我希望能够将任何UIColor变成渐变。我打算这样做的方法是使用Core Graphics绘制渐变。我想要做的是获得一种颜色,让我们说:
[UIColor colorWithRed:0.5 green:0.5 blue:0.5 alpha:1.0];
并得到一个UIColor,这是一些深色调和一些浅色调。有谁知道如何做到这一点?谢谢。
- (UIColor *)lighterColorForColor:(UIColor *)c
{
CGFloat r, g, b, a;
if ([c getRed:&r green:&g blue:&b alpha:&a])
return [UIColor colorWithRed:MIN(r + 0.2, 1.0)
green:MIN(g + 0.2, 1.0)
blue:MIN(b + 0.2, 1.0)
alpha:a];
return nil;
}
- (UIColor *)darkerColorForColor:(UIColor *)c
{
CGFloat r, g, b, a;
if ([c getRed:&r green:&g blue:&b alpha:&a])
return [UIColor colorWithRed:MAX(r - 0.2, 0.0)
green:MAX(g - 0.2, 0.0)
blue:MAX(b - 0.2, 0.0)
alpha:a];
return nil;
}
像这样使用它:
UIColor *baseColor = // however you obtain your color
UIColor *lighterColor = [self lighterColorForColor:baseColor];
UIColor *darkerColor = [self darkerColorForColor:baseColor];
编辑:正如@Anchu Chimala指出的那样,为了获得最大的灵活性,这些方法应该作为UIColor类实现。另外,根据@ Riley的想法,将颜色设置为更暗或更亮而不是添加或减去常数值可能是更好的主意。正如@jrturton指出的那样,没有必要操纵RGB组件;最好修改亮度属性本身。总而言之:
@implementation UIColor (LightAndDark)
- (UIColor *)lighterColor
{
CGFloat h, s, b, a;
if ([self getHue:&h saturation:&s brightness:&b alpha:&a])
return [UIColor colorWithHue:h
saturation:s
brightness:MIN(b * 1.3, 1.0)
alpha:a];
return nil;
}
- (UIColor *)darkerColor
{
CGFloat h, s, b, a;
if ([self getHue:&h saturation:&s brightness:&b alpha:&a])
return [UIColor colorWithHue:h
saturation:s
brightness:b * 0.75
alpha:a];
return nil;
}
@end
UIColor扩展和修复lighterColorForColor
extension UIColor {
class func darkerColorForColor(color: UIColor) -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if color.getRed(&r, green: &g, blue: &b, alpha: &a){
return UIColor(red: max(r - 0.2, 0.0), green: max(g - 0.2, 0.0), blue: max(b - 0.2, 0.0), alpha: a)
}
return UIColor()
}
class func lighterColorForColor(color: UIColor) -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if color.getRed(&r, green: &g, blue: &b, alpha: &a){
let tmpColor = UIColor(red: min(r + 0.2, 1.0), green: min(g + 0.2, 1.0), blue: min(b + 0.2, 1.0), alpha: a)
println(tmpColor)
return tmpColor
}
return UIColor()
}
}
此线程中的所有其他答案都使用RGB颜色系统或只是更改HSB系统的色调或亮度值。正如在this great blog post中详细解释的那样,使颜色变浅或变暗的正确方法是改变其luminance
值。没有其他答案那样做。如果你想做得对,那么在阅读博客文章后使用我的解决方案或自己编写。
不幸的是,默认情况下更改UIColor的任何属性都非常麻烦。此外,Apple甚至不支持任何基于LAB的色彩空间,如UIColor
类中的HCL(LAB中的L
是我们正在寻找的luminance
值)。
使用HandyUIKit(通过Carthage安装)增加了对HCL的支持,让您的生活更轻松:
import HandyUIKit
let color = UIColor(red: 0.5, green: 0.5, blue: 0.5, alpha: 1.0)
// create a new UIColor object with a specific luminance (slightly lighter)
color.change(.luminance, to: 0.7)
还可以选择应用相对更改(推荐):
// create a new UIColor object with slightly darker color
color.change(.luminance, by: -0.2)
请注意,HandyUIKit还在您的项目中添加了一些其他方便的UI功能 - 请查看其README on GitHub以获取更多详细信息。
我希望它有所帮助!
