<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Canvas制作圆形进度条Loading效果 | jQuery特效|手机微信网站特效| 脚本之家</title>
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<style>
/*框架预览 CSS*/
* { margin: 0; padding: 0; }
body { text-align: center; background-color: #0cc; }
.mkeHeadBox{ padding: 30px 10px; text-overflow: ellipsis; white-space: nowrap; margin: 0; color: #fff; text-align: center; overflow: hidden; letter-spacing: 1px; font: 26px/26px "微软雅黑"; }
.mkeFooterBox{ padding: 25px 10px; text-overflow: ellipsis; margin: 0; color: #fff; font-size: 14px; line-height: 24px; text-align: center; overflow: hidden;}
.mkeContentBox:after{height:0; clear:both;}
.mkeFooterBox p,.mkeFooterBox div{padding:0; margin:0; line-height:26px; font-size:14px;}
.mkeFooterBox a{color:#fff; white-space:nowrap}
.mkeButton{background:#F36; display:inline-block; text-decoration:none; width:102px; border-radius:0.3em; transition:all 0.3s ease}
.mkeButton:hover{ background: #FF1550; }
.mkeURL{font-size:24px;}
.mkeFooterBox .mKeBannerAD{ width: 728px; height: 90px; margin: 18px auto 0; }
.mkeFooterBox .mSmallKeBannerAD{display:none;}
@media only screen and (max-width:900px){
.mkeButton {display:block; margin:8px auto 0;}
}
@media only screen and (max-width:767px){
.mkeHeadBox{font-size:18px; padding:15px 10px;}
.mkeFooterBox p,.mkeFooterBox div{ line-height:24px; font-size:12px;}
.mkeURL{font-size:22px;}
.mkeFooterBox .mKeBannerAD{display:none;}
.mkeFooterBox .mSmallKeBannerAD{width:300px; height:250px; margin:18px auto 0; display:block;}
}
/*End*/
</style>
</head>
<body class="mkeBody">
<div class="mkeHeadBox">Canvas制作圆形进度条Loading效果</div>
<div class="mkeContentBox">
<!--效果html开始-->
<canvas id="canvas" width="300" height="500" style="background:#0cc;"></canvas>
<script>
window.onload = function(){
var canvas = document.getElementById('canvas'), //获取canvas元素
context = canvas.getContext('2d'), //获取画图环境，指明为2d
centerX = canvas.width/2, //Canvas中心点x轴坐标
centerY = canvas.height/2, //Canvas中心点y轴坐标
rad = Math.PI*2/100, //将360度分成100份，那么每一份就是rad度
speed = 0.1; //加载的快慢就靠它了
//绘制蓝色外圈
function blueCircle(n){
context.save();
context.strokeStyle = "#fff"; //设置描边样式
context.lineWidth = 5; //设置线宽
context.beginPath(); //路径开始
context.arc(centerX, centerY, 100 , -Math.PI/2, -Math.PI/2 +n*rad, false); //用于绘制圆弧context.arc(x坐标，y坐标，半径，起始角度，终止角度，顺时针/逆时针)
context.stroke(); //绘制
context.closePath(); //路径结束
context.restore();
}
//绘制白色外圈
function whiteCircle(){
context.save();
context.beginPath();
context.strokeStyle = "white";
context.arc(centerX, centerY, 100 , 0, Math.PI*2, false);
context.stroke();
context.closePath();
context.restore();
}
//百分比文字绘制
function text(n){
context.save(); //save和restore可以保证样式属性只运用于该段canvas元素
context.strokeStyle = "#fff"; //设置描边样式
context.font = "40px Arial"; //设置字体大小和字体
//绘制字体，并且指定位置
context.strokeText(n.toFixed(0)+"%", centerX-25, centerY+10);
context.stroke(); //执行绘制
context.restore();
}
//动画循环
(function drawFrame(){
window.requestAnimationFrame(drawFrame, canvas);
context.clearRect(0, 0, canvas.width, canvas.height);
whiteCircle();
text(speed);
blueCircle(speed);
if(speed > 100) speed = 0;
speed += 0.1;
}());
}
</script>
<!--效果html结束-->
</div>
</body>
</html>
