Objective-C 中的颜色工具

ColorUtils.m

/// 参考 WeexSDK `WXConvert.m` 中的 `+UIColor:` 方法 （且在其基础上添加了对 #rrggbbaa 格式的支持）
/// @param colorString 颜色字符串, 支持以下格式:
///         #fff
///         #rrggbb
///         #rrggbbaa
///         rgb(r,g,b)
///         rgba(r,g,b,a)
+ (UIColor *)colorWithColorString:(NSString *)colorString {
    // 1. check cache
    static NSCache *colorCache;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        colorCache = [[NSCache alloc] init];
        colorCache.countLimit = 64;
    });
    
    if ([colorString isKindOfClass:[NSNull class]] || !colorString) {
        return nil;
    }
    
    UIColor *color = [colorCache objectForKey:colorString];
    if (color) {
        return color;
    }
    
    // Default color is white
    double red = 255, green = 255, blue = 255, alpha = 1.0;
    
    if([colorString isKindOfClass:[NSString class]]){
        
        /* `WXConvert.m` 中的 knownColors 相关功能用不上, 已删除*/
        
        NSString *rgba = colorString;
        
        if ([rgba hasPrefix:@"#"]) {
            // #fff
            if ([rgba length] == 4) {
              unichar f =   [rgba characterAtIndex:1];
              unichar s =   [rgba characterAtIndex:2];
              unichar t =   [rgba characterAtIndex:3];
              rgba = [NSString stringWithFormat:@"#%C%C%C%C%C%C", f, f, s, s, t, t];
            }
            
            uint32_t colorValue = 0;
            sscanf(rgba.UTF8String, "#%x", &colorValue);
            
            if ([rgba length] == 7) {
                // #rrggbb
                red     = ((colorValue & 0xFF0000) >> 16) / 255.0;
                green   = ((colorValue & 0x00FF00) >> 8) / 255.0;
                blue    = (colorValue & 0x0000FF) / 255.0;
            } else if ([rgba length] == 9) {
                // #rrggbbaa
                red     = ((colorValue & 0xFF000000) >> 24) / 255.0;
                green     = ((colorValue & 0x00FF0000) >> 16) / 255.0;
                blue   = ((colorValue & 0x0000FF00) >> 8) / 255.0;
                alpha    = (colorValue & 0x000000FF) / 255.0;
            }
            
        } else if ([rgba hasPrefix:@"rgb("]) {
            // rgb(r,g,b)
            int r,g,b;
            sscanf(rgba.UTF8String, "rgb(%d,%d,%d)", &r, &g, &b);
            red = r / 255.0;
            green = g / 255.0;
            blue = b / 255.0;
        } else if ([rgba hasPrefix:@"rgba("]) {
            // rgba(r,g,b,a)
            int r,g,b;
            sscanf(rgba.UTF8String, "rgba(%d,%d,%d,%lf)", &r, &g, &b, &alpha);
            red = r / 255.0;
            green = g / 255.0;
            blue = b / 255.0;
        }
    }
    
    color = [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
    // 6. cache color
    if (color && colorString) {
        [colorCache setObject:color forKey:colorString];
    }
    
    return color;
}

WeexColorUtils.m

// WeexSDK `WXConvert.m` 中的 `+UIColor:` 方法
+ (UIColor *)UIColor:(id)value
{
    // 1. check cache
    static NSCache *colorCache;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        colorCache = [[NSCache alloc] init];
        colorCache.countLimit = 64;
    });
    
    if ([value isKindOfClass:[NSNull class]] || !value) {
        return nil;
    }
    
    UIColor *color = [colorCache objectForKey:value];
    if (color) {
        return color;
    }
    
    // Default color is white
    double red = 255, green = 255, blue = 255, alpha = 1.0;
    
