如何根据背景颜色设置黑白之间的字体颜色

Question

我有一个十六进制颜色的数组（动态值），我想将浅色背景的字体颜色设置为黑色，将深色背景的颜色设置为白色

        /* array for example */
        var colorHexCode = ["#ECECEC", "#FFF", "#F4F2ED"];
        for (var i = 0; i < colorHexCode.length; i++) {
            var ColorLayerDiv = document.createElement("div");
            ColorLayerDiv.style.height = "10px";
            ColorLayerDiv.style.backgroundColor = colorHexCode[i];
            $('#Layers').append(ColorLayerDiv);
        }

我想像这样自动设置字体颜色：

是否可以使用 js 或查询来做到这一点？如果可以，你能给我举个例子吗

Answer 1

解决办法：

这段代码，来源：http://codepen.io/davidhalford/pen/ywEva;

threshold = 130; /* about half of 256. Lower threshold equals more dark text on dark background  */

            hRed = hexToR(hex);
            hGreen = hexToG(hex);
            hBlue = hexToB(hex);


            function hexToR(h) {return parseInt((cutHex(h)).substring(0,2),16)}
            function hexToG(h) {return parseInt((cutHex(h)).substring(2,4),16)}
            function hexToB(h) {return parseInt((cutHex(h)).substring(4,6),16)}
            function cutHex(h) {return (h.charAt(0)=="#") ? h.substring(1,7):h}

            cBrightness = ((hRed * 299) + (hGreen * 587) + (hBlue * 114)) / 1000;
              if (cBrightness > threshold){return "#000000";} else { return "#ffffff";} 
          }

感谢@jcubic

Answer 2

在这里你可以找到你的颜色是深还是浅：

  (function ($) {

        $.fn.lightOrDark = function () {

        var r, b, g, hsp
          , a = this.css('background-color');

        if (a.match(/^rgb/)) {
            a = a.match(/^rgba?\((\d+),\s*(\d+),\s*(\d+)(?:,\s*(\d+(?:\.\d+)?))?\)$/);
            r = a[1];
            g = a[2];
            b = a[3];
        } else {
            a = +("0x" + a.slice(1).replace( // thanks to jed : http://gist.github.com/983661
                a.length < 5 && /./g, '$&$&'
              )
            );
            r = a >> 16;
            b = a >> 8 & 255;
            g = a & 255;
        }
        hsp = Math.sqrt( // HSP equation from http://alienryderflex.com/hsp.html
          0.299 * (r * r) +
          0.587 * (g * g) +
          0.114 * (b * b)
        );
        if (hsp > 127.5) {
            alert('light');
        } else {
            alert('dark');
        }
    }

})(jQuery);

Answer 3

您可以处理颜色并计算亮度。

var colorHexCode = ["#ECECEC", "#FFF", "#F4F2ED","#777", "#FF0", '#00F'];
        for (var i = 0; i < colorHexCode.length; i++) {
            var ColorLayerDiv = document.createElement("div");
            ColorLayerDiv.style.height = "20px";
            ColorLayerDiv.style.backgroundColor = colorHexCode[i];

            //text color
            var c = colorHexCode[i];
            var brightness = 0;
            for(var j = 1; j< c.length; ++j){
                    var rgb = c[j];
                if(c.length==4)            
                    rgb += rgb;
                else {
                    j+=1;
                  rgb += c[j];
                }  
                var b = parseInt(rgb, 16);
                brightness += b;
            }
            ColorLayerDiv.innerText = c;
            ColorLayerDiv.style.color = brightness >= (255*3/2) ? 'black' : 'white';

            $('#Layers').append(ColorLayerDiv);
        }