一、问题:
<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="500" height="500" style="border:1px solid #c3c3c3;">
Your browser does not support the canvas element.
</canvas>
<script type="text/javascript" >
var c=document.getElementById("myCanvas");
var cxt=c.getContext("2d");
var img=new Image();
img.src="1.jpg";
cxt.drawImage(img,0,0,500,500);
</script>
</body>
</html>
在11行处加onload事件
<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="500" height="500" style="border:1px solid #c3c3c3;">
Your browser does not support the canvas element.
</canvas>
<script type="text/javascript" >
var c=document.getElementById("myCanvas");
var cxt=c.getContext("2d");