javascript+HTML5 Canvas绘制转盘抽奖

.lunck_draw_wrap{display:block;width:95%;margin-right:auto;} .lunck_draw_wrap .turnplate{display:block;width:106%; position:relative;} .lunck_draw_wrap .turnplate canvas.item{left:1px; position: relative; top:9px; width:100%;} .lunck_draw_wrap .turnplate img.pointer{ height:37.5%; left:34.6%; position: absolute; top:30%; width:31.5%;}

var turnplate ={ restaraunts:[],//大转盘奖品名称 lucky:[],//奖品内容 colors:[],//大转盘奖品区块对应背景颜色 goodsimgArr:[],//奖品图片页面标签 outsideRadius:175,//大转盘外圆的半径 textRadius:140,//大转盘奖品位置距离圆心的距离 insideRadius:65,//大转盘内圆的半径 startAngle:0,//开始角度 bRotate:false//false:停止;ture:旋转 };

$.each(data.list,function(key, value){ turnplate.restaraunts.push(value.data0); turnplate.lucky.push(value.data1); turnplate.goodsimgArr.push(getLuckyImg + value.data4); if(key %2==0) turnplate.colors.push("#fff"); else turnplate.colors.push("#5fcbd4"); }) 

[ { "data0":"一等奖", "data1":"iphone6s", "data2":"0", "data3":"0", "data4":"201510161406303384.png", "data5":"XXXX网络科技", "data6":"浙江省衢州市柯城区XXXXX", "data7":"0570-XXXXXX" },...... ]

turnplate.goodsimgArr.push('../images/hongbao.png') turnplate.restaraunts.push("优胜奖"); turnplate.colors.push("#5fcbd4"); //页面所有元素加载完毕后执行drawRouletteWheel()方法对转盘进行渲染 preloadimages(turnplate.goodsimgArr).done(function(images){ drawRouletteWheel(); });

//对奖品图片预加载 function preloadimages(arr){ var newimages =[], loadedimages =0 var postaction =function(){}//此处增加了一个postaction函数 var arr =(typeof arr !="object")?[arr]: arr function imageloadpost(){ loadedimages++ if(loadedimages == arr.length){ postaction(newimages)//加载完成用我们调用postaction函数并将newimages数组做为参数传递进去 } } for(var i =0; i < arr.length; i++){ newimages[i]=newImage() newimages[i].src = arr[i] newimages[i].onload =function(){ imageloadpost() } newimages[i].onerror =function(){ imageloadpost() } } return{//此处返回一个空白对象的done方法 done:function(f){ postaction = f || postaction } } }

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 ="rgba(0,0,0,0)"; //font 属性设置或返回画布上文本内容的当前字体属性 ctx.font ='bold 18px Microsoft YaHei'; for(var i =0; i < turnplate.restaraunts.length; i++){ //根据当前奖品索引 计算绘制的扇形开始弧度 var angle = turnplate.startAngle + i * arc; //根据奖品参数 绘制扇形填充颜色 ctx.fillStyle = turnplate.colors[i]; //开始绘制扇形 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） //绘制大圆 ctx.arc(212,212, turnplate.outsideRadius, angle, angle + arc,false); //绘制小圆 ctx.arc(212,212, 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---- //奖品默认字体颜色 ctx.fillStyle ="#fff"; var text = turnplate.restaraunts[i]; var lukyname = turnplate.lucky[i]; var line_height =17; //translate方法重新映射画布上的 (0,0) 位置 ctx.translate(212+Math.cos(angle + arc /2)* turnplate.textRadius,212+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); //绘制奖品图片 var img =newImage(); img.src = turnplate.goodsimgArr[i]; ctx.drawImage(img,-17,35); //由于设计的转盘色块是交错的，所以这样可以实现相邻奖品区域字体颜色不同 if(i %2==0){ ctx.fillStyle ="#f7452f"; } //将字体绘制在对应坐标 ctx.fillText(text,-ctx.measureText(text).width /2,0); //设置字体 ctx.font =' 14px Microsoft YaHei'; //绘制奖品名称 if(text !="优胜奖"){ ctx.fillText(lukyname,-ctx.measureText(lukyname).width /2,25); }else{ ctx.fillText("优麦币",-ctx.measureText("优麦币").width /2,25); } //把当前画布返回（插入）到上一个save()状态之前 ctx.restore(); ctx.save(); //----绘制奖品结束---- } } }

<divclass="lunck_draw_wrap"> <divclass="turnplate"style=" background-size:100%100%;"> <canvasclass="item"id="wheelcanvas"width="422px"height="422px"></canvas> <imgclass="pointer"style="top:0px; left:0px; width:100%; height:100%;"src="../images/chouzhang12.png"/> <imgclass="pointer"src="../images/hianji .png"/> </div> </div>

$('.lunck_draw_wrap').delegate("img.pointer","click",function(){ if(turnplate.bRotate)return; turnplate.bRotate =!turnplate.bRotate; $.getJSON("../AJAX/lottery.ashx","",function(data){ //1090系统配置错误，1091用户未登陆或用户数据异常，1092用户剩余积分不足,1093未中奖 hideInput("code",data.code) if(data.code.toString()=="1090"){ iosalert("系统配置错误") }elseif(data.code.toString()=="1091"){ iosalert("用户未登陆或用户数据异常") }elseif(data.code.toString()=="1092"){ iosalert("用户剩余积分不足") }elseif(data.code.toString()=="1094"){ iosalert("超过每日抽奖次数") } else{ var upoint =0; upoint = parseInt($("#uPoint").html())- parseInt($("#sPoint").html()); $("#uPoint").html(upoint); if(data.isWin =='true'){ item = getArrayIndex(turnplate.restaraunts, data.name); rotateFn(item +1,"恭喜获得，"+ turnplate.restaraunts[item]); } else{ rotateFn(0,"恭喜获得优胜奖！"); } } }) });

//旋转转盘 item:奖品位置; txt：提示语; var rotateFn =function(item, txt){ //根据传进来的奖品序号 计算相应的弧度 var angles = item *(360/ turnplate.restaraunts.length)-(360/(turnplate.restaraunts.length *2)); if(angles <270){ angles =270- angles; }else{ angles =360- angles +270; } //强制停止转盘的转动 $('#wheelcanvas').stopRotate(); //调用转动方法，设置转动所需参数和回调函数 $('#wheelcanvas').rotate({ //起始角度 angle:0, //转动角度 +1800是为了多转几圈 animateTo: angles +1800, duration:8000, callback:function(){ iosSuccess(txt); turnplate.bRotate =!turnplate.bRotate; if($("#code").val()!="1093"){ delayLoad(getHttpPrefix +"graphicdetails.html?lukyid="+ $("#code").val()) } } }); };