<html>
<body>
<h3>访问 CANVAS 元素</h3>
<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
您的浏览器不支持 HTML5 canvas 标签。</canvas>
<p>点击按钮在画布上绘图。</p>
<button onclick="myFunction()">尝试一下</button>
<script>
function myFunction()
{
var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
ctx.fillStyle="#FF0000";
ctx.fillRect(20,20,150,100);
}
</script>
</body>
</html>