    if([value isKindOfClass:[NSString class]]){
        // 2. check if is color keyword or transparent
        static NSDictionary *knownColors;
        static dispatch_once_t onceTokenKnownColors;
        dispatch_once(&onceTokenKnownColors, ^{
            knownColors = @{
                            // https://www.w3.org/TR/css3-color/#svg-color
                            @"aliceblue": @"#f0f8ff",
                            @"antiquewhite": @"#faebd7",
                            @"aqua": @"#00ffff",
                            @"aquamarine": @"#7fffd4",
                            @"azure": @"#f0ffff",
                            @"beige": @"#f5f5dc",
                            @"bisque": @"#ffe4c4",
                            @"black": @"#000000",
                            @"blanchedalmond": @"#ffebcd",
                            @"blue": @"#0000ff",
                            @"blueviolet": @"#8a2be2",
                            @"brown": @"#a52a2a",
                            @"burlywood": @"#deb887",
                            @"cadetblue": @"#5f9ea0",
                            @"chartreuse": @"#7fff00",
                            @"chocolate": @"#d2691e",
                            @"coral": @"#ff7f50",
                            @"cornflowerblue": @"#6495ed",
                            @"cornsilk": @"#fff8dc",
                            @"crimson": @"#dc143c",
                            @"cyan": @"#00ffff",
                            @"darkblue": @"#00008b",
                            @"darkcyan": @"#008b8b",
                            @"darkgoldenrod": @"#b8860b",
                            @"darkgray": @"#a9a9a9",
                            @"darkgrey": @"#a9a9a9",
                            @"darkgreen": @"#006400",
                            @"darkkhaki": @"#bdb76b",
                            @"darkmagenta": @"#8b008b",
                            @"darkolivegreen": @"#556b2f",
                            @"darkorange": @"#ff8c00",
                            @"darkorchid": @"#9932cc",
                            @"darkred": @"#8b0000",
                            @"darksalmon": @"#e9967a",
                            @"darkseagreen": @"#8fbc8f",
                            @"darkslateblue": @"#483d8b",
                            @"darkslategray": @"#2f4f4f",
                            @"darkslategrey": @"#2f4f4f",
                            @"darkturquoise": @"#00ced1",
                            @"darkviolet": @"#9400d3",
                            @"deeppink": @"#ff1493",
                            @"deepskyblue": @"#00bfff",
                            @"dimgray": @"#696969",
                            @"dimgrey": @"#696969",
                            @"dodgerblue": @"#1e90ff",
                            @"firebrick": @"#b22222",
                            @"floralwhite": @"#fffaf0",
                            @"forestgreen": @"#228b22",
                            @"fuchsia": @"#ff00ff",
                            @"gainsboro": @"#dcdcdc",
                            @"ghostwhite": @"#f8f8ff",
                            @"gold": @"#ffd700",
                            @"goldenrod": @"#daa520",
                            @"gray": @"#808080",
                            @"grey": @"#808080",
                            @"green": @"#008000",
                            @"greenyellow": @"#adff2f",
                            @"honeydew": @"#f0fff0",
                            @"hotpink": @"#ff69b4",
                            @"indianred": @"#cd5c5c",
                            @"indigo": @"#4b0082",
                            @"ivory": @"#fffff0",
                            @"khaki": @"#f0e68c",
                            @"lavender": @"#e6e6fa",
                            @"lavenderblush": @"#fff0f5",
                            @"lawngreen": @"#7cfc00",
                            @"lemonchiffon": @"#fffacd",
                            @"lightblue": @"#add8e6",
                            @"lightcoral": @"#f08080",
                            @"lightcyan": @"#e0ffff",
                            @"lightgoldenrodyellow": @"#fafad2",
                            @"lightgray": @"#d3d3d3",
                            @"lightgrey": @"#d3d3d3",
                            @"lightgreen": @"#90ee90",
                            @"lightpink": @"#ffb6c1",
                            @"lightsalmon": @"#ffa07a",
                            @"lightseagreen": @"#20b2aa",
                            @"lightskyblue": @"#87cefa",
                            @"lightslategray": @"#778899",
                            @"lightslategrey": @"#778899",
                            @"lightsteelblue": @"#b0c4de",
                            @"lightyellow": @"#ffffe0",
                            @"lime": @"#00ff00",
                            @"limegreen": @"#32cd32",
                            @"linen": @"#faf0e6",
                            @"magenta": @"#ff00ff",
                            @"maroon": @"#800000",
                            @"mediumaquamarine": @"#66cdaa",
                            @"mediumblue": @"#0000cd",
                            @"mediumorchid": @"#ba55d3",
                            @"mediumpurple": @"#9370db",
                            @"mediumseagreen": @"#3cb371",
                            @"mediumslateblue": @"#7b68ee",
                            @"mediumspringgreen": @"#00fa9a",
                            @"mediumturquoise": @"#48d1cc",
                            @"mediumvioletred": @"#c71585",
                            @"midnightblue": @"#191970",
                            @"mintcream": @"#f5fffa",
                            @"mistyrose": @"#ffe4e1",
                            @"moccasin": @"#ffe4b5",
                            @"navajowhite": @"#ffdead",
                            @"navy": @"#000080",
                            @"oldlace": @"#fdf5e6",
                            @"olive": @"#808000",
                            @"olivedrab": @"#6b8e23",
                            @"orange": @"#ffa500",
                            @"orangered": @"#ff4500",
                            @"orchid": @"#da70d6",
                            @"palegoldenrod": @"#eee8aa",
                            @"palegreen": @"#98fb98",
                            @"paleturquoise": @"#afeeee",
                            @"palevioletred": @"#db7093",
                            @"papayawhip": @"#ffefd5",
                            @"peachpuff": @"#ffdab9",
                            @"peru": @"#cd853f",
                            @"pink": @"#ffc0cb",
                            @"plum": @"#dda0dd",
                            @"powderblue": @"#b0e0e6",
                            @"purple": @"#800080",
                            @"rebeccapurple": @"#663399",
                            @"red": @"#ff0000",
                            @"rosybrown": @"#bc8f8f",
                            @"royalblue": @"#4169e1",
                            @"saddlebrown": @"#8b4513",
                            @"salmon": @"#fa8072",
                            @"sandybrown": @"#f4a460",
                            @"seagreen": @"#2e8b57",
                            @"seashell": @"#fff5ee",
                            @"sienna": @"#a0522d",
                            @"silver": @"#c0c0c0",
                            @"skyblue": @"#87ceeb",
                            @"slateblue": @"#6a5acd",
                            @"slategray": @"#708090",
                            @"slategrey": @"#708090",
                            @"snow": @"#fffafa",
                            @"springgreen": @"#00ff7f",
                            @"steelblue": @"#4682b4",
                            @"tan": @"#d2b48c",
                            @"teal": @"#008080",
                            @"thistle": @"#d8bfd8",
                            @"tomato": @"#ff6347",
                            @"turquoise": @"#40e0d0",
                            @"violet": @"#ee82ee",
                            @"wheat": @"#f5deb3",
                            @"white": @"#ffffff",
                            @"whitesmoke": @"#f5f5f5",
                            @"yellow": @"#ffff00",
                            @"yellowgreen": @"#9acd32",
                            
