public static extern int DescribePixelFormat(HWND hdc, int n, int un, ref PIXELFORMATDESCRIPTOR lpPixelFormatDescriptor);
public static extern int SetPixelFormat(HWND hdc, int n, ref PIXELFORMATDESCRIPTOR pcPixelFormatDescriptor);
public static extern int ChoosePixelFormat(HWND hdc, ref PIXELFORMATDESCRIPTOR pPixelFormatDescriptor);