运行不显示图形，只显示空白的800x800的面板
<body>
<canvas id="canvas" style="border:1px solid #aaa; display:block; margin:50px auto;">当前浏览器不支持Canvas，请更换浏览器再试。</canvas>
<script>
var tangram=[
{p:[{x:0,y:0},{x:800,y:0},{x:400,y:400}],color:"#caff67"},
{p:[{x:0,y:0},{x:400,y:400},{x:0,y:800}],color:"#67becf"},
{p:[{x:800,y:0},{x:800,y:400},{x:600,y:600},{x:600,y:200}],color:"#ef3d61"},
{p:[{x:600,y:200},{x:600,y:600},{x:400,y:400}],color:"#f9f51a"},
{p:[{x:400,y:400},{x:600,y:600},{x:400,y:800}],color:"#a594c0"},
{p:[{x:200,y:600},{x:400,y:800},{x:0,y:800}],color:"#fa8ecc"},
{p:[{x:800,y:400},{x:800,y:800},{x:400,y:800}],color:"#f6ca29"}
];
window.onload=function(){
var canvas=document.getElementById("canvas");
canvas.width=800;
canvas.height=800;
var context=canvas.getContext("2d");
for(var i=0; i<tangram.length; i++){
draw(tangram[i],context);
}
}
function draw(piece,cxt){
cxt.beginPath();
cxt.moveTo(piece.p[0].x, piece.p[0].y);
for(var i=1; i<piece.p.length; i++){
cxt.lineTo(piece.p[i].x, piece.p[i].y);
}
cxt.colsePath();
cxt.fillStyle=piece.color;
cxt.fill();
}
</script>
</body>
