html5 canvas 圆形径向渐变

<!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>圆形径向渐变</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(){

        var gr = context.createRadialGradient(50,50,25,100,100,100);

        //添加颜色端点

        gr.addColorStop(0,'rgb(255,0,0)');

        gr.addColorStop(.5,'rgb(0,255,0)');

        gr.addColorStop(1,'rgb(255,0,0)');

        //应用fillStyle生成渐变

        context.fillStyle = gr;

        context.arc(100,100,50,(Math.PI/180)*0,(Math.PI/180)*360,false);

        context.fill();

    }

}

</script>

<canvas id="canvas" width="500" height="500">

你的浏览器无法使用canvas

小白童鞋；你的支持是我最大的快乐！！

</canvas>

</body>

</html>
巴特西

html5 canvas 圆形径向渐变

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