(x_draw_glyph_string): Be sure to draw underline within the current

line area.

2 files changed, 8 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 3dd1a95177e..62ea887f9f0 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -4,7 +4,8 @@
         s->underline_thickness and s->underline_position.
 
         * xterm.c (x_draw_glyph_string): Be sure to update
-        s->underline_thickness and s->underline_position.
+        s->underline_thickness and s->underline_position.  Be sore to draw
+        underline within the current line area.
 
         * fontset.c: Delete unused variables and add casting for char *
         throughout the file.
diff --git a/src/xterm.c b/src/xterm.c
index b4c49d4085f..b2683298ca0 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -2743,6 +2743,12 @@ x_draw_glyph_string (s)
                     position = (s->font->descent + 1) / 2;
                 }
             }
+          /* Check the sanity of thickness and position.  We should
+             avoid drawing underline out of the current line area.  */
+          if (s->y + s->height <= s->ybase + position)
+            position = s->y + s->height - 1;
+          if (s->y + s->height < s->ybase + position + thickness)
+            thickness = (s->y + s->height) - (s->ybase + position);
           s->underline_thickness = thickness;
           s->underline_position = position;
           y = s->ybase + position;