code: func ReadPixels(x int32, y int32, width int32, height int32, format uint32, xtype uint32, pixels unsafe.Pointer) {
  	syscall.Syscall9(gpReadPixels, 7, uintptr(x), uintptr(y), uintptr(width), uintptr(height), uintptr(format), uintptr(xtype), uintptr(pixels), 0, 0)
  }
docs: // read a block of pixels from the frame buffer