Cache glyph textures in render nodes

This is a quick implementation that avoids many
glyph cache lookups. We keep an array of direct
pointers in the text render node, and throw those
cached pointers away whenever any atlases have
been dropped (since that may invalidate the cached
glyphs).

gsk/gl/gskglglyphcache.c

@@ -269,13 +269,7 @@ gsk_gl_glyph_cache_lookup_or_add (GskGLGlyphCache         *cache,
 
   if (value)
     {
-      if (value->atlas && !value->used)
-        {
-          gsk_gl_texture_atlas_mark_used (value->atlas, value->draw_width, value->draw_height);
-          value->used = TRUE;
-        }
-      value->accessed = TRUE;
-
+      gsk_gl_glyph_cache_entry_validate (cache, value);
       *cached_glyph_out = value;
       return;
     }
@@ -334,6 +328,8 @@ gsk_gl_glyph_cache_begin_frame (GskGLGlyphCache *self,
     {
       guint dropped = 0;
 
+      self->atlas_timestamp++;
+
       g_hash_table_iter_init (&iter, self->hash_table);
       while (g_hash_table_iter_next (&iter, (gpointer *)&key, (gpointer *)&value))
         {
@@ -375,3 +371,15 @@ gsk_gl_glyph_cache_begin_frame (GskGLGlyphCache *self,
       GSK_NOTE(GLYPH_CACHE, g_message ("%d glyphs cached", g_hash_table_size (self->hash_table)));
     }
 }
+
+void
+gsk_gl_glyph_cache_entry_validate (GskGLGlyphCache  *cache,
+                                   GskGLCachedGlyph *value)
+{
+  value->accessed = TRUE;
+  if (value->atlas && !value->used)
+    {
+      gsk_gl_texture_atlas_mark_used (value->atlas, value->draw_width, value->draw_height);
+      value->used = TRUE;
+    }
+}

gsk/gl/gskglglyphcacheprivate.h

@@ -16,6 +16,7 @@ typedef struct
   GskGLTextureAtlases *atlases;
 
   int timestamp;
+  int atlas_timestamp; /* incremented whenever an atlas is dropped */
 } GskGLGlyphCache;
 
 typedef struct
@@ -79,5 +80,7 @@ void                     gsk_gl_glyph_cache_lookup_or_add   (GskGLGlyphCache
                                                              GlyphCacheKey          *lookup,
                                                              GskGLDriver            *driver,
                                                              const GskGLCachedGlyph **cached_glyph_out);
+void                    gsk_gl_glyph_cache_entry_validate   (GskGLGlyphCache *cache,
+                                                             GskGLCachedGlyph *entry);
 
 #endif

gsk/gl/gskglrenderer.c

@@ -536,6 +536,39 @@ render_fallback_node (GskGLRenderer       *self,
   ops_draw (builder, offscreen_vertex_data);
 }
 
+typedef struct {
+  int timestamp;
+  GskGLCachedGlyph *glyphs[];
+} TextRenderData;
+
+static inline TextRenderData *
+ensure_render_data (GskRenderNode *node,
+                    GskGLGlyphCache *cache)
+{
+  TextRenderData *data;
+  int num_glyphs;
+
+  num_glyphs = gsk_text_node_get_num_glyphs (node);
+  data = gsk_text_node_get_render_data (node);
+  if (data)
+    {
+      if (data->timestamp < cache->atlas_timestamp)
+        {
+          memset (data->glyphs, 0, sizeof (gpointer) * num_glyphs);
+          data->timestamp = cache->atlas_timestamp;
+        }
+    }
+  else
+    {
+      data = g_new0 (TextRenderData, sizeof (TextRenderData) + sizeof (gpointer) * num_glyphs);
+      data->timestamp = cache->atlas_timestamp;
+
+      gsk_text_node_set_render_data (node, data);
+    }
+
+  return data;
+}
+
 static inline void
 render_text_node (GskGLRenderer   *self,
                   GskRenderNode   *node,
@@ -553,6 +586,7 @@ render_text_node (GskGLRenderer   *self,
   float x = offset->x + builder->dx;
   float y = offset->y + builder->dy;
   GlyphCacheKey lookup;
+  TextRenderData *render_data;
 
   /* If the font has color glyphs, we don't need to recolor anything */
   if (!force_color && gsk_text_node_has_color_glyphs (node))
@@ -565,6 +599,8 @@ render_text_node (GskGLRenderer   *self,
       ops_set_color (builder, color);
     }
 
+  render_data = ensure_render_data (node, self->glyph_cache);
+
   lookup.font = (PangoFont *)font;
   lookup.scale = (guint) (text_scale * 1024);
 
@@ -585,12 +621,19 @@ render_text_node (GskGLRenderer   *self,
       cx = (float)(x_position + gi->geometry.x_offset) / PANGO_SCALE;
       cy = (float)(gi->geometry.y_offset) / PANGO_SCALE;
 
-      glyph_cache_key_set_glyph_and_shift (&lookup, gi->glyph, x + cx, y + cy);
+      glyph = render_data->glyphs[i];
+      if (!glyph)
+        {
+          glyph_cache_key_set_glyph_and_shift (&lookup, gi->glyph, x + cx, y + cy);
 
-      gsk_gl_glyph_cache_lookup_or_add (self->glyph_cache,
-                                        &lookup,
-                                        self->gl_driver,
-                                        &glyph);
+          gsk_gl_glyph_cache_lookup_or_add (self->glyph_cache,
+                                            &lookup,
+                                            self->gl_driver,
+                                            &glyph);
+          render_data->glyphs[i] = (GskGLCachedGlyph *)glyph;
+        }
+
+      gsk_gl_glyph_cache_entry_validate (self->glyph_cache, render_data->glyphs[i]);
 
       if (glyph->texture_id == 0)
         goto next;

gsk/gskrendernodeimpl.c

@@ -3414,6 +3414,7 @@ struct _GskTextNode
   GdkRGBA color;
   graphene_point_t offset;
 
+  gpointer render_data;
   guint num_glyphs;
   PangoGlyphInfo glyphs[];
 };
@@ -3423,6 +3424,7 @@ gsk_text_node_finalize (GskRenderNode *node)
 {
   GskTextNode *self = (GskTextNode *) node;
 
+  g_free (self->render_data);
   g_object_unref (self->font);
 }
 
@@ -3625,6 +3627,24 @@ gsk_text_node_get_offset (GskRenderNode *node)
   return &self->offset;
 }
 
+void
+gsk_text_node_set_render_data (GskRenderNode *node,
+                               gpointer       data)
+{
+  GskTextNode *self = (GskTextNode *) node;
+
+  self->render_data = data;
+}
+
+gpointer
+gsk_text_node_get_render_data (GskRenderNode *node)
+{
+  GskTextNode *self = (GskTextNode *) node;
+
+  return self->render_data;
+}
+
+
 /*** GSK_BLUR_NODE ***/
 
 typedef struct _GskBlurNode GskBlurNode;

gsk/gskrendernodeprivate.h

@@ -46,6 +46,10 @@ void            gsk_render_node_diff             (GskRenderNode             *nod
 void            gsk_render_node_diff_impossible  (GskRenderNode             *node1,
                                                   GskRenderNode             *node2,
                                                   cairo_region_t            *region);
+void            gsk_text_node_set_render_data    (GskRenderNode *node,
+                                                  gpointer       data);
+gpointer        gsk_text_node_get_render_data    (GskRenderNode *node);
+                                                  
 
 
 G_END_DECLS