例如,黑色的反色应该是白色。
10 回答
- - 编辑 - -
根据@amleszk 的回答,我用这种方法更新了 UIColor 扩展/类别:
迅速
func inverseColor() -> UIColor {
var alpha: CGFloat = 1.0
var red: CGFloat = 0.0, green: CGFloat = 0.0, blue: CGFloat = 0.0
if self.getRed(&red, green: &green, blue: &blue, alpha: &alpha) {
return UIColor(red: 1.0 - red, green: 1.0 - green, blue: 1.0 - blue, alpha: alpha)
}
var hue: CGFloat = 0.0, saturation: CGFloat = 0.0, brightness: CGFloat = 0.0
if self.getHue(&hue, saturation: &saturation, brightness: &brightness, alpha: &alpha) {
return UIColor(hue: 1.0 - hue, saturation: 1.0 - saturation, brightness: 1.0 - brightness, alpha: alpha)
}
var white: CGFloat = 0.0
if self.getWhite(&white, alpha: &alpha) {
return UIColor(white: 1.0 - white, alpha: alpha)
}
return self
}
Objective-C
- (UIColor *)inverseColor {
CGFloat alpha;
CGFloat red, green, blue;
if ([self getRed:&red green:&green blue:&blue alpha:&alpha]) {
return [UIColor colorWithRed:1.0 - red green:1.0 - green blue:1.0 - blue alpha:alpha];
}
CGFloat hue, saturation, brightness;
if ([self getHue:&hue saturation:&saturation brightness:&brightness alpha:&alpha]) {
return [UIColor colorWithHue:1.0 - hue saturation:1.0 - saturation brightness:1.0 - brightness alpha:alpha];
}
CGFloat white;
if ([self getWhite:&white alpha:&alpha]) {
return [UIColor colorWithWhite:1.0 - white alpha:alpha];
}
return nil;
}
---- 已弃用 ----
根据@grc 的回答,我使用这种方法创建了一个 UIColor 类别:
- (UIColor *)inverseColor {
CGColorRef oldCGColor = self.CGColor;
int numberOfComponents = CGColorGetNumberOfComponents(oldCGColor);
// can not invert - the only component is the alpha
// e.g. self == [UIColor groupTableViewBackgroundColor]
if (numberOfComponents == 1) {
return [UIColor colorWithCGColor:oldCGColor];
}
const CGFloat *oldComponentColors = CGColorGetComponents(oldCGColor);
CGFloat newComponentColors[numberOfComponents];
int i = numberOfComponents - 1;
newComponentColors[i] = oldComponentColors[i]; // alpha
while (--i >= 0) {
newComponentColors[i] = 1 - oldComponentColors[i];
}
CGColorRef newCGColor = CGColorCreate(CGColorGetColorSpace(oldCGColor), newComponentColors);
UIColor *newColor = [UIColor colorWithCGColor:newCGColor];
CGColorRelease(newCGColor);
return newColor;
}
iOS5+
-(UIColor*) inverseColor
{
CGFloat r,g,b,a;
[self getRed:&r green:&g blue:&b alpha:&a];
return [UIColor colorWithRed:1.-r green:1.-g blue:1.-b alpha:a];
}
这应该有效:
// oldColor is the UIColor to invert
const CGFloat *componentColors = CGColorGetComponents(oldColor.CGColor);
UIColor *newColor = [[UIColor alloc] initWithRed:(1.0 - componentColors[0])
green:(1.0 - componentColors[1])
blue:(1.0 - componentColors[2])
alpha:componentColors[3]];
Swift 的方法是扩展 UIColor:
extension UIColor {
func inverse () -> UIColor {
var r:CGFloat = 0.0; var g:CGFloat = 0.0; var b:CGFloat = 0.0; var a:CGFloat = 0.0;
if self.getRed(&r, green: &g, blue: &b, alpha: &a) {
return UIColor(red: 1.0-r, green: 1.0 - g, blue: 1.0 - b, alpha: a)
