From 3d2c4f0c2ff8fab4262988aad65b170e5b479b20 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 27 Sep 2013 17:06:29 -0400
Subject: [PATCH] Fix hiding of default_ignorables if font doesn't have space
 glyph

Based on patch from Jonathan Kew.  See discussion on the list.
---
 src/hb-ot-shape.cc | 40 ++++++++++++++++++++++++++++++----------
 1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/src/hb-ot-shape.cc b/src/hb-ot-shape.cc
index 15f4461b5..4ed6b8420 100644
--- a/src/hb-ot-shape.cc
+++ b/src/hb-ot-shape.cc
@@ -533,22 +533,42 @@ hb_ot_hide_default_ignorables (hb_ot_shape_context_t *c)
   if (c->buffer->flags & HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES)
     return;
 
-  hb_codepoint_t space = 0;
+  hb_codepoint_t space;
+  enum {
+    SPACE_DONT_KNOW,
+    SPACE_AVAILABLE,
+    SPACE_UNAVAILABLE
+  } space_status = SPACE_DONT_KNOW;
 
   unsigned int count = c->buffer->len;
+  hb_glyph_info_t *info = c->buffer->info;
+  hb_glyph_position_t *pos = c->buffer->pos;
+  unsigned int j = 0;
   for (unsigned int i = 0; i < count; i++)
-    if (unlikely (!is_a_ligature (c->buffer->info[i]) &&
-		  _hb_glyph_info_is_default_ignorable (&c->buffer->info[i])))
+  {
+    if (unlikely (!is_a_ligature (info[i]) &&
+		  _hb_glyph_info_is_default_ignorable (&info[i])))
     {
-      if (!space) {
-        /* We assume that the space glyph is not gid0. */
-        if (unlikely (!c->font->get_glyph (' ', 0, &space)) || !space)
-	return; /* No point! */
+      if (space_status == SPACE_DONT_KNOW)
+	space_status = c->font->get_glyph (' ', 0, &space) ? SPACE_AVAILABLE : SPACE_UNAVAILABLE;
+
+      if (space_status == SPACE_AVAILABLE)
+      {
+	info[i].codepoint = space;
+	pos[i].x_advance = 0;
+	pos[i].y_advance = 0;
       }
-      c->buffer->info[i].codepoint = space;
-      c->buffer->pos[i].x_advance = 0;
-      c->buffer->pos[i].y_advance = 0;
+      else
+	continue; /* Delete it. */
     }
+    if (j != i)
+    {
+      info[j] = info[i];
+      pos[j] = pos[i];
+    }
+    j++;
+  }
+  c->buffer->len = j;
 }