html5 canvas从圆开始

浏览数：27 / 时间：2015年06月09日

<!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>

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