code: func (i *Image) Pixels() []byte {
  	c := &pixelsCommand{
  		result: nil,
  		img:    i,
  	}
  	theCommandQueue.Enqueue(c)
  	theCommandQueue.Flush()
  	return c.result
  }
docs: // Pixels returns the image's pixels.
  // Pixels might return nil when OpenGL error happens.