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先看图效果图：

这边UI的 设计图 长这样

 

 一个圆环的进度展示，这个圆环上开始位置 是齐口的，终点圆口，并且有一个圆；

列举了两种实现方式：

• 第一种 纯的CSS实现；原理是 叠加 和 旋转 而成。缺点在某些机型上面应为遮罩没有对齐（uniapp 半个像素不显示的问题，其他平台没有这问题），会出现白边（没有遮挡好的情况）
•  第二种 createCanvasContext 直接画弧线；动态计算原点位置 叠加 显示

第一种实现方式 

理论上：纯css  两个半圆在相应的取值范围内 旋转，旋转的时候被父对象 遮罩剩余的部分

第一步： 两个半圆在旋转，旋转时候被父对象 clip 掉 剩余部分，两个红色底就是两个半圆的父元素，红色第里面的两个深色块就是 将要旋转的 元素；

<view class="box0-parent">
  <view class="box0" :style="box0Style">
  </view>
</view>
<view class="box1-parent">
  <view class="box1" :style="box1Style">
  </view>
</view>
 
 
.box0-parent {
  position: absolute;
  top: 580rpx;
  width: 284rpx;
  height: 284rpx;
  background-color: #dd2124;
  clip: rect(0px, 142rpx, 284rpx, 0px);
 
  // border-radius: 50%;
  .box0 {
    position: absolute;
    top: 0;
    width: 284rpx;
    height: 284rpx;
    background-color: #2C405A;
    clip: rect(0px, 142rpx, 284rpx, 0px);
    border-radius: 50%;
  }
}
 
.box1-parent {
  position: absolute;
  top: 580rpx;
  width: 284rpx;
  height: 284rpx;
  background-color: #c34c24;
  clip: rect(0px, 284rpx, 284rpx, 142rpx);
  // border-radius: 50%;
 
  .box1 {
    position: absolute;
    top: 0;
    width: 284rpx;
    height: 284rpx;
    background-color: #5a4600;
    clip: rect(0px, 284rpx, 284rpx, 142rpx);
    border-radius: 50%;
    // transform: rotate(60deg);
  }
}

 第二步： 调整下参数； 再调下颜色

<template>
  <view class="process">
 
    <view class="box0-parent">
      <view class="box0" :style="box0Style">
      </view>
    </view>
    <view class="box1-parent">
      <view class="box1" :style="box1Style">
      </view>
    </view>
 
    <view class="input-range">
      <text> {{percent}}%</text> <text style="margin-left: 100rpx;">{{percent*3.6}}</text>
      <slider @changing="onChange" value="0" max="100" min="0" v-model="percent" activeColor="#FFCC33"
        backgroundColor="#000000" block-color="#8A6DE9"></slider>
    </view>
 
 
  </view>
 
</template>
 
<script>
 
  export default {
    data() {
      return {
        percent: 30,
      }
    },
    computed: {
      box0Style() {
        if (this.percent >= 50) {
          return `transform: rotate(${180 + this.percent*3.6}deg)`
        } else {
          return ``
        }
      },
      box1Style() {
        if (this.percent <= 50) {
          return `transform: rotate(${this.percent*3.6}deg)`
        } else {
          return `display: none;`
        }
      }
    },
    methods: {
      onChange(value) {
        // console.log(value.detail.value)
        this.percent = value.detail.value
      }
    }
  }
</script>
 
<style lang="scss" scoped>
  .process {
    width: 100%;
 
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
 
 
    .input-range {
      position: absolute;
      top: 980rpx;
      width: 300rpx;
    }
 
    .box0-parent {
      position: absolute;
      top: 580rpx;
      width: 284rpx;
      height: 284rpx;
      background-color: #dd2124;
      clip: rect(0px, 142rpx, 284rpx, 0px);
 
      // border-radius: 50%;
      .box0 {
        position: absolute;
        top: 0;
        width: 284rpx;
        height: 284rpx;
        //background-color: #2C405A;
        background-color: #2168F9;
        clip: rect(0px, 142rpx, 284rpx, 0px);
        border-radius: 50%;
      }
    }
 
    .box1-parent {
      position: absolute;
      top: 580rpx;
      width: 284rpx;
      height: 284rpx;
      //background-color: #c34c24;
      background-color: #dd2124;
      // background-color: #2168F9;
      clip: rect(0px, 284rpx, 284rpx, 142rpx);
      // border-radius: 50%;
 
