Take account of periodic fringe bitmap's dependency on y-position in redrawing.

* dispextern.h (struct glyph_row): New member fringe_bitmap_periodic_p.

* dispnew.c (shift_glyph_matrix, scrolling_window): Mark scrolled row
for fringe update if it has periodic bitmap.
(row_equal_p): Also compare left_fringe_offset,	right_fringe_offset,
and fringe_bitmap_periodic_p.

* fringe.c (get_fringe_bitmap_data): New function.
(draw_fringe_bitmap_1, update_window_fringes): Use it.
(update_window_fringes): Record periodicity of fringe bitmap in glyph
row.  Mark glyph row for fringe update if periodicity changed.

* xdisp.c (try_window_reusing_current_matrix): Don't mark scrolled row
for fringe update unless it has periodic bitmap.

5 files changed, 56 insertions, 23 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index cdc8ed8999c..3f53eabb5d1 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,20 @@
+2011-05-25  YAMAMOTO Mitsuharu  <mituharu@math.s.chiba-u.ac.jp>
+
+	* dispextern.h (struct glyph_row): New member fringe_bitmap_periodic_p.
+
+	* dispnew.c (shift_glyph_matrix, scrolling_window): Mark scrolled row
+	for fringe update if it has periodic bitmap.
+	(row_equal_p): Also compare left_fringe_offset,	right_fringe_offset,
+	and fringe_bitmap_periodic_p.
+
+	* fringe.c (get_fringe_bitmap_data): New function.
+	(draw_fringe_bitmap_1, update_window_fringes): Use it.
+	(update_window_fringes): Record periodicity of fringe bitmap in glyph
+	row.  Mark glyph row for fringe update if periodicity changed.
+
+	* xdisp.c (try_window_reusing_current_matrix): Don't mark scrolled row
+	for fringe update unless it has periodic bitmap.
+
 2011-05-25  Kenichi Handa  <handa@m17n.org>
 
 	* xdisp.c (get_next_display_element): Set correct it->face_id for
diff --git a/src/dispextern.h b/src/dispextern.h
index 8ae5e23fa97..5f9f7824361 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -786,6 +786,10 @@ struct glyph_row
   /* Vertical offset of the right fringe bitmap.  */
   signed right_fringe_offset : FRINGE_HEIGHT_BITS;
 
+  /* 1 means that at least one of the left and right fringe bitmaps is
+     periodic and thus depends on the y-position of the row.  */
+  unsigned fringe_bitmap_periodic_p : 1;
+
   /* 1 means that we must draw the bitmaps of this row.  */
   unsigned redraw_fringe_bitmaps_p : 1;
 
diff --git a/src/dispnew.c b/src/dispnew.c
index 5fd29e2d591..4c460abd636 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -1012,6 +1012,8 @@ shift_glyph_matrix (w, matrix, start, end, dy)
 	row->visible_height -= min_y - row->y;
       if (row->y + row->height > max_y)
 	row->visible_height -= row->y + row->height - max_y;
+      if (row->fringe_bitmap_periodic_p)
+	row->redraw_fringe_bitmaps_p = 1;
     }
 }
 
@@ -1533,8 +1535,11 @@ row_equal_p (w, a, b, mouse_face_p)
 	  || a->cursor_in_fringe_p != b->cursor_in_fringe_p
 	  || a->left_fringe_bitmap != b->left_fringe_bitmap
 	  || a->left_fringe_face_id != b->left_fringe_face_id
+	  || a->left_fringe_offset != b->left_fringe_offset
 	  || a->right_fringe_bitmap != b->right_fringe_bitmap
 	  || a->right_fringe_face_id != b->right_fringe_face_id
+	  || a->right_fringe_offset != b->right_fringe_offset
+	  || a->fringe_bitmap_periodic_p != b->fringe_bitmap_periodic_p
 	  || a->overlay_arrow_bitmap != b->overlay_arrow_bitmap
 	  || a->exact_window_width_line_p != b->exact_window_width_line_p
 	  || a->overlapped_p != b->overlapped_p
@@ -5226,13 +5231,7 @@ scrolling_window (w, header_line_p)
 	    to = MATRIX_ROW (current_matrix, r->desired_vpos + j);
 	    from = MATRIX_ROW (desired_matrix, r->desired_vpos + j);
 	    to_overlapped_p = to->overlapped_p;
-	    if (!from->mode_line_p && !w->pseudo_window_p
-		&& (to->left_fringe_bitmap != from->left_fringe_bitmap
-		    || to->right_fringe_bitmap != from->right_fringe_bitmap
-		    || to->left_fringe_face_id != from->left_fringe_face_id
-		    || to->right_fringe_face_id != from->right_fringe_face_id
-		    || to->overlay_arrow_bitmap != from->overlay_arrow_bitmap))
-	      from->redraw_fringe_bitmaps_p = 1;
+	    from->redraw_fringe_bitmaps_p = from->fringe_bitmap_periodic_p;
 	    assign_row (to, from);
 	    to->enabled_p = 1, from->enabled_p = 0;
 	    to->overlapped_p = to_overlapped_p;
diff --git a/src/fringe.c b/src/fringe.c
index 880fe2c6e42..e160353914e 100644
--- a/src/fringe.c
+++ b/src/fringe.c
@@ -541,6 +541,20 @@ get_fringe_bitmap_name (bn)
   return num;
 }
 
+/* Get fringe bitmap data for bitmap number BN.  */
+
+static struct fringe_bitmap *
+get_fringe_bitmap_data (int bn)
+{
+  struct fringe_bitmap *fb;
+
+  fb = fringe_bitmaps[bn];
+  if (fb == NULL)
+    fb = &standard_bitmaps[bn < MAX_STANDARD_FRINGE_BITMAPS
+			   ? bn : UNDEF_FRINGE_BITMAP];
+
+  return fb;
+}
 
