[gtk] glyph cache: Fix handling of big glyphs

[Matthias Clasen <matthiasc src gnome org>]

commit 7bff3abe8e141955f2562991d0d93bd8e26b5324
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Oct 12 18:26:09 2019 -0400

    glyph cache: Fix handling of big glyphs
    
    We were putting big glyphs in the cache, in their
    own texture, but forgetting to mark the texture
    as permanent, so it could be reused, leading to
    occasional misrendering. Fix this by marking these
    textures as permanent, and explicitly freeing them
    when the cache entry gets old.

 gsk/gl/gskglglyphcache.c        | 36 +++++++++++++++++++++++++-----------
 gsk/gl/gskglglyphcacheprivate.h |  1 +
 gsk/gl/gskglrenderer.c          |  2 +-
 3 files changed, 27 insertions(+), 12 deletions(-)
---
diff --git a/gsk/gl/gskglglyphcache.c b/gsk/gl/gskglglyphcache.c
index f6c00d3046..7cc899e82c 100644
--- a/gsk/gl/gskglglyphcache.c
+++ b/gsk/gl/gskglglyphcache.c
@@ -15,13 +15,17 @@
 
 /* Cache eviction strategy
  *
- * We mark glyphs as accessed every time we use them. Every
- * few frames, we mark glyphs that haven't been accessed since
- * the last check as old.
+ * We mark glyphs as accessed every time we use them.
+ * Every few frames, we mark glyphs that haven't been
+ * accessed since the last check as old.
  *
- * We keep count of the pixels of each atlas that are taken up by old
- * data. When the fraction of old pixels gets too high, we drop the
- * atlas and all the items it contained.
+ * We keep count of the pixels of each atlas that are
+ * taken up by old data. When the fraction of old pixels
+ * gets too high, we drop the atlas and all the items it
+ * contained.
+ *
+ * Big glyphs are not stored in the atlas, they get their
+ * own texture, but they are still cached.
  */
 
 #define MAX_FRAME_AGE (60)
@@ -239,6 +243,7 @@ add_to_cache (GskGLGlyphCache  *self,
     {
       value->atlas = NULL;
       value->texture_id = gsk_gl_driver_create_texture (driver, width, height);
+      gsk_gl_driver_mark_texture_permanent (driver, value->texture_id);
 
       gsk_gl_driver_bind_source_texture (driver, value->texture_id);
       gsk_gl_driver_init_texture_empty (driver, value->texture_id, GL_LINEAR, GL_LINEAR);
@@ -316,6 +321,7 @@ gsk_gl_glyph_cache_lookup_or_add (GskGLGlyphCache         *cache,
 
 void
 gsk_gl_glyph_cache_begin_frame (GskGLGlyphCache *self,
+                                GskGLDriver     *driver,
                                 GPtrArray       *removed_atlases)
 {
   GHashTableIter iter;
@@ -348,14 +354,22 @@ gsk_gl_glyph_cache_begin_frame (GskGLGlyphCache *self,
         {
           if (!value->accessed)
             {
-              if (value->atlas && value->used)
+              if (value->atlas)
+                {
+                  if (value->used)
+                    {
+                      gsk_gl_texture_atlas_mark_unused (value->atlas, value->draw_width, value->draw_height);
+                      value->used = FALSE;
+                    }
+                }
+              else
                 {
-                  gsk_gl_texture_atlas_mark_unused (value->atlas, value->draw_width, value->draw_height);
-                  value->used = FALSE;
+                  gsk_gl_driver_destroy_texture (driver, value->texture_id);
+                  g_hash_table_iter_remove (&iter);
                 }
             }
-
-          value->accessed = FALSE;
+          else
+            value->accessed = FALSE;
        }
 
       GSK_NOTE(GLYPH_CACHE, g_message ("%d glyphs cached", g_hash_table_size (self->hash_table)));
diff --git a/gsk/gl/gskglglyphcacheprivate.h b/gsk/gl/gskglglyphcacheprivate.h
index 75f7a8de19..16a6feb471 100644
--- a/gsk/gl/gskglglyphcacheprivate.h
+++ b/gsk/gl/gskglglyphcacheprivate.h
@@ -73,6 +73,7 @@ GskGLGlyphCache *        gsk_gl_glyph_cache_new             (GdkDisplay *display
 GskGLGlyphCache *        gsk_gl_glyph_cache_ref             (GskGLGlyphCache *self);
 void                     gsk_gl_glyph_cache_unref           (GskGLGlyphCache        *self);
 void                     gsk_gl_glyph_cache_begin_frame     (GskGLGlyphCache        *self,
+                                                             GskGLDriver            *driver,
                                                              GPtrArray              *removed_atlases);
 void                     gsk_gl_glyph_cache_lookup_or_add   (GskGLGlyphCache        *self,
                                                              GlyphCacheKey          *lookup,
diff --git a/gsk/gl/gskglrenderer.c b/gsk/gl/gskglrenderer.c
index 913472f3af..82b5e3018c 100644
--- a/gsk/gl/gskglrenderer.c
+++ b/gsk/gl/gskglrenderer.c
@@ -3207,7 +3207,7 @@ gsk_gl_renderer_do_render (GskRenderer           *renderer,
 
   removed = g_ptr_array_new ();
   gsk_gl_texture_atlases_begin_frame (self->atlases, removed);
-  gsk_gl_glyph_cache_begin_frame (self->glyph_cache, removed);
+  gsk_gl_glyph_cache_begin_frame (self->glyph_cache, self->gl_driver, removed);
   gsk_gl_icon_cache_begin_frame (self->icon_cache, removed);
   gsk_gl_shadow_cache_begin_frame (&self->shadow_cache, self->gl_driver);
   g_ptr_array_unref (removed);