用Canvas+js 实现简单圆形百分比统计图表

<div class="box">
    <ul>
        <li>
            <canvas id="one" width="200" height="200"></canvas>
        </li>
        <li>
            <canvas id="two" width="200" height="200"></canvas>
        </li>
        <li>
            <canvas id="three" width="200" height="200"></canvas>
        </li>
    </ul>
</div>

body {
    margin: 0;
    padding: 50px 0;
    background-color: #444;
}
ul,li {
    list-style: none;
    margin: 0;
    padding: 0;
}
ul li {
    float: left;
    width: 33%;
    text-align: center;
}

function drawCircle(_options){
    var options = _options || {};    //获取或定义options对象;
    options.angle = options.angle || 1;
    options.color = options.color || ‘#fff‘;
    options.lineWidth = options.lineWidth || 10;
    options.lineCap = options.lineCap || ‘square‘;

    var oBoxOne = document.getElementById(options.id);
    var sCenter = oBoxOne.width / 2;
    var ctx = oBoxOne.getContext(‘2d‘);
    var nBegin = Math.PI / 2;
    var nEnd = Math.PI * 2;
    var grd = ctx.createLinearGradient(0, 0, oBoxOne.width, 0);
    grd.addColorStop(0, ‘red‘);
    grd.addColorStop(0.5, ‘yellow‘);
    grd.addColorStop(1, ‘green‘);

    ctx.textAlign = ‘center‘;
    ctx.font = ‘normal normal bold 20px Arial‘;
    ctx.fillStyle = options.color == ‘grd‘ ? grd : options.color;
    ctx.fillText((options.angle * 100) + ‘%‘, sCenter, sCenter);
    /*ctx.strokeStyle = grd;
    ctx.strokeText((options.angle * 100) + ‘%‘, sCenter, sCenter);*/
    ctx.lineCap = options.lineCap;
    ctx.strokeStyle = options.color == ‘grd‘ ? grd : options.color;
    ctx.lineWidth = options.lineWidth;

    ctx.beginPath();
    ctx.strokeStyle = ‘#D8D8D8‘;
    ctx.arc(sCenter, sCenter, (sCenter - options.lineWidth), -nBegin, nEnd, false);
    ctx.stroke();

    var imd = ctx.getImageData(0, 0, 240, 240);
    function draw(current) {
        ctx.putImageData(imd, 0, 0);
        ctx.beginPath();
        ctx.strokeStyle = options.color == ‘grd‘ ? grd : options.color;
        ctx.arc(sCenter, sCenter, (sCenter - options.lineWidth), -nBegin, (nEnd * current) - nBegin, false);
        ctx.stroke();
    }

    var t = 0;
    var timer = null;
    function loadCanvas(angle) {
        timer = setInterval(function(){
            if (t > angle) {
                draw(options.angle);
                clearInterval(timer);
            }else{
                draw(t);
                t += 0.02;
            }
        }, 20);
    }
    loadCanvas(options.angle);
    timer = null;

}