Changes subtreeShouldRenderToSeparateSurface logic to account for explicit clipping

cc/layer_tree_host_common_unittest.cc

Index: cc/layer_tree_host_common_unittest.cc
diff --git a/cc/layer_tree_host_common_unittest.cc b/cc/layer_tree_host_common_unittest.cc
index 15776469e6911b7405d9179195c8d3e60451b0b2..88dee5b8e60ed2d0ea98412a8491c35ea946598e 100644
--- a/cc/layer_tree_host_common_unittest.cc
+++ b/cc/layer_tree_host_common_unittest.cc
@@ -113,6 +113,22 @@ private:
     }
 };
 
+class LayerCanClipSelf : public Layer {
+public:
+    LayerCanClipSelf()
+        : Layer()
+    {
+    }
+
+    virtual bool drawsContent() const OVERRIDE { return true; }
+    virtual bool canClipSelf() const OVERRIDE { return true; }
+
+private:
+    virtual ~LayerCanClipSelf()
+    {
+    }
+};
+
 class MockContentLayerClient : public ContentLayerClient {
 public:
     MockContentLayerClient() { }
@@ -335,6 +351,7 @@ TEST(LayerTreeHostCommonTest, verifyTransformsForSingleRenderSurface)
     parentTranslationToAnchor.Translate(25, 30);
     gfx::Transform parentSublayerMatrix;
     parentSublayerMatrix.Scale3d(0.9, 1, 3.3);
+
     gfx::Transform parentTranslationToCenter;
     parentTranslationToCenter.Translate(50, 60);
     gfx::Transform parentCompositeTransform = parentTranslationToAnchor * parentLayerTransform * MathUtil::inverse(parentTranslationToAnchor)
@@ -369,6 +386,91 @@ TEST(LayerTreeHostCommonTest, verifyTransformsForSingleRenderSurface)
     EXPECT_TRANSFORMATION_MATRIX_EQ(surfaceSublayerCompositeTransform, child->renderTarget()->renderSurface()->screenSpaceTransform());
 }
 
+TEST(LayerTreeHostCommonTest, verifySeparateRenderTargetRequirement)
+{
+  {
+      scoped_refptr<Layer> root = Layer::create();
+      scoped_refptr<Layer> parent = Layer::create();
+      scoped_refptr<Layer> child = Layer::create();
+      scoped_refptr<Layer> grandChild = make_scoped_refptr(new LayerCanClipSelf());
+      root->addChild(parent);
+      parent->addChild(child);
+      child->addChild(grandChild);
+      parent->setMasksToBounds(true);
+      child->setMasksToBounds(true);
+
+      gfx::Transform identityMatrix;
+      gfx::Transform parentLayerTransform;
+      gfx::Transform parentSublayerMatrix;
+      gfx::Transform childLayerMatrix;
+
+      // No render surface should exist yet.
+      ASSERT_FALSE(root->renderSurface());

[danakj, 2012/12/19 22:46:56]

nit: you can use EXPECT_ for these tests. generally we only use ASSERT_ for
something like checking the size of an array, to avoid crashing afterward.

+      ASSERT_FALSE(parent->renderSurface());
+      ASSERT_FALSE(child->renderSurface());
+      ASSERT_FALSE(grandChild->renderSurface());
+
+      // One-time setup of root layer
+      parentLayerTransform.Scale3d(1, 0.9, 1);
+      parentSublayerMatrix.Scale3d(0.9, 1, 3.3);
+      childLayerMatrix.Rotate(20);
+
+      setLayerPropertiesForTesting(root      .get(), identityMatrix      , identityMatrix      , gfx::PointF(   0,    0), gfx::PointF(0, 0), gfx::Size(  1,   2), false);

[danakj, 2012/12/19 22:46:56]

these extra spaces are funny, i'd remove them. lining up things across lines is
generally bad and makes future diffs larger.

[whunt, 2013/01/04 19:12:27]

I'm actually surprised about the push-back I get for block formatting here at
Google.  Block formatting makes the code easier to read (as a block) and makes
it easier to spot errors/inconsistencies between lines.  On top of that it
improves programmer productivity by enabling block editing in good editors.

I've never worked anywhere it wasn't considered good.

