是否有将UIColor转换为色相饱和度亮度的功能？

Question

我可以用RGB值设置uicolor:

[UIColor colorWithRed:0.53 green:0.37 blue:0.11 alpha:1.00];

我可以用hsb值设置uicolor:

[UIColor colorWithHue:0.10 saturation:0.16 brightness:0.13 alpha:1.00];

我也可以将它转换回RGB:

CGFloat* colors = CGColorGetComponents(Color1.CGColor);

但我如何从uicolor获得HSB？

Answer 1

使用UIColor方法: getHue:saturation:brightness:alpha:

来自Apple文档:
"返回构成HSB颜色空间中颜色的组件."

- (BOOL)getHue:(CGFloat *)hue saturation:(CGFloat *)saturation brightness:(CGFloat *)brightness alpha:(CGFloat *)alpha

例:

UIColor *testColor = [UIColor colorWithRed:0.53 green:0.37 blue:0.11 alpha:1.00];

CGFloat hue;
CGFloat saturation;
CGFloat brightness;
CGFloat alpha;
BOOL success = [testColor getHue:&hue saturation:&saturation brightness:&brightness alpha:&alpha];
NSLog(@"success: %i hue: %0.2f, saturation: %0.2f, brightness: %0.2f, alpha: %0.2f", success, hue, saturation, brightness, alpha);

NSLog输出:

成功:1色调:0.10,饱和度:0.79,亮度:0.53,alpha:1.00

以下是@WhiteTiger提供的方法的更正版本:

// Test values
CGFloat red = 0.53;
CGFloat green = 0.37;
CGFloat blue = 0.11;

CGFloat hue = 0;
CGFloat saturation = 0;
CGFloat brightness = 0;

CGFloat minRGB = MIN(red, MIN(green,blue));
CGFloat maxRGB = MAX(red, MAX(green,blue));

if (minRGB==maxRGB) {
    hue = 0;
    saturation = 0;
    brightness = minRGB;
} else {
    CGFloat d = (red==minRGB) ? green-blue : ((blue==minRGB) ? red-green : blue-red);
    CGFloat h = (red==minRGB) ? 3 : ((blue==minRGB) ? 1 : 5);
    hue = (h - d/(maxRGB - minRGB)) / 6.0;
    saturation = (maxRGB - minRGB)/maxRGB;
    brightness = maxRGB;
}
NSLog(@"hue: %0.2f, saturation: %0.2f, value: %0.2f", hue, saturation, brightness);

NSLog输出:

色调:0.10,饱和度:0.79,值:0.53

Answer 2

这是使用Swift功能(扩展,计算属性和元组)在几行代码中执行相同操作的好方法.

extension UIColor {
  var hsba: (h: CGFloat, s: CGFloat, b: CGFloat, a: CGFloat) {
    var hsba: (h: CGFloat, s: CGFloat, b: CGFloat, a: CGFloat) = (0, 0, 0, 0)
    self.getHue(&(hsba.h), saturation: &(hsba.s), brightness: &(hsba.b), alpha: &(hsba.a))
    return hsba
  }
}

Swift 3.2/4次要更新

Swift 3.2/4强制执行使用前一代码触发的新警告,因为您hsba在同一次调用中多次修改变量getHue

同时访问参数'hsba',但修改需要独占访问; 考虑复制到局部变量.

extension UIColor {
    var hsba:(h: CGFloat, s: CGFloat,b: CGFloat,a: CGFloat) {
        var h: CGFloat = 0, s: CGFloat = 0, b: CGFloat = 0, a: CGFloat = 0
        self.getHue(&h, saturation: &s, brightness: &b, alpha: &a)
        return (h: h, s: s, b: b, a: a)
    }
 }