手机移动端实现 jquery和HTML5 Canvas的幸运大奖盘特效

XML/HTML代码<div class="container">  <img src="images/1.png" id="shan-img" style="display:none;" />  <img src="images/2.png" id="sorry-img" style="display:none;" />  <div class="banner">   <div class="turnplate" style="background-image:url(images/turnplate-bg.png);background-size:100% 100%;">    <canvas class="item" id="wheelcanvas" width="422px" height="422px"></canvas>    <img class="pointer" src="images/turnplate-pointer.png"/>   </div>  </div> </div> 

.banner{display:block;width:95%;margin-left:auto;margin-right:auto;margin-bottom: 20px;} .banner .turnplate{display:block;width:100%;position:relative;} .banner .turnplate canvas.item{width:100%;} .banner .turnplate img.pointer{position:absolute;width:31.5%;height:42.5%;left:34.6%;top:23%;} 

var turnplate={   restaraunts:[],    //大转盘奖品名称   colors:[],     //大转盘奖品区块对应背景颜色   outsideRadius:192,   //大转盘外圆的半径   textRadius:155,    //大转盘奖品位置距离圆心的距离   insideRadius:68,   //大转盘内圆的半径   startAngle:0,    //开始角度       bRotate:false    //false:停止;ture:旋转 };   $(document).ready(function(){  //动态添加大转盘的奖品与奖品区域背景颜色  turnplate.restaraunts = ["50M免费流量包", "10金币", "谢谢参与", "5金币", "10M免费流量包", "20M免费流量包", "20金币 ", "30M免费流量包", "100M免费流量包", "2金币"];  turnplate.colors = ["#FFF4D6", "#FFFFFF", "#FFF4D6", "#FFFFFF","#FFF4D6", "#FFFFFF", "#FFF4D6", "#FFFFFF","#FFF4D6", "#FFFFFF"];       var rotateTimeOut = function (){   $('#wheelcanvas').rotate({    angle:0,    animateTo:2160,    duration:8000,    callback:function (){     alert('网络超时，请检查您的网络设置！');    }   });  };    //旋转转盘 item:奖品位置; txt：提示语;  var rotateFn = function (item, txt){   var angles = item * (360 / turnplate.restaraunts.length) - (360 / (turnplate.restaraunts.length*2));   if(angles<270){    angles = 270 - angles;    }else{    angles = 360 - angles + 270;   }   $('#wheelcanvas').stopRotate();   $('#wheelcanvas').rotate({    angle:0,    animateTo:angles+1800,    duration:8000,    callback:function (){     alert(txt);     turnplate.bRotate = !turnplate.bRotate;    }   });  };    $('.pointer').click(function (){   if(turnplate.bRotate)return;   turnplate.bRotate = !turnplate.bRotate;   //获取随机数(奖品个数范围内)   var item = rnd(1,turnplate.restaraunts.length);   //奖品数量等于10,指针落在对应奖品区域的中心角度[252, 216, 180, 144, 108, 72, 36, 360, 324, 288]   rotateFn(item, turnplate.restaraunts[item-1]);  }); });   function rnd(n, m){  var random = Math.floor(Math.random()*(m-n+1)+n);  return random;    }     //页面所有元素加载完毕后执行drawRouletteWheel()方法对转盘进行渲染 window.onload=function(){  drawRouletteWheel(); };   function drawRouletteWheel() {    var canvas = document.getElementById("wheelcanvas");    if (canvas.getContext) {   //根据奖品个数计算圆周角度   var arc = Math.PI / (turnplate.restaraunts.length/2);   var ctx = canvas.getContext("2d");   //在给定矩形内清空一个矩形   ctx.clearRect(0,0,422,422);   //strokeStyle 属性设置或返回用于笔触的颜色、渐变或模式    ctx.strokeStyle = "#FFBE04";   //font 属性设置或返回画布上文本内容的当前字体属性   ctx.font = '16px Microsoft YaHei';      for(var i = 0; i < turnplate.restaraunts.length; i++) {        var angle = turnplate.startAngle + i * arc;    ctx.fillStyle = turnplate.colors[i];    ctx.beginPath();    //arc(x,y,r,起始角,结束角,绘制方向) 方法创建弧/曲线（用于创建圆或部分圆）      ctx.arc(211, 211, turnplate.outsideRadius, angle, angle + arc, false);      ctx.arc(211, 211, turnplate.insideRadius, angle + arc, angle, true);    ctx.stroke();     ctx.fill();    //锁画布(为了保存之前的画布状态)    ctx.save();           //----绘制奖品开始----    ctx.fillStyle = "#E5302F";    var text = turnplate.restaraunts[i];    var line_height = 17;    //translate方法重新映射画布上的 (0,0) 位置    ctx.translate(211 + Math.cos(angle + arc / 2) * turnplate.textRadius, 211 + Math.sin(angle + arc / 2) * turnplate.textRadius);         //rotate方法旋转当前的绘图    ctx.rotate(angle + arc / 2 + Math.PI / 2);         /** 下面代码根据奖品类型、奖品名称长度渲染不同效果，如字体、颜色、图片效果。(具体根据实际情况改变) **/    if(text.indexOf("M")>0){//流量包     var texts = text.split("M");     for(var j = 0; j<texts.length; j++){      ctx.font = j == 0?'bold 20px Microsoft YaHei':'16px Microsoft YaHei';      if(j == 0){       ctx.fillText(texts[j]+"M", -ctx.measureText(texts[j]+"M").width / 2, j * line_height);      }else{       ctx.fillText(texts[j], -ctx.measureText(texts[j]).width / 2, j * line_height);      }     }    }else if(text.indexOf("M") == -1 && text.length>6){//奖品名称长度超过一定范围      text = text.substring(0,6)+"||"+text.substring(6);     var texts = text.split("||");     for(var j = 0; j<texts.length; j++){      ctx.fillText(texts[j], -ctx.measureText(texts[j]).width / 2, j * line_height);     }    }else{     //在画布上绘制填色的文本。文本的默认颜色是黑色     //measureText()方法返回包含一个对象，该对象包含以像素计的指定字体宽度     ctx.fillText(text, -ctx.measureText(text).width / 2, 0);    }         //添加对应图标    if(text.indexOf("金币")>0){     var img= document.getElementById("shan-img");     img.onload=function(){       ctx.drawImage(img,-15,10);        };      ctx.drawImage(img,-15,10);     }else if(text.indexOf("谢谢参与")>=0){     var img= document.getElementById("sorry-img");     img.onload=function(){       ctx.drawImage(img,-15,10);        };      ctx.drawImage(img,-15,10);     }    //把当前画布返回（调整）到上一个save()状态之前     ctx.restore();    //----绘制奖品结束----   }     }  }