canvas绘制环形进度条

 <!DOCTYPE html>
 <html >
 <head>
     <meta http-equiv="content-type" content="text/html" charset="utf-8">
     <meta name="author" content="xuyunfei">
     <meta name="description" content="">
     <meta name="keywords" content="test,html">
     <title>环形进度条</title>
 </head>
 <body>
 </br></br></br></br>

 <div style="width:300px; height:300px; margin:20px auto">
      <canvas id="canvas" width="300" height="300">
         <p>抱歉，您的浏览器不支持canvas</p>
      </canvas>
 </div>

 <script type="text/javascript">
     function toCanvas(id ,progress){
                 // canvas进度条
                 var canvas = document.getElementById(id),
                 ctx = canvas.getContext("2d"),
                 percent = progress,  //最终百分比
                 circleX = canvas.width / 2,  //中心x坐标
                 circleY = canvas.height / 2,  //中心y坐标
                 radius = 100, //圆环半径
                 lineWidth = 5,  //圆形线条的宽度
                 fontSize = 20; //字体大小
                  //两端圆点
                 // function smallcircle1(cx, cy, r) {
                 //     ctx.beginPath();
                 //     //ctx.moveTo(cx + r, cy);
                 //     ctx.lineWidth = 1;
                 //     ctx.fillStyle = '#06a8f3';
                 //     ctx.arc(cx, cy, r,0,Math.PI*2);
                 //     ctx.fill();
                 // }
                 //  function smallcircle2(cx, cy, r) {
                 //      ctx.beginPath();
                 //      //ctx.moveTo(cx + r, cy);
                 //      ctx.lineWidth = 1;
                 //      ctx.fillStyle = '#00f8bb';
                 //      ctx.arc(cx, cy, r,0,Math.PI*2);
                 //      ctx.fill();
                 //  }

                  //画圆
                  function circle(cx, cy, r) {
                      ctx.beginPath();
                      //ctx.moveTo(cx + r, cy);
                      ctx.lineWidth = lineWidth;
                      ctx.strokeStyle = '#eee';
                      ctx.arc(cx, cy, r, 0, (Math.PI*2),true);
                      ctx.stroke();
                  }

                  //画弧线
                  function sector(cx, cy, r, startAngle, endAngle, anti) {
                      ctx.beginPath();
                      //ctx.moveTo(cx, cy + r); // 从圆形底部开始画
                      ctx.lineWidth = lineWidth;

                      // 渐变色 - 可自定义
                     //  var linGrad = ctx.createLinearGradient(
                     //      circleX-radius-lineWidth, circleY, circleX+radius+lineWidth, circleY
                     //  );
                     //  linGrad.addColorStop(0.0, '#06a8f3');
                      //linGrad.addColorStop(0.5, '#9bc4eb');
                     //  linGrad.addColorStop(1.0, '#00f8bb');
                     //  ctx.strokeStyle = linGrad;
                      ctx.strokeStyle = 'red';

                       //圆弧两端的样式
                      ctx.lineCap = 'round';

                      //圆弧
                     //  ctx.arc(
                     //      cx, cy, r,
                     //      -1.5,
                     //      -1.5 + endAngle/100 * (Math.PI*5/3),
                     //      false
                     //  );
                      ctx.arc(
                          cx, cy, r,
                          (Math.PI*-1/2),
                          (Math.PI*-1/2) + endAngle/100 * (Math.PI*2),
                          false
                      );
                      ctx.stroke();
                  }

                   //刷新
                  function loading() {
                      if (process >= percent) {
                         //  clearInterval(circleLoading);
                         process = 0.0;
                      }

                       //清除canvas内容
                      ctx.clearRect(0, 0, circleX * 2, circleY * 2);

                     //中间的字
                      ctx.font = fontSize + 'px April';
                      ctx.textAlign = 'center';
                      ctx.textBaseline = 'middle';
                      ctx.fillStyle = '#999';
                      ctx.fillText(parseFloat(process).toFixed(0) + '%', circleX, circleY);    

                      //圆形
                      circle(circleX, circleY, radius);

                       //圆弧
                      sector(circleX, circleY, radius, (Math.PI*-1/2), process);
                      //两端圆点
                     //  smallcircle1(150+Math.cos(2*Math.PI/360*120)*100, 150+Math.sin(2*Math.PI/360*120)*100, 5);
                     //  smallcircle2(150+Math.cos(2*Math.PI/360*(120+process*3))*100, 150+Math.sin(2*Math.PI/360*(120+process*3))*100, 5);
                      //控制结束时动画的速度
                     //  if (process / percent > 0.90) {
                     //      process += 0.30;
                     //  } else if (process / percent > 0.80) {
                     //      process += 0.55;
                     //  } else if (process / percent > 0.70) {
                     //      process += 0.75;
                     //  } else {
                          process += 1.0;
                     //  }
                  }

                  var process = 0.0;  //进度
                  var circleLoading = window.setInterval(function () {
                      loading();
                  }, 1000);

             }

             //第二部分，调用封装好的代码：
             toCanvas('canvas',100);

         </script>
     </body>
 </html>