code: func (c *Canvas) DrawColorMask(t pixel.Target, matrix pixel.Matrix, mask color.Color) {
  	c.sprite.DrawColorMask(t, matrix, mask)
  }
docs: // DrawColorMask draws the content of the Canvas onto another Target, transformed by the given
  // Matrix and multiplied by the given mask, just like if it was a Sprite containing the whole Canvas.
  //
  // If the color mask is nil, a fully opaque white mask will be used causing no effect.