cc : Snap texture layers to pixel boundary

cc/trees/layer_tree_host_common_unittest.cc

Index: cc/trees/layer_tree_host_common_unittest.cc
diff --git a/cc/trees/layer_tree_host_common_unittest.cc b/cc/trees/layer_tree_host_common_unittest.cc
index 73f82c08f23181e89cc90abb2ba8005d0cf3176c..4a2a1e527cf04fcb15d675bfc0e12387c877e8c5 100644
--- a/cc/trees/layer_tree_host_common_unittest.cc
+++ b/cc/trees/layer_tree_host_common_unittest.cc
@@ -3525,6 +3525,45 @@ TEST_F(LayerTreeHostCommonTest, OcclusionBySiblingOfTarget) {
   EXPECT_TRUE(expected_occlusion.IsEqual(actual_occlusion));
 }
 
+TEST_F(LayerTreeHostCommonTest, TextureLayerSnapping) {
+  FakeImplTaskRunnerProvider task_runner_provider;
+  TestSharedBitmapManager shared_bitmap_manager;
+  TestTaskGraphRunner task_graph_runner;
+  std::unique_ptr<CompositorFrameSink> compositor_frame_sink =
+      FakeCompositorFrameSink::Create3d();
+  FakeLayerTreeHostImpl host_impl(&task_runner_provider, &shared_bitmap_manager,
+                                  &task_graph_runner);
+
+  std::unique_ptr<LayerImpl> root =
+      LayerImpl::Create(host_impl.active_tree(), 1);
+  std::unique_ptr<TextureLayerImpl> child =
+      TextureLayerImpl::Create(host_impl.active_tree(), 2);
+
+  LayerImpl* child_ptr = child.get();
+
+  root->SetBounds(gfx::Size(100, 100));
+  child->SetBounds(gfx::Size(100, 100));
+  child->SetDrawsContent(true);
+  gfx::Transform fractional_translate;
+  fractional_translate.Translate(10.5f, 10.5f);

[enne (OOO), 2016/10/26 20:32:32]

Can you use a translation in of these components where x and 1-x are not equal
to make sure that there's not a sign error somewhere?

[jaydasika, 2016/10/26 21:49:13]

Done.

+  child->test_properties()->transform = fractional_translate;
+
+  host_impl.SetViewportSize(root->bounds());
+
+  root->test_properties()->AddChild(std::move(child));
+  host_impl.active_tree()->SetRootLayerForTesting(std::move(root));
+  host_impl.SetVisible(true);
+  host_impl.InitializeRenderer(compositor_frame_sink.get());
+  host_impl.active_tree()->BuildLayerListAndPropertyTreesForTesting();
+  bool update_lcd_text = false;
+  host_impl.active_tree()->UpdateDrawProperties(update_lcd_text);
+
+  EXPECT_NE(child_ptr->ScreenSpaceTransform(), fractional_translate);
+  fractional_translate.RoundTranslationComponents();
+  EXPECT_TRANSFORMATION_MATRIX_EQ(child_ptr->ScreenSpaceTransform(),

[enne (OOO), 2016/10/26 20:32:32]

Could you also map this rect into screen space and verify that it's nearly
integers? I have to stare at this to think if fractional translate is right or
it should be the negation of that.

[jaydasika, 2016/10/26 21:49:13]

Done.

+                                  fractional_translate);
+}
+
 TEST_F(LayerTreeHostCommonTest,
        OcclusionForLayerWithUninvertibleDrawTransform) {
   FakeImplTaskRunnerProvider task_runner_provider;