https://codepen.io/hihust-knighterrant/pen/YzOPLgB
渐变色图例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<!-- <script type="text/javascript" src="./js/demo.js"></script> -->
</head>
<body>
<div id="div" style="position: absolute; width:150px;height: 20px;margin:200px;"></div>
<script>
/*
* startColor：开始颜色hex
* endColor：结束颜色hex
* step:几个阶级（几步）
*/
function gradientColor(startColor, endColor, step) {
startRGB = this.colorRgb(startColor); //转换为rgb数组模式
startR = startRGB[0];
startG = startRGB[1];
startB = startRGB[2];
endRGB = this.colorRgb(endColor);
endR = endRGB[0];
endG = endRGB[1];
endB = endRGB[2];
sR = (endR - startR) / step; //总差值
sG = (endG - startG) / step;
sB = (endB - startB) / step;
var colorArr = [];
for (var i = 0; i < step; i++) {
//计算每一步的hex值
var hex = this.colorHex('rgb(' + parseInt((sR * i + startR)) + ',' + parseInt((sG * i + startG)) + ',' +
parseInt((sB * i + startB)) + ')');
colorArr.push(hex);
}
return colorArr;
}
// 将hex表示方式转换为rgb表示方式(这里返回rgb数组模式)
gradientColor.prototype.colorRgb = function (sColor) {
var reg = /^#([0-9a-fA-f]{3}|[0-9a-fA-f]{6})$/;
var sColor = sColor.toLowerCase();
if (sColor && reg.test(sColor)) {
if (sColor.length === 4) {
var sColorNew = "#";
for (var i = 1; i < 4; i += 1) {
sColorNew += sColor.slice(i, i + 1).concat(sColor.slice(i, i + 1));
}
sColor = sColorNew;
}
//处理六位的颜色值
var sColorChange = [];
for (var i = 1; i < 7; i += 2) {
sColorChange.push(parseInt("0x" + sColor.slice(i, i + 2)));
}
return sColorChange;
} else {
return sColor;
}
};
// 将rgb表示方式转换为hex表示方式
gradientColor.prototype.colorHex = function (rgb) {
var _this = rgb;
var reg = /^#([0-9a-fA-f]{3}|[0-9a-fA-f]{6})$/;
if (/^(rgb|RGB)/.test(_this)) {
var aColor = _this.replace(/(?:(|)|rgb|RGB)*/g, "").split(",");
var strHex = "#";
for (var i = 0; i < aColor.length; i++) {
var hex = Number(aColor[i]).toString(16);
hex = hex < 10 ? 0 + '' + hex : hex; // 保证每个rgb的值为2位
if (hex === "0") {
hex += hex;
}
strHex += hex;
}
if (strHex.length !== 7) {
strHex = _this;
}
return strHex;
} else if (reg.test(_this)) {
var aNum = _this.replace(/#/, "").split("");
if (aNum.length === 6) {
return _this;
} else if (aNum.length === 3) {
var numHex = "#";
for (var i = 0; i < aNum.length; i += 1) {
numHex += (aNum[i] + aNum[i]);
}
return numHex;
}
} else {
return _this;
}
}
function setColor(){
var color = ["#2396B5","#E4F5A0","#F89A3D","#C1253D"];
for(var i = 0;i<color.length-1;i++){
var gradient = new gradientColor(color[i], color[i+1], 50);
for(var j = 0;j<gradient.length;j++){
var div = document.getElementById("div");
var span = document.createElement("span");
span.id = 'legend' + (i+1);
span.style.width = "1px";
span.style.height = "20px";
span.style.float = "left";
span.style.backgroundColor = gradient[j];
div.appendChild(span);
}
}
};
setColor();
// console.log(gradient); //控制台输出
</script>
</body>
</html>