journal: Support per-framebuffer journals

Instead of having a single journal per context, we now have a
CoglJournal object for each CoglFramebuffer. This means we now don't
have to flush the journal when switching/pushing/popping between
different framebuffers so for example a Clutter scene that involves some
ClutterEffect actors that transiently redirect to an FBO can still be
batched.

This also allows us to track state in the journal that relates to the
current frame of its associated framebuffer which we'll need for our
optimization for using the CPU to handle reading a single pixel back
from a framebuffer when we know the whole scene is currently comprised
of simple rectangles in a journal.

cogl/cogl-texture.c

@@ -49,6 +49,7 @@
 #include "cogl-pipeline.h"
 #include "cogl-context.h"
 #include "cogl-handle.h"
+#include "cogl-object-private.h"
 #include "cogl-primitives.h"
 #include "cogl-framebuffer-private.h"
 
@@ -118,6 +119,14 @@ cogl_texture_unref (CoglHandle handle)
   cogl_handle_unref (handle);
 }
 
+void
+_cogl_texture_init (CoglTexture *texture,
+                    const CoglTextureVtable *vtable)
+{
+  texture->vtable = vtable;
+  texture->framebuffers = NULL;
+}
+
 void
 _cogl_texture_free (CoglTexture *texture)
 {
@@ -1473,3 +1482,52 @@ cogl_texture_get_data (CoglHandle       handle,
 
   return byte_size;
 }
+
+static void
+_cogl_texture_framebuffer_destroy_cb (void *user_data,
+                                      void *instance)
+{
+  CoglTexture *tex = user_data;
+  CoglFramebuffer *framebuffer = instance;
+
+  tex->framebuffers = g_list_remove (tex->framebuffers, framebuffer);
+}
+
+void
+_cogl_texture_associate_framebuffer (CoglHandle handle,
+                                     CoglFramebuffer *framebuffer)
+{
+  CoglTexture *tex = COGL_TEXTURE (handle);
+  static CoglUserDataKey framebuffer_destroy_notify_key;
+
+  /* Note: we don't take a reference on the framebuffer here because
+   * that would introduce a circular reference. */
+  tex->framebuffers = g_list_prepend (tex->framebuffers, framebuffer);
+
+  /* Since we haven't taken a reference on the framebuffer we setup
+   * some private data so we will be notified if it is destroyed... */
+  _cogl_object_set_user_data (COGL_OBJECT (framebuffer),
+                              &framebuffer_destroy_notify_key,
+                              tex,
+                              _cogl_texture_framebuffer_destroy_cb);
+}
+
+const GList *
+_cogl_texture_get_associated_framebuffers (CoglHandle handle)
+{
+  CoglTexture *tex = COGL_TEXTURE (handle);
+  return tex->framebuffers;
+}
+
+void
+_cogl_texture_flush_journal_rendering (CoglHandle handle)
+{
+  CoglTexture *tex = COGL_TEXTURE (handle);
+  GList *l;
+
+  /* It could be that a referenced texture is part of a framebuffer
+   * which has an associated journal that must be flushed before it
+   * can be sampled from by the current primitive... */
+  for (l = tex->framebuffers; l; l = l->next)
+    _cogl_framebuffer_flush_journal (l->data);
+}