Moving RenderSurface creation outside of CalcDrawProps

cc/trees/layer_tree_host_common.cc

Index: cc/trees/layer_tree_host_common.cc
diff --git a/cc/trees/layer_tree_host_common.cc b/cc/trees/layer_tree_host_common.cc
index 840a32b2ef4a59037f22e33e251c9edee72bc649..0d94d15ed8695529768f2cfd81315665d5cca1cd 100644
--- a/cc/trees/layer_tree_host_common.cc
+++ b/cc/trees/layer_tree_host_common.cc
@@ -14,7 +14,9 @@
 #include "cc/layers/layer_iterator.h"
 #include "cc/layers/render_surface.h"
 #include "cc/layers/render_surface_impl.h"
+#include "cc/test/fake_layer_tree_host_impl.h"
 #include "cc/trees/layer_sorter.h"
+#include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/transform.h"
@@ -548,9 +550,8 @@ static inline void SavePaintPropertiesLayer(Layer* layer) {
     layer->replica_layer()->mask_layer()->SavePaintProperties();
 }
 
-template <typename LayerType>
 static bool SubtreeShouldRenderToSeparateSurface(
-    LayerType* layer,
+    Layer* layer,
     bool axis_aligned_with_respect_to_parent) {
   //
   // A layer and its descendants should render onto a new RenderSurfaceImpl if
@@ -1815,23 +1816,25 @@ static void CalculateDrawPropertiesInternal(
 
   bool render_to_separate_surface;
   if (globals.can_render_to_separate_surface) {
-    render_to_separate_surface = SubtreeShouldRenderToSeparateSurface(
-          layer, combined_transform.Preserves2dAxisAlignment());
+    render_to_separate_surface = layer->ShouldHaveRenderSurface();
   } else {
-    render_to_separate_surface = IsRootLayer(layer);
+    render_to_separate_surface =
+        layer->ShouldHaveRenderSurface() && IsRootLayer(layer);

[danakj, 2014/08/26 18:06:13]

the root has to have a surface, and nothing else is allowed in this case. can
you instead do

bool render_to_separate_surface = layer->ShouldHaveRenderSurface();

// Root must own a surface.
DCHECK(!IsRootLayer(layer) || render_to_separate_surface);
// When globals.can_render_to_separate_surface is false, non-root layers can't
own a surface.
DCHECK(globals.can_render_to_separate_surface ||
    IsRootLayer(layer) ||
    !render_to_separate_surface);

[awoloszyn, 2014/08/28 19:31:43]

We may still have a render-surface if !globals.can_render_to_separate_surface,
since that can be changed per-frame on the impl-thread. The first check is done
already on 1983
if (render_to_...) { 
} else {
 DCHECK(layer->parent());
}
but I will add the second check.

   }
+  layer->SetRenderSurfaceActive(render_to_separate_surface);

[danakj, 2014/08/26 18:06:13]

The RS computation decides if the render surface should exist. ISTM that this
method call should not exist, cuz the surface already exists or not correctly.

[awoloszyn, 2014/08/28 19:31:43]

Done.

+
   if (render_to_separate_surface) {
     // Check back-face visibility before continuing with this surface and its
     // subtree
     if (!layer->double_sided() && TransformToParentIsKnown(layer) &&
         IsSurfaceBackFaceVisible(layer, combined_transform)) {
-      layer->ClearRenderSurfaceLayerList();
+      layer->SetRenderSurfaceActive(false);

[danakj, 2014/08/26 18:06:13]

And since the RS exists or not correctly, we shouldn't be deleting it here?

[awoloszyn, 2014/08/28 19:31:43]

Done.

       return;
     }
 
     typename LayerType::RenderSurfaceType* render_surface =
-        CreateOrReuseRenderSurface(layer);
-
+        layer->render_surface();
+    render_surface->ClearLayerLists();
     if (IsRootLayer(layer)) {
       // The root layer's render surface size is predetermined and so the root
       // layer can't directly support non-identity transforms.  It should just
@@ -2006,8 +2009,6 @@ static void CalculateDrawPropertiesInternal(
         animating_opacity_to_screen;
     data_for_children.parent_matrix = combined_transform;
 
-    layer->ClearRenderSurface();
-
     // Layers without render_surfaces directly inherit the ancestor's clip
     // status.
     layer_or_ancestor_clips_descendants = ancestor_clips_subtree;
@@ -2383,8 +2384,38 @@ static void ProcessCalcDrawPropsInputs(
   data_for_recursion->subtree_is_visible_from_ancestor = true;
 }
 
+void CreateOrDestroyRenderSurface(Layer* layer, gfx::Transform* transform) {
+  if (SubtreeShouldRenderToSeparateSurface(
+          layer,
+          transform->IsIdentity() || transform->Preserves2dAxisAlignment())) {
+    transform->MakeIdentity();
+    layer->SetShouldHaveRenderSurface(true);
+    if (!layer->render_surface()) {
+      layer->CreateRenderSurface();
+    }
+    return;
+  }
+  if (layer->render_surface())
+    layer->ClearRenderSurface();
+  layer->SetShouldHaveRenderSurface(false);
+}
+
+static void CreateRenderSurfaces(Layer* layer,
+                                 const gfx::Transform& parent_transform) {
+  if (!layer)
+    return;
+  gfx::Transform transformForChildren = layer->transform();
+  transformForChildren *= parent_transform;
+  CreateOrDestroyRenderSurface(layer, &transformForChildren);
+
+  for (size_t i = 0; i < layer->children().size(); ++i) {
+    CreateRenderSurfaces(layer->children()[i], transformForChildren);
+  }
+}
+
 void LayerTreeHostCommon::CalculateDrawProperties(
     CalcDrawPropsMainInputs* inputs) {
+  CreateRenderSurfaces(inputs->root_layer, gfx::Transform());
   LayerList dummy_layer_list;
   SubtreeGlobals<Layer> globals;
   DataForRecursion<Layer> data_for_recursion;