cc: Don't draw and swap if the frame will not change.

cc/trees/layer_tree_host_unittest_damage.cc

Index: cc/trees/layer_tree_host_unittest_damage.cc
diff --git a/cc/trees/layer_tree_host_unittest_damage.cc b/cc/trees/layer_tree_host_unittest_damage.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a66b798a107b30c0041201479a2cea7e384763ea
--- /dev/null
+++ b/cc/trees/layer_tree_host_unittest_damage.cc
@@ -0,0 +1,275 @@
+// Copyright 2012 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.h"
+
+#include "cc/test/fake_content_layer.h"
+#include "cc/test/fake_content_layer_client.h"
+#include "cc/test/layer_tree_test.h"
+#include "cc/trees/damage_tracker.h"
+#include "cc/trees/layer_tree_impl.h"
+
+namespace cc {
+namespace {
+
+// These tests deal with damage tracking.
+class LayerTreeHostDamageTest : public LayerTreeTest {};
+
+class LayerTreeHostDamageTestNoDamageDoesNotSwap
+    : public LayerTreeHostDamageTest {
+  virtual void BeginTest() OVERRIDE {
+    expect_swap_and_succeed_ = 0;
+    did_swaps_ = 0;
+    did_swap_and_succeed_ = 0;
+    PostSetNeedsCommitToMainThread();
+  }
+
+  virtual void SetupTree() OVERRIDE {
+    scoped_refptr<FakeContentLayer> root = FakeContentLayer::Create(&client_);
+    root->SetBounds(gfx::Size(10, 10));
+
+    // Most of the layer isn't visible.
+    content_ = FakeContentLayer::Create(&client_);
+    content_->SetBounds(gfx::Size(100, 100));
+    root->AddChild(content_);
+
+    layer_tree_host()->SetRootLayer(root);
+    LayerTreeHostDamageTest::SetupTree();
+  }
+
+  virtual bool PrepareToDrawOnThread(LayerTreeHostImpl* host_impl,
+                                     LayerTreeHostImpl::FrameData* frame_data,
+                                     bool result) OVERRIDE {
+    EXPECT_TRUE(result);
+
+    int source_frame = host_impl->active_tree()->source_frame_number();
+    switch (source_frame) {
+      case 0:
+        // The first frame has damage, so we should draw and swap.
+        ++expect_swap_and_succeed_;
+        break;
+      case 1:
+        // The second frame has no damage, so we should not draw and swap.
+        break;
+      case 2:
+        // The third frame has damage again, so we should draw and swap.
+        ++expect_swap_and_succeed_;
+        break;
+      case 3:
+        // The fourth frame has no visible damage, so we should not draw and
+        // swap.
+        EndTest();
+        break;
+    }
+    return result;
+  }
+
+  virtual void SwapBuffersOnThread(LayerTreeHostImpl* host_impl,
+                                   bool result) OVERRIDE {
+    ++did_swaps_;
+    if (result)
+      ++did_swap_and_succeed_;
+    EXPECT_EQ(expect_swap_and_succeed_, did_swap_and_succeed_);
+  }
+
+  virtual void DidCommit() OVERRIDE {
+    int next_frame = layer_tree_host()->commit_number();
+    switch (next_frame) {
+      case 1:
+        layer_tree_host()->SetNeedsCommit();
+        break;
+      case 2:
+        // Cause visible damage.
+        content_->SetNeedsDisplayRect(
+            gfx::Rect(layer_tree_host()->layout_viewport_size()));
+        break;
+      case 3:
+        // Cause non-visible damage.
+        content_->SetNeedsDisplayRect(gfx::Rect(90, 90, 10, 10));
+        break;
+    }
+  }
+
+  virtual void AfterTest() OVERRIDE {
+    EXPECT_EQ(4, did_swaps_);
+    EXPECT_EQ(2, expect_swap_and_succeed_);
+    EXPECT_EQ(expect_swap_and_succeed_, did_swap_and_succeed_);
+  }
+
+  FakeContentLayerClient client_;
+  scoped_refptr<FakeContentLayer> content_;
+  int expect_swap_and_succeed_;
+  int did_swaps_;
+  int did_swap_and_succeed_;
+};
+
+SINGLE_AND_MULTI_THREAD_TEST_F(LayerTreeHostDamageTestNoDamageDoesNotSwap);
+
+class LayerTreeHostDamageTestNoDamageReadbackDoesDraw
+    : public LayerTreeHostDamageTest {
+  virtual void BeginTest() OVERRIDE {
+    PostSetNeedsCommitToMainThread();
+  }
+
+  virtual void SetupTree() OVERRIDE {
+    scoped_refptr<FakeContentLayer> root = FakeContentLayer::Create(&client_);
+    root->SetBounds(gfx::Size(10, 10));
+
+    // Most of the layer isn't visible.
+    content_ = FakeContentLayer::Create(&client_);
+    content_->SetBounds(gfx::Size(100, 100));
+    root->AddChild(content_);
+
+    layer_tree_host()->SetRootLayer(root);
+    LayerTreeHostDamageTest::SetupTree();
+  }
+
+  virtual bool PrepareToDrawOnThread(LayerTreeHostImpl* host_impl,
+                                     LayerTreeHostImpl::FrameData* frame_data,
+                                     bool result) OVERRIDE {
+    EXPECT_TRUE(result);
+
+    int source_frame = host_impl->active_tree()->source_frame_number();
+    switch (source_frame) {
+      case 0:
+        // The first frame draws and clears any damage.
