Add ClipNode when Render Surface Inherits Clip

cc/trees/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/trees/layer_tree_host_common.h"
 
 #include <algorithm>
 #include <set>
 
 #include "cc/animation/layer_animation_controller.h"
@@ skipping 8222 matching lines @@
   LayerTreeHostCommon::PreCalculateMetaInformationForTesting(root.get());
 
   EXPECT_FALSE(root->layer_or_descendant_is_drawn());
   EXPECT_FALSE(root->visited());
   EXPECT_FALSE(root->sorted_for_recursion());
   EXPECT_FALSE(child->layer_or_descendant_is_drawn());
   EXPECT_FALSE(child->visited());
   EXPECT_FALSE(child->sorted_for_recursion());
 }
 
+TEST_F(LayerTreeHostCommonTest, RenderSurfaceClipsSubtree) {

[jaydasika, 2015/07/30 19:44:46]

This unit test will crash without this patch.

+  // Ensure that a Clip Node is added when a render surface applies clip.
+  LayerImpl* root = root_layer();
+  LayerImpl* significant_transform = AddChildToRoot<LayerImpl>();
+  LayerImpl* layer_clips_subtree = AddChild<LayerImpl>(significant_transform);
+  LayerImpl* render_surface = AddChild<LayerImpl>(layer_clips_subtree);
+  LayerImpl* test_layer = AddChild<LayerImpl>(render_surface);
+
+  const gfx::Transform identity_matrix;
+  gfx::Transform transform1(0.35, 0.0, -0.9, 0.0, 0.87, 0.35, 0.33, 0.0, 0.32,
+                            -0.93, 0.12, 0.0, 0.0, 0.0, -0.0025, 1);
+  gfx::Transform transform2(-1.14, -0.09, +0.32, +7.98, -0.38, -0.19, -0.9366,
+                            +0.04, +0.15, -1.19, +0.12, +17.4304, 0, 0, 0, 1);

[ajuma, 2015/07/30 20:56:50]

I assume these numbers come from an actual page where you observed this, but is
it possible to have 'nicer' transforms and still have a test that fails at ToT
but passes with your patch? That would make this test a lot easier to
understand.

[jaydasika, 2015/07/31 00:46:29]

I am still working on it. transform2 has to be such that it is not axis aligned
with parent.

+
+  layer_clips_subtree->SetMasksToBounds(true);
+  test_layer->SetDrawsContent(true);
+
+  SetLayerPropertiesForTesting(root, identity_matrix, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(30, 30), true, false,
+                               true);
+  SetLayerPropertiesForTesting(significant_transform, transform1,
+                               gfx::Point3F(), gfx::PointF(), gfx::Size(30, 30),
+                               true, false, false);
+  SetLayerPropertiesForTesting(layer_clips_subtree, identity_matrix,
+                               gfx::Point3F(), gfx::PointF(), gfx::Size(30, 30),
+                               true, false, false);
+  SetLayerPropertiesForTesting(render_surface, transform2, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(30, 30), true, false,
+                               true);
+  SetLayerPropertiesForTesting(test_layer, identity_matrix, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(30, 30), true, false,
+                               false);
+
+  ExecuteCalculateDrawProperties(root);
+
+  ClipTree tree = root->layer_tree_impl()->property_trees()->clip_tree;
+  ClipNode* node = tree.Node(3);
+  EXPECT_EQ(node->owner_id, render_surface->id());
+  EXPECT_TRUE(node->data.render_surface_applies_clip);

[ajuma, 2015/07/30 20:56:50]

Please also add an expectation for the test_layer's visible rect (since that's
what's ultimately being fixed by this patch).

[jaydasika, 2015/07/31 00:46:29]

Done.

+}
+
 }  // namespace
 }  // namespace cc