I removed the spaces as requested but if I were to debug this code the first
thing I would do is add them back so I could easily check for inconsistencies
between lines.
 
On 2012/12/19 22:46:56, danakj wrote:

+      setLayerPropertiesForTesting(parent    .get(), parentLayerTransform, parentSublayerMatrix, gfx::PointF(0.25, 0.25), gfx::PointF(0, 0), gfx::Size(100, 120), false);
+      setLayerPropertiesForTesting(child     .get(), childLayerMatrix    , identityMatrix      , gfx::PointF(   0,    0), gfx::PointF(0, 0), gfx::Size( 16,  18), false);
+      setLayerPropertiesForTesting(grandChild.get(), identityMatrix      , identityMatrix      , gfx::PointF(   0,    0), gfx::PointF(0, 0), gfx::Size(  8,  10), false);
+
+      executeCalculateDrawProperties(root.get());
+
+      // Render surfaces should have been created according to clipping rules now (grandchild can clip self).
+      ASSERT_TRUE(root->renderSurface());
+      ASSERT_FALSE(parent->renderSurface());
+      ASSERT_FALSE(child->renderSurface());
+      ASSERT_FALSE(grandChild->renderSurface());
+  }
+  {

[danakj, 2012/12/19 22:46:56]

if you made LayerCanClipSelf let you change the canClipSelf value, you could
avoid all this 2nd copy of boilerplate code here, and just
grandChild->setCanClipSelf(false), and run executeCalcDrawProps() again.

+      scoped_refptr<Layer> root = Layer::create();
+      scoped_refptr<Layer> parent = Layer::create();
+      scoped_refptr<Layer> child = Layer::create();
+      // This layer cannot clip itself, a feature we are testing here.
+      scoped_refptr<Layer> grandChild = make_scoped_refptr(new LayerWithForcedDrawsContent());
+      root->addChild(parent);
+      parent->addChild(child);
+      child->addChild(grandChild);
+      parent->setMasksToBounds(true);
+      child->setMasksToBounds(true);
+
+      gfx::Transform identityMatrix;
+      gfx::Transform parentLayerTransform;
+      gfx::Transform parentSublayerMatrix;
+      gfx::Transform childLayerMatrix;
+
+      // No render surface should exist yet.
+      ASSERT_FALSE(root->renderSurface());
+      ASSERT_FALSE(parent->renderSurface());
+      ASSERT_FALSE(child->renderSurface());
+      ASSERT_FALSE(grandChild->renderSurface());
+
+      // One-time setup of root layer
+      parentLayerTransform.Scale3d(1, 0.9, 1);
+      parentSublayerMatrix.Scale3d(0.9, 1, 3.3);
+      childLayerMatrix.Rotate(20);
+
+      setLayerPropertiesForTesting(root      .get(), identityMatrix      , identityMatrix      , gfx::PointF(   0,    0), gfx::PointF(0, 0), gfx::Size(  1,   2), false);

[danakj, 2012/12/19 22:46:56]

same here

+      setLayerPropertiesForTesting(parent    .get(), parentLayerTransform, parentSublayerMatrix, gfx::PointF(0.25, 0.25), gfx::PointF(0, 0), gfx::Size(100, 120), false);
+      setLayerPropertiesForTesting(child     .get(), childLayerMatrix    , identityMatrix      , gfx::PointF(   0,    0), gfx::PointF(0, 0), gfx::Size( 16,  18), false);
+      setLayerPropertiesForTesting(grandChild.get(), identityMatrix      , identityMatrix      , gfx::PointF(   0,    0), gfx::PointF(0, 0), gfx::Size(  8,  10), false);
+
+      executeCalculateDrawProperties(root.get());
+
+      // Render surfaces should have been created according to clipping rules now (grandchild can't clip self).
+      ASSERT_TRUE(root->renderSurface());
+      ASSERT_FALSE(parent->renderSurface());
+      ASSERT_TRUE(child->renderSurface());
+      ASSERT_FALSE(grandChild->renderSurface());
+  }
+}
+
 TEST(LayerTreeHostCommonTest, verifyTransformsForReplica)
 {
     scoped_refptr<Layer> root = Layer::create();