                        課程
                    
                        /前端開發
                        
                            /Html5
                        
                        /Canvas繪圖詳解

為什么使用了那個JS還是不能兼容IE？

<!DOCTYPE?html>
<html>
????<head>
????????<meta?charset="UTF-8">
????????<title>綜合使用arc和arcTo繪制一輪彎月</title>
????????<!--[if?IE]><script?type="text/javascript"?src="js/excanvas.js"></script><![endif]-->
????</head>
????<body>
????????<canvas?id="canvas"?style="margin:?0?auto;?display:?block;?border:?1px?solid?#ddd;">
????????????當前瀏覽器不支持canvas畫布，請更換瀏覽器之后再打開吧！
????????</canvas>
????????<br?/>
????????<script?type="text/javascript">
????????????window.onload=function(){
????????????????var?canvas?=?document.getElementById('canvas');
????????????????canvas.width=800;
????????????????canvas.height=800;
????????????????var?context?=?canvas.getContext('2d');
????????????????
????????????????context.arc(400,400,300,0.5*Math.PI,1.5*Math.PI,true);
????????????????context.moveTo(400,100);
????????????????context.arcTo(1200,400,400,700,(400-100)*dis(400,100,1200,400)/(1200-400));??//?把圖畫出來，根據同一個角的兩個tan值相等可以算出來
????????????????context.stroke();
????????????}
????????????
????????????function?dis(x1,x2,y1,y2){
????????????????return?Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
????????????}
????????</script>
????</body>
</html>

我是拿上次畫的月亮的那個去做這個兼容，結果在谷歌上顯示是這樣的