Mus: Fixes rendering of transparent containers.

components/mus/ws/platform_display_unittest.cc

Index: components/mus/ws/platform_display_unittest.cc
diff --git a/components/mus/ws/platform_display_unittest.cc b/components/mus/ws/platform_display_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ad0e660a51e97b3aecd63571d2eb7f015a647f8d
--- /dev/null
+++ b/components/mus/ws/platform_display_unittest.cc
@@ -0,0 +1,141 @@
+// Copyright 2016 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 <memory>
+
+#include "base/memory/ptr_util.h"
+#include "base/test/test_message_loop.h"
+#include "cc/quads/render_pass.h"
+#include "cc/quads/shared_quad_state.h"
+#include "components/mus/ws/platform_display.h"
+#include "components/mus/ws/server_window.h"
+#include "components/mus/ws/server_window_surface_manager.h"
+#include "components/mus/ws/test_server_window_delegate.h"
+#include "components/mus/ws/test_utils.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace mus {
+namespace ws {
+namespace test {
+namespace {
+
+// Makes the window visible and creates the default surface for it.
+void InitWindow(ServerWindow* window) {
+  window->SetVisible(true);
+  ServerWindowSurfaceManager* surface_manager =
+      window->GetOrCreateSurfaceManager();
+  surface_manager->CreateSurface(mojom::SurfaceType::DEFAULT,
+                                 mojo::InterfaceRequest<mojom::Surface>(),
+                                 mojom::SurfaceClientPtr());
+}
+
+// Gets the RenderPassList from the |delegated_frame_data| of the
+// CompositorFrame, confirms it has exactly one RenderPass, and returns its
+// SharedQuadStateList.
+cc::SharedQuadStateList* GetSharedQuadStateListFromCompositorFrame(
+    cc::CompositorFrame* cf) {
+  cc::DelegatedFrameData* frame_data = cf->delegated_frame_data.get();
+  EXPECT_TRUE(frame_data);

[sky, 2016/06/27 15:17:08]

If frame_data is null then line 40 crashes. I recommend no assertions in this
function and the caller can assert on the return value.

[mfomitchev, 2016/06/30 22:06:03]

Done.

+  EXPECT_EQ(1u, frame_data->render_pass_list.size());
+  cc::RenderPass* render_pass = frame_data->render_pass_list.back().get();
+  EXPECT_TRUE(render_pass);
+  cc::SharedQuadStateList* quad_state_list =
+      &render_pass->shared_quad_state_list;
+  EXPECT_TRUE(quad_state_list);
+  return quad_state_list;
+}
+
+}  // namespace
+
+class PlatformDisplayTest : public testing::Test {
+ public:
+  PlatformDisplayTest() {}
+  ~PlatformDisplayTest() override {}
+
+  // Calls GenerateCompositorFrame() on the |platform_display_|.
+  std::unique_ptr<cc::CompositorFrame> GenerateCompositorFrame();
+
+  ServerWindow* root_window() {
+    return platform_display_delegate_->GetRootWindow();
+  }
+
+  TestServerWindowDelegate* test_window_delegate() { return &window_delegate_; }
+
+ private:
+  // testing::Test:
+  void SetUp() override;
+  void TearDown() override;
+
+  std::unique_ptr<DefaultPlatformDisplay> platform_display_;
+  std::unique_ptr<TestPlatformDisplayDelegate> platform_display_delegate_;
+  TestServerWindowDelegate window_delegate_;
+
+  // Needed so that Mojo classes can be initialized.
+  base::TestMessageLoop message_loop_;
+
+  DISALLOW_COPY_AND_ASSIGN(PlatformDisplayTest);
+};
+
+std::unique_ptr<cc::CompositorFrame>
+PlatformDisplayTest::GenerateCompositorFrame() {
+  return platform_display_->GenerateCompositorFrame();
+}
+
+void PlatformDisplayTest::SetUp() {
+  testing::Test::SetUp();
+  platform_display_delegate_.reset(new TestPlatformDisplayDelegate(
+      base::WrapUnique(new ServerWindow(&window_delegate_, WindowId()))));
+  platform_display_.reset(
+      new DefaultPlatformDisplay(PlatformDisplayInitParams()));
+  platform_display_->set_delegate_for_testing(platform_display_delegate_.get());
+  InitWindow(root_window());
+}
+
+void PlatformDisplayTest::TearDown() {
+  platform_display_.reset();
+  platform_display_delegate_.reset();
+}
+
+// Tests correctness of the SharedQuadStateList in the CompositorFrame generated
+// by DefaultPlatformDisplay::GenerateCompositorFrame() from the window tree.
+TEST_F(PlatformDisplayTest, GenerateCompositorFrame) {
+  ServerWindow child_window(test_window_delegate(), WindowId());
+  root_window()->Add(&child_window);
+  InitWindow(&child_window);
+  const float root_opacity = .5f;
+  const float child_opacity = .4f;
+  root_window()->SetOpacity(root_opacity);
+  child_window.SetOpacity(child_opacity);
+
+  std::unique_ptr<cc::CompositorFrame> cf = GenerateCompositorFrame();
+  cc::SharedQuadStateList* quad_state_list =
+      GetSharedQuadStateListFromCompositorFrame(cf.get());
+  // Both child and root have a DEFAULT Surface and no underlay Surfaces, so
+  // there should be two SharedQuadStates int he list.
+  EXPECT_EQ(2u, quad_state_list->size());

[sky, 2016/06/27 15:17:08]

How fragile is this code? By that I mean it seems as though it would be easy to
make slight changes to DrawWindowTree() that would effect what gets generated
and have to update this function.

I'm also wondering if we should make it so a test can directly call
DrawWindowTree().

[Fady Samuel, 2016/06/27 15:20:03]

drive-by +1 I think DrawWindowTree and associated methods should move out into a
separate class. WindowTreeFrameGenerator?

[mfomitchev, 2016/06/30 22:06:03]

Switched to testing DrawWindowTree directly. I am still checking the number of
quads that gets generated. I think it should be reasonably stable, since it
should match the number of surfaces per window, which I assume shouldn't change
too much?

+  cc::SharedQuadState* root_sqs = quad_state_list->back();
+  cc::SharedQuadState* child_sqs = quad_state_list->front();
+  EXPECT_EQ(root_opacity, root_sqs->opacity);
+  // Child's SharedQuadState contains the effective opacity of the child layer,
+  // which should be a product of the child and the parent opacity.
+  EXPECT_EQ(child_opacity * root_opacity, child_sqs->opacity);
+
+  // Create the UNDERLAY Surface for the child window, and confirm that this
+  // creates an extra SharedQuadState in the CompositorFrame.
+  child_window.GetOrCreateSurfaceManager()->CreateSurface(
+      mojom::SurfaceType::UNDERLAY, mojo::InterfaceRequest<mojom::Surface>(),
+      mojom::SurfaceClientPtr());
+
+  cf = GenerateCompositorFrame();
+  quad_state_list = GetSharedQuadStateListFromCompositorFrame(cf.get());
+  EXPECT_EQ(3u, quad_state_list->size());
+  auto it = quad_state_list->begin();
+  EXPECT_EQ(child_opacity * root_opacity, (*it)->opacity);
+  EXPECT_EQ(child_opacity * root_opacity, (*++it)->opacity);
+  EXPECT_EQ(root_opacity, (*++it)->opacity);
+}
+
+}  // namespace test
+}  // namespace ws
+}  // namespace mus