From 0e99fa7a1e0191328b0616b5a901fb1ab14dd1fb Mon Sep 17 00:00:00 2001
From: Robert Bragg <robert@linux.intel.com>
Date: Mon, 13 Sep 2010 23:05:49 +0100
Subject: [PATCH] material: pass material owner for layer pre changes

When notifying a backend about a layer being modified we now pass the
layers current owner for reference. NB: Although a layer can indirectly
be referenced by multiple layers, a layer is considered immutable once
it has dependants, so there is only ever one material associated with a
layer being modified. Passing the material pointer to the backends
layer_pre_change callback can be useful for backends that associate
their private state with materials and may need to update that state in
response to layer changes.
---
 cogl/cogl-material-arbfp.c   | 11 ++++++++++-
 cogl/cogl-material-private.h |  3 ++-
 cogl/cogl-material.c         |  7 ++++---
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/cogl/cogl-material-arbfp.c b/cogl/cogl-material-arbfp.c
index 7a81a846d..e64234816 100644
--- a/cogl/cogl-material-arbfp.c
+++ b/cogl/cogl-material-arbfp.c
@@ -1073,10 +1073,19 @@ _cogl_material_backend_arbfp_material_set_parent_notify (
                                      NULL);
 }
 
+/* NB: layers are considered immutable once they have any dependants
+ * so although multiple materials can end up depending on a single
+ * static layer, we can guarantee that if a layer is being *changed*
+ * then it can only have one material depending on it.
+ *
+ * XXX: Don't forget this is *pre* change, we can't read the new value
+ * yet!
+ */
 static void
 _cogl_material_backend_arbfp_layer_pre_change_notify (
+                                                CoglMaterial *owner,
                                                 CoglMaterialLayer *layer,
-                                                CoglMaterialLayerState changes)
+                                                CoglMaterialLayerState change)
 {
   /* TODO: we could be saving snippets of texture combine code along
    * with each layer and then when a layer changes we would just free
diff --git a/cogl/cogl-material-private.h b/cogl/cogl-material-private.h
index ca260c2ee..e5e62988e 100644
--- a/cogl/cogl-material-private.h
+++ b/cogl/cogl-material-private.h
@@ -557,7 +557,8 @@ typedef struct _CoglMaterialBackend
                                       CoglMaterialState change,
                                       const CoglColor *new_color);
   void (*material_set_parent_notify) (CoglMaterial *material);
-  void (*layer_pre_change_notify) (CoglMaterialLayer *layer,
+  void (*layer_pre_change_notify) (CoglMaterial *owner,
+                                   CoglMaterialLayer *layer,
                                    CoglMaterialLayerState change);
 
   void (*free_priv) (CoglMaterial *material);
diff --git a/cogl/cogl-material.c b/cogl/cogl-material.c
index a8ecf461a..557bcb217 100644
--- a/cogl/cogl-material.c
+++ b/cogl/cogl-material.c
@@ -1418,7 +1418,8 @@ _cogl_material_prune_to_n_layers (CoglMaterial *material, int n)
 }
 
 static void
-_cogl_material_backend_layer_change_notify (CoglMaterialLayer *layer,
+_cogl_material_backend_layer_change_notify (CoglMaterial *owner,
+                                            CoglMaterialLayer *layer,
                                             CoglMaterialLayerState change)
 {
   int i;
@@ -1433,7 +1434,7 @@ _cogl_material_backend_layer_change_notify (CoglMaterialLayer *layer,
           _cogl_material_backends[i]->layer_pre_change_notify)
         {
           const CoglMaterialBackend *backend = _cogl_material_backends[i];
-          backend->layer_pre_change_notify (layer, change);
+          backend->layer_pre_change_notify (owner, layer, change);
         }
     }
 }
@@ -1594,7 +1595,7 @@ _cogl_material_layer_pre_change_notify (CoglMaterial *required_owner,
    * this layer (required_owner), and there are no other layers
    * dependant on this layer so it's ok to modify it. */
 
-  _cogl_material_backend_layer_change_notify (layer, change);
+  _cogl_material_backend_layer_change_notify (required_owner, layer, change);
 
   /* If the layer being changed is the same as the last layer we
    * flushed to the corresponding texture unit then we keep a track of