Use the scheduler to drive the Sky compositor

examples/sky_compositor_app/sky_compositor_app.cc

 // Copyright 2014 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 "base/macros.h"
 #include "mojo/application/application_runner_chromium.h"
 #include "mojo/public/c/system/main.h"
 #include "mojo/public/cpp/application/application_connection.h"
 #include "mojo/public/cpp/application/application_delegate.h"
 #include "mojo/public/cpp/application/application_impl.h"
 #include "mojo/services/public/cpp/view_manager/view.h"
 #include "mojo/services/public/cpp/view_manager/view_manager.h"
 #include "mojo/services/public/cpp/view_manager/view_manager_client_factory.h"
 #include "mojo/services/public/cpp/view_manager/view_manager_delegate.h"
 #include "sky/compositor/layer.h"
 #include "sky/compositor/layer_host.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 
 namespace examples {
 namespace {
 
 gfx::Size ToSize(const mojo::Rect& rect) {
   return gfx::Size(rect.width, rect.height);
 }
+
+int RadiusAt(base::TimeDelta delta) {
+  return 50 + (delta.InMilliseconds() % 6000) * 100 / 6000;
+}
 }
 
 class SkyCompositorApp : public mojo::ApplicationDelegate,
                          public mojo::ViewManagerDelegate,
                          public sky::LayerClient,
                          public sky::LayerHostClient {
  public:
   SkyCompositorApp() : shell_(nullptr), view_(nullptr) {}
   virtual ~SkyCompositorApp() {}
 
   void Initialize(mojo::ApplicationImpl* app) override {
     shell_ = app->shell();
     view_manager_client_factory_.reset(
         new mojo::ViewManagerClientFactory(app->shell(), this));
   }
 
   bool ConfigureIncomingConnection(
       mojo::ApplicationConnection* connection) override {
     connection->AddService(view_manager_client_factory_.get());
     return true;
   }
 
   void OnEmbed(mojo::ViewManager* view_manager,
                mojo::View* root,
                mojo::ServiceProviderImpl* exported_services,
                scoped_ptr<mojo::ServiceProvider> imported_services) override {
     view_ = root;
+    base_time_ = base::TimeTicks::Now();
 
     layer_host_.reset(new sky::LayerHost(this));
     root_layer_ = make_scoped_refptr(new sky::Layer(this));
     layer_host_->SetRootLayer(root_layer_);
+    layer_host_->SetNeedsAnimate();
   }
 
   void OnViewManagerDisconnected(mojo::ViewManager* view_manager) override {
     base::MessageLoop::current()->Quit();
   }
 
  private:
   // sky::LayerHostClient
   mojo::Shell* GetShell() override { return shell_; }
 
-  void BeginFrame() override { root_layer_->SetSize(ToSize(view_->bounds())); }
+  void BeginFrame(base::TimeTicks frame_time) override {
+    root_layer_->SetSize(ToSize(view_->bounds()));
+    layer_host_->SetNeedsAnimate();
+  }
 
   void OnSurfaceIdAvailable(mojo::SurfaceIdPtr surface_id) override {
     view_->SetSurfaceId(surface_id.Pass());
   }
 
   // sky::LayerHostClient
   void PaintContents(SkCanvas* canvas, const gfx::Rect& clip) override {
+    base::TimeTicks frame_time = base::TimeTicks::Now();
+    printf("Frame delta: %f\n",
+           (frame_time - last_frame_time_).InMillisecondsF());
+    last_frame_time_ = frame_time;
+
+    canvas->clear(SK_ColorGREEN);
     SkPaint paint;
-    paint.setColor(SK_ColorGREEN);
+    paint.setColor(SK_ColorBLUE);
     paint.setFlags(SkPaint::kAntiAlias_Flag);
-    canvas->drawCircle(50, 100, 100, paint);
+    canvas->drawCircle(50, 100, RadiusAt(frame_time - base_time_), paint);
   }
 
   mojo::Shell* shell_;
   scoped_ptr<mojo::ViewManagerClientFactory> view_manager_client_factory_;
   mojo::View* view_;
 
   scoped_ptr<sky::LayerHost> layer_host_;
   scoped_refptr<sky::Layer> root_layer_;
 
+  base::TimeTicks base_time_;
+  base::TimeTicks last_frame_time_;
+
   DISALLOW_COPY_AND_ASSIGN(SkyCompositorApp);
 };
 
 }  // namespace examples
 
 MojoResult MojoMain(MojoHandle handle) {
   mojo::ApplicationRunnerChromium runner(new examples::SkyCompositorApp);
   return runner.Run(handle);
 }