DirectX based screen capturer logic

webrtc/modules/desktop_capture/screen_capturer_win.cc

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/modules/desktop_capture/screen_capturer.h"
 
 #include <memory>
 #include <utility>
 
 #include "webrtc/modules/desktop_capture/desktop_capture_options.h"
+#include "webrtc/modules/desktop_capture/win/screen_capturer_win_directx.h"
 #include "webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.h"
 #include "webrtc/modules/desktop_capture/win/screen_capturer_win_magnifier.h"
 
 namespace webrtc {
 
 // static
 ScreenCapturer* ScreenCapturer::Create(const DesktopCaptureOptions& options) {
-  std::unique_ptr<ScreenCapturer> gdi_capturer(
-      new ScreenCapturerWinGdi(options));
+  std::unique_ptr<ScreenCapturer> capturer;
+  if (options.use_directx_capturer() &&
+      ScreenCapturerWinDirectx::Initialize()) {
+    capturer.reset(new ScreenCapturerWinDirectx(options));

[Sergey Ulanov, 2016/04/14 23:10:42]

I think here we need to check Windows version and create DirectX capturer only
on windows 8 and above.

[Hzj_jie, 2016/04/15 19:42:17]

Not really, Windows 7 with platform update may also work with the new capturer.
But if the system does not support what we need to do the capturing, Initialize
function will eventually fail.

+  } else {
+    capturer.reset(new ScreenCapturerWinGdi(options));
+  }
 
   if (options.allow_use_magnification_api())
-    return new ScreenCapturerWinMagnifier(std::move(gdi_capturer));
+    return new ScreenCapturerWinMagnifier(std::move(capturer));
 
-  return gdi_capturer.release();
+  return capturer.release();
 }
 
 }  // namespace webrtc