怎么让这个圆只画一次
<html>
<head>
<meta charset="gb2312" />
<title></title>
<style type="text/css">
canvas {
margin-left:200px;
border: 1px solid #000;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="400"></canvas>
<script type="text/javascript">
window.onload = function(){
var canvas = document.getElementById('canvas');
if( canvas.getContext ){
//alert('支持 Canvas')
var ctx = canvas.getContext('2d')
var i = 0;
setInterval(function(){
ctx.clearRect(0,0,400,400);
ctx.beginPath();
ctx.arc(200,200,160,(Math.PI/180) * i,Math.PI*2,false);
ctx.stroke();
i++
},10)
}
}
</script>
</body>
</html>
[解决办法]
<html><head><meta charset="gb2312" /><title></title><style type="text/css">canvas {margin-left:200px;border: 1px solid #000;}</style></head><body><canvas id="canvas" width="400" height="400"></canvas><script type="text/javascript">window.onload = function(){var canvas = document.getElementById('canvas');if( canvas.getContext ){//alert('支持 Canvas')var ctx = canvas.getContext('2d')var i = 0;var t = setInterval(function(){if( i >= 360 ){ clearInterval(t);}ctx.clearRect(0,0,400,400);ctx.beginPath();ctx.arc(200,200,160,(Math.PI/180) * i,Math.PI*2,false);ctx.stroke();i++},10)} }</script></body></html>