从UIColor中获得较浅和较深的颜色 [英] Get Slightly Lighter and Darker Color from UIColor

问题描述

我一直希望能够将任何UIColor变成渐变.我打算这样做的方法是使用Core Graphics绘制渐变.我想做的就是获得一种颜色，让我们说:

I was looking to be able to turn any UIColor into a gradient. The way I am intending to do this is by using Core Graphics to draw a gradient. What I am trying to do is to get a color, lets say:

[UIColor colorWithRed:0.5 green:0.5 blue:0.5 alpha:1.0];

并获得一个UIColor，它的颜色要深一些，而阴影要浅一些.有谁知道如何做到这一点?谢谢.

and get a UIColor which is a few shades darker and a few shades lighter. Does anyone know how to do this? Thank you.

推荐答案

- (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，应将这些方法实现为UIColor类别.同样，从@Riley的想法来看，最好是按比例使颜色更深或更浅，而不是添加或减去常量值.正如@jrturton所指出的，没有必要操纵RGB组件.最好修改亮度属性本身.总而言之:

EDIT: as @Anchu Chimala pointed out, for maximum flexibility, these methods should be implemented as an UIColor category. Also, from @Riley's idea, it may be a better idea to make the color proprtionally darker or lighter instead of adding or subtracting constant values. As @jrturton pointed out, it's not necessary to manipulate the RGB components; it's better to modify the brightness property itself. All in all:

@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

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