c++ - How to access pixels data from ID3D11Texture2D?

Question

I'm using Windows Desktop Duplication API to make my own mirroring protocol. I have this piece of code :

// Get new frame
HRESULT hr = m_DeskDupl->AcquireNextFrame(500, &FrameInfo, &DesktopResource);
if (hr == DXGI_ERROR_WAIT_TIMEOUT)
{
    *Timeout = true;
    return DUPL_RETURN_SUCCESS;
}

Here is the FrameInfo structure :

`typedef struct _FRAME_DATA {
ID3D11Texture2D* Frame;
DXGI_OUTDUPL_FRAME_INFO FrameInfo;
_Field_size_bytes_((MoveCount * sizeof(DXGI_OUTDUPL_MOVE_RECT)) +    (DirtyCount * sizeof(RECT))) BYTE* MetaData;
UINT DirtyCount;
UINT MoveCount;
 } FRAME_DATA;`

I would like to extract the pixel buffer from ID3D11Texture2D* Frame; How can I extract on a BYTE * or unsigned char * and have a RGB sequence ? Thank you !

Answer 1

You need to create a second texture of the same size with CPU read access using ID3D11Device::CreateTexture2D, copy whole frame or just updated parts to this texture on GPU using ID3D11DeviceContext::CopyResource or ID3D11DeviceContext::CopySubresourceRegion (it is possible to retrieve which parts were updated using IDXGIOutputDuplication::GetFrameDirtyRects and IDXGIOutputDuplication::GetFrameMoveRects), map second texture to make it accessible by CPU using ID3D11DeviceContext::Map which gives you D3D11_MAPPED_SUBRESOURCE struct containing pointer to buffer with frame data and it's size, that is what you are looking for.

Microsoft provides a rather detailed Desktop Duplication API usage sample implementing all the steps mentioned above.

There is also a straight sample demonstrating how to save ID3D11Texture2D data to file.