Hi,

I have implemented these functions to get single pixel color:

// Get Pixel Color
ID3D11Resource* SourceResource;
ID3D11Texture2D* DestinationTexture2D;
ID3D11DeviceContext* Context = nullptr;

    void CreateSourceResource(IDXGISwapChain* pSwapChain)
    {
        HRESULT hr = 0;
        IDXGIResource* backbufferptr = nullptr;
        ID3D11DeviceContext* context = nullptr;
    
        hr = pSwapChain->GetBuffer(0, __uuidof(IDXGIResource), (void**)&backbufferptr);
    
        if (hr < 0) {
            return;
        }
    
        hr = backbufferptr->QueryInterface(__uuidof(ID3D11Resource), (void**)&SourceResource);
    
        if (hr < 0) {
            return;
        }
    
        return;
    }
    
    void CreateDestinationTexture2D(IDXGISwapChain* pSwapChain)
    {
        HRESULT hr = 0;
        ID3D11Device* device = nullptr;
        ID3D11Texture2D* DestResource = nullptr;
    
        hr = pSwapChain->GetDevice(__uuidof(ID3D11Device), (void**)&device);
    
        if (hr < 0) {
            return;
        }
    
        D3D11_TEXTURE2D_DESC TextureDesciption = { };
        TextureDesciption.Format = DXGI_FORMAT_R32_UINT;
        TextureDesciption.Width = 1;
        TextureDesciption.Height = 1;
        TextureDesciption.MipLevels = 1;
        TextureDesciption.ArraySize = 1;
        TextureDesciption.SampleDesc.Count = 1;
        TextureDesciption.Usage = D3D11_USAGE_STAGING;
        TextureDesciption.BindFlags = 0;
        TextureDesciption.CPUAccessFlags = D3D11_CPU_ACCESS_READ;
        TextureDesciption.MiscFlags = 0;
    
        hr = device->CreateTexture2D(&TextureDesciption, nullptr, &DestinationTexture2D);
    
        if (hr < 0) {
            return;
        }
    
        device->GetImmediateContext(&Context);
    
        if (!Context) {
            return;
        }
    
      
        return;
    }
    
    
    RGBTRIPLE GetPixelDX11(int X, int Y)
    {
        RGBTRIPLE rgb;
        HRESULT hr = 0;
        D3D11_MAPPED_SUBRESOURCE MappedSubresource;
        D3D11_BOX srcBox;
    
        srcBox.left = X;
        srcBox.right = X + 1;
        srcBox.bottom = Y + 1;
        srcBox.top = Y;
        srcBox.front = 0;
        srcBox.back = 1;
    
        Context->CopySubresourceRegion(DestinationTexture2D, 0, 0, 0, 0, SourceResource, 0, &srcBox);
    
        hr = Context->Map(DestinationTexture2D, 0, D3D11_MAP_READ, 0, &MappedSubresource);
    
        uint32_t* pPixels = reinterpret_cast<uint32_t*>(MappedSubresource.pData);
    
        rgb.rgbtRed = (pPixels[0] >> 16) & 0xff;
        rgb.rgbtGreen = (pPixels[0] >> 8) & 0xff;
        rgb.rgbtBlue = pPixels[0] & 0xff;
    
        return rgb;
    }

    RGBTRIPLE GetPixelColor(int x, int y)
    {
        RGBTRIPLE rgb;
        HDC dc = GetDC(NULL);
    
        int RealX = round(x * 1);
        int RealY = round(y * 1);
    
        RGBTRIPLE color2 = GetPixelDX11(RealX, RealY);
    
        COLORREF color = GetPixel(dc, RealX, RealY);
        ReleaseDC(NULL, dc);
    
        rgb.rgbtRed = GetRValue(color);
        rgb.rgbtGreen = GetGValue(color);
        rgb.rgbtBlue = GetBValue(color);
    
        return rgb;
    }

and when I call GetPixel (GDI+) I get the correct color but when I call GetPixelDX11 the result is always zero.

I have checked at debug that all HRESULT are "OK"

I have only a bit experience in DX11 and I'am unsure about these lines:

 uint32_t* pPixels = reinterpret_cast<uint32_t*>(MappedSubresource.pData);

        rgb.rgbtRed = (pPixels[0] >> 16) & 0xff;
        rgb.rgbtGreen = (pPixels[0] >> 8) & 0xff;
        rgb.rgbtBlue = pPixels[0] & 0xff;

and about the format:

DXGI_FORMAT_R32_UINT

because this is the initialization:

// this function initializes and prepares Direct3D for use
void InitD3D(HWND hWnd)
{
    // create a struct to hold information about the swap chain
    DXGI_SWAP_CHAIN_DESC scd;

    // clear out the struct for use
    ZeroMemory(&scd, sizeof(DXGI_SWAP_CHAIN_DESC));

    // fill the swap chain description struct
    scd.BufferCount = 1;                                   // one back buffer
    scd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;    // use 32-bit color
    scd.BufferDesc.Width = Screen_Width;                   // set the back buffer width
    scd.BufferDesc.Height = Screen_Height;                 // set the back buffer height
    scd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;     // how swap chain is to be used
    scd.OutputWindow = hWnd;                               // the window to be used
    scd.SampleDesc.Count = 4;                              // how many multisamples
    scd.Windowed = true;                                   // windowed/full-screen mode
    scd.Flags = DXGI_SWAP_CHAIN_FLAG_ALLOW_MODE_SWITCH;    // allow full-screen switching

    // create a device, device context and swap chain using the information in the scd struct
    D3D11CreateDeviceAndSwapChain(NULL, D3D_DRIVER_TYPE_HARDWARE, NULL, NULL,  NULL,  NULL, D3D11_SDK_VERSION, &scd,  &swapchain, &dev, NULL, &devcon);

    // get the address of the back buffer
    ID3D11Texture2D* pBackBuffer;
    swapchain->GetBuffer(0, __uuidof(ID3D11Texture2D), (LPVOID*)&pBackBuffer);

    // use the back buffer address to create the render target
    dev->CreateRenderTargetView(pBackBuffer, NULL, &backbuffer);
    pBackBuffer->Release();

    // set the render target as the back buffer
    devcon->OMSetRenderTargets(1, &backbuffer, NULL);

    // Set the viewport
    D3D11_VIEWPORT viewport;
    ZeroMemory(&viewport, sizeof(D3D11_VIEWPORT));

    viewport.TopLeftX = 0;
    viewport.TopLeftY = 0;
    viewport.Width = Screen_Width;
    viewport.Height = Screen_Height;
   
    devcon->RSSetViewports(1, &viewport);

    InitPipeline();

    DrawAll();

    CreateDestinationTexture2D(swapchain);

    CreateSourceResource(swapchain);

    GetPixelColor(30, 30);

}

Can you help me please ?

Thanks !