Add wgc demo

demo/SimpleCapture.h

@@ -0,0 +1,49 @@
+#pragma once
+
+class SimpleCapture {
+public:
+  SimpleCapture(
+      winrt::Windows::Graphics::DirectX::Direct3D11::IDirect3DDevice const
+          &device,
+      winrt::Windows::Graphics::Capture::GraphicsCaptureItem const &item);
+  ~SimpleCapture() { Close(); }
+
+  void StartCapture();
+  winrt::Windows::UI::Composition::ICompositionSurface
+  CreateSurface(winrt::Windows::UI::Composition::Compositor const &compositor);
+
+  void Close();
+
+private:
+  void OnFrameArrived(
+      winrt::Windows::Graphics::Capture::Direct3D11CaptureFramePool const
+          &sender,
+      winrt::Windows::Foundation::IInspectable const &args);
+
+  void CheckClosed() {
+    if (m_closed.load() == true) {
+      throw winrt::hresult_error(RO_E_CLOSED);
+    }
+  }
+
+  HRESULT
+  CreateMappedTexture(winrt::com_ptr<ID3D11Texture2D> src_texture,
+                      UINT width = 0, UINT height = 0);
+
+private:
+  winrt::Windows::Graphics::Capture::GraphicsCaptureItem m_item{nullptr};
+  winrt::Windows::Graphics::Capture::Direct3D11CaptureFramePool m_framePool{
+      nullptr};
+  winrt::Windows::Graphics::Capture::GraphicsCaptureSession m_session{nullptr};
+  winrt::Windows::Graphics::SizeInt32 m_lastSize;
+
+  winrt::Windows::Graphics::DirectX::Direct3D11::IDirect3DDevice m_device{
+      nullptr};
+  winrt::com_ptr<IDXGISwapChain1> m_swapChain{nullptr};
+  winrt::com_ptr<ID3D11DeviceContext> m_d3dContext{nullptr};
+  winrt::com_ptr<ID3D11Texture2D> m_mappedTexture{nullptr};
+
+  std::atomic<bool> m_closed = false;
+  winrt::Windows::Graphics::Capture::Direct3D11CaptureFramePool::
+      FrameArrived_revoker m_frameArrived;
+};