问题描述
鉴于UIColor,我需要确定它是亮还是暗。如果我可以访问颜色的十六进制值,我可以检查它是否大于或小于某个阈值十六进制数,但似乎没有办法做到这一点。在那儿?或者有其他方法可以检查UIColor的亮度值吗?
Given a UIColor, I need to determine if it is "light" or "dark". If I could access the hex value of the color, I could just check if it was greater than or less than a certain threshold hex number, but there appears to be no way to do that. Is there? Or is there another way I could check the brightness value of a UIColor?
推荐答案
你可以安装用于扩展 UIColor
以了解HSV / HSB并进行比较 [aUIColor brightness]
You could install this Category for extending UIColor
for knowing HSV/HSB and compare [aUIColor brightness]
编辑:
我在一些,它的主旨是:
I found the same code in some github-hosted project, made a gist of it: https://gist.github.com/1252197
#import "UIColor-HSVAdditions.h"
@implementation UIColor (UIColor_HSVAdditions)
+(struct hsv_color)HSVfromRGB:(struct rgb_color)rgb
{
struct hsv_color hsv;
CGFloat rgb_min, rgb_max;
rgb_min = MIN3(rgb.r, rgb.g, rgb.b);
rgb_max = MAX3(rgb.r, rgb.g, rgb.b);
hsv.val = rgb_max;
if (hsv.val == 0) {
hsv.hue = hsv.sat = 0;
return hsv;
}
rgb.r /= hsv.val;
rgb.g /= hsv.val;
rgb.b /= hsv.val;
rgb_min = MIN3(rgb.r, rgb.g, rgb.b);
rgb_max = MAX3(rgb.r, rgb.g, rgb.b);
hsv.sat = rgb_max - rgb_min;
if (hsv.sat == 0) {
hsv.hue = 0;
return hsv;
}
if (rgb_max == rgb.r) {
hsv.hue = 0.0 + 60.0*(rgb.g - rgb.b);
if (hsv.hue < 0.0) {
hsv.hue += 360.0;
}
} else if (rgb_max == rgb.g) {
hsv.hue = 120.0 + 60.0*(rgb.b - rgb.r);
} else /* rgb_max == rgb.b */ {
hsv.hue = 240.0 + 60.0*(rgb.r - rgb.g);
}
return hsv;
}
-(CGFloat)hue
{
struct hsv_color hsv;
struct rgb_color rgb;
rgb.r = [self red];
rgb.g = [self green];
rgb.b = [self blue];
hsv = [UIColor HSVfromRGB: rgb];
return (hsv.hue / 360.0);
}
-(CGFloat)saturation
{
struct hsv_color hsv;
struct rgb_color rgb;
rgb.r = [self red];
rgb.g = [self green];
rgb.b = [self blue];
hsv = [UIColor HSVfromRGB: rgb];
return hsv.sat;
}
-(CGFloat)brightness
{
struct hsv_color hsv;
struct rgb_color rgb;
rgb.r = [self red];
rgb.g = [self green];
rgb.b = [self blue];
hsv = [UIColor HSVfromRGB: rgb];
return hsv.val;
}
-(CGFloat)value
{
return [self brightness];
}
@end
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