我有一个iOS SKColor,我想将其转换为更浅的阴影(不透明,不透明/不透明),因此我想使用HSL亮度实现一个函数,该函数返回一个SKColor。即。在函数内部,将原始SKColor转换为等效的HSL,然后对HSL亮度应用一个值以获得较浅的颜色阴影,然后将此HSL颜色转换回我可以使用的SKColor。
Xcode 8.2.1•Swift 3.0.2
extension UIColor { convenience init(hue: CGFloat, saturation: CGFloat, lightness: CGFloat, alpha: CGFloat = 1) { let offset = saturation * (lightness < 0.5 ? lightness : 1 - lightness) let brightness = lightness + offset let saturation = lightness > 0 ? 2 * offset / brightness : 0 self.init(hue: hue, saturation: saturation, brightness: brightness, alpha: alpha) } var lighter: UIColor? { return applying(lightness: 1.25) } func applying(lightness value: CGFloat) -> UIColor? { guard let hsl = hsl else { return nil } return UIColor(hue: hsl.hue, saturation: hsl.saturation, lightness: hsl.lightness * value, alpha: hsl.alpha) } var hsl: (hue: CGFloat, saturation: CGFloat, lightness: CGFloat, alpha: CGFloat)? { var red: CGFloat = 0, green: CGFloat = 0, blue: CGFloat = 0, alpha: CGFloat = 0, hue: CGFloat = 0 guard getRed(&red, green: &green, blue: &blue, alpha: &alpha), getHue(&hue, saturation: nil, brightness: nil, alpha: nil) else { return nil } let upper = max(red, green, blue) let lower = min(red, green, blue) let range = upper - lower let lightness = (upper + lower) / 2 let saturation = range == 0 ? 0 : range / (lightness < 0.5 ? lightness * 2 : 2 - lightness * 2) return (hue, saturation, lightness, alpha) } }
let purple = UIColor(red: 160/255, green: 118/255, blue: 200/255, alpha: 1) let lighter = purple.lighter