<!DOCTYPE HTML>
<html>
<body>
<canvas id="myCanvas" width="800" height="600" style="border:1px solid"></canvas>
<script type="text/javascript">
// get canvas instance
var canvas=document.getElementById("myCanvas");
var ctx=canvas.getContext("2d");
// draw a line
ctx.moveTo(10,10);
ctx.lineTo(150,50);
ctx.lineTo(10,50);
ctx.stroke();
// draw a circle
ctx.beginPath();
ctx.arc(100,100,30,0,Math.PI*2,true);
ctx.closePath();
ctx.stroke();
// fill a circle
ctx.fillStyle="#FF0000";
ctx.beginPath();
ctx.arc(100,200,30,0,Math.PI*2,true);
ctx.closePath();
ctx.fill();
// create linear gradient
var linearGrd=ctx.createLinearGradient(0,0,270,0);
linearGrd.addColorStop(0,"black");
linearGrd.addColorStop(0.5,"red");
linearGrd.addColorStop(1,"white");
ctx.fillStyle=linearGrd;
ctx.fillRect(120,230,140,40);
// create radial gradient
var radialGrd = ctx.createRadialGradient(400,400,50,400,400,100);
radialGrd.addColorStop(0,"red");
radialGrd.addColorStop(1,"white");
ctx.fillStyle=radialGrd;
ctx.fillRect(300,300,500,500);
// draw image
var img=new Image();
img.src="e.jpg";
img.onload=function(){
ctx.drawImage(img,0,0,50,50,0,400,50,50);
};
</script>
</body>
</html>原文地址：http://antlove.blog.51cto.com/10057557/1662754
