R2L lines.

 xdisp.c (IT_OVERFLOW_NEWLINE_INTO_FRINGE): For R2L lines,
 consider the left fringe, not the right one.
 (set_cursor_from_row): Don't reverse pos_before and pos_after for
 reversed glyph rows.  Set cursor.x to negative value when the
 cursor might be on the left fringe.
 (extend_face_to_end_of_line): Append the stretch glyph only if its
 width is positive.
 (notice_overwritten_cursor, draw_phys_cursor_glyph)
 (erase_phys_cursor): For reversed cursor_row, support cursor on
 the left fringe.
 w32term.c (w32_draw_window_cursor): For reversed glyph rows,
 draw cursor on the left fringe.
 xterm.c (x_draw_window_cursor): For reversed glyph rows, draw
 cursor on the left fringe.
 fringe.c (draw_fringe_bitmap): For reversed glyph rows, allow
 cursor on the left fringe.
 dispnew.c (update_text_area): Handle reversed desired rows when
 the cursor is on the left fringe.
 (set_window_cursor_after_update): Limit cursor's hpos by -1 from
 below, not by 0, for when the cursor is on the left fringe.

6 files changed, 96 insertions, 54 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 268a245caf3..e6faa0a4c9e 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -2,6 +2,31 @@
 
         Implement display of R2L paragraphs in GUI sessions.
 
+        * xdisp.c (IT_OVERFLOW_NEWLINE_INTO_FRINGE): For R2L lines,
+        consider the left fringe, not the right one.
+        (set_cursor_from_row): Don't reverse pos_before and pos_after for
+        reversed glyph rows.  Set cursor.x to negative value when the
+        cursor might be on the left fringe.
+        (extend_face_to_end_of_line): Append the stretch glyph only if its
+        width is positive.
+        (notice_overwritten_cursor, draw_phys_cursor_glyph)
+        (erase_phys_cursor): For reversed cursor_row, support cursor on
+        the left fringe.
+
+        * w32term.c (w32_draw_window_cursor): For reversed glyph rows,
+        draw cursor on the left fringe.
+
+        * xterm.c (x_draw_window_cursor): For reversed glyph rows, draw
+        cursor on the left fringe.
+
+        * fringe.c (draw_fringe_bitmap): For reversed glyph rows, allow
+        cursor on the left fringe.
+
+        * dispnew.c (update_text_area): Handle reversed desired rows when
+        the cursor is on the left fringe.
+        (set_window_cursor_after_update): Limit cursor's hpos by -1 from
+        below, not by 0, for when the cursor is on the left fringe.
+
         * xdisp.c [HAVE_WINDOW_SYSTEM]: Add prototype for
         append_stretch_glyph.
         (set_cursor_from_row) <cursor_x>: Remove unused variable.  Fix
diff --git a/src/dispnew.c b/src/dispnew.c
index 2be00c9c3b0..7ab2bf35811 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -4251,7 +4251,9 @@ update_text_area (w, vpos)
              doesn't work with lbearing/rbearing), so we must do it
              this way.  */
           if (vpos == w->phys_cursor.vpos
-              && w->phys_cursor.hpos >= desired_row->used[TEXT_AREA])
+              && (desired_row->reversed_p
+                  ? (w->phys_cursor.hpos < 0)
+                  : (w->phys_cursor.hpos >= desired_row->used[TEXT_AREA])))
             {
               w->phys_cursor_on_p = 0;
               x = -1;
@@ -4415,7 +4417,7 @@ set_window_cursor_after_update (w)
     }
 
   /* Window cursor can be out of sync for horizontally split windows.  */
-  hpos = max (0, hpos);
+  hpos = max (-1, hpos); /* -1 is for when cursor is on the left fringe */
   hpos = min (w->current_matrix->matrix_w - 1, hpos);
   vpos = max (0, vpos);
   vpos = min (w->current_matrix->nrows - 1, vpos);
diff --git a/src/fringe.c b/src/fringe.c
index 952e95a5517..335dde03c8a 100644
--- a/src/fringe.c
+++ b/src/fringe.c
@@ -825,7 +825,7 @@ draw_fringe_bitmap (w, row, left_p)
 {
   int overlay = 0;
 
-  if (!left_p && row->cursor_in_fringe_p)
+  if (left_p == row->reversed_p && row->cursor_in_fringe_p)
     {
       Lisp_Object cursor = Qnil;
 
