colorOverlay function
Implementation
RGBA colorOverlay(RGBA color, num red, num green, num blue, num scale) {
return new RGBA(
red: clampPixel((color.red - (color.red - red) * scale).round()),
green: clampPixel((color.green - (color.green - green) * scale).round()),
blue: clampPixel((color.blue - (color.blue - blue) * scale).round()),
alpha: color.alpha,
);
}