<view class="button-group">
  <view class="outter-circle">
    <view class="inner-parts brown" bindtap="button" data-type="volAdd">
      <text class="rotate">+</text>
    </view>
    <view class="inner-parts silver" bindtap="button" data-type="chaAdd">
      <text class="rotate">+</text>
    </view>
    <view class="inner-parts blue" bindtap="button" data-type="chaDes">
      <text class="rotate">-</text>
    </view>
    <view class="inner-parts gold" bindtap="button" data-type="volDes">
      <text class="rotate">-</text>
    </view>

    <view class="inner-circle" bindtap="button" data-type="ok">
      <text class="ok rotate">ok</text>
    </view>
  </view>
</view>

.button-group {
  padding-top: 20rpx;
  width: 300rpx;
  height: 300rpx;
  background-color: pink;
}
.outter-circle {
  position: relative;
  margin-left: 10rpx;
  width: 280rpx;
  height: 280rpx;
  background-color: lightcyan;
  border-radius: 100%;
  overflow: hidden;
  transform-origin: center;
  transform: rotate(45deg);
}
.inner-parts {
  float: left;
  width: 140rpx;
  height: 140rpx;
  line-height: 140rpx;
  text-align: center;
}
.silver {
  background-color: silver;
}
.gold {
  background-color: gold;
}
.blue {
  background-color: blue;
}
.brown {
  background-color: brown;
}
.inner-circle {
  position: absolute;
  margin-top: 70rpx;
  margin-left: 70rpx;
  width: 140rpx;
  height: 140rpx;
  line-height: 140rpx;
  text-align: center;
  border-radius: 100%;
  background-color: lightblue;
}
.rotate {
  display: inline-block;
  transform: rotate(-45deg);
}

button: function(e) {
    var buttonType = e.currentTarget.dataset.type
    console.log(buttonType)
    switch (buttonType) {
      case 'chaAdd':
        console.log('backward the channel')
      break
      case 'chaDes':
        console.log('forward the channel')
      break
      case 'volAdd':
        console.log('strengthen the volumn')
      break
      case 'volDes':
        console.log('weaken the volumn')
      break
      default:
        console.log('ok')
    }
  }