js 各种颜色模式之间的转换

/* RGBColor
parameter: 
    r, g, b

method:
    set(r, g, b: Number): this;            //rgb: 0 - 255; 第一个参数可以为 css color
    setFormHex(hex: Number): this;         //
    setFormHSV(h, s, v: Number): this;    //h:0-360; s,v:0-100; 颜色, 明度, 暗度
    setFormString(str: String): Number;    //str: 英文|css color; 返回的是透明度 (如果为 rgba 则返回a; 否则总是返回1)

    copy(v: RGBColor): this;
    clone(): RGBColor;

    getHex(): Number;
    getHexString(): String;
    getHSV(result: Object{h, s, v}): result;    //result: 默认是一个新的Object
    getRGBA(alpha: Number): String;             //alpha: 0 - 1; 默认 1
    getStyle()                                     //.getRGBA()别名

    stringToColor(str: String): String; //str 转为 css color; 如果str不是color格式则返回 ""

*/
class RGBColor{

    constructor(r = 255, g = 255, b = 255){
        this.r = r;
        this.g = g;
        this.b = b;

    }

    copy(v){
        this.r = v.r;
        this.g = v.g;
        this.b = v.b;
        return this;
    }

    clone(){
        return new this.constructor().copy(this);
    }

    set(r, g, b){
        if(typeof r !== "string"){
            this.r = r || 255;
            this.g = g || 255;
            this.b = b || 255;
        }

        else this.setFormString(r);
        
        return this;
    }

    setFormHex(hex){
        hex = Math.floor( hex );

        this.r = hex >> 16 & 255;
        this.g = hex >> 8 & 255;
        this.b = hex & 255;
        return this;
    }

    setFormHSV(h, s, v){
        h = h >= 360 ? 0 : h;
        var s=s/100;
        var v=v/100;
        var h1=Math.floor(h/60) % 6;
        var f=h/60-h1;
        var p=v*(1-s);
        var q=v*(1-f*s);
        var t=v*(1-(1-f)*s);
        var r,g,b;
        switch(h1){
            case 0:
                r=v;
                g=t;
                b=p;
                break;
            case 1:
                r=q;
                g=v;
                b=p;
                break;
            case 2:
                r=p;
                g=v;
                b=t;
                break;
            case 3:
                r=p;
                g=q;
                b=v;
                break;
            case 4:
                r=t;
                g=p;
                b=v;
                break;
            case 5:
                r=v;
                g=p;
                b=q;
                break;
        }

        this.r = Math.round(r*255);
        this.g = Math.round(g*255);
        this.b = Math.round(b*255);
        return this;
    }

    setFormString(color){
        if(typeof color !== "string") return 1;
        var _color = this.stringToColor(color);
        
        if(_color[0] === "#"){
            const len = _color.length;
            if(len === 4){
                _color = _color.slice(1);
                this.setFormHex(parseInt("0x"+_color + "" + _color));
            }
            else if(len === 7) this.setFormHex(parseInt("0x"+_color.slice(1)));
            
        }

        else if(_color[0] === "r" && _color[1] === "g" && _color[2] === "b"){
            const arr = [];
            for(let k = 0, len = _color.length, v = "", is = false; k < len; k++){
                
                if(is === true){
                    if(_color[k] === "," || _color[k] === ")"){
                        arr.push(parseFloat(v));
                        v = "";
                    }
                    else v += _color[k];
                    
                }

                else if(_color[k] === "(") is = true;
                
            }

            this.set(arr[0], arr[1], arr[2]);
            return arr[3] === undefined ? 1 : arr[3];
        }
        
        return 1;
    }

    getHex(){

        return Math.max( 0, Math.min( 255, this.r ) ) << 16 ^ Math.max( 0, Math.min( 255, this.g ) ) << 8 ^ Math.max( 0, Math.min( 255, this.b ) ) << 0;

    }

    getHexString(){

        return '#' + ( '000000' + this.getHex().toString( 16 ) ).slice( - 6 );

    }

    getHSV(result){
        result = result || {}
        var r=this.r/255;
        var g=this.g/255;
        var b=this.b/255;
        var h,s,v;
        var min=Math.min(r,g,b);
        var max=v=Math.max(r,g,b);
        var l=(min+max)/2;
        var difference = max-min;
        
        if(max==min){
            h=0;
        }else{
            switch(max){
                case r: h=(g-b)/difference+(g < b ? 6 : 0);break;
                case g: h=2.0+(b-r)/difference;break;
                case b: h=4.0+(r-g)/difference;break;
            }
            h=Math.round(h*60);
        }
        if(max==0){
            s=0;
        }else{
            s=1-min/max;
        }
        s=Math.round(s*100);
        v=Math.round(v*100);
        result.h = h;
        result.s = s;
        result.v = v;
        return result;
    }

    getStyle(){
        return this.getRGBA(1);
    }

    getRGBA(alpha){
        alpha = typeof alpha === 'number' ? alpha : 1;
        return 'rgba('+this.r+','+this.g+','+this.b+','+alpha+')';
    }

    stringToColor(str){
        var _color = "";
        for(let k = 0, len = str.length; k < len; k++){
            if(str[k] === " ") continue;
            _color += str[k];
        }
        
        if(_color[0] === "#" || (_color[0] === "r" && _color[1] === "g" && _color[2] === "b")) return _color;
        else{
            for(let k = 0, len = ColorRefTable.length; k < len; k++){
                str = ColorRefTable[k];
                if(str[0] === _color) return str[1];
            }
        }

        return "";
    }

}

Object.defineProperties(RGBColor.prototype, {

    isRGBColor: {
        configurable: false,
        enumerable: false,
        writable: false,
        value: true,
    }

});