 /* Draw the bitmap WHICH in one of the left or right fringes of
    window W.  ROW is the glyph row for which to display the bitmap; it
@@ -593,10 +607,7 @@ draw_fringe_bitmap_1 (w, row, left_p, overlay, which)
 	face_id = FRINGE_FACE_ID;
     }
 
-  fb = fringe_bitmaps[which];
-  if (fb == NULL)
-    fb = &standard_bitmaps[which < MAX_STANDARD_FRINGE_BITMAPS
-			   ? which : UNDEF_FRINGE_BITMAP];
+  fb = get_fringe_bitmap_data (which);
 
   period = fb->period;
 
@@ -1075,12 +1086,8 @@ update_window_fringes (w, keep_current_p)
 
       if (bn != NO_FRINGE_BITMAP)
 	{
-	  struct fringe_bitmap *fb;
+	  struct fringe_bitmap *fb = get_fringe_bitmap_data (bn);
 
-	  fb = fringe_bitmaps[bn];
-	  if (fb == NULL)
-	    fb = &standard_bitmaps[bn < MAX_STANDARD_FRINGE_BITMAPS
-				   ? bn : UNDEF_FRINGE_BITMAP];
 	  if (fb->align == ALIGN_BITMAP_TOP && fb->period == 0)
 	    {
 	      struct glyph_row *row1;
@@ -1134,12 +1141,8 @@ update_window_fringes (w, keep_current_p)
 
       if (bn != NO_FRINGE_BITMAP)
 	{
-	  struct fringe_bitmap *fb;
+	  struct fringe_bitmap *fb = get_fringe_bitmap_data (bn);
 
-	  fb = fringe_bitmaps[bn];
-	  if (fb == NULL)
-	    fb = &standard_bitmaps[bn < MAX_STANDARD_FRINGE_BITMAPS
-				   ? bn : UNDEF_FRINGE_BITMAP];
 	  if (fb->align == ALIGN_BITMAP_BOTTOM && fb->period == 0)
 	    {
 	      struct glyph_row *row1;
@@ -1175,6 +1178,7 @@ update_window_fringes (w, keep_current_p)
       int left, right;
       unsigned left_face_id, right_face_id;
       int left_offset, right_offset;
+      int periodic_p;
 
       row = w->desired_matrix->rows + rn;
       cur = w->current_matrix->rows + rn;
@@ -1183,6 +1187,7 @@ update_window_fringes (w, keep_current_p)
 
       left_face_id = right_face_id = DEFAULT_FACE_ID;
       left_offset = right_offset = 0;
+      periodic_p = 0;
 
       /* Decide which bitmap to draw in the left fringe.  */
       if (WINDOW_LEFT_FRINGE_WIDTH (w) == 0)
@@ -1270,6 +1275,9 @@ update_window_fringes (w, keep_current_p)
       else
 	right = NO_FRINGE_BITMAP;
 
+      periodic_p = (get_fringe_bitmap_data (left)->period != 0
+		    || get_fringe_bitmap_data (right)->period != 0);
+
       if (row->y != cur->y
 	  || row->visible_height != cur->visible_height
 	  || row->ends_at_zv_p != cur->ends_at_zv_p
@@ -1279,6 +1287,7 @@ update_window_fringes (w, keep_current_p)
 	  || right_face_id != cur->right_fringe_face_id
 	  || left_offset != cur->left_fringe_offset
 	  || right_offset != cur->right_fringe_offset
+	  || periodic_p != cur->fringe_bitmap_periodic_p
 	  || cur->redraw_fringe_bitmaps_p)
 	{
 	  redraw_p = row->redraw_fringe_bitmaps_p = 1;
@@ -1291,6 +1300,7 @@ update_window_fringes (w, keep_current_p)
 	      cur->right_fringe_face_id = right_face_id;
 	      cur->left_fringe_offset = left_offset;
 	      cur->right_fringe_offset = right_offset;
+	      cur->fringe_bitmap_periodic_p = periodic_p;
 	    }
 	}
 
@@ -1309,6 +1319,7 @@ update_window_fringes (w, keep_current_p)
       row->right_fringe_face_id = right_face_id;
       row->left_fringe_offset = left_offset;
       row->right_fringe_offset = right_offset;
+      row->fringe_bitmap_periodic_p = periodic_p;
     }
 
   return redraw_p && !keep_current_p;
diff --git a/src/xdisp.c b/src/xdisp.c
index 0f21c82e1f1..1f42e427428 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -14255,7 +14255,8 @@ try_window_reusing_current_matrix (w)
 		row->visible_height -= min_y - row->y;
 	      if (row->y + row->height > max_y)
 		row->visible_height -= row->y + row->height - max_y;
-	      row->redraw_fringe_bitmaps_p = 1;
+	      if (row->fringe_bitmap_periodic_p)
+		row->redraw_fringe_bitmaps_p = 1;
 
 	      it.current_y += row->height;
 
@@ -14417,7 +14418,8 @@ try_window_reusing_current_matrix (w)
 	    row->visible_height -= min_y - row->y;
 	  if (row->y + row->height > max_y)
 	    row->visible_height -= row->y + row->height - max_y;
-	  row->redraw_fringe_bitmaps_p = 1;
+	  if (row->fringe_bitmap_periodic_p)
+	    row->redraw_fringe_bitmaps_p = 1;
 	}
 
       /* Scroll the current matrix.  */