DirectX based screen capturer logic

webrtc/modules/desktop_capture/win/screen_capturer_win_directx.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_SCREEN_CAPTURER_WIN_DIRECTX_H_
+#define WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_SCREEN_CAPTURER_WIN_DIRECTX_H_
+
+#include "webrtc/modules/desktop_capture/screen_capturer.h"
+
+#include <memory>
+#include <vector>
+
+#include <D3DCommon.h>
+#include <D3D11.h>
+#include <DXGI1_2.h>
+#include <windows.h>
+#include <wrl/client.h>
+
+#include "webrtc/base/scoped_ptr.h"
+#include "webrtc/base/thread_annotations.h"
+#include "webrtc/modules/desktop_capture/desktop_capture_options.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/system_wrappers/include/critical_section_wrapper.h"
+
+namespace webrtc {
+
+class Differ;
+
+// ScreenCapturerWinDirectX captures 32bit RGB using DirectX.
+class ScreenCapturerWinDirectX : public ScreenCapturer {
+ public:
+  // Initializes DirectX related components. Returns false if any error
+  // happened, any instance of this class won't be able to work in such status.
+  // Thread safe, guarded by kInitializeLock.
+  static bool Initialize();
+
+  explicit ScreenCapturerWinDirectX(const DesktopCaptureOptions& options);
+  virtual ~ScreenCapturerWinDirectX();
+
+  void Start(Callback* callback) override;
+  void SetSharedMemoryFactory(
+      rtc::scoped_ptr<SharedMemoryFactory> shared_memory_factory) override;
+  void Capture(const DesktopRegion& region) override;
+  bool GetScreenList(ScreenList* screens) override;
+  bool SelectScreen(ScreenId id) override;
+
+ private:
+  // In milliseconds, consistent with windows api.
+  const static uint32_t kAcquireTimeout = 10;
+
+  static bool DoInitialize();
+
+  // Initializes kDXGIOutputDuplication. Returns false if it fails to execute
+  // windows api.
+  static bool DuplicateOutput();
+
+  // Initializes kStage and kSurface from a CPU inaccessible IDXGIResource.
+  // Returns false if it fails to execute windows api.
+  static bool CreateTexture(ID3D11Texture2D* texture);
+
+  // Detect update regions in last frame, if anything wrong, returns false.
+  // ProcessFrame will insert a whole desktop size as updated region instead.
+  static bool DetectUpdatedRegion(const DXGI_OUTDUPL_FRAME_INFO& frame_info,
+                                  DesktopFrame* frame);
+
+  // Windows accepts only one DirectX duplication per application, so most of

[Sergey Ulanov, 2016/03/31 18:41:17]

Ouch, is it documented anywhere?
This is an issue, particularly for chrome where multiple applications may need
to use desktop capture API

[Hzj_jie, 2016/04/05 23:15:18]

Yes, http://shortn/_geEQFIizM3. We are fine with multiple applications, but one
application can build only one IDXGIOutputDuplication. This impacts the decision
of follow static variables.

+  // these com instances are static.
+  static bool kInitialized GUARDED_BY(kInitializeLock);
+  static bool kInitializeResult GUARDED_BY(kInitializeLock);
+  static ID3D11Device* kD3D11Device GUARDED_BY(kInitializeLock);
+  static ID3D11DeviceContext* kD3D11Context GUARDED_BY(kInitializeLock);
+  static IDXGIOutput1* kDXGIOutput1 GUARDED_BY(kInitializeLock);
+  static Microsoft::WRL::ComPtr<IDXGIOutputDuplication> kDXGIOutputDuplication
+      GUARDED_BY(kDuplicationLock);
+  // Update with kDXGIOutputDuplication
+  static DesktopSize kDesktopSize GUARDED_BY(kAcquireLock);
+  // Update during ProcessFrame or DuplicateOutput (CreateTexture), they are
+  // always pointing to the same object (thread unsafely).
+  static Microsoft::WRL::ComPtr<ID3D11Texture2D> kStage
+      GUARDED_BY(kAcquireLock);
+  static Microsoft::WRL::ComPtr<IDXGISurface> kSurface GUARDED_BY(kAcquireLock);
+  // Update during ProcessFrame (DetectUpdatedRegion).
+  static std::vector<BYTE> kMetaDataBuffer GUARDED_BY(kAcquireLock);
+
+  // Lock in Initialize function.
+  static CriticalSectionWrapper kInitializeLock;
+  // Lock when kDXGIOutputDuplication needs to be updated.
+  static CriticalSectionWrapper kDuplicationLock;
+  // Lock when kDXGIOutputDuplication is acquiring a frame or is being updated.
+  static CriticalSectionWrapper kAcquireLock;
+
+  // Process one frame received from AcquireNextFrame function, returns false if
+  // anything wrong, and Capture function will call
+  // callback_->OnCaptureCompleted(nullptr), otherwise
+  // callback_->OnCaptureCompleted(frame) will be called.
+  static bool ProcessFrame(const DXGI_OUTDUPL_FRAME_INFO& frame_info,
+                           IDXGIResource* resource,
+                           DesktopFrame** frame);
+
+  void CallbackUnchanged();
+  void CallbackError();
+
+  // std::unique_ptr<SharedMemoryFactory> shared_memory_factory_;
+  Callback* callback_;
+
+  bool set_thread_execution_state_failed_;
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(ScreenCapturerWinDirectX);
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_SCREEN_CAPTURER_WIN_DIRECTX_H_