@@ -857,7 +857,7 @@ draw_fringe_bitmap (w, row, left_p)
           int bm = get_logical_cursor_bitmap (w, cursor);
           if (bm != NO_FRINGE_BITMAP)
             {
-              draw_fringe_bitmap_1 (w, row, 0, 2, bm);
+              draw_fringe_bitmap_1 (w, row, left_p, 2, bm);
               overlay = EQ (cursor, Qbox) ? 3 : 1;
             }
         }
diff --git a/src/w32term.c b/src/w32term.c
index 7222e26efd2..0b71b7e02b7 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -5136,10 +5136,12 @@ w32_draw_window_cursor (w, glyph_row, x, y, cursor_type, cursor_width, on_p, act
         }
 
       if (glyph_row->exact_window_width_line_p
-          && w->phys_cursor.hpos >= glyph_row->used[TEXT_AREA])
+          && (glyph_row->reversed_p
+              ? (w->phys_cursor.hpos < 0)
+              : (w->phys_cursor.hpos >= glyph_row->used[TEXT_AREA])))
         {
           glyph_row->cursor_in_fringe_p = 1;
-          draw_fringe_bitmap (w, glyph_row, 0);
+          draw_fringe_bitmap (w, glyph_row, glyph_row->reversed_p);
           return;
         }
 
diff --git a/src/xdisp.c b/src/xdisp.c
index f93ed533c28..1320b8a7380 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -326,12 +326,14 @@ extern Lisp_Object Voverflow_newline_into_fringe;
 /* Test if overflow newline into fringe.  Called with iterator IT
    at or past right window margin, and with IT->current_x set.  */
 
-#define IT_OVERFLOW_NEWLINE_INTO_FRINGE(it)     \
-  (!NILP (Voverflow_newline_into_fringe)        \
-   && FRAME_WINDOW_P (it->f)                    \
-   && WINDOW_RIGHT_FRINGE_WIDTH (it->w) > 0     \
-   && it->current_x == it->last_visible_x       \
-   && it->line_wrap != WORD_WRAP)
+#define IT_OVERFLOW_NEWLINE_INTO_FRINGE(IT)             \
+  (!NILP (Voverflow_newline_into_fringe)                \
+   && FRAME_WINDOW_P ((IT)->f)                          \
+   && ((IT)->bidi_it.paragraph_dir == R2L               \
+       ? (WINDOW_LEFT_FRINGE_WIDTH ((IT)->w) > 0)       \
+       : (WINDOW_RIGHT_FRINGE_WIDTH ((IT)->w) > 0))     \
+   && (IT)->current_x == (IT)->last_visible_x           \
+   && (IT)->line_wrap != WORD_WRAP)
 
 #else /* !HAVE_WINDOW_SYSTEM */
 #define IT_OVERFLOW_NEWLINE_INTO_FRINGE(it) 0
@@ -12600,9 +12602,6 @@ set_cursor_from_row (w, row, matrix, delta, delta_bytes, dy, dvpos)
              to front, so swap the edge pointers.  */
           glyphs_end = end = glyph - 1;
           glyph += row->used[TEXT_AREA] - 1;
-          /* Reverse the known positions in the row.  */
-          last_pos = pos_after = MATRIX_ROW_START_CHARPOS (row) + delta;
-          pos_before = MATRIX_ROW_END_CHARPOS (row) + delta;
 
           while (glyph > end + 1
                  && INTEGERP (glyph->object)
@@ -12768,7 +12767,10 @@ set_cursor_from_row (w, row, matrix, delta, delta_bytes, dy, dvpos)
           }
         --glyph;
         if (glyph == glyphs_end) /* don't dereference outside TEXT_AREA */
-          break;
+          {
+            x--;                /* can't use any pixel_width */
+            break;
+          }
         x -= glyph->pixel_width;
     }
 
