Don't create render passes for transparent images.

cc/layer_tree_host_common_unittest.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/layer_tree_host_common.h"
 
 #include "cc/content_layer.h"
 #include "cc/content_layer_client.h"
 #include "cc/layer.h"
 #include "cc/layer_animation_controller.h"
@@ skipping 323 matching lines @@
     root->addChild(parent);
     parent->addChild(child);
     child->addChild(grandChild);
 
     // One-time setup of root layer
     WebTransformationMatrix identityMatrix;
     setLayerPropertiesForTesting(root.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(1, 2), false);
 
     // Child is set up so that a new render surface should be created.
     child->setOpacity(0.5);
+    child->setForceRenderSurface(true);
 
     WebTransformationMatrix parentLayerTransform;
     parentLayerTransform.scale3d(1, 0.9, 1);
     WebTransformationMatrix parentTranslationToAnchor;
     parentTranslationToAnchor.translate(25, 30);
     WebTransformationMatrix parentSublayerMatrix;
     parentSublayerMatrix.scale3d(0.9, 1, 3.3);
     WebTransformationMatrix parentTranslationToCenter;
     parentTranslationToCenter.translate(50, 60);
     WebTransformationMatrix parentCompositeTransform = parentTranslationToAnchor * parentLayerTransform * parentTranslationToAnchor.inverse()
@@ skipping 1008 matching lines @@
 
     setLayerPropertiesForTesting(parent.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(500, 500), false);
     setLayerPropertiesForTesting(child.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(20, 20), false);
     setLayerPropertiesForTesting(grandChild.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(45, 45), gfx::Size(10, 10), false);
     setLayerPropertiesForTesting(greatGrandChild.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(10, 10), false);
     setLayerPropertiesForTesting(leafNode1.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(500, 500), false);
     setLayerPropertiesForTesting(leafNode2.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(20, 20), false);
 
     child->setMasksToBounds(true);
     child->setOpacity(0.4f);
+    child->setForceRenderSurface(true);
     grandChild->setOpacity(0.5);
     greatGrandChild->setOpacity(0.4f);
 
     std::vector<scoped_refptr<Layer> > renderSurfaceLayerList;
     int dummyMaxTextureSize = 512;
     LayerTreeHostCommon::calculateDrawTransforms(parent.get(), parent->bounds(), 1, 1, dummyMaxTextureSize, renderSurfaceLayerList);
 
     ASSERT_EQ(2U, renderSurfaceLayerList.size());
     EXPECT_EQ(parent->id(), renderSurfaceLayerList[0]->id());
     EXPECT_EQ(child->id(), renderSurfaceLayerList[1]->id());
@@ skipping 26 matching lines @@
     child->addChild(grandChild);
     grandChild->addChild(leafNode);
 
     setLayerPropertiesForTesting(parent.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(100, 100), false);
     setLayerPropertiesForTesting(child.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(20, 20), false);
     setLayerPropertiesForTesting(grandChild.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(200, 200), gfx::Size(10, 10), false);
     setLayerPropertiesForTesting(leafNode.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(10, 10), false);
 
     parent->setMasksToBounds(true);
     child->setOpacity(0.4f);
+    child->setForceRenderSurface(true);
     grandChild->setOpacity(0.4f);
+    grandChild->setForceRenderSurface(true);
 
     std::vector<scoped_refptr<Layer> > renderSurfaceLayerList;
     int dummyMaxTextureSize = 512;
     LayerTreeHostCommon::calculateDrawTransforms(parent.get(), parent->bounds(), 1, 1, dummyMaxTextureSize, renderSurfaceLayerList);
 
     // Without an animation, we should cull child and grandChild from the renderSurfaceLayerList.
     ASSERT_EQ(1U, renderSurfaceLayerList.size());
     EXPECT_EQ(parent->id(), renderSurfaceLayerList[0]->id());
 
