[WebRTC] Two DirectX capturers cannot work concurrently

webrtc/modules/desktop_capture/win/dxgi_output_duplicator.h

 /*
  *  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.
  */
 
 #ifndef WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_DXGI_OUTPUT_DUPLICATOR_H_
 #define WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_DXGI_OUTPUT_DUPLICATOR_H_
 
 #include <comdef.h>
 #include <wrl/client.h>
 #include <DXGI.h>
 #include <DXGI1_2.h>
 
 #include <memory>
 #include <vector>
 
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/thread_annotations.h"
-#include "webrtc/modules/desktop_capture/desktop_frame.h"
 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
 #include "webrtc/modules/desktop_capture/desktop_region.h"
+#include "webrtc/modules/desktop_capture/shared_desktop_frame.h"
 #include "webrtc/modules/desktop_capture/win/d3d_device.h"
 #include "webrtc/modules/desktop_capture/win/dxgi_texture.h"
 
 namespace webrtc {
 
 // Duplicates the content on one IDXGIOutput, i.e. one monitor attached to one
 // video card. None of functions in this class is thread-safe.
 // TODO(zijiehe): Understand the meaning of rotation.
 class DxgiOutputDuplicator {
  public:
@@ skipping 16 matching lines @@
 
   // Destructs this instance. We need to make sure texture_ has been released
   // before duplication_.
   ~DxgiOutputDuplicator();
 
   // Initializes duplication_ object.
   bool Initialize();
 
   // Copies the content of current IDXGIOutput to the |target|. To improve the
   // performance, this function copies only regions merged from
-  // |last_frame|.updated_region and DetectUpdatedRegion(). The |offset| decides
-  // the
-  // offset in the |target| where the content should be copied to. i.e. this
+  // |context|->updated_region and DetectUpdatedRegion(). The |offset| decides
+  // the offset in the |target| where the content should be copied to. i.e. this
   // function copies the content to the rectangle of (offset.x(), offset.y()) to
   // (offset.x() + desktop_rect_.width(), offset.y() + desktop_rect_.height()).
-  // The |last_frame| is always expected to be translated by the same offset.
   // Returns false in case of a failure.
   bool Duplicate(Context* context,
-                 const DesktopFrame* last_frame,
-                 const DesktopVector offset,
-                 DesktopFrame* target);
+                 const DesktopVector& offset,

[Sergey Ulanov, 2016/09/02 23:57:35]

Don't need &. DesktopVector is small, just 8 bytes. The reference is also 8
bytes. So you are not achieving anything by passing a reference here. Also
remove const. Same for other functions below

[Hzj_jie, 2016/09/05 21:24:22]

I used to use const to ensure this parameter won't be changed in the logic.
Done.

+                 SharedDesktopFrame* target);
 
   // Returns the desktop rect covered by this DxgiOutputDuplicator.
   DesktopRect desktop_rect() const { return desktop_rect_; }
 
  private:
   friend class DxgiAdapterDuplicator;
 
   // Detects updated region translated by offset from IDXGIOutput1. This
   // function will set the |updated_region| as entire DesktopRect starts from
   // offset if it failed to execute Windows APIs.
   void DetectUpdatedRegion(const DXGI_OUTDUPL_FRAME_INFO& frame_info,
-                           const DesktopVector offset,
+                           const DesktopVector& offset,
                            DesktopRegion* updated_region);
 
   // Returns untranslated updated region, which are directly returned by Windows
   // APIs. Returns false in case of a failure.
   bool DoDetectUpdatedRegion(const DXGI_OUTDUPL_FRAME_INFO& frame_info,
                              DesktopRegion* updated_region);
 
   bool ReleaseFrame();
 
   // Initializes duplication_ instance. Expects duplication_ is in empty status.
   // Returns false if system does not support IDXGIOutputDuplication.
   bool DuplicateOutput();
 
   // Returns a DesktopRect with the same size of desktop_size_, but translated
   // by offset.
-  DesktopRect TranslatedDesktopRect(const DesktopVector offset);
+  DesktopRect TranslatedDesktopRect(const DesktopVector& offset);
 
   void Setup(Context* context);
 
   void Unregister(const Context* const context);
 
   // Spreads changes from |context| to other registered Context(s) in
   // contexts_.
   void SpreadContextChange(const Context* const context);
 
+  // Returns a DesktopRect in the coordinate of |texture_|->AsDesktopFrame().
+  DesktopRect SourceRect(DesktopRect rect);
+
+  // Returns a DesktopRect in the coordinate of |offset|.
+  DesktopRect TargetRect(DesktopRect rect, DesktopVector offset);
+
   const D3dDevice& device_;
   const Microsoft::WRL::ComPtr<IDXGIOutput1> output_;
   const DesktopRect desktop_rect_;
   Microsoft::WRL::ComPtr<IDXGIOutputDuplication> duplication_;
   DXGI_OUTDUPL_DESC desc_;
   std::vector<uint8_t> metadata;
   std::unique_ptr<DxgiTexture> texture_;
 
   // After each AcquireNextFrame() function call, updated_region_(s) of all
   // active Context(s) need to be updated. Since they have missed the
   // change this time. And during next Duplicate() function call, their
   // updated_region_ will be merged and copied.
   std::vector<Context*> contexts_;
+
+  // The last full frame of this output and its offset. If on AcquireNextFrame()
+  // failed because of timeout, i.e. no update, we can copy content from
+  // |last_frame_|.
+  std::unique_ptr<SharedDesktopFrame> last_frame_;
+  DesktopVector last_frame_offset_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_DXGI_OUTPUT_DUPLICATOR_H_