[Athena] minimum impl to add screen/background and test windows

athena/screen/background_controller.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 "athena/screen/background_controller.h"
+
+#include "ui/aura/window.h"
+#include "ui/compositor/layer.h"
+#include "ui/gfx/canvas.h"
+#include "ui/gfx/image/image_skia.h"
+#include "ui/views/view.h"
+#include "ui/views/widget/widget.h"
+
+namespace athena {
+
+class BackgroundView : public views::View {
+ public:
+  BackgroundView() {}
+  virtual ~BackgroundView() {}
+
+  void SetImage(const gfx::ImageSkia& image) {
+    image_ = image;
+    SchedulePaint();
+  }
+
+  // views::View
+  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE {
+    canvas->DrawImageInt(image_,
+                         0,
+                         0,
+                         image_.width(),
+                         image_.height(),
+                         0,
+                         0,
+                         width(),
+                         height(),
+                         true);
+  }
+
+ private:
+  gfx::ImageSkia image_;
+
+  DISALLOW_COPY_AND_ASSIGN(BackgroundView);
+};
+
+BackgroundController::BackgroundController(aura::Window* container) {
+  // TODO(oshima): Using widget to just draw an image is probably
+  // overkill. Just use WindowDelegate to draw the background and
+  // remove dependency to ui/views.
+
+  views::Widget* background_widget = new views::Widget;
+  views::Widget::InitParams params(
+      views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
+  params.parent = container;
+  background_widget->Init(params);
+  background_widget->GetNativeWindow()->layer()->SetMasksToBounds(true);
+  background_view_ = new BackgroundView;
+  background_widget->SetContentsView(background_view_);
+  background_widget->Show();
+}
+
+BackgroundController::~BackgroundController() {
+  // background_widget is owned by the container and will be deleted
+  // when the container is deleted.
+}
+
+void BackgroundController::SetImage(const gfx::ImageSkia& image) {
+  // TODO(oshima): implement cross fede animation.
+  background_view_->SetImage(image);
+}
+
+}  // namespace athena