public static extern int DescribePixelFormat ( IntPtr hdc, int pixelFormatIndex, uint descriptorSize, ref PixelFormatDescriptor ppfd );
public static extern bool SetPixelFormat ( IntPtr hdc, int pixelFormatIndex, ref PixelFormatDescriptor ppfd );
public static extern int ChoosePixelFormat(IntPtr hdc, ref PixelFormatDescriptor ppfd);