Get Raw Pixel Data with DirectXTK - c++

Question

I would like to access pixel buffer data from Dirty Rect after calling AcquireNextFrame from DXGI.
Here is my code to get pixel buffer data from D3D11Texture2D :
BYTE* DISPLAYMANAGER::GetImageData(ID3D11Texture2D* texture2D, D3D11_TEXTURE2D_DESC Desc)
{
if (texture2D != NULL)
{
D3D11_TEXTURE2D_DESC description;
texture2D->GetDesc(&description);
description.BindFlags = 0;
description.CPUAccessFlags = D3D11_CPU_ACCESS_READ | D3D11_CPU_ACCESS_WRITE;
description.Usage = D3D11_USAGE_STAGING;
description.Format = DXGI_FORMAT_B8G8R8A8_UNORM;
ID3D11Texture2D* texTemp = NULL;
HRESULT hr = m_Device->CreateTexture2D(&description, NULL, &texTemp);
if (FAILED(hr))
{
if (texTemp)
{
texTemp->Release();
texTemp = NULL;
}
return NULL;
}
m_DeviceContext->CopyResource(texTemp, texture2D);
D3D11_MAPPED_SUBRESOURCE mapped;
unsigned int subresource = D3D11CalcSubresource(0, 0, 0);
hr = m_DeviceContext->Map(texTemp, subresource, D3D11_MAP_READ_WRITE, 0, &mapped);
if (FAILED(hr))
{
texTemp->Release();
texTemp = NULL;
return NULL;
}
unsigned char *captureData = new unsigned char[Desc.Width * Desc.Height * 4];
RtlZeroMemory(captureData, Desc.Width * Desc.Height * 4);
const int pitch = mapped.RowPitch;
unsigned char *source = static_cast<unsigned char*>(mapped.pData);
unsigned char *dest = captureData;
for (int i = 0; i < Desc.Height; i++) {
memcpy(captureData, source, Desc.Width * 4);
source += pitch;
captureData += Desc.Width * 4;
}
for (int i = 0; i < Desc.Width * Desc.Height * 4; i++) {
//trace(L"Pixel[%d] = %x\n", i, dest[i]);
}
m_DeviceContext->Unmap(texTemp, 0);
return dest;
}
else
return NULL;
}
Output of dest is full of '0' value. Even mapped.pData is full of '0'. I don't know why.
Here is where I call my function GetImageData
DUPL_RETURN DISPLAYMANAGER::ProcessFrame(_In_ FRAME_DATA* Data, _Inout_ ID3D11Texture2D* SharedSurf, INT OffsetX, INT OffsetY, _In_ DXGI_OUTPUT_DESC* DeskDesc)
{
DUPL_RETURN Ret = DUPL_RETURN_SUCCESS;
// Process dirties and moves
if (Data->FrameInfo.TotalMetadataBufferSize)
{
D3D11_TEXTURE2D_DESC Desc;
Data->Frame->GetDesc(&Desc);
if (Data->MoveCount)
{
Ret = CopyMove(SharedSurf, reinterpret_cast<DXGI_OUTDUPL_MOVE_RECT*>(Data->MetaData), Data->MoveCount, OffsetX, OffsetY, DeskDesc, Desc.Width, Desc.Height);
if (Ret != DUPL_RETURN_SUCCESS)
{
return Ret;
}
}
if (Data->DirtyCount)
{
Ret = CopyDirty(Data->Frame, SharedSurf, reinterpret_cast<RECT*>(Data->MetaData + (Data->MoveCount * sizeof(DXGI_OUTDUPL_MOVE_RECT))), Data->DirtyCount, OffsetX, OffsetY, DeskDesc, Desc);
GetImageData(Data->Frame, Desc); //here I would like to extract the dirty rect buffer pixel (BGRA value).
}
}
return Ret;
}
Is it possible to do it ? I got this code from Microsoft Sample Desktop Duplication API. Thanks!