Merge from trunk.

1 files changed, 71 insertions, 13 deletions

diff --git a/src/dispnew.c b/src/dispnew.c
index 88f7541407..e53e3fdf80 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -431,7 +431,7 @@ margin_glyphs_to_reserve (struct window *w, int total_glyphs, Lisp_Object margin
 
 #if XASSERTS
 /* Return non-zero if ROW's hash value is correct, zero if not.  */
-static int
+int
 verify_row_hash (struct glyph_row *row)
 {
   return row->hash == row_hash (row);
@@ -608,7 +608,6 @@ adjust_glyph_matrix (struct window *w, struct glyph_matrix *matrix, int x, int y
 		  row->glyphs[LAST_AREA]
 		    = row->glyphs[LEFT_MARGIN_AREA] + dim.width;
 		}
-	      xassert (!row->enabled_p || verify_row_hash (row));
 	      ++row;
 	    }
 	}
@@ -3575,12 +3574,11 @@ update_window (struct window *w, int force_p)
 
       rif->update_window_begin_hook (w);
       yb = window_text_bottom_y (w);
-
-      /* If window has a header line, update it before everything else.
-	 Adjust y-positions of other rows by the header line height.  */
       row = desired_matrix->rows;
       end = row + desired_matrix->nrows - 1;
 
+      /* Take note of the header line, if there is one.  We will
+	 update it below, after updating all of the window's lines.  */
       if (row->mode_line_p)
 	{
 	  header_line_row = row;
@@ -3625,6 +3623,8 @@ update_window (struct window *w, int force_p)
 
       /* Update the rest of the lines.  */
       for (; row < end && (force_p || !input_pending); ++row)
+	/* scrolling_window resets the enabled_p flag of the rows it
+	   reuses from current_matrix.  */
 	if (row->enabled_p)
 	  {
 	    int vpos = MATRIX_ROW_VPOS (row, desired_matrix);
@@ -4550,18 +4550,69 @@ scrolling_window (struct window *w, int header_line_p)
 	  {
 	    rif->clear_window_mouse_face (w);
 	    rif->scroll_run_hook (w, r);
+	  }
 
-	    /* Invalidate runs that copy from where we copied to.  */
-	    for (j = i + 1; j < nruns; ++j)
+	/* Truncate runs that copy to where we copied to, and
+	   invalidate runs that copy from where we copied to.  */
+	for (j = nruns - 1; j > i; --j)
+	  {
+	    struct run *p = runs[j];
+	    int truncated_p = 0;
+
+	    if (p->nrows > 0
+		&& p->desired_y < r->desired_y + r->height
+		&& p->desired_y + p->height > r->desired_y)
 	      {
-		struct run *p = runs[j];
+		if (p->desired_y < r->desired_y)
+		  {
+		    p->nrows = r->desired_vpos - p->desired_vpos;
+		    p->height = r->desired_y - p->desired_y;
+		    truncated_p = 1;
+		  }
+		else
+		  {
+		    int nrows_copied = (r->desired_vpos + r->nrows
+					- p->desired_vpos);
+
+		    if (p->nrows <= nrows_copied)
+		      p->nrows = 0;
+		    else
+		      {
+			int height_copied = (r->desired_y + r->height
+					     - p->desired_y);
+
+			p->current_vpos += nrows_copied;
+			p->desired_vpos += nrows_copied;
+			p->nrows -= nrows_copied;
+			p->current_y += height_copied;
+			p->desired_y += height_copied;
+			p->height -= height_copied;
+			truncated_p = 1;
+		      }
+		  }
+	      }
 
-		if ((p->current_y >= r->desired_y
+	    if (r->current_y != r->desired_y
+		/* The condition below is equivalent to
+		   ((p->current_y >= r->desired_y
 		     && p->current_y < r->desired_y + r->height)
-		    || (p->current_y + p->height >= r->desired_y
+		    || (p->current_y + p->height > r->desired_y
 			&& (p->current_y + p->height
-			    < r->desired_y + r->height)))
-		  p->nrows = 0;
+			    <= r->desired_y + r->height)))
+		   because we have 0 < p->height <= r->height.  */
+		&& p->current_y < r->desired_y + r->height
+		&& p->current_y + p->height > r->desired_y)
+	      p->nrows = 0;
+
+	    /* Reorder runs by copied pixel lines if truncated.  */
+	    if (truncated_p && p->nrows > 0)
+	      {
+		int k = nruns - 1;
+
+		while (runs[k]->nrows == 0 || runs[k]->height < p->height)
+		  k--;
+		memmove (runs + j, runs + j + 1, (k - j) * sizeof (*runs));
+		runs[k] = p;
 	      }
 	  }
 
@@ -4576,7 +4627,14 @@ scrolling_window (struct window *w, int header_line_p)
 	    to_overlapped_p = to->overlapped_p;
 	    from->redraw_fringe_bitmaps_p = from->fringe_bitmap_periodic_p;
 	    assign_row (to, from);
-	    to->enabled_p = 1, from->enabled_p = 0;
+	    /* The above `assign_row' actually does swap, so if we had
+	       an overlap in the copy destination of two runs, then
+	       the second run would assign a previously disabled bogus
+	       row.  But thanks to the truncation code in the
+	       preceding for-loop, we no longer have such an overlap,
+	       and thus the assigned row should always be enabled.  */
+	    xassert (to->enabled_p);
+	    from->enabled_p = 0;
 	    to->overlapped_p = to_overlapped_p;
 	  }
       }