HTML5Canvas移动手机端的幸运大奖盘特效

<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----
 } 
 } 
}