JavaScript结合HTML5 Canvas绘制图片的实现方法

<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="200" height="100"
style="border:1px solid #c3c3c3;">
Your browser does not support the HTML5 canvas tag.
</canvas>
<script type="text/javascript">
var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
var img=new Image();
img.onload = function(){
ctx.drawImage(img,0,0);
};
img.src="img_flwr.png";
</script>
</body>
</html>