Allow CopyFromBackingStore to fallback to copying from the renderer side if the accelerated surface…

content/renderer/render_view_impl.cc

 // Copyright (c) 2012 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 "content/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/auto_reset.h"
@@ skipping 1098 matching lines @@
                         OnPluginImeCompositionCompleted)
     IPC_MESSAGE_HANDLER(ViewMsg_SelectPopupMenuItem, OnSelectPopupMenuItem)
     IPC_MESSAGE_HANDLER(ViewMsg_SetInLiveResize, OnSetInLiveResize)
     IPC_MESSAGE_HANDLER(ViewMsg_SetWindowVisibility, OnSetWindowVisibility)
     IPC_MESSAGE_HANDLER(ViewMsg_WindowFrameChanged, OnWindowFrameChanged)
 #endif
     IPC_MESSAGE_HANDLER(ViewMsg_ReleaseDisambiguationPopupDIB,
                         OnReleaseDisambiguationPopupDIB)
     IPC_MESSAGE_HANDLER(ViewMsg_WindowSnapshotCompleted,
                         OnWindowSnapshotCompleted)
+    IPC_MESSAGE_HANDLER(ViewMsg_Snapshot, OnSnapshot)
 
     // Have the super handle all other messages.
     IPC_MESSAGE_UNHANDLED(handled = RenderWidget::OnMessageReceived(message))
   IPC_END_MESSAGE_MAP()
 
   if (!msg_is_ok) {
     // The message had a handler, but its deserialization failed.
     // Kill the renderer to avoid potential spoofing attacks.
     CHECK(false) << "Unable to deserialize message in RenderViewImpl.";
   }
@@ skipping 763 matching lines @@
 }
 
 void RenderViewImpl::OnWindowSnapshotCompleted(const int snapshot_id,
     const gfx::Size& size, const std::vector<unsigned char>& png) {
   PendingSnapshotMap::iterator it = pending_snapshots_.find(snapshot_id);
   DCHECK(it != pending_snapshots_.end());
   it->second.Run(size, png);
   pending_snapshots_.erase(it);
 }
 
+namespace {
+
+bool CaptureSnapshot(WebView* view,
+                     const gfx::Rect& src_subrect,
+                     SkBitmap* snapshot) {
+  base::TimeTicks beginning_time = base::TimeTicks::Now();
+
+  view->layout();
+  const WebSize& size = view->size();

[jamesr, 2013/03/18 22:41:18]

I'm not sure about this - the size of a WebWidget is its logical size, not
physical pixel.  On a high DPI device these won't be the same.  I think you want
to be talking in terms of the device/physical pixels here and probably just want
to intersect with physical_backing_size_

[justinlin, 2013/03/18 23:27:51]

Done. Yea, this old stuff didn't really work with HiDPI. Fixed now.

+  gfx::Rect viewport_size = gfx::IntersectRects(
+      src_subrect, gfx::Rect(size.width, size.height));
+
+  skia::RefPtr<SkCanvas> canvas = skia::AdoptRef(
+      skia::CreatePlatformCanvas(viewport_size.width(),
+                                 viewport_size.height(),
+                                 true,
+                                 NULL,
+                                 skia::RETURN_NULL_ON_FAILURE));
+  if (!canvas)
+    return false;
+
+  view->paint(webkit_glue::ToWebCanvas(canvas.get()), viewport_size);
+
+  const SkBitmap& bitmap = skia::GetTopDevice(*canvas)->accessBitmap(false);
+  if (!bitmap.copyTo(snapshot, SkBitmap::kARGB_8888_Config))
+    return false;
+
+  UMA_HISTOGRAM_TIMES("Renderer4.Snapshot",
+                      base::TimeTicks::Now() - beginning_time);
+  return true;
+}
+
+}  // namespace
+
+void RenderViewImpl::OnSnapshot(const gfx::Rect& src_subrect) {
+  SkBitmap snapshot;
+  bool error = false;
+
+  if (!webview()->mainFrame() || !CaptureSnapshot(webview(),
+                                                  src_subrect,
+                                                  &snapshot))
+    error = true;
+
+  DCHECK(error == snapshot.empty()) <<
+      "Snapshot should be empty on error, non-empty otherwise.";
+
+  Send(new ViewHostMsg_Snapshot(routing_id_, !error, snapshot));
+}
+
 // WebKit::WebViewClient ------------------------------------------------------
 
 WebView* RenderViewImpl::createView(
     WebFrame* creator,
     const WebURLRequest& request,
     const WebWindowFeatures& features,
     const WebString& frame_name,
     WebNavigationPolicy policy) {
   // Check to make sure we aren't overloading on popups.
   if (shared_popup_counter_->data > kMaximumNumberOfUnacknowledgedPopups)
@@ skipping 4680 matching lines @@
   TransportDIB* dib = TransportDIB::CreateWithHandle(dib_handle);
   RenderProcess::current()->ReleaseTransportDIB(dib);
 }
 
 void RenderViewImpl::DidCommitCompositorFrame() {
   RenderWidget::DidCommitCompositorFrame();
   FOR_EACH_OBSERVER(RenderViewObserver, observers_, DidCommitCompositorFrame());
 }
 
 }  // namespace content