<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>html5实现待机动画的效果</title>
</head>
<body>
<canvas id="can1" width="400" height="300" style="border: 1px solid red">
</canvas>
<script type="text/javascript">
var can1=document.getElementByIdx_x("can1");
var cxt=can1.getContext("2d");
var cw=parseInt(can1.width);
var ch=parseInt(can1.height);
//该计数器是用来控制透明度的,这样可以实现动画效果
var count=0;
aim();
function aim(){
cxt.clearRect(0,0,400,300);
//下边开始绘制我们的36个小长方形
for(var i=0;i<36;i++){
cxt.save();
//绘制原理是绘制完我们的长方形图形之后,将其旋转
var r=(i*10)*Math.PI/180;
//1,将坐标原点移动到我们画布的中心
cxt.translate(cw/2,ch/2);
cxt.rotate(r);
if(i==count){
cxt.globalAlpha=1.0;
}
else{
cxt.globalAlpha=0.3;
}
cxt.beginPath();
cxt.fillStyle="gray";
cxt.fillRect(0,0,100,5);
cxt.restore();
}
count=(count+1)6;
}
setInterval("aim()",100);
</script>
</body>
</html>