}
return .black // Return a default colour
}
}
GRC 的解决方案有一个问题:CGColorGetComponents 以 0.0-1.0 的范围返回,而不是 2-255。所以你应该使用
UIColor *newColor = [[UIColor alloc] initWithRed:(1.0 - componentColors[0])
green:(1.0 - componentColors[1])
blue:(1.0 - componentColors[2])
alpha:componentColors[3]];
反而。否则一切都将是白色的(1.0 和更大)
与使用的 amleszk 类似,它也是 1.-color,而不是 255。顺便说一句,1. 代表浮点 1.0,您应该键入 1.0 而不是 1.,以避免混淆
扩展UIColor
以添加计算属性的Swiftinverted
解决方案:
extension UIColor {
var inverted: UIColor {
var a: CGFloat = 0.0, r: CGFloat = 0.0, g: CGFloat = 0.0, b: CGFloat = 0.0
return getRed(&r, green: &g, blue: &b, alpha: &a) ? UIColor(red: 1.0-r, green: 1.0-g, blue: 1.0-b, alpha: a) : .black
}
}
用于任何UIColor
实例(.red
、.blue
、.white
等),例如:
view.backgroundColor = UIColor.blue.inverted //Results in yellow background
view.backgroundColor = UIColor.black.inverted //Results in white background
所以为了帮助所有 swifters 来这里寻找答案 - 这就是它在 swift 中的样子:
func inverseColor(color: UIColor) -> UIColor{
var a: CGFloat = 0.0; var r: CGFloat = 0.0; var g: CGFloat = 0.0; var b: CGFloat = 0.0;
color.getRed(&r, green: &g, blue: &b, alpha: &a);
return UIColor(red: -r, green: -g, blue: -b, alpha: a);
}
我使用了 Dade 的答案并对其进行了一些调整,因为我正在寻找一种在给定背景颜色的情况下计算文本前景色的好方法。
因此,如果您想为给定的背景颜色获得漂亮的文本颜色,我建议您这样做。它为您提供给定背景颜色中最亮的颜色:
extension UIColor {
func maxBright() -> UIColor {
var r:CGFloat = 0.0; var g:CGFloat = 0.0; var b:CGFloat = 0.0; var a:CGFloat = 0.0;
if self.getRed(&r, green: &g, blue: &b, alpha: &a) {
let d:CGFloat = 1.0 - max(r,g,b)
return UIColor(red: r + d, green: g + d , blue: b + d, alpha: 1.0)
}
return self
}
}
它的工作原理就像向上滑动 RGB 滑块,直到最亮的组件达到最大值。
例子:
titleLable.backgroundColor = UIColor.blackColor()
titleLabel.textColor = titleLabel.backgroundColor?.maxBright()
会给你一个黑底白字标签。尝试其他颜色,你会看到有趣的结果 :)
这可能不是您想要的,但它确实为文本前/后颜色提供了有趣的结果。
只是分享
你没有得到灰色的反色。所以当你使用灰色背景和它的反色作为文本颜色时的效果
这甚至适用于灰色,我只是在@iWills 代码中添加了一些额外的代码。
//====== TO GET THE OPPOSIT COLORS =====
-(UIColor *)reverseColorOf :(UIColor *)oldColor
{
CGColorRef oldCGColor = oldColor.CGColor;
int numberOfComponents = CGColorGetNumberOfComponents(oldCGColor);
// can not invert - the only component is the alpha
if (numberOfComponents == 1) {
return [UIColor colorWithCGColor:oldCGColor];
}
const CGFloat *oldComponentColors = CGColorGetComponents(oldCGColor);
CGFloat newComponentColors[numberOfComponents];
int i = numberOfComponents - 1;
newComponentColors[i] = oldComponentColors[i]; // alpha
while (--i >= 0) {
newComponentColors[i] = 1 - oldComponentColors[i];
}
CGColorRef newCGColor = CGColorCreate(CGColorGetColorSpace(oldCGColor), newComponentColors);
UIColor *newColor = [UIColor colorWithCGColor:newCGColor];
CGColorRelease(newCGColor);
//=====For the GRAY colors 'Middle level colors'
CGFloat white = 0;
[oldColor getWhite:&white alpha:nil];
if(white>0.3 && white < 0.67)
{
if(white >= 0.5)
newColor = [UIColor darkGrayColor];
else if (white < 0.5)
newColor = [UIColor blackColor];
}
return newColor;
}