Wrap ScreenCapturer with ScreenCapturerDifferWrapper

webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc

 /*
  *  Copyright (c) 2016 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/win/screen_capturer_win_directx.h"
 
 #include <utility>
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/timeutils.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
+#include "webrtc/modules/desktop_capture/screen_capturer_differ_wrapper.h"
 
 namespace webrtc {
 
 using Microsoft::WRL::ComPtr;
 
+// static
 bool ScreenCapturerWinDirectx::IsSupported() {
   // Forward IsSupported function call to DxgiDuplicatorController.
   return DxgiDuplicatorController::Instance()->IsSupported();
 }
 
+// static
+std::unique_ptr<ScreenCapturer> ScreenCapturerWinDirectx::Create(
+    const DesktopCaptureOptions& options) {
+  if (!IsSupported()) {
+    return std::unique_ptr<ScreenCapturer>();

[Sergey Ulanov, 2016/09/07 22:47:23]

return nullptr;

+  }
+
+  // Windows is known to return larger updated region, so we wrap a
+  // ScreenCapturerDirectx instance with ScreenCapturerDifferWrapper.
+  return std::unique_ptr<ScreenCapturer>(new ScreenCapturerDifferWrapper(

[Sergey Ulanov, 2016/09/07 22:47:23]

I think it's better to keep this code in ScreenCapturer::Create(). It doesn't
look right that ScreenCapturerWinDirectx::Create() creates a capturer that isn't
ScreenCapturerWinDirectx

+      std::unique_ptr<ScreenCapturer>(new ScreenCapturerWinDirectx(options))));
+}
+
 ScreenCapturerWinDirectx::ScreenCapturerWinDirectx(
     const DesktopCaptureOptions& options)
     : callback_(nullptr) {}
 
 ScreenCapturerWinDirectx::~ScreenCapturerWinDirectx() {}
 
 void ScreenCapturerWinDirectx::Start(Callback* callback) {
   RTC_DCHECK(!callback_);
   RTC_DCHECK(callback);
 
@@ skipping 91 matching lines @@
 
   int screen_count = DxgiDuplicatorController::Instance()->ScreenCount();
   if (id >= 0 && id < screen_count) {
     current_screen_id = id;
     return true;
   }
   return false;
 }
 
 }  // namespace webrtc