Inhibit null-string composition component (Bug#6988).

2 files changed, 14 insertions, 3 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index d114f0897eb..c41202bcfee 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2012-02-01  Kenichi Handa  <handa@m17n.org>
+
+        * xdisp.c (BUILD_COMPOSITE_GLYPH_STRING): Initialize first_s to
+        NULL (Bug#6988).
+        (x_produce_glyphs): If the component of a composition is a null
+        string, set it->pixel_width to 1 to avoid zero-width glyph.
+
 2012-01-31  Glenn Morris  <rgm@gnu.org>
 
         * nsterm.m (syms_of_nsterm) <x-toolkit-scroll-bars>:
diff --git a/src/xdisp.c b/src/xdisp.c
index c90184f4a4c..864517b950c 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -22738,7 +22738,7 @@ compute_overhangs_and_x (struct glyph_string *s, int x, int backward_p)
     ptrdiff_t cmp_id = (row)->glyphs[area][START].u.cmp.id;                 \
     struct composition *cmp = composition_table[cmp_id];                    \
     XChar2b *char2b;                                                        \
-    struct glyph_string *first_s IF_LINT (= NULL);                          \
+    struct glyph_string *first_s = NULL;                                    \
     int n;                                                                  \
                                                                             \
     char2b = (XChar2b *) alloca ((sizeof *char2b) * cmp->glyph_len);        \
@@ -24400,7 +24400,7 @@ x_produce_glyphs (struct it *it)
           /* Initialize the bounding box.  */
           if (pcm)
             {
-              width = pcm->width;
+              width = cmp->glyph_len > 0 ? pcm->width : 0;
               ascent = pcm->ascent;
               descent = pcm->descent;
               lbearing = pcm->lbearing;
@@ -24408,7 +24408,7 @@ x_produce_glyphs (struct it *it)
             }
           else
             {
-              width = font->space_width;
+              width = cmp->glyph_len > 0 ? font->space_width : 0;
               ascent = FONT_BASE (font);
               descent = FONT_DESCENT (font);
               lbearing = 0;
@@ -24595,6 +24595,10 @@ x_produce_glyphs (struct it *it)
         it->glyph_row->contains_overlapping_glyphs_p = 1;
 
       it->pixel_width = cmp->pixel_width;
+      if (it->pixel_width == 0)
+        /* We assure that all visible glyphs have at least 1-pixel
+           width.  */
+        it->pixel_width = 1;
       it->ascent = it->phys_ascent = cmp->ascent;
       it->descent = it->phys_descent = cmp->descent;
       if (face->box != FACE_NO_BOX)