+        break;
+      case 1: {
+        // The second frame is a readback, we should have damage in the readback
+        // rect, but not swap.
+        RenderSurfaceImpl* root_surface =
+            host_impl->active_tree()->root_layer()->render_surface();
+        gfx::RectF root_damage =
+            root_surface->damage_tracker()->current_damage_rect();
+        root_damage.Intersect(root_surface->content_rect());
+        EXPECT_TRUE(root_damage.Contains(gfx::Rect(3, 3, 1, 1)));
+        break;
+      }
+      case 2:
+        NOTREACHED();
+        break;
+    }
+    return result;
+  }
+
+  virtual void DidCommitAndDrawFrame() OVERRIDE {
+    int next_frame = layer_tree_host()->commit_number();
+    switch (next_frame) {
+      case 1: {
+        char pixels[4];
+        layer_tree_host()->CompositeAndReadback(static_cast<void*>(&pixels),
+                                                gfx::Rect(3, 3, 1, 1));
+        EndTest();
+        break;
+      }
+    }
+  }
+
+  virtual void AfterTest() OVERRIDE {}
+
+  FakeContentLayerClient client_;
+  scoped_refptr<FakeContentLayer> content_;
+};
+
+SINGLE_AND_MULTI_THREAD_TEST_F(LayerTreeHostDamageTestNoDamageReadbackDoesDraw);
+
+class LayerTreeHostDamageTestForcedFullDamage : public LayerTreeHostDamageTest {
+  virtual void BeginTest() OVERRIDE {
+    PostSetNeedsCommitToMainThread();
+  }
+
+  virtual void SetupTree() OVERRIDE {
+    root_ = FakeContentLayer::Create(&client_);
+    child_ = FakeContentLayer::Create(&client_);
+
+    root_->SetBounds(gfx::Size(500, 500));
+    child_->SetPosition(gfx::Point(100, 100));
+    child_->SetBounds(gfx::Size(30, 30));
+
+    root_->AddChild(child_);
+    layer_tree_host()->SetRootLayer(root_);
+    LayerTreeHostDamageTest::SetupTree();
+  }
+
+  virtual bool PrepareToDrawOnThread(LayerTreeHostImpl* host_impl,
+                                     LayerTreeHostImpl::FrameData* frame_data,
+                                     bool result) OVERRIDE {
+    EXPECT_TRUE(result);
+
+    RenderSurfaceImpl* root_surface =
+        host_impl->active_tree()->root_layer()->render_surface();
+    gfx::RectF root_damage =
+        root_surface->damage_tracker()->current_damage_rect();
+    root_damage.Intersect(root_surface->content_rect());
+
+    int source_frame = host_impl->active_tree()->source_frame_number();
+    switch (source_frame) {
+      case 0:
+        // The first frame draws and clears any damage.
+        EXPECT_EQ(gfx::RectF(root_surface->content_rect()).ToString(),
+                  root_damage.ToString());
+        EXPECT_FALSE(frame_data->has_no_damage);
+        break;
+      case 1:
+        // If we get a frame without damage then we don't draw.
+        EXPECT_EQ(gfx::RectF().ToString(), root_damage.ToString());
+        EXPECT_TRUE(frame_data->has_no_damage);
+
+        // Then we set full damage for the next frame.
+        host_impl->SetFullRootLayerDamage();
+        break;
+      case 2:
+        // The whole frame should be damaged as requested.
+        EXPECT_EQ(gfx::RectF(root_surface->content_rect()).ToString(),
+                  root_damage.ToString());
+        EXPECT_FALSE(frame_data->has_no_damage);
+
+        // Just a part of the next frame should be damaged.
+        child_damage_rect_ = gfx::RectF(10, 11, 12, 13);
+        break;
+      case 3:
+        // The update rect in the child should be damaged.
+        EXPECT_EQ(gfx::RectF(100+10, 100+11, 12, 13).ToString(),
+                  root_damage.ToString());
+        EXPECT_FALSE(frame_data->has_no_damage);
+
+        // If we damage part of the frame, but also damage the full
+        // frame, then the whole frame should be damaged.
+        child_damage_rect_ = gfx::RectF(10, 11, 12, 13);
+        host_impl->SetFullRootLayerDamage();
+        break;
+      case 4:
+        // The whole frame is damaged.
+        EXPECT_EQ(gfx::RectF(root_surface->content_rect()).ToString(),
+                  root_damage.ToString());
+        EXPECT_FALSE(frame_data->has_no_damage);
+
+        EndTest();
+        break;
+    }
+    return result;
+  }
+
+  virtual void DidCommitAndDrawFrame() OVERRIDE {
+    if (!TestEnded())
+      layer_tree_host()->SetNeedsCommit();
+
+    if (!child_damage_rect_.IsEmpty()) {
+      child_->SetNeedsDisplayRect(child_damage_rect_);
+      child_damage_rect_ = gfx::RectF();
+    }
+  }
+
+  virtual void AfterTest() OVERRIDE {}
+
+  FakeContentLayerClient client_;
+  scoped_refptr<FakeContentLayer> root_;
+  scoped_refptr<FakeContentLayer> child_;
+  gfx::RectF child_damage_rect_;
+};
+
+SINGLE_AND_MULTI_THREAD_TEST_F(LayerTreeHostDamageTestForcedFullDamage);
+
+}  // namespace
+}  // namespace cc