cogl-atlas-texture: Flush the journal before adding a new texture

When the atlas is reorganised we could potentially be moving around
textures that are already referenced in the journal. We therefore need
to flush the journal otherwise they will be rendered with incorrect
texture coordinates. We also need to flush the journal even if we are
not reorganizing so that we can rely on the old texture contents
remaining in the atlas after migrating a texture out.

cogl/cogl-atlas-texture.c

@@ -3,7 +3,7 @@
  *
  * An object oriented GL/GLES Abstraction/Utility Layer
  *
- * Copyright (C) 2009 Intel Corporation.
+ * Copyright (C) 2009,2010 Intel Corporation.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -39,6 +39,7 @@
 #include "cogl-handle.h"
 #include "cogl-texture-driver.h"
 #include "cogl-atlas.h"
+#include "cogl-journal-private.h"
 
 #include <stdlib.h>
 
@@ -354,6 +355,13 @@ _cogl_atlas_texture_migrate_out_of_atlas (CoglAtlasTexture *atlas_tex)
 
       COGL_NOTE (ATLAS, "Migrating texture out of the atlas");
 
+      /* Although this texture is being moved out of the atlas, we
+         don't need to flush the journal here because the contents of
+         the old image will still be left in the same position in the
+         atlas. The only way this would get overwritten would be if a
+         new texture was added, but in that case we flush the journal
+         anyway */
+
       cogl_handle_unref (atlas_tex->sub_texture);
 
       /* Create a new texture at the right size, not including the
@@ -962,6 +970,22 @@ _cogl_atlas_texture_new_from_bitmap (CoglHandle       bmp_handle,
       return COGL_INVALID_HANDLE;
     }
 
+  /* We need to flush the journal when adding a new atlas texture for
+     two reasons:
+
+     1) If the atlas gets reorganized then any existing textures may
+        be moved so the coordinates in journal will be wrong.
+
+     2) We don't want to flush before migrating a texture out of the
+        atlas because we will potentially already be in the middle of
+        a flush to cause the migration. Therefore we rely on the old
+        contents of the texture still remaining in the atlas so that
+        any existing journal entries will still be valid. However once
+        the texture is migrated out the space would be free to be
+        reclaimed by this new texture. That won't matter if we flush
+        now */
+  _cogl_journal_flush ();
+
   /* We need to allocate the texture now because we need the pointer
      to set as the data for the rectangle in the atlas */
   atlas_tex = g_new (CoglAtlasTexture, 1);