<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>非零环绕原则</title>
</head>
<body>
<canvas id="canvas" style="margin:0 auto;border:1px #ddd solid">
The current browser does not support Canvas, can replace the browser a try!
</canvas>
<script>
window.onload = function(){
var canvas = document.getElementById('canvas');
canvas.width = 1024;
canvas.height = 768;
if(canvas.getContext('2d')){
var context = canvas.getContext('2d');
context.beginPath();
context.rect(100,100,600,600);
pathRect(context,200,200,400,200);
pathTriangle(context,300,450,150,650,450,650);
context.arc(550,550,100,0,Math.PI*2,true);
context.closePath();
context.fillStyle = "#058";
context.shadowColor = "gray";
context.shadowOffsetX = 10;
context.shadowOffsetY = 10;
context.shadowBlur = 10;
context.fill();
}else{
alert('当前游览器不支持Canvas，请更换游览器后再试！');
}
}
function pathRect(cxt,x,y,width,height){
cxt.moveTo(x,y);
cxt.lineTo(x,y+height);
cxt.lineTo(x+width,y+height);
cxt.lineTo(x+width,y)
cxt.lineTo(x,y);
}
function pathTriangle(cxt,x1,y1,x2,y2,x3,y3){
cxt.moveTo(x1,y1);
cxt.lineTo(x2,y2);
cxt.lineTo(x3,y3);
cxt.lineTo(x1,y1);
}
</script>
</body>
</html>
