mirrorBrightness method
mirror the brightness of a color. keep the hue and saturation
factor
= 1 will return the inverted color, 0 will return the same color
Implementation
LayerColor mirrorBrightness([double factor = 1]) => LayerColor(
back: back.mirrorBrightness(factor),
front: front.mirrorBrightness(factor),
border: border?.mirrorBrightness(factor),
borderContext: borderContext?.mirrorBrightness(factor));