[DirectX, C++] Pobieranie wartości koloru piksela z powierzchni

HRESULT DrawDevice::DrawFrame( BYTE * pBits )
{
    HRESULT hr = S_OK;
    BYTE * pbScanline0 = NULL;
    LONG lStride = 0;
    D3DLOCKED_RECT lr;
   
    IDirect3DSurface9 * pSurf = NULL;
    IDirect3DSurface9 * pBB = NULL;
   
    if( m_pDevice == NULL || m_pSwapChain == NULL )
    {
        return S_OK;
    }
   
    // Get the swap-chain surface.
    hr = m_pSwapChain->GetBackBuffer( 0, D3DBACKBUFFER_TYPE_MONO, & pSurf );
    if( FAILED( hr ) ) { goto done; }
   
    // Lock the swap-chain surface.
    hr = pSurf->LockRect( & lr, NULL, D3DLOCK_NOSYSLOCK );
    if( FAILED( hr ) ) { goto done; }
   
    // Convert the frame. This also copies it to the Direct3D surface.
   
    BYTE * pDst =( BYTE * ) lr.pBits;
    BYTE * pSrc = pBits;
   
    for( int y = 0; y <( int ) m_height; y++ )
    {
        memcpy( pDst, pSrc, m_lDefaultStride );
        pDst += lr.Pitch;
        pSrc += m_lDefaultStride;
    }
   
    hr = pSurf->UnlockRect();
   
    if( FAILED( hr ) ) { goto done; }
   
   
    // Color fill the back buffer.
    hr = m_pDevice->GetBackBuffer( 0, 0, D3DBACKBUFFER_TYPE_MONO, & pBB );
   
    if( FAILED( hr ) ) { goto done; }
   
    hr = m_pDevice->ColorFill( pBB, NULL, D3DCOLOR_XRGB( 0, 0, 0x80 ) );
   
    if( FAILED( hr ) ) { goto done; }
   
   
    // Blit the frame.
   
    hr = m_pDevice->StretchRect( pSurf, NULL, pBB, & m_rcDest, D3DTEXF_LINEAR );
   
    if( FAILED( hr ) ) { goto done; }
   
   
    // Present the frame.
   
    hr = m_pDevice->Present( NULL, NULL, NULL, NULL );
   
   
    done:
   
    if( pSurf != NULL )
         pSurf->Release();
   
    if( pBB != NULL )
         pBB->Release();
   
    return hr;
}