      .box1 {
        position: absolute;
        top: 0;
        width: 284rpx;
        height: 284rpx;
        // background-color: #5a4600;
        background-color: #2168F9;
        clip: rect(0px, 284rpx, 284rpx, 142rpx);
        border-radius: 50%;
        // transform: rotate(60deg);
      }
    }
 
  }
</style>

然后加上蓝色底色，圆环换上白色；真理下就能得到这么的 圆环了；

至于 白色圆点  直接绝对定位于半圆， 随着半圆移动即可；每个半圆都有一个

第二种实现方式

使用的是 canvas 中的 arc  （画弧线来实现的）

uni.createCanvasContexthttps://uniapp.dcloud.io/api/canvas/CanvasContext.html

 
<canvas class="canvas-content" :canvas-id="canvasId" :id="canvasId">
</canvas>
 
methods: {
  onChange(value) {
    // console.log(value.detail.value)
    this.percent = value.detail.value
    this.drawCircleByProgress()
  },
  drawCircleByProgress(){
    // 表示进度的两端为圆形  目前没有找到只设置一段的方式
    this.canvasContent.setLineCap('round'); //圆形     
    this.canvasContent.setLineCap('square'); //方形
    // 设置线条的宽度和颜色
    this.canvasContent.setLineWidth(uni.upx2px(30));
    this.canvasContent.setStrokeStyle('#ff0000');
          
    let endAngle = ((2 * Math.PI) / 100) * this.percent + this.startAngle;
    
    this.canvasContent.beginPath();
    // 半径为整个canvas宽度的一半
    let radius = uni.upx2px(284) / 2;
    this.canvasContent.arc(radius, radius, radius - uni.upx2px(30), this.startAngle, endAngle, false);
    this.canvasContent.stroke();
    
    this.canvasContent.draw();
  }
}
 
.canvas-content{
  width: 284rpx;
  height: 284rpx;
  background-color: #059cdd;
}

这种方式对于圆环中的 画一个白色球； 需要通过 弧度计算圆上一点的位置；

drawCircleByProgress() {
  // 表示进度的两端为圆形  目前没有找到只设置一段的方式
  this.canvasContent.setLineCap('round'); //圆形     
  this.canvasContent.setLineCap('square'); //方形
 
  let width = uni.upx2px(30)
 
  // 设置线条的宽度和颜色
  this.canvasContent.setLineWidth(width);
  this.canvasContent.setStrokeStyle('#ff0000');
 
 
  // 画圆环
  let endAngle = ((2 * Math.PI) / 100) * this.percent + this.startAngle;
  this.canvasContent.beginPath();
  // 半径为整个canvas宽度的一半
  let radius = uni.upx2px(284) / 2;
  this.canvasContent.arc(radius, radius, radius - width, this.startAngle, endAngle, false);
  this.canvasContent.stroke();
 
 
 
  //原点要在 圆弧前面一点点的位置 所有这个加了 0.1；
  let p0x = radius + Math.cos(endAngle + .1) * (radius - width)
  let p0y = radius + Math.sin(endAngle + .1) * (radius - width)
  // 画圆球
  this.canvasContent.beginPath()
  this.canvasContent.arc(p0x, p0y, width / 2, 0, 2 * Math.PI)
  this.canvasContent.setFillStyle('#F0AD4E');
  this.canvasContent.fill()
  // 画白色圆球
  this.canvasContent.beginPath()
  this.canvasContent.arc(p0x, p0y, width * 0.4, 0, 2 * Math.PI)
  this.canvasContent.setFillStyle('#FFFFFF');
  this.canvasContent.fill()
 
  this.canvasContent.draw();
}

真理下就能得到下面的例子了

完整代码：

<template>
  <view class="process">
 
    <canvas class="canvas-content" :canvas-id="canvasId" :id="canvasId">
    </canvas>
 
    <view class="box0-parent">
      <view class="box0" :style="box0Style">
      </view>
    </view>
    <view class="box1-parent">
      <view class="box1" :style="box1Style">
      </view>
    </view>
    <view class="input-range">
      <text> {{percent}}%</text> <text style="margin-left: 100rpx;">{{percent*3.6}}</text>
      <slider @changing="onChange" value="0" max="100" min="0" v-model="percent" activeColor="#FFCC33"
        backgroundColor="#000000" block-color="#8A6DE9"></slider>
    </view>
 
  </view>
</template>
 
<script>
  export default {
    data() {
      return {
        percent: 30,
        canvasId: 'canvasId',
        canvasContent: null,
        startAngle: -Math.PI / 2, //canvas画圆的起始角度，默认为3点钟方向即90度 方向，定位位到12位置 0度
      }
    },
    computed: {
      box0Style() {
        if (this.percent >= 50) {
          return `transform: rotate(${180 + this.percent*3.6}deg)`
        } else {
          return ``
        }
      },
      box1Style() {
        if (this.percent <= 50) {
          return `transform: rotate(${this.percent*3.6}deg)`
        } else {
          return `display: none;`
        }
      }
    },
    onShow() {
      this.canvasContent = uni.createCanvasContext(this.canvasId, this)
      this.drawCircleByProgress()
    },
    methods: {
      onChange(value) {
        // console.log(value.detail.value)
        this.percent = value.detail.value
        this.drawCircleByProgress()
      },
      drawCircleByProgress() {
        // 表示进度的两端为圆形  目前没有找到只设置一段的方式
        this.canvasContent.setLineCap('round'); //圆形     
        this.canvasContent.setLineCap('square'); //方形
 
        let width = uni.upx2px(30)
 
        // 设置线条的宽度和颜色
        this.canvasContent.setLineWidth(width);
        this.canvasContent.setStrokeStyle('#ff0000');
 
        let endAngle = ((2 * Math.PI) / 100) * this.percent + this.startAngle;
 
        this.canvasContent.beginPath();
        // 半径为整个canvas宽度的一半
        let radius = uni.upx2px(284) / 2;
        this.canvasContent.arc(radius, radius, radius - width, this.startAngle, endAngle, false);
        this.canvasContent.stroke();
 
        //原点要在 圆弧前面一点点的位置 所有这个加了 0.1；
        let p0x = radius + Math.cos(endAngle + .1) * (radius - width)
        let p0y = radius + Math.sin(endAngle + .1) * (radius - width)
 
 
        this.canvasContent.beginPath()
        this.canvasContent.arc(p0x, p0y, width / 2, 0, 2 * Math.PI)
        this.canvasContent.setFillStyle('#F0AD4E');
        this.canvasContent.fill()
 
        this.canvasContent.beginPath()
        this.canvasContent.arc(p0x, p0y, width * 0.4, 0, 2 * Math.PI)
        this.canvasContent.setFillStyle('#FFFFFF');
        this.canvasContent.fill()
 
        this.canvasContent.draw();
      }
    }
  }
</script>
 
<style lang="scss" scoped>
  .process {
    width: 100%;
 
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
 
    .canvas-content {
      width: 284rpx;
      height: 284rpx;
      background-color: #059cdd;
    }
 
    .input-range {
      position: absolute;
      top: 750rpx;
      width: 300rpx;
    }
 
    .box0-parent {
      position: absolute;
      top: 380rpx;
      width: 284rpx;
      height: 284rpx;
      background-color: #dd2124;
      clip: rect(0px, 142rpx, 284rpx, 0px);
 
      // border-radius: 50%;
      .box0 {
        position: absolute;
        top: 0;
        width: 284rpx;
        height: 284rpx;
        //background-color: #2C405A;
        background-color: #2168F9;
        clip: rect(0px, 142rpx, 284rpx, 0px);
        border-radius: 50%;
      }
    }
 
    .box1-parent {
      position: absolute;
      top: 380rpx;
      width: 284rpx;
      height: 284rpx;
      //background-color: #c34c24;
      background-color: #dd2124;
      // background-color: #2168F9;
      clip: rect(0px, 284rpx, 284rpx, 142rpx);
 
      // border-radius: 50%;
      .box1 {
        position: absolute;
        top: 0;
        width: 284rpx;
        height: 284rpx;
        // background-color: #5a4600;
        background-color: #2168F9;
        clip: rect(0px, 284rpx, 284rpx, 142rpx);
        border-radius: 50%;
        // transform: rotate(60deg);
      }
    }
 
  }
</style>

原文链接:https://blog.csdn.net/nicepainkiller/article/details/125327485