HSV-RGB-convert.js

// 16进制色值转换成rgba
function HEX2RGB(HEX, opacity){
    opacity=opacity || "1.0";
    HEX = HEX.replace("#","");
    var r = parseInt(HEX.substring(0,2),16);
    var g = parseInt(HEX.substring(2,4),16);
    var b = parseInt(HEX.substring(4,6),16);
    return "rgba("+r+","+g+","+b+","+opacity+")";
}


// rgba色值转换成16进制以及透明度
function HSV2RGB(h, s, v, opacity){
  // inputs h=hue=0-360, s=saturation=0-1, v=value=0-1
  // algorithm from Wikipedia on HSV conversion
    var toHex = function(decimalValue, places){
        if(places == undefined || isNaN(places))  places = 2;
        var hex = new Array("0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F");
        var next = 0;
        var hexidecimal = "";
        decimalValue=Math.floor(decimalValue);
        while(decimalValue > 0){
            next = decimalValue % 16;
            decimalValue = Math.floor((decimalValue - next)/16);
            hexidecimal = hex[next] + hexidecimal;
        }
        while (hexidecimal.length < places){
            hexidecimal = "0"+hexidecimal;
        }
        return hexidecimal;
    }
    var hi = Math.floor(h / 60) % 6;
    var f = h / 60 - Math.floor(h / 60);
    var p = v * (1 - s);
    var q = v * (1 - f * s);
    var t = v * (1 - (1 - f) * s);
    var r = v;  // case hi==0 below
    var g = t;
    var b = p;
    switch(hi){
        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;
    }
    //  At this point r,g,b are in 0...1 range.  Now convert into rgba or #FFFFFF notation
    if(opacity){
        return "rgba(" + Math.round(255*r) + "," + Math.round(255 * g) + "," + Math.round(255 * b) + "," + opacity + ")";
    }else{
        return "#" + toHex(r * 255) + toHex(g * 255) + toHex(b * 255);
    }
}