public void isPNG()
{
string file = "test.png";
Assert.IsFalse(SdlImage.IMG_isPNG(Sdl.SDL_RWFromFile(file, "rb")) == IntPtr.Zero);
Assert.AreEqual(SdlImage.IMG_isPNG(Sdl.SDL_RWFromFile("test.bmp", "rb")), IntPtr.Zero);
this.Quit();
}