本文實例講述了javascript+html5實現繪制圓環的方法。分享給大家供大家參考。具體如下：
<!DOCTYPE html><html><head> <title> </title> <meta http-equiv="Content-Type" content="text/html;charset=UTF-8"></head><body> <fieldset> <canvas id="myCanvas" width="400px" height="400px" >Your browser does not support the HTML5 canvas tag.</canvas></fieldset><script type="text/javascript"> function yuanhuan(ctx,data,option){ var cood=option.cood; var radius=option.radius; var lastpos=pos=0; for(var i=0;i<data.length;i++){ ctx.beginPath(); ctx.moveTo(cood.x,cood.y); ctx.fillStyle = data[i].bgcolor; pos=lastpos+Math.PI*2*data[i].value/100; ctx.arc(cood.x,cood.y,radius,lastpos,pos,false); ctx.fill(); lastpos=pos; } ctx.beginPath(); ctx.fillStyle ="white"; radius*=0.5; ctx.arc(cood.x,cood.y,radius,0,Math.PI*2 ,false); ctx.fill(); }var data=[ {bgcolor:'yellowgreen',value:30}, {bgcolor:'green',value:30}, {bgcolor:'yellow',value:40} ]; var canvas = document.getElementById("myCanvas"); var ctx = canvas.getContext("2d"); yuanhuan(ctx,data,{cood:{x:200,y:200},radius:150})</script></body></html>希望本文所述對大家的javascript程序設計有所幫助。
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