小程序 幸运转盘

 getLottery: function () {
    var that = this
    var awardIndex = Math.random() * 6 >>> 0;

    // 获取奖品配置
    var awardsConfig = app.awardsConfig,
        runNum = 8
    if (awardIndex < 2) awardsConfig.chance = false
    console.log(awardIndex)



    // 旋转抽奖
    app.runDegs = app.runDegs || 0
    console.log('deg', app.runDegs)
    app.runDegs = app.runDegs + (360 - app.runDegs % 360) + (360 * runNum - awardIndex * (360 / 6))
    console.log('deg', app.runDegs)

    var animationRun = wx.createAnimation({
      duration: 4000,
      timingFunction: 'ease'
    })
    that.animationRun = animationRun
    animationRun.rotate(app.runDegs).step()
    that.setData({
      animationData: animationRun.export(),
      btnDisabled: 'disabled'
    })

   // 绘制转盘
    var awardsConfig = app.awardsConfig.awards,
        len = awardsConfig.length,
        rotateDeg = 360 / len / 2 + 90,
        html = [],
        turnNum = 1 / len  // 文字旋转 turn 值
    that.setData({
      btnDisabled: app.awardsConfig.chance ? '' : 'disabled'  
    })
    var ctx = wx.createContext()
    for (var i = 0; i < len; i++) {
      // 保存当前状态
      ctx.save();
      // 开始一条新路径
      ctx.beginPath();
      // 位移到圆心，下面需要围绕圆心旋转
      ctx.translate(150, 150);
      // 从(0, 0)坐标开始定义一条新的子路径
      ctx.moveTo(0, 0);
      // 旋转弧度,需将角度转换为弧度,使用 degrees * Math.PI/180 公式进行计算。
      ctx.rotate((360 / len * i - rotateDeg) * Math.PI/180);
      // 绘制圆弧
      ctx.arc(0, 0, 150, 0,  2 * Math.PI / len, false);

      // 颜色间隔
      if (i % 2 == 0) {
          ctx.setFillStyle('rgba(255,184,32,.1)');
      }else{
          ctx.setFillStyle('rgba(255,203,63,.1)');
      }

      // 填充扇形
      ctx.fill();
      // 绘制边框
      ctx.setLineWidth(0.5);
      ctx.setStrokeStyle('rgba(228,55,14,.1)');
      ctx.stroke();

      // 恢复前一个状态
      ctx.restore();

      // 奖项列表
      html.push({turn: i * turnNum + 'turn', lineTurn: i * turnNum + turnNum / 2 + 'turn', award: awardsConfig[i].name});    
    }

<view class="top">
	<image class="userinfo-avatar" src="{{head}}" background-size="cover"></image>
	<text style="font-size:40rpx">失散多年的哥哥</text>
</view>

<view class="mid">
	<button bindtap="gotoLottery" type="primary" style="width:600rpx;background-color:#D75858">去抽奖</button>
</view>

<view class="txt">
	<text wx:if="{{awardsList.length > 0}}">恭喜您获得了以下奖品：</text>
	<text wx:if="{{awardsList.length == 0}}">您还中奖，快去抽奖吧</text>
</view>

<view class="gift" wx:for="{{awardsList}}" wx:key="unique">
	<text style="font-size:34rpx;margin-left:30rpx">{{item}}</text>
</view>