From 22ce8a7111f9e814e92754eec9cf521d9586fb08 Mon Sep 17 00:00:00 2001
From: Neil Roberts <neil@linux.intel.com>
Date: Mon, 22 Feb 2010 16:40:49 +0000
Subject: [PATCH] cogl-pango-glyph-cache: Don't put zero-sized glyphs in the
 cache

It now avoids trying to reserve space for zero-sized glyphs. That
happens for example when the layout contains a space. This was causing
the regular glyph cache to be used because the global atlas does not
support zero-sized images. That would then break up the
batching. Instead it now still reserves an entry in the cache but
leaves the texture as COGL_INVALID_HANDLE.
---
 clutter/cogl/pango/cogl-pango-glyph-cache.c | 39 +++++++++++++--------
 clutter/cogl/pango/cogl-pango-render.c      |  7 +++-
 2 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/clutter/cogl/pango/cogl-pango-glyph-cache.c b/clutter/cogl/pango/cogl-pango-glyph-cache.c
index b1fbd9285..3c6ec5a59 100644
--- a/clutter/cogl/pango/cogl-pango-glyph-cache.c
+++ b/clutter/cogl/pango/cogl-pango-glyph-cache.c
@@ -70,7 +70,8 @@ struct _CoglPangoGlyphCacheKey
 static void
 cogl_pango_glyph_cache_value_free (CoglPangoGlyphCacheValue *value)
 {
-  cogl_handle_unref (value->texture);
+  if (value->texture)
+    cogl_handle_unref (value->texture);
   g_slice_free (CoglPangoGlyphCacheValue, value);
 }
 
@@ -307,7 +308,6 @@ cogl_pango_glyph_cache_lookup (CoglPangoGlyphCache *cache,
 
       value = g_slice_new (CoglPangoGlyphCacheValue);
       value->texture = COGL_INVALID_HANDLE;
-      value->dirty = TRUE;
 
       pango_font_get_glyph_extents (font, glyph, &ink_rect, NULL);
       pango_extents_to_pixels (&ink_rect, NULL);
@@ -317,18 +317,29 @@ cogl_pango_glyph_cache_lookup (CoglPangoGlyphCache *cache,
       value->draw_width = ink_rect.width;
       value->draw_height = ink_rect.height;
 
-      /* Try adding the glyph to the global atlas... */
-      if (!cogl_pango_glyph_cache_add_to_global_atlas (cache,
-                                                       font,
-                                                       glyph,
-                                                       value) &&
-          !cogl_pango_glyph_cache_add_to_local_atlas (cache,
-                                                      font,
-                                                      glyph,
-                                                      value))
+      /* If the glyph is zero-sized then we don't need to reserve any
+         space for it and we can just avoid painting anything */
+      if (ink_rect.width < 1 || ink_rect.height < 1)
+        value->dirty = FALSE;
+      else
         {
-          cogl_pango_glyph_cache_value_free (value);
-          return NULL;
+          /* Try adding the glyph to the global atlas... */
+          if (!cogl_pango_glyph_cache_add_to_global_atlas (cache,
+                                                           font,
+                                                           glyph,
+                                                           value) &&
+              /* If it fails try the local atlas */
+              !cogl_pango_glyph_cache_add_to_local_atlas (cache,
+                                                          font,
+                                                          glyph,
+                                                          value))
+            {
+              cogl_pango_glyph_cache_value_free (value);
+              return NULL;
+            }
+
+          value->dirty = TRUE;
+          cache->has_dirty_glyphs = TRUE;
         }
 
       key = g_slice_new (CoglPangoGlyphCacheKey);
@@ -336,8 +347,6 @@ cogl_pango_glyph_cache_lookup (CoglPangoGlyphCache *cache,
       key->glyph = glyph;
 
       g_hash_table_insert (cache->hash_table, key, value);
-
-      cache->has_dirty_glyphs = TRUE;
     }
 
   return value;
diff --git a/clutter/cogl/pango/cogl-pango-render.c b/clutter/cogl/pango/cogl-pango-render.c
index 0d6f477e0..597f7898c 100644
--- a/clutter/cogl/pango/cogl-pango-render.c
+++ b/clutter/cogl/pango/cogl-pango-render.c
@@ -501,6 +501,11 @@ cogl_pango_renderer_set_dirty_glyph (PangoFont *font,
 
   COGL_NOTE (PANGO, "redrawing glyph %i", glyph);
 
+  /* Glyphs that don't take up any space will end up without a
+     texture. These should never become dirty so they shouldn't end up
+     here */
+  g_return_if_fail (value->texture != COGL_INVALID_HANDLE);
+
   surface = cairo_image_surface_create (CAIRO_FORMAT_A8,
                                         value->draw_width,
                                         value->draw_height);
@@ -824,7 +829,7 @@ cogl_pango_renderer_draw_glyphs (PangoRenderer    *renderer,
                                             PANGO_UNKNOWN_GLYPH_WIDTH,
                                             PANGO_UNKNOWN_GLYPH_HEIGHT);
             }
-	  else
+	  else if (cache_value->texture)
 	    {
 	      x += (float)(cache_value->draw_x);
 	      y += (float)(cache_value->draw_y);