Adding overview / layer framework to Activities so that unloaded / sleeping activities can be shown…

athena/content/content_proxy.h

Index: athena/content/content_proxy.h
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+// 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.
+
+#ifndef ATHENA_CONTENT_CONTENT_PROXY_H_
+#define ATHENA_CONTENT_CONTENT_PROXY_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/gfx/image/image_skia.h"
+
+namespace aura {
+class Window;
+}
+
+namespace views {
+class View;
+class WebView;
+}
+
+typedef unsigned int SkColor;
+
+namespace athena {
+
+class Activity;
+class AppActivity;
+class AppActivityProxy;
+class WebActivity;
+
+// This object creates and holds proxy content which gets shown instead of the
+// actual web content, generated from the passed |web_view|.
+// The created |proxy_content_| will be destroyed with the destruction of this
+// object.
+// Calling EvictContent() will release the rendered content and replaces it with
+// a solid color to save memory.
+// Calling Reparent() will transfer the |proxy_content_| to an ActivityProxy,
+// allowing the destruction of the original activity / content.
+class ContentProxy {
+ public:
+  // Creates the object by creating a sized down |web_view| layer and making it
+  // visible inside |activity|'s window.
+  ContentProxy(views::WebView* web_view, Activity* activity);
+  // TODO(skuhne): Add a function to create this object from a passed PNG, so
+  // that we can create it from a session restore.
+
+  // With the destruction of the object, the layer should get destroyed and the
+  // content should become visible again.
+  virtual ~ContentProxy();
+
+  // Called when the content will get unloaded.
+  void ContentWillUnload();
+
+  // Can be called to save resources by creating a layer with a solid color
+  // instead of creating a content image layer.
+  // Note: Currently the GPU does create a full size texture and fills it with
+  // the given color - so there isn't really memory savings yet.
+  void EvictContent();
+
+  // Get the image of the content. If there is no image known, an empty image
+  // will be returned.
+  gfx::ImageSkia GetContentImage();
+
+  // Transfer the owned |proxy_content_| to the |new_parent_window|.
+  // Once called, the |web_view_| will be made visible again and the connection
+  // to it will be removed since the old activity might go away.
+  // Note: This function should only be used by AppActivity.
+  void Reparent(aura::Window* new_parent_window);
+
+ private:
+  // Make the original (web)content visible. This call should only be paired
+  // with HideOriginalContent.
+  void ShowOriginalContent();
+
+  // Make the content invisible. This call should only be paired with
+  // MakeVisible.
+  void HideOriginalContent();
+
+  // Creates proxy content from |web_view_|. If there is no |web_view_|,
+  // a solid |proxy_content_| with |background_color_| will be created.
+  void CreateProxyContent();
+
+  // Creates a solid |proxy_content_| with |background_color_|.
+  void CreateSolidProxyContent();
+
+  // Show the |proxy_content_| in the current |window_|.
+  void ShowProxyContent();
+
+  // Removes the |proxy_content_| from the window again.
+  void HideProxyContent();
+
+  // The web view which is associated with this object. It will be NULL after
+  // the object got called with Reparent(), since the Activity which owns it
+  // will be destroyed shortly after.
+  views::WebView* web_view_;
+
+  // The window which shows our |proxy_content_|,
+  aura::Window* window_;
+
+  // The background color to use when evicted.
+  SkColor background_color_;
+
+  // If we have an image (e.g. from session restore) it is stored here.
+  gfx::ImageSkia image_;
+
+  // True if the content is loaded.
+  bool content_loaded_;
+
+  // The content representation which which will be presented to the user. It
+  // will either contain a shrunken down image of the |web_view| content or a
+  // solid |background_color_|.
+  scoped_ptr<views::View> proxy_content_;
+
+  DISALLOW_COPY_AND_ASSIGN(ContentProxy);
+};
+
+}  // namespace athena
+
+#endif  // ATHENA_CONTENT_CONTENT_PROXY_H_