[Chromoting] Improve DirectX capturer to support multiple outputs

webrtc/modules/desktop_capture/win/dxgi_texture_staging.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_TEXTURE_STAGING_H_
+#define WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_DXGI_TEXTURE_STAGING_H_
+
+#include <wrl/client.h>
+#include <D3D11.h>
+#include <DXGI1_2.h>
+
+#include "webrtc/modules/desktop_capture/desktop_geometry.h"
+#include "webrtc/modules/desktop_capture/desktop_region.h"
+#include "webrtc/modules/desktop_capture/win/d3d_device.h"
+#include "webrtc/modules/desktop_capture/win/dxgi_texture.h"
+
+namespace webrtc {
+
+// A pair of an ID3D11Texture2D and an IDXGISurface. We need an ID3D11Texture2D
+// instance to copy GPU texture to RAM, but an IDXGISurface instance to map the
+// texture into a bitmap buffer. These two instances are pointing to a same
+// object.
+//
+// An ID3D11Texture2D is created by an ID3D11Device, so a DxgiTexture cannot be
+// shared between two DxgiAdapterDuplicators.
+class DxgiTextureStaging : public DxgiTexture {
+ public:
+  // Creates a DxgiTextureStaging instance. Caller must maintain the lifetime
+  // of input device to make sure it outlives this instance.
+  DxgiTextureStaging(const DesktopRect& desktop_rect, const D3dDevice& device);
+
+  ~DxgiTextureStaging() override;
+
+  // Copies selected regions of a frame represented by frame_info and resource.
+  // Returns false if anything wrong.
+  bool CopyFrom(const DXGI_OUTDUPL_FRAME_INFO& frame_info,
+                IDXGIResource* resource,
+                const DesktopRegion& region) override;
+
+  bool DoRelease() override;
+
+ private:
+  // Initializes stage_ from a CPU inaccessible IDXGIResource. Returns false if
+  // it failed to execute Windows APIs, or the size of the texture is not
+  // consistent with desktop_rect.
+  bool InitializeStage(ID3D11Texture2D* texture);
+
+  // Makes sure stage_ and surface_ are always pointing to a same object.
+  // We need an ID3D11Texture2D instance for
+  // ID3D11DeviceContext::CopySubresourceRegion, but an IDXGISurface for
+  // IDXGISurface::Map.
+  void AssertStageAndSurfaceAreSameObject();
+
+  const DesktopRect desktop_rect_;
+  const D3dDevice& device_;
+  Microsoft::WRL::ComPtr<ID3D11Texture2D> stage_;
+  Microsoft::WRL::ComPtr<IDXGISurface> surface_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_DXGI_TEXTURE_STAGING_H_