基于Vue实现图片在指定区域内移动的思路详解

  当图片比要显示的区域大时，需要将多余的部分隐藏掉，我们可以通过绝对定位来实现，并通过动态修改图片的left值和top值从而实现图片的移动。具体实现效果如下图，如果我们移动的是div 实现思路相仿。

此处需要注意的是

我们在移动图片时，需要通过draggable="false" 将图片的 <img src="/static/pano-dev/test/image-2.jpg" draggable="false" />，否则按下鼠标监听onmousemove事件时监听不到

然后还需要禁用图片的选中css

/*禁止元素选中*/
-moz-user-select: none; /*火狐*/
-webkit-user-select: none; /*webkit浏览器*/
-ms-user-select: none; /*ie10*/
-khtml-user-select: none; /*早期浏览器*/
user-select: none;

vue 代码

<style lang="less" scoped>
@import url("./test.less");
</style>
<template>
 <div class="page">
  <div class="image-move-wapper">
   <div class="image-show-box" ref="imageshowbox">
    <div class="drag-container" ref="dragcontainer" :style="'left:' + dragcontainer.newpoint.left+'px; top:' + dragcontainer.newpoint.top+'px'" @mousedown="dragcontainermousedown">
     <div class="drag-image-box">
      <img src="/static/pano-dev/test/image-2.jpg" draggable="false" />
      <div