<template>
 <div class="progress-wrapper" :style="wrapStyle">
  <div class="progress" @mousedown="mousedownHandler" @mouseover="mouseoverHandler"
    @mousemove="mousemoveHandler" @mouseup="mouseupHandler" :style="pBarStyle">
   <div class="left" :style="leftStyle">
    <div class="ball" :style="ballStyle"></div>
   </div>
   <slot></slot>
  </div>
 </div>
</template>

export default {
  name: 'ProgressBar',
  props: {
   leftBg: String,
   bgc: String,
   ballBgc: String,
   height: String,
   width: String,
   max: {
    type: Number,
    default: 100,
   },
   min: {
    type: Number,
    default: 0,
   },
   value: {
    type: Number,
    default: 36,
   },
  },
  data: function () {
   return {
    pValue: this.value,
    pMax: this.max,
    pMin: this.min,
    wrapStyle: {
     'width': this.width,
    },
    pBarStyle: {
     'backgroundColor': this.bgc,
     'height': this.height,
    },
    leftStyle: {
     'width': this.progressPercent + '%',
     'background': this.leftBg,
     'height': this.height,
    },
    ballStyle: {
     'backgroundColor': this.ballBgc,
     'height': this.height,
     'width': this.height,
     'borderRadius': parseInt(this.height) / 2 + 'px',
     'right': - parseInt(this.height) / 2 + 'px',
    },
    // 标记是否按下鼠标
    isMouseDownOnBall: false,
   }
  },
  computed: {
   progressPercent(){
    return (this.pValue - this.pMin) / (this.pMax - this.pMin) * 100;
   },
   progressElement(){
    return this.$el.getElementsByClassName('progress')[0];
   },
  },
  methods: {
   mousedownHandler(e){
    if(e.which === 1){
     this.isMouseDownOnBall = true;
    }
   },
   mousemoveHandler(e){
    if(this.isMouseDownOnBall === true){
     // 修改进度条本身
     let decimal = (e.clientX - this.$el.offsetLeft) / this.progressElement.clientWidth;
     let percent = decimal * 100;
     this.leftStyle.width = percent + '%';
     // 修改value
     this.pValue = this.pMin + decimal * (this.pMax - this.pMin);
     this.$emit('pbar-drag', this.pValue, percent);
    }
   },
   mouseupHandler(e){
    if(this.isMouseDownOnBall){
     // 修改进度条本身
     let decimal = (e.clientX - this.$el.offsetLeft) / this.progressElement.clientWidth;
     let percent = decimal * 100;
     this.leftStyle.width = percent + '%';
     // 修改value
     this.pValue = this.pMin + decimal * (this.pMax - this.pMin);
     this.$emit('pbar-seek', this.pValue, percent);
     this.isMouseDownOnBall = false;
    }
   },
   mouseoverHandler(e){
    // 没有按左键进入进度条
    if(e.which === 0){
     this.isMouseDownOnBall = false;
    }
   }
  },
  watch: {
   max(cur, old){
    this.pMax = cur;
   },
   min(cur, old){
    this.pMin = cur;
   },
   value(cur, old){
    this.pValue = cur;
   },
   progressPercent(cur, old){
    this.leftStyle.width = cur + '%';
   }
  },
  mounted(){
   // 数据验证
   if(this.max < this.min){
    console.error("max can't less than min !");
   }
   // 初始百分比
   this.leftStyle.width = (this.pValue - this.pMin) / (this.pMax - this.pMin) * 100 + '%';
  },
 }

npm install vue-draggable-progressbar --save
import progressBar from 'vue-draggable-progressbar'

<progress-bar ref="aa"></progress-bar>
<progress-bar width="40%" leftBg="greenyellow" bgc="#ccc" ballBgc="red"></progress-bar>
<progress-bar width="60%" leftBg="linear-gradient(to right, yellow, pink)" bgc="#ccc" ballBgc="red"></progress-bar>
<progress-bar width="80%" leftBg="yellow" bgc="#ccc" ballBgc="red" height="30px"></progress-bar>
<progress-bar leftBg="greenyellow" bgc="#ccc" ballBgc="rgba(255,0,0,0.2)" height="40px"></progress-bar>
<progress-bar leftBg="greenyellow" bgc="#ccc" ballBgc="red" :max="max" :value="value" :min="min"
    @pbar-drag="drag" @pbar-seek="seek"></progress-bar>