Remote Assistance on Chrome OS Part I - Aura Desktop Capturer

remoting/host/chromeos/aura_desktop_capturer.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 "remoting/host/chromeos/aura_desktop_capturer.h"
+
+#include "ash/shell.h"
+#include "base/bind.h"
+#include "cc/output/copy_output_request.h"
+#include "cc/output/copy_output_result.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "third_party/webrtc/modules/desktop_capture/desktop_frame.h"
+#include "ui/aura/window_tree_host.h"
+#include "ui/gfx/screen.h"
+
+namespace remoting {
+
+AuraDesktopCapturer::AuraDesktopCapturer()
+    : callback_(NULL), desktop_window_(NULL), weak_factory_(this) {
+}
+
+AuraDesktopCapturer::~AuraDesktopCapturer() {
+}
+
+void AuraDesktopCapturer::Start(webrtc::DesktopCapturer::Callback* callback) {
+  desktop_window_ = ash::Shell::GetPrimaryRootWindow();
+  DCHECK(desktop_window_) << "Failed to retrieve the Aura Shell root window";
+  callback_ = callback;
+}
+
+void AuraDesktopCapturer::Capture(const webrtc::DesktopRegion&) {
+  scoped_ptr<cc::CopyOutputRequest> request =
+      cc::CopyOutputRequest::CreateBitmapRequest(base::Bind(
+          &AuraDesktopCapturer::OnFrameCaptured, weak_factory_.GetWeakPtr()));
+
+  int width = desktop_window_->bounds().width();
+  int height = desktop_window_->bounds().height();
+  gfx::Rect window_rect = gfx::Rect(width, height);
+
+  request->set_area(window_rect);
+  DCHECK(desktop_window_);
+  desktop_window_->layer()->RequestCopyOfOutput(request.Pass());
+}
+
+void AuraDesktopCapturer::OnFrameCaptured(
+    scoped_ptr<cc::CopyOutputResult> result) {
+  DCHECK(result->HasBitmap());
+
+  scoped_ptr<SkBitmap> bitmap = result->TakeBitmap();
+
+  int width = bitmap->width();
+  int height = bitmap->height();
+
+  webrtc::DesktopSize size(width, height);
+  scoped_ptr<webrtc::DesktopFrame> frame(new webrtc::BasicDesktopFrame(size));
+
+  DCHECK(bitmap->bytesPerPixel() == 4)
+      << "DesktopFrame objects always hold RGBA data.";
+  DCHECK(static_cast<int>(bitmap->rowBytes()) == frame->stride());
+
+  uint8_t* bitmapData = reinterpret_cast<uint8_t*>(bitmap->getPixels());

[Sergey Ulanov, 2014/09/06 02:03:25]

bitmap_data

[kelvinp, 2014/09/09 21:19:46]

Done.

+
+  bitmap->lockPixels();
+  const webrtc::DesktopRect& rect = webrtc::DesktopRect::MakeWH(width, height);
+  frame->CopyPixelsFrom(bitmapData, bitmap->rowBytes(), rect);

[Sergey Ulanov, 2014/09/06 02:03:25]

Ideally we want to avoid copying pixels. You can achieve that by adding
DesktopFrame implementation that wraps SkBitmap. E.g. take a look at
DesktopFrameWin that wraps HDC on windows.

[kelvinp, 2014/09/09 21:19:46]

Done.

+  bitmap->unlockPixels();
+
+  // |VideoScheduler| always checks |updated_region| is not empty before
+  // encoding a given frame.
+  frame->mutable_updated_region()->SetRect(rect);
+
+  callback_->OnCaptureCompleted(frame.release());
+}
+
+}  // namespace remoting