     // Now put an animating transform on child.
@@ skipping 207 matching lines @@
     setLayerPropertiesForTesting(leafNode2.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(10, 10), false);
     setLayerPropertiesForTesting(leafNode3.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(10, 10), false);
     setLayerPropertiesForTesting(leafNode4.get(), identityMatrix, identityMatrix, gfx::PointF(0, 0), gfx::PointF(0, 0), gfx::Size(10, 10), false);
 
     child->setMasksToBounds(true);
     grandChild3->setMasksToBounds(true);
     grandChild4->setMasksToBounds(true);
 
     // Force everyone to be a render surface.
     child->setOpacity(0.4f);
+    child->setForceRenderSurface(true);
     grandChild1->setOpacity(0.5);
+    grandChild1->setForceRenderSurface(true);
     grandChild2->setOpacity(0.5);
+    grandChild2->setForceRenderSurface(true);
     grandChild3->setOpacity(0.5);
+    grandChild3->setForceRenderSurface(true);
     grandChild4->setOpacity(0.5);
+    grandChild4->setForceRenderSurface(true);
 
     std::vector<scoped_refptr<Layer> > renderSurfaceLayerList;
     int dummyMaxTextureSize = 512;
     LayerTreeHostCommon::calculateDrawTransforms(parent.get(), parent->bounds(), 1, 1, dummyMaxTextureSize, renderSurfaceLayerList);
 
     ASSERT_TRUE(grandChild1->renderSurface());
     ASSERT_TRUE(grandChild2->renderSurface());
     ASSERT_TRUE(grandChild3->renderSurface());
     EXPECT_FALSE(grandChild4->renderSurface()); // Because grandChild4 is entirely clipped, it is expected to not have a renderSurface.
 
@@ skipping 2958 matching lines @@
 
     int nonexistentId = -1;
     EXPECT_EQ(root, LayerTreeHostCommon::findLayerInSubtree(root.get(), root->id()));
     EXPECT_EQ(child, LayerTreeHostCommon::findLayerInSubtree(root.get(), child->id()));
     EXPECT_EQ(grandChild, LayerTreeHostCommon::findLayerInSubtree(root.get(), grandChild->id()));
     EXPECT_EQ(maskLayer, LayerTreeHostCommon::findLayerInSubtree(root.get(), maskLayer->id()));
     EXPECT_EQ(replicaLayer, LayerTreeHostCommon::findLayerInSubtree(root.get(), replicaLayer->id()));
     EXPECT_EQ(0, LayerTreeHostCommon::findLayerInSubtree(root.get(), nonexistentId));
 }
 
+TEST(LayerTreeHostCommonTest, verifyTransparentImageRenderSurfaceCreation)
+{
+    // Make sure that we don't create render passes for transparent images.

[jamesr, 2012/11/27 01:34:46]

this test doesn't appear to have anything to do with image layers in particular,
it's more about opacity with exactly 1 descendant that draws - could you refine
the comment + test name?

+    scoped_refptr<Layer> root = Layer::create();
+    scoped_refptr<Layer> child = Layer::create();
+    scoped_refptr<LayerWithForcedDrawsContent> grandChild = make_scoped_refptr(new LayerWithForcedDrawsContent());
+
+    const WebTransformationMatrix identityMatrix;
+    setLayerPropertiesForTesting(root.get(), identityMatrix, identityMatrix, gfx::PointF(), gfx::PointF(), gfx::Size(100, 100), false);
+    setLayerPropertiesForTesting(child.get(), identityMatrix, identityMatrix, gfx::PointF(), gfx::PointF(), gfx::Size(10, 10), false);
+    setLayerPropertiesForTesting(grandChild.get(), identityMatrix, identityMatrix, gfx::PointF(), gfx::PointF(), gfx::Size(10, 10), false);
+
+    root->addChild(child);
+    child->addChild(grandChild);
+    child->setOpacity(0.5f);
+
+    executeCalculateDrawTransformsAndVisibility(root.get());
+
+    EXPECT_FALSE(child->renderSurface());
+}
+
 }  // namespace
 }  // namespace cc