肥胖-超重–正常–偏瘦，四个区间，用渐变色柱体显示，小三角标记位置。
根据接口返回的值，小三角移动到不同的区间不同的位置。
百分比显示；

<template>
  <div class="box">
    <div class="bmi-show">
      <div class="triangle" :style="{ bottom: percentage }"></div>
      <div class="linearShow"></div>
      <div class="range">
        <p>肥胖</p>
        <p>超重</p>
        <p>正常</p>
        <p>偏瘦</p>
      </div>
    </div>
  </div>
</template>
<script>
export default {
  data() {
    return {
      bmi: "",
      percentage: ""
    };
  },
  //  项目中使用的是computed， this.bmi是从接口拿到的数据。
  //  现在单页面，写到watch里面，是因为bmi的值在computed中不能改变，不然发生报错；
  watch: {
    percentage() {
      console.log(this.bmi);
      if (!this.bmi) return "";
      if (this.bmi < 14.5) this.bmi = 14.5;
      if (this.bmi > 33.5) this.bmi = 33.5;
      let diff = this.bmi - 14.5;
      return `calc(${(diff * 100) / 19}% - 4px)`;
    }
  }
};
</script>
<style lang="scss" scoped>
.box {
  position: relative;
}
.bmi-show {
  position: absolute;
  right: 40px;
  top: 50px;
  display: flex;
  .triangle {
    width: 0;
    height: 0;
    border-top: 4px solid transparent;
    border-left: 4px solid #000;
    border-bottom: 4px solid transparent;
    position: absolute;
    left: -10px;
  }
  .linearShow {
    width: 10px;
    height: 170px;
    border-radius: 8px;
    background: linear-gradient(
      360deg,
      #00d5ed 0%,
      #7aec01 28%,
      #ffd500 67%,
      #f74d00
    );
  }
  .range {
    margin-left: 10px;
    font-size: 16px;
    color: #000;
    line-height: 33px;
    display: flex;
    flex-direction: column;
    justify-content: space-around;
    align-items: center;
  }
}
</style>