我不确定你是否正在寻找某种Objective-C答案,但根据RGBA指定的颜色如何工作,我认为你可以根据任意因素简单地缩放RGB值以获得“更轻”或“阴暗”的阴影。例如,您可能有一个蓝色:
[UIColor colorWithRed:0.0 green:0.0 blue:1.0 alpha:1.0];
想要更深的蓝色?将RGB值乘以0.9:
[UIColor colorWithRed:0.0 green:0.0 blue:0.9 alpha:1.0];
瞧。或许你有橙色:
[UIColor colorWithRed:1.0 green:0.4 blue:0.0 alpha:1.0];
选择另一个比例因子,比如0.8:
[UIColor colorWithRed:0.8 green:0.32 blue:0.0 alpha:1.0];
这是你正在寻找的那种效果吗?
适用于iOS 12的Swift 4.x在Xcode 10中测试过
从你的颜色开始作为UIColor并选择一个变暗因子(作为CGFloat)
let baseColor = UIColor.red
let darkenFactor: CGFloat = 2
CGColor类型有一个可选值components
,它将颜色分解为RGBA(作为CGFloat数组,其值介于0和1之间)。然后,您可以使用从CGColor中获取的RGBA值重建UIColor并对其进行操作。
let darkenedBase = UIColor(displayP3Red: startColor.cgColor.components![0] / darkenFactor, green: startColor.cgColor.components![1] / darkenFactor, blue: startColor.cgColor.components![2] / darkenFactor, alpha: 1)
在这个例子中,每个RGB值被除以2,使得颜色一半变暗。 alpha值保持不变,但您可以选择将暗因子应用于alpha值而不是RGB。
理想情况下,函数应封装在名为UIColor
的UIColor+Brightness.swift
扩展中,并具有可配置的亮度 - 请参见下面的示例:
import UIKit
extension UIColor {
func lighterColorWithBrightnessFactor(brightnessFactor:CGFloat) -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if self.getRed(&r, green:&g, blue:&b, alpha:&a) {
return UIColor(red:min(r + brightnessFactor, 1.0),
green:min(g + brightnessFactor, 1.0),
blue:min(b + brightnessFactor, 1.0),
alpha:a)
}
return UIColor()
}
}
我根据状态值渲染彩色单元格:
为此我在使用CryingHippo的建议收到错误后,根据一些旧的objc代码写了一个swift扩展:
extension UIColor{
func darker(darker: CGFloat) -> UIColor{
var red: CGFloat = 0.0
var green: CGFloat = 0.0
var blue: CGFloat = 0.0
if self.colorSpace == UIColorSpace.genericGrayColorSpace(){
red = whiteComponent - darker
green = whiteComponent - darker
blue = whiteComponent - darker
} else {
red = redComponent - darker
green = greenComponent - darker
blue = blueComponent - darker
}
if red < 0{
green += red/2
blue += red/2
}
if green < 0{
red += green/2
blue += green/2
}
if blue < 0{
green += blue/2
red += blue/2
}
return UIColor(
calibratedRed: red,
green: green,
blue: blue,
alpha: alphaComponent
)
}
func lighter(lighter: CGFloat) -> UIColor{
return darker(-lighter)
}
}
同样适用于NSColor
。只需用UIColor
替换NSColor
。
这是一个UIColor类别,它还允许控制颜色变化量。
- (UIColor *)lighterColorWithDelta:(CGFloat)delta
{
CGFloat r, g, b, a;
if ([self getRed:&r green:&g blue:&b alpha:&a])
return [UIColor colorWithRed:MIN(r + delta, 1.0)
green:MIN(g + delta, 1.0)
blue:MIN(b + delta, 1.0)
alpha:a];
return nil;
}
- (UIColor *)darkerColorWithDelta:(CGFloat)delta
{
CGFloat r, g, b, a;
if ([self getRed:&r green:&g blue:&b alpha:&a])
return [UIColor colorWithRed:MAX(r - delta, 0.0)
green:MAX(g - delta, 0.0)
blue:MAX(b - delta, 0.0)
alpha:a];
return nil;
}
基于@Sebyddd的Swift扩展回答:
import Foundation
import UIKit
extension UIColor{
func colorWith(brightness: CGFloat) -> UIColor{
