我写的这段代码怎么不能再浏览器中显示不出效果，请帮我看一下我错在哪里，谢谢！
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script>
window.onload=function(){
var canvas=document.getElementById("canvas");
if(canvas.getContext("2d")){
var context=canvas.getContext("2d");
}else{
alert("当前浏览器不支持canvas,请更换浏览器后再试！");
}
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},{x:200,y:600}],color:"#594c0"},
{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.closePath();
cxt.fillStyle=piece.color;
cxt.fill();
}
}
</script>
</head>
<body>
<canvas id="canvas" width="1024" height="768" style="border:1px solid #aaa;display:block;margin:50px auto;"></canvas>
</body>
</html>
慕粉32157321回答
-
李晓健
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); } }这里多写了一层 window.onload，因为你上面已经有了一层，所以这层不必要了,应该是window.onload=function(){ var canvas=document.getElementById("canvas"); if(canvas.getContext("2d")){ var context=canvas.getContext("2d"); }else{ alert("当前浏览器不支持canvas,请更换浏览器后再试！"); } 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},{x:200,y:600}],color:"#594c0"}, {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"} ]; 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.closePath(); cxt.fillStyle=piece.color; cxt.fill(); } }
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