Implement webview.captureVisibleRegion()

content/browser/frame_host/render_widget_host_view_child_frame.h

 // 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 CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_
 #define CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
+#include <deque>
 #include <vector>
 
+#include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "build/build_config.h"
 #include "cc/resources/returned_resource.h"
 #include "cc/surfaces/surface_factory_client.h"
 #include "cc/surfaces/surface_id_allocator.h"
 #include "content/browser/compositor/image_transport_factory.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/readback_types.h"
@@ skipping 28 matching lines @@
       public cc::SurfaceFactoryClient {
  public:
   explicit RenderWidgetHostViewChildFrame(RenderWidgetHost* widget);
   ~RenderWidgetHostViewChildFrame() override;
 
   void set_cross_process_frame_connector(
       CrossProcessFrameConnector* frame_connector) {
     frame_connector_ = frame_connector;
   }
 
+  // This functions registers single-use callbacks that want to be notified when
+  // the next frame is swapped. The callback is triggered by
+  // OnSwapCompositorFrame, which is the appropriate time to request pixel
+  // readback for the frame that is about to be drawn. Once called, the callback
+  // pointer is released.
+  // TODO(wjmaclean): We should consider making this available in other view
+  // types, such as RenderWidgetHostViewAura.
+  void RegisterFrameSwappedCallback(scoped_ptr<base::Closure> callback);
+
   // RenderWidgetHostView implementation.
   void InitAsChild(gfx::NativeView parent_view) override;
   RenderWidgetHost* GetRenderWidgetHost() const override;
   void SetSize(const gfx::Size& size) override;
   void SetBounds(const gfx::Rect& rect) override;
   void Focus() override;
   bool HasFocus() const override;
   bool IsSurfaceAvailableForCopy() const override;
   void Show() override;
   void Hide() override;
@@ skipping 97 matching lines @@
   void SurfaceDrawn(uint32_t output_surface_id, cc::SurfaceDrawStatus drawn);
 
  protected:
   friend class RenderWidgetHostView;
   friend class RenderWidgetHostViewChildFrameTest;
   friend class RenderWidgetHostViewGuestSurfaceTest;
 
   // Clears current compositor surface, if one is in use.
   void ClearCompositorSurfaceIfNecessary();
 
+  void ProcessFrameSwappedCallbacks();
+
   // The last scroll offset of the view.
   gfx::Vector2dF last_scroll_offset_;
 
   // Members will become private when RenderWidgetHostViewGuest is removed.
   // The model object.
   RenderWidgetHostImpl* host_;
 
   // Flag determining whether we render into a compositing Surface.
   bool use_surfaces_;
 
@@ skipping 10 matching lines @@
 
   // frame_connector_ provides a platform abstraction. Messages
   // sent through it are routed to the embedding renderer process.
   CrossProcessFrameConnector* frame_connector_;
 
   base::WeakPtr<RenderWidgetHostViewChildFrame> AsWeakPtr() {
     return weak_factory_.GetWeakPtr();
   }
 
  private:
+  void SubmitSurfaceCopyRequest(const gfx::Rect& src_subrect,
+                                const gfx::Size& dst_size,
+                                const ReadbackRequestCallback& callback,
+                                const SkColorType preferred_color_type);
+
+  using FrameSwappedCallbackList = std::deque<scoped_ptr<base::Closure>>;
+  // Since frame-drawn callbacks are "fire once", we use std::deque to make
+  // it convenient to swap() when processing the list.
+  FrameSwappedCallbackList frame_swapped_callbacks_;
+
   base::WeakPtrFactory<RenderWidgetHostViewChildFrame> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewChildFrame);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_