                            // https://www.w3.org/TR/css3-color/#transparent
                            @"transparent": @"rgba(0,0,0,0)",
                            };
        });
        NSString *rgba = knownColors[value];
        if (!rgba) {
            rgba = value;
        }
        
        if ([rgba hasPrefix:@"#"]) {
            // #fff
            if ([rgba length] == 4) {
              unichar f =   [rgba characterAtIndex:1];
              unichar s =   [rgba characterAtIndex:2];
              unichar t =   [rgba characterAtIndex:3];
              rgba = [NSString stringWithFormat:@"#%C%C%C%C%C%C", f, f, s, s, t, t];
            }
            
            // 3. #rrggbb
            uint32_t colorValue = 0;
            sscanf(rgba.UTF8String, "#%x", &colorValue);
            red     = ((colorValue & 0xFF0000) >> 16) / 255.0;
            green   = ((colorValue & 0x00FF00) >> 8) / 255.0;
            blue    = (colorValue & 0x0000FF) / 255.0;
        } else if ([rgba hasPrefix:@"rgb("]) {
            // 4. rgb(r,g,b)
            int r,g,b;
            sscanf(rgba.UTF8String, "rgb(%d,%d,%d)", &r, &g, &b);
            red = r / 255.0;
            green = g / 255.0;
            blue = b / 255.0;
        } else if ([rgba hasPrefix:@"rgba("]) {
            // 5. rgba(r,g,b,a)
            int r,g,b;
            sscanf(rgba.UTF8String, "rgba(%d,%d,%d,%lf)", &r, &g, &b, &alpha);
            red = r / 255.0;
            green = g / 255.0;
            blue = b / 255.0;
        }
        
    } else if([value isKindOfClass:[NSNumber class]]) {
        NSUInteger colorValue = [value unsignedIntegerValue];
        red     = ((colorValue & 0xFF0000) >> 16) / 255.0;
        green   = ((colorValue & 0x00FF00) >> 8) / 255.0;
        blue    = (colorValue & 0x0000FF) / 255.0;
    }
    
    color = [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
    // 6. cache color
    if (color && value) {
        [colorCache setObject:color forKey:value];
    }
    
    return color;
}