@@ -16851,20 +16853,23 @@ extend_face_to_end_of_line (it)
                           - WINDOW_BOX_LEFT_EDGE_X(it->w)
                           - WINDOW_TOTAL_FRINGE_WIDTH(it->w)
                           - row_width;
-          stretch_ascent =
-            (((it->ascent + it->descent)
-              * FONT_BASE (font)) / FONT_HEIGHT (font));
-          saved_pos = it->position;
-          saved_avoid_cursor = it->avoid_cursor_p;
-          saved_face_id = it->face_id;
-          bzero (&it->position, sizeof it->position);
-          it->avoid_cursor_p = 1;
-          it->face_id = face->id;
-          append_stretch_glyph (it, make_number (0), stretch_width,
-                                it->ascent + it->descent, stretch_ascent);
-          it->position = saved_pos;
-          it->avoid_cursor_p = saved_avoid_cursor;
-          it->face_id = saved_face_id;
+          if (stretch_width > 0)
+            {
+              stretch_ascent =
+                (((it->ascent + it->descent)
+                  * FONT_BASE (font)) / FONT_HEIGHT (font));
+              saved_pos = it->position;
+              saved_avoid_cursor = it->avoid_cursor_p;
+              saved_face_id = it->face_id;
+              bzero (&it->position, sizeof it->position);
+              it->avoid_cursor_p = 1;
+              it->face_id = face->id;
+              append_stretch_glyph (it, make_number (0), stretch_width,
+                                    it->ascent + it->descent, stretch_ascent);
+              it->position = saved_pos;
+              it->avoid_cursor_p = saved_avoid_cursor;
+              it->face_id = saved_face_id;
+            }
         }
 #endif  /* HAVE_WINDOW_SYSTEM */
     }
@@ -23221,7 +23226,7 @@ notice_overwritten_cursor (w, area, x0, x1, y0, y1)
   if (row->cursor_in_fringe_p)
     {
       row->cursor_in_fringe_p = 0;
-      draw_fringe_bitmap (w, row, 0);
+      draw_fringe_bitmap (w, row, row->reversed_p);
       w->phys_cursor_on_p = 0;
       return;
     }
@@ -23322,7 +23327,9 @@ draw_phys_cursor_glyph (w, row, hl)
   /* If cursor hpos is out of bounds, don't draw garbage.  This can
      happen in mini-buffer windows when switching between echo area
      glyphs and mini-buffer.  */
-  if (w->phys_cursor.hpos < row->used[TEXT_AREA])
+  if ((row->reversed_p
+       ? (w->phys_cursor.hpos >= 0)
+       : (w->phys_cursor.hpos < row->used[TEXT_AREA])))
     {
       int on_p = w->phys_cursor_on_p;
       int x1;
@@ -23402,7 +23409,7 @@ erase_phys_cursor (w)
   if (cursor_row->cursor_in_fringe_p)
     {
       cursor_row->cursor_in_fringe_p = 0;
-      draw_fringe_bitmap (w, cursor_row, 0);
+      draw_fringe_bitmap (w, cursor_row, cursor_row->reversed_p);
       goto mark_cursor_off;
     }
 
@@ -23411,7 +23418,9 @@ erase_phys_cursor (w)
      should have cleared the cursor.  Note that we wouldn't be
      able to erase the cursor in this case because we don't have a
      cursor glyph at hand.  */
-  if (w->phys_cursor.hpos >= cursor_row->used[TEXT_AREA])
+  if ((cursor_row->reversed_p
+       ? (w->phys_cursor.hpos < 0)
+       : (w->phys_cursor.hpos >= cursor_row->used[TEXT_AREA])))
     goto mark_cursor_off;
 
   /* If the cursor is in the mouse face area, redisplay that when
diff --git a/src/xterm.c b/src/xterm.c
index 29ed5bb865c..712d4aaa162 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -7492,36 +7492,40 @@ x_draw_window_cursor (w, glyph_row, x, y, cursor_type, cursor_width, on_p, activ
       w->phys_cursor_on_p = 1;
 
       if (glyph_row->exact_window_width_line_p
-          && w->phys_cursor.hpos >= glyph_row->used[TEXT_AREA])
+          && (glyph_row->reversed_p
+              ? (w->phys_cursor.hpos < 0)
+              : (w->phys_cursor.hpos >= glyph_row->used[TEXT_AREA])))
         {
           glyph_row->cursor_in_fringe_p = 1;
-          draw_fringe_bitmap (w, glyph_row, 0);
+          draw_fringe_bitmap (w, glyph_row, glyph_row->reversed_p);
         }
       else
-      switch (cursor_type)
         {
-        case HOLLOW_BOX_CURSOR:
-          x_draw_hollow_cursor (w, glyph_row);
-          break;
+          switch (cursor_type)
+            {
+            case HOLLOW_BOX_CURSOR:
+              x_draw_hollow_cursor (w, glyph_row);
+              break;
 
-        case FILLED_BOX_CURSOR:
-          draw_phys_cursor_glyph (w, glyph_row, DRAW_CURSOR);
-          break;
+            case FILLED_BOX_CURSOR:
+              draw_phys_cursor_glyph (w, glyph_row, DRAW_CURSOR);
+              break;
 
-        case BAR_CURSOR:
-          x_draw_bar_cursor (w, glyph_row, cursor_width, BAR_CURSOR);
-          break;
+            case BAR_CURSOR:
+              x_draw_bar_cursor (w, glyph_row, cursor_width, BAR_CURSOR);
+              break;
 
-        case HBAR_CURSOR:
-          x_draw_bar_cursor (w, glyph_row, cursor_width, HBAR_CURSOR);
-          break;
+            case HBAR_CURSOR:
+              x_draw_bar_cursor (w, glyph_row, cursor_width, HBAR_CURSOR);
+              break;
 
-        case NO_CURSOR:
-          w->phys_cursor_width = 0;
-          break;
+            case NO_CURSOR:
+              w->phys_cursor_width = 0;
+              break;
 
-        default:
-          abort ();
+            default:
+              abort ();
+            }
         }
 
 #ifdef HAVE_X_I18N