老师，哪儿有问题呢

来源：9-2 编程练习

慕丝5187111

2018-11-04 17:24:20

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>canvas离屏</title>
    <style>

    </style>
</head>
<body>
<canvas width="800px" height="800px" id="canvas">您的浏览器不支持canvas</canvas>
<canvas width="800px" height="800px" id="offcanvas">您的浏览器不支持canvas</canvas>
<script>
    var canvas=document.getElementById("canvas");
    var context=canvas.getContext("2d");
    //补充代码
 var img = new Image();
    img.src = "http://climg.mukewang.com/5aa6633400017bc704170220.jpg";
    img.onload = function(){
        context.drawImage(img,0,0);
    }

    var offcanvas=document.getElementById("offcanvas");
    var offcontext=canvas.getContext("2d");
    offcontext.font = "bold 30px sons-serif";
    offcontext.fillStyle = "rgba(255,255,255,0.5)"
 offcontext.fillText('==www.imooc.com=',50,200);

    context.drawImage(offcanvas,0,0,offcanvas.width,offcanvas.height,0,0,canvas.width,canvas.height);
</script>
</body>
</html>

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