cc: Allow output readback/copy requests to specify a sub-rect to copy.

cc/output/copy_output_request.h

 // Copyright 2013 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 CC_OUTPUT_COPY_OUTPUT_REQUEST_H_
 #define CC_OUTPUT_COPY_OUTPUT_REQUEST_H_
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
-#include "ui/gfx/size.h"
+#include "ui/gfx/rect.h"
 
 class SkBitmap;
 
 namespace cc {
 class CopyOutputResult;
 class TextureMailbox;
 
 class CC_EXPORT CopyOutputRequest {
  public:
   typedef base::Callback<void(scoped_ptr<CopyOutputResult> result)>
       CopyOutputRequestCallback;
 
   static scoped_ptr<CopyOutputRequest> CreateEmptyRequest() {
     return make_scoped_ptr(new CopyOutputRequest);
   }
   static scoped_ptr<CopyOutputRequest> CreateRequest(
       const CopyOutputRequestCallback& result_callback) {
     return make_scoped_ptr(new CopyOutputRequest(false, result_callback));
   }
   static scoped_ptr<CopyOutputRequest> CreateBitmapRequest(
       const CopyOutputRequestCallback& result_callback) {
     return make_scoped_ptr(new CopyOutputRequest(true, result_callback));
   }
   static scoped_ptr<CopyOutputRequest> CreateRelayRequest(
       const CopyOutputRequest& original_request,
       const CopyOutputRequestCallback& result_callback) {
-    return make_scoped_ptr(new CopyOutputRequest(
-        original_request.force_bitmap_result(), result_callback));
+    scoped_ptr<CopyOutputRequest> relay = CreateRequest(result_callback);
+    relay->force_bitmap_result_ = original_request.force_bitmap_result_;
+    relay->has_area_ = original_request.has_area_;
+    relay->area_ = original_request.area_;
+    return relay.Pass();
   }
 
   ~CopyOutputRequest();
 
   bool IsEmpty() const { return result_callback_.is_null(); }
+
   bool force_bitmap_result() const { return force_bitmap_result_; }
 
+  // By default copy requests copy the entire layer's subtree output. If an
+  // area is given, then the intersection of this rect (in layer space) with
+  // the layer's subtree output will be returned.
+  void set_area(gfx::Rect area) {
+    has_area_ = true;
+    area_ = area;
+  }
+  bool has_area() const { return has_area_; }
+  gfx::Rect area() const { return area_; }
+
   void SendResult(scoped_ptr<CopyOutputResult> result);
   void SendBitmapResult(scoped_ptr<SkBitmap> bitmap);
   void SendTextureResult(gfx::Size size,
                          scoped_ptr<TextureMailbox> texture_mailbox);
 
   bool Equals(const CopyOutputRequest& other) const {
     return result_callback_.Equals(other.result_callback_) &&
         force_bitmap_result_ == other.force_bitmap_result_;
   }
 
  private:
   CopyOutputRequest();
   explicit CopyOutputRequest(bool force_bitmap_result,
                              const CopyOutputRequestCallback& result_callback);
 
   bool force_bitmap_result_;
+  bool has_area_;
+  gfx::Rect area_;
   CopyOutputRequestCallback result_callback_;
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_COPY_OUTPUT_REQUEST_H_