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if getRed(&r, green: &g, blue: &b, alpha: &a){
return UIColor(red: max(r + brightness, 0.0), green: max(g + brightness, 0.0), blue: max(b + brightness, 0.0), alpha: a)
}
return UIColor()
}
}
对于较暗的颜色,这是最简单的:theColor = [theColor shadowWithLevel:s]; //s :0.0到1.0
extension UIColor {
var lighterColor: UIColor {
return lighterColor(removeSaturation: 0.5, resultAlpha: -1)
}
func lighterColor(removeSaturation val: CGFloat, resultAlpha alpha: CGFloat) -> UIColor {
var h: CGFloat = 0, s: CGFloat = 0
var b: CGFloat = 0, a: CGFloat = 0
guard getHue(&h, saturation: &s, brightness: &b, alpha: &a)
else {return self}
return UIColor(hue: h,
saturation: max(s - val, 0.0),
brightness: b,
alpha: alpha == -1 ? a : alpha)
}
}
用法:
let lightColor = somethingDark.lighterColor
- (UIColor *)lighterColorRemoveSaturation:(CGFloat)removeS
resultAlpha:(CGFloat)alpha {
CGFloat h,s,b,a;
if ([self getHue:&h saturation:&s brightness:&b alpha:&a]) {
return [UIColor colorWithHue:h
saturation:MAX(s - removeS, 0.0)
brightness:b
alpha:alpha == -1? a:alpha];
}
return nil;
}
- (UIColor *)lighterColor {
return [self lighterColorRemoveSaturation:0.5
resultAlpha:-1];
}
@rchampourlier对@ user529758的评论是正确的(接受的答案) - HSB(或HSV)和RGB解决方案给出了完全不同的结果。 RGB只是增加(或使颜色更接近)白色,HSB解决方案使颜色更接近Brigtness量表的边缘 - 基本上以黑色开始,以纯色结束......
基本上亮度(值)使颜色更接近或更接近黑色,其中饱和度使其更接近白色...
如下所示:
因此,使颜色实际上更亮(即更接近白色......)的解决方案是使其饱和度值更小,从而得出此解决方案:
- (UIColor *)lighterColor {
CGFloat h,s,b,a;
if ([self getHue:&h saturation:&s brightness:&b alpha:&a]) {
return [UIColor colorWithHue:h
saturation:MAX(s - 0.3, 0.0)
brightness:b /*MIN(b * 1.3, 1.0)*/
alpha:a];
}
return nil;
}
使用getHue的iOS和OS X的Swift通用扩展:
#if os(OSX)
import Cocoa
public typealias PXColor = NSColor
#else
import UIKit
public typealias PXColor = UIColor
#endif
extension PXColor {
func lighter(amount : CGFloat = 0.25) -> PXColor {
return hueColorWithBrightnessAmount(1 + amount)
}
func darker(amount : CGFloat = 0.25) -> PXColor {
return hueColorWithBrightnessAmount(1 - amount)
}
private func hueColorWithBrightnessAmount(amount: CGFloat) -> PXColor {
var hue : CGFloat = 0
var saturation : CGFloat = 0
var brightness : CGFloat = 0
var alpha : CGFloat = 0
#if os(iOS)
if getHue(&hue, saturation: &saturation, brightness: &brightness, alpha: &alpha) {
return PXColor( hue: hue,
saturation: saturation,
brightness: brightness * amount,
alpha: alpha )
} else {
return self
}
#else
getHue(&hue, saturation: &saturation, brightness: &brightness, alpha: &alpha)
return PXColor( hue: hue,
saturation: saturation,
brightness: brightness * amount,
alpha: alpha )
#endif
}
}
用法:
let color = UIColor(red: 0.5, green: 0.8, blue: 0.8, alpha: 1.0)
color.lighter(amount:0.5)
color.darker(amount:0.5)
或(使用默认值):
color.lighter()
color.darker()
样品:
user529758在Swift中的解决方案:
颜色较深:
func darkerColorForColor(color: UIColor) -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if color.getRed(&r, green: &g, blue: &b, alpha: &a){
return UIColor(red: max(r - 0.2, 0.0), green: max(g - 0.2, 0.0), blue: max(b - 0.2, 0.0), alpha: a)
}
return UIColor()
}
颜色较浅:
func lighterColorForColor(color: UIColor) -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if color.getRed(&r, green: &g, blue: &b, alpha: &a){
return UIColor(red: min(r + 0.2, 1.0), green: min(g + 0.2, 1.0), blue: min(b + 0.2, 1.0), alpha: a)
}
return UIColor()
}
我只是想用RGB来给出相同的结果
其结果与AFAIK相同,而是以渐变“颜色变为白色”或“颜色变为黑色”,以渐变大小的x%选择颜色。
为此,数学很简单:
// UIColor+Mix.swift
import UIKit
extension UIColor {
func mixLighter (amount: CGFloat = 0.25) -> UIColor {
return mixWithColor(UIColor.white, amount:amount)
}
func mixDarker (amount: CGFloat = 0.25) -> UIColor {
return mixWithColor(UIColor.black, amount:amount)
}
func mixWithColor(_ color: UIColor, amount: CGFloat = 0.25) -> UIColor {
var r1 : CGFloat = 0
var g1 : CGFloat = 0
var b1 : CGFloat = 0
var alpha1 : CGFloat = 0
var r2 : CGFloat = 0
var g2 : CGFloat = 0
var b2 : CGFloat = 0
var alpha2 : CGFloat = 0
self.getRed (&r1, green: &g1, blue: &b1, alpha: &alpha1)
color.getRed(&r2, green: &g2, blue: &b2, alpha: &alpha2)
return UIColor( red:r1*(1.0-amount)+r2*amount,
green:g1*(1.0-amount)+g2*amount,
blue:b1*(1.0-amount)+b2*amount,
alpha: alpha1 )
}
}
以下是一些颜色的示例
如果将RGB颜色转换为HSL color model,则可以将L =亮度分量从L = 0.0(黑色)变为L = 0.5(自然色)到L = 1.0(白色)。 UIColor
不能直接处理HSL,但有转换RGB HSL的公式。
没有任何解决方案适用于所有颜色和阴影,但后来偶然发现了this library,它为UIColor提供了一套非常好的实现扩展。
具体来说,它具有减轻功能,作为其HSL实施的一部分:(UIColor *)lighten:(CGFloat)amount
- 完美运行。
Sebyddd
解决方案作为扩展:
extension UIColor {
func darker() -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if self.getRed(&r, green: &g, blue: &b, alpha: &a){
return UIColor(red: max(r - 0.2, 0.0), green: max(g - 0.2, 0.0), blue: max(b - 0.2, 0.0), alpha: a)
}
return UIColor()
}
func lighter() -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if self.getRed(&r, green: &g, blue: &b, alpha: &a){
return UIColor(red: min(r + 0.2, 1.0), green: min(g + 0.2, 1.0), blue: min(b + 0.2, 1.0), alpha: a)
}
return UIColor()
}
}
用法:
let darkerYellow = UIColor.yellow.darker()
let lighterYellow = UIColor.yellow.lighter()
如果你想让user529758的解决方案使用灰色阴影(比如[UIColor lightGrayColor]
或[UIColor darkGrayColor]
,你必须改进它:
- (UIColor *)lighterColor
{
CGFloat h, s, b, a;
if ([self getHue:&h saturation:&s brightness:&b alpha:&a]) {
return [UIColor colorWithHue:h
saturation:s
brightness:MIN(b * 1.3, 1.0)
alpha:a];
}
CGFloat white, alpha;
if ([self getWhite:&white alpha:&alpha]) {
white = MIN(1.3*white, 1.0);
return [UIColor colorWithWhite:white alpha:alpha];
}
return nil;
}
getHue:saturation:brightness:alpha
在灰色阴影调用时失败(并返回false
)因此你需要使用getWhite:alpha
。