🚀 go-pugleaf

"Robert G. Hoover" <not.a.real.address@anywhere.sorry> wrote:
>

Please trim your posts.

> [...] I see that BitBlt needs a source DC. I don't have one.

I would suggest that you use a TBitmap instead. It's 
Canvas::Handle is a DC and you can get a DC for the
screen this way:

    HWND hWnd = ::GetDesktopWindow();
    HDC hDC = ::GetWindowDC( hWnd );

If you need to manipulate the TBitmap, you can use it's Pixels[][] 
property (very slow) or you can use it's ScanLine[] property
(very fast). The following sample converts the TBitmap to gray
scale but note that the offsets differ for variouse PixelFormat
styles. The sample assumes pf24bit.

    for( int y = 0; y < Bmp->Height; ++y )
      {
          BYTE* ScanLine = static_cast<BYTE*>( Bmp->ScanLine[y] );
          for( int x = 0; x < Bmp->Width; ++x )
            {
                BYTE R = ScanLine[ x * 3 + 0 ];
                BYTE G = ScanLine[ x * 3 + 1 ];
                BYTE B = ScanLine[ x * 3 + 2 ];
                BYTE L = (BYTE)((R * 0.299) + (G * 0.587) + (B * 0.114));
                ScanLine[ x * 3 + 0 ] = L;
                ScanLine[ x * 3 + 1 ] = L;
                ScanLine[ x * 3 + 2 ] = L;
            }
      }

~ JD