<!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>html5 canvas从圆开始</title>
<script src="js/modernizr.js"></script>
</head>
<body>
<script type="text/javascript">
window.addEventListener('load',eventWindowLoaded,false);
function eventWindowLoaded(){
canvasApp();
}
function canvasSupport(){
return Modernizr.canvas;
}
function canvasApp(){
if(!canvasSupport()){
return;
}else{
var theCanvas = document.getElementById('canvas')
var context = theCanvas.getContext("2d")
}
drawScreen();
function drawScreen(){
//颜色粉色，线宽10,
context.beginPath();
context.strokeStyle="pink";
context.lineWidth=10;
context.arc(100,100,20,(Math.PI/180)*0,(Math.PI/180)*360,false);
//100,100圆心的位置
//20半径
//开始喝结束的弧度制从0-360
//1弧度 = π/180°弧度不是角度哦
//true和false对象弧线方向
context.stroke();
context.closePath();
context.beginPath();
context.arc(200,100,20,(Math.PI/180)*0,(Math.PI/180)*90,false);
context.stroke();
context.closePath();
context.beginPath();
context.arc(300,100,20,(Math.PI/180)*0,(Math.PI/180)*90,true);
context.stroke();
context.closePath();
}
}
</script>
<canvas id="canvas" width="500" height="500">
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</canvas>
</body>
</html>
