(Ffont_shape_text): If the font driver doesn't have a

shaper function, make zero-width glyphs to have at least one-pixel
width.

1 files changed, 40 insertions, 4 deletions

diff --git a/src/font.c b/src/font.c
index 8347a0d5b23..9a0e621d95f 100644
--- a/src/font.c
+++ b/src/font.c
@@ -3567,12 +3567,42 @@ FONT-OBJECT.  */)
     }
 
   CHECK_FONT_GET_OBJECT (font_object, font);
-  if (! font->driver->shape)
-    return from;
-
   len = end - start;
   gstring = Ffont_make_gstring (font_object, make_number (len));
   Ffont_fill_gstring (gstring, font_object, from, to, string);
+  if (! font->driver->shape)
+    {
+      /* Make zero-width glyphs to have one pixel width to make the
+         display routine not lose the cursor.  */
+      for (i = 0; i < len; i++)
+        {
+          Lisp_Object g = LGSTRING_GLYPH (gstring, i);
+          unsigned code = LGLYPH_CODE (g);
+          struct font_metrics metrics;
+
+          if (font->driver->text_extents (font, &code, 1, &metrics) == 0)
+            {
+              Lisp_Object gstr = Ffont_make_gstring (font_object,
+                                                     make_number (1));
+              LGSTRING_SET_WIDTH (gstr, 1);
+              LGSTRING_SET_LBEARING (gstr, metrics.lbearing);
+              LGSTRING_SET_RBEARING (gstr, metrics.rbearing + 1);
+              LGSTRING_SET_ASCENT (gstr, metrics.ascent);
+              LGSTRING_SET_DESCENT (gstr, metrics.descent);
+              LGLYPH_SET_FROM (g, 0);
+              LGLYPH_SET_TO (g, 1);
+              LGSTRING_SET_GLYPH (gstr, 0, g);
+              from = make_number (start + i);
+              to = make_number (start + i + 1);
+              if (NILP (string))
+                Fcompose_region_internal (from, to, gstr, Qnil);
+              else
+                Fcompose_region_internal (string, from, to, gstr, Qnil);
+            }
+        }
+      return make_number (end);
+    }
+
   
   /* Try at most three times with larger gstring each time.  */
   for (i = 0; i < 3; i++)
@@ -3653,7 +3683,13 @@ FONT-OBJECT.  */)
           LGSTRING_SET_ASCENT (gstr, metrics.ascent);
           LGSTRING_SET_DESCENT (gstr, metrics.descent);
           for (k = i; i < j; i++)
-            LGSTRING_SET_GLYPH (gstr, i - k, LGSTRING_GLYPH (gstring, i));
+            {
+              Lisp_Object g = LGSTRING_GLYPH (gstring, i);
+
+              LGLYPH_SET_FROM (g, LGLYPH_FROM (g) - this_from);
+              LGLYPH_SET_TO (g, LGLYPH_TO (g) - this_to);
+              LGSTRING_SET_GLYPH (gstr, i - k, LGSTRING_GLYPH (gstring, i));
+            }
           from = make_number (start + this_from);
           to = make_number (start + this_to);
           if (NILP (string))