canvas实现环形进度条

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>多用户留言系统-</title>
<meta name="description" content="">
<meta name="keywords" content="">
<!--[if IE]>
<script src="html5.js"></script>
<script src="excanvas.compiled.js"></script>
<![endif]-->


<link href="" rel="stylesheet">
<style>
/*html5*/
article,aside,dialog,footer,header,section,footer,nav,figure,menu,canvas{display:block}
</style>
</head>
<body>
<canvas id="canvas" width="300" height="300">
<p>抱歉，您的浏览器不支持canvas</p>
</canvas>

</body>
</html>

<script type="text/javascript">
window.onload = function(){
toCanvas('canvas',50);
}

function toCanvas(id ,progress){

var canvas = document.getElementById(id),
ctx = canvas.getContext("2d"),
percent = progress, 
circleX = canvas.width / 2, 
circleY = canvas.height / 2, 
radius = 100, 
lineWidth = 5, 
fontSize = 20; 

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 = '#06a8f3';
ctx.arc(cx, cy, r,0,Math.PI*2);
ctx.fill();
}


function circle(cx, cy, r) {
ctx.beginPath();
//ctx.moveTo(cx + r, cy);
ctx.lineWidth = lineWidth;
ctx.strokeStyle = '#eee';
ctx.arc(cx, cy, r, Math.PI*2/3, Math.PI * 1/3);
ctx.stroke();
}


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, '#06a8f3');
ctx.strokeStyle = linGrad;


ctx.lineCap = 'round';


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


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


ctx.clearRect(0, 0, circleX * 2, circleY * 2);


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


sector(circleX, circleY, radius, Math.PI*2/3, process);

smallcircle1(150+Math.cos(2*Math.PI/360*120)*100, 150+Math.sin(2*Math.PI/360*120)*100, 2);
smallcircle2(150+Math.cos(2*Math.PI/360*(120+process*3))*100, 150+Math.sin(2*Math.PI/360*(120+process*3))*100, 2);

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; 
var circleLoading = window.setInterval(function () {
loading();
}, 20);

}
</script>
canvas实现环形进度条

推荐阅读
