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[网页设计]html5 canvas 弧形描边渐变


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html ="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>弧形描边渐变</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.strokeStyle = gr;    context.arc(100,100,50,(Math.PI/180)*0,(Math.PI/180)*360,false);    context.stroke();        }}</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>