Photoshop 图层混合效果
//
// UIColor+Combine.swift
// iScales
//
// Created by OrangeEvan on 2017/10/26.
// Copyright © 2017年 NetEase. All rights reserved.
//
import Foundation
import UIKit
extension UIColor {
// MARK: - 常用叠图
// Alpha Blending 前景色叠图
func blendAlpha(coverColor: UIColor) -> UIColor {
let c1 = coverColor.rgbaTuple()
let c2 = self.rgbaTuple()
let c1r = CGFloat(c1.r)
let c1g = CGFloat(c1.g)
let c1b = CGFloat(c1.b)
let c2r = CGFloat(c2.r)
let c2g = CGFloat(c2.g)
let c2b = CGFloat(c2.b)
// 前景色叠图公式
let r = c1r * c1.a + c2r * (1 - c1.a)
let g = c1g * c1.a + c2g * (1 - c1.a)
let b = c1b * c1.a + c2b * (1 - c1.a)
return UIColor.init(red: r/255.0, green: g/255.0, blue: b/255.0, alpha: 1.0)
}
// MARK: - 去亮度型
/// Darken 变暗 B<=A: C=B; B>=A: C=A
func blendDarken(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { return ($0 <= $1) ? $0 : $1 }
}
/// Multiply 正片叠底 C = A*B
func blendMultiply(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { return $0 * $1 }
}
/// Color Burn 颜色加深 C=1-(1-B)/A
func blendColorBurn(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { return 1 - (1 - $0) / $1 }
}
/// Linear Burn 线性加深 C=A+B-1
func blendLinearBurn(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { return ($1 + $0) - 1.0 }
}
// MARK: - 去暗型
/// Lighten 变亮 B>=A: C=B; B<=A: C=A
func blendLighten(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { return ($0 >= $1) ? $0 : $1 }
}
/// Screen 滤色 C=1-(1-A)*(1-B), 也可以写成 1-C=(1-A)*(1-B)
func blendScreen(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { return 1 - (1 - $1) * (1 - $0) }
}
/// Color Dodge 颜色减淡 C=B/(1-A)
func blendColorDodge(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) {
if $1 >= 1.0 { return $1 }
else { return min(1.0, $0 / (1 - $1)) }
}
}
/// Linear Dodge 线性减淡 C=A+B
func blendLinearDodge(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { return min(1, $1 + $0) }
}
// MARK: - 溶合型
/// Overlay 叠加 B<=0.5: C=2*A*B; B>0.5: C=1-2*(1-A)*(1-B)
func blendOverlay(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) {
if $0 <= 0.5 { return 2 * $1 * $0 }
else { return 1 - 2 * (1 - $1) * (1 - $0) }
}
}
/// Soft Light 柔光 A<=0.5: C=(2*A-1)*(B-B*B)+B; A>0.5: C=(2*A-1)*(sqrt(B)-B)+B
func blendSoftLight(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) {
if $1 <= 0.5 { return (2 * $1 - 1) * ($0 - $0 * $0) + $0 }
else { return (2 * $1 - 1)*( sqrt($0) - $0) + $0 }
}
}
/// Hard Light 强光 A<=0.5: C=2*A*B; A>0.5: C=1-2*(1-A)*(1-B)
func blendHardLight(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) {
if $1 <= 0.5 { return 2 * $1 * $0 }
else { return 1 - 2 * (1 - $1) * (1 - $0) }
}
}
/// Vivid Light 亮光 A<=0.5: C=1-(1-B)/(2*A); A>0.5: C=B/(2*(1-A))
func blendVividLight(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) {
if $1 <= 0.5 { return self.fitIn((1 - (1 - $0) / (2 * $1)), ceil: 1.0) }
else { return self.fitIn($0 / (2 * (1 - $1)), ceil: 1.0) }
}
}
/// Linear Light 线性光 C=B+2*A-1
func blendLinearLight(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { return self.fitIn($0 + 2 * $1 - 1, ceil: 1.0) }
}
/// Pin Light 点光
/// B<2*A-1: C=2*A-1
/// 2*A-1<B<2*A: C=B
/// B>2*A: C=2*A
func blendPinLight(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) {
if $0 <= 2 * $1 - 1 { return 2 * $1 - 1 }
else if (2 * $1 - 1 < $0) && ($0 < 2 * $1) { return $0}
else { return 2 * $1 }
}
}
/// Hard Mix 实色混合A<1-B: C=0; A>1-B: C=1
func blendHardMix(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) {
if $1 <= 1 - $0 { return 0 }
else { return 1 }
}
}
// MARK: - 色差型
/// Difference 差值 C=|A-B|
func blendDifference(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { fabs($1 - $0) }
}
/// Exclusion 排除 C = A+B-2*A*B
func blendExclusion(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { $1 + $0 - 2 * $1 * $0 }
}
/// 减去 C=A-B
func blendMinus(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) { $1 - $0 }
}
/// 划分 C=A/B
func blendDivision(coverColor: UIColor,alpha: CGFloat = 1.0) -> UIColor {
return blendProcedure(coverColor: coverColor, alpha: alpha) {
if $0 == 0{
return 1.0
}else {
return self.fitIn($1 / $0, ceil: 1.0)
}
}
}
// MARK: 处理函数
func blendProcedure(
coverColor: UIColor,
alpha: CGFloat,
procedureBlock: ((_ baseValue: CGFloat,_ topValue: CGFloat) -> CGFloat)?
) -> UIColor {
let baseCompoment = self.rgbaTuple()
let topCompoment = coverColor.rgbaTuple()
// 该层透明度
let mixAlpha = alpha * topCompoment.a + (1.0 - alpha) * baseCompoment.a
// RGB 值
let mixR = procedureBlock?(
baseCompoment.r / 255.0,
topCompoment.r / 255.0)
?? (baseCompoment.r) / 255.0
let mixG = procedureBlock?(
baseCompoment.g / 255.0,
topCompoment.g / 255.0)
?? (baseCompoment.g) / 255.0
let mixB = procedureBlock?(
baseCompoment.b / 255.0,
topCompoment.b / 255.0)
?? baseCompoment.b / 255.0
return UIColor.init(red: fitIn(mixR),
green: fitIn(mixG),
blue: fitIn(mixB),
alpha: mixAlpha)
}
// 防止越界
func fitIn(_ value: CGFloat, ceil: CGFloat = 255) -> CGFloat { return max(min(value,ceil),0) }
func fitIn(_ value: Double, ceil: CGFloat = 255) -> CGFloat { return fitIn(CGFloat(value), ceil: ceil) }
// 返回 RBGA
func rgbaTuple() -> (r: CGFloat, g: CGFloat, b: CGFloat,a: CGFloat) {
var r: CGFloat = 0
var g: CGFloat = 0
var b: CGFloat = 0
var a: CGFloat = 0
self.getRed(&r, green: &g, blue: &b, alpha: &a)
r = r * 255
g = g * 255
b = b * 255
return ((r),(g),(b),a)
}
}