滑动提示条算法

╰半橙微兮° 2023-02-10 05:25 59阅读 0赞

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTc4ODY5MQ_size_16_color_FFFFFF_t_70_pic_center]

## 需求 ##

项目需求中会有滑块，滑块下有提示条（滑动上面的内容，下面的**提示对应滑动**）  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTc4ODY5MQ_size_16_color_FFFFFF_t_70]

## 草稿 ##

设计一个功能不能盲目地敲代码，实现理解思路该怎么走，下面是我的思路图和相对应的字段（**a:屏幕的宽度/b:滚动内容的宽度/c:滚动条的长度/d:滚动条背景的长度**）  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTc4ODY5MQ_size_16_color_FFFFFF_t_70 1]  
**监听触摸：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTc4ODY5MQ_size_16_color_FFFFFF_t_70 2]

## 实例：解析 ##

**xxx.vue**

<template>
        <div class="hot_slider">
          <div class="hot_slider_content">
            <div class="hot_content_inner">
              <a class="inner_items">
                <img src="xxx.png" />
                <span>京东</span>
              </a>
              <a class="inner_items">
                <img src="yyy.png" />
                <span>淘宝</span>
              </a>
                ------------------
            </div>
          </div>
          
          <div class="hot_slider_bottom">
            <div class="hot_slider_bottom_inner" :style="innerBarStyle"></div>
          </div>
        </div>
    </template>
    
    <script>
      export default { 
        name:"Xxx",
        data(){ 
              return { 
                // 1、获取屏幕的宽度a
                screenW: window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth,
                // 2、滚动内容的宽度b
                scrollContentW: 720,
                // 3、滚动条的长度c
                barXWidth: 0,
                // 4、滚动条背景的长度d
                bgBarW: 100,
                // 5、起点
                startX: 0,
                // 6、记录结束点
                endFlag: 0,
                // 7、移动的距离
                barMoveWidth: 0
              }
            },
            //监听barXWidth样式的变化
            computed:{ 
              innerBarStyle(){ 
                return { 
                  width: `${ this.barXWidth}px`,
                  left: `${ this.barMoveWidth}px`
                }
              }
            },
            mounted() { 
               this.getBottomBarWidth();
               this.bindEvent();
            },
            methods:{ 
              // 获取滚动条的长度
              getBottomBarWidth(){ 
                this.barXWidth = this.bgBarW * (this.screenW / this.scrollContentW)
              },
              // 移动端事件监听
              bindEvent(){ 
                 this.$el.addEventListener('touchstart',this.handleTouchStart,false);
                 this.$el.addEventListener('touchmove',this.handleTouchMove,false);
                 this.$el.addEventListener('touchend',this.handleTouchEnd,false);
              },
              // 开始触摸
              handleTouchStart(event){ 
                 // console.log(event.touches);
                 // 1、获取第一个触点
                let touch = event.touches[0];
                 // 2、求出起始点
                this.startX = Number(touch.pageX);
                // console.log(this.startX);
              },
              // 开始移动
              handleTouchMove(){ 
                // console.log('开始移动');
                // 1、获取第一个触点
                let touch = event.touches[0];
                // 2、求出移动的距离
                let moveWidth = Number(touch.pageX) - this.startX;
                // console.log(moveWidth);
                // 3、求出滚动条走的距离
                this.barMoveWidth = -((this.bgBarW / this.scrollContentW) * moveWidth - this.endFlag);

// 4、 边界值处理
                if(this.barMoveWidth <= 0){  // 左边
                  this.barMoveWidth = 0;
                }else if(this.barMoveWidth >= this.bgBarW - this.barXWidth){  // 右边
                  this.barMoveWidth = this.bgBarW - this.barXWidth;
                }
              },
              // 结束触摸
              handleTouchEnd(){ 
                console.log('结束触摸');
                this.endFlag = this.barMoveWidth;
              },
            }
          }
    </script>
    
    <style scoped>
      .hot_slider{ 
          width: 100%;
          height: 160px;
          position: relative;
          background-color: #FFFFFF;
          padding-bottom: 8px;
        }
      .hot_slider_content{ 
        width: 100&;
        overflow-x: scroll;
      }
      .hot_content_inner{ 
        width: 720px;
        height: 180px;
        display: flex;
        flex-wrap:wrap;/* 一行显示不下去自动化 */
      }
      .inner_items{ 
        width: 90px;
        height: 90px;
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        font-size: 14px;
        color: #666666;
      }
      .inner_items img{ 
        width: 40%;
        margin-bottom: 5px;
      }
    /* 禁用原生活动条 */
     .hot_slider_content::-webkit-scrollbar{ 
       display: none;
     }
      .hot_slider_bottom{ 
        width: 100px;
        height: 3px;
        background-color: #EEEEEE;
        position: absolute;
        left: 50%;
        margin-left: -50px;
        bottom: -6px;
      }
      .hot_slider_bottom_inner{ 
        position: absolute;
        left: 0;
        height: 100%;
        background-color: brown;
        width: 0;
      }
    </style>

## 总结 ##

**养成先打草稿再设计的好习惯。  
继续温习样式的动态绑定和移动端触摸事件的监听流程。**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTc4ODY5MQ_size_16_color_FFFFFF_t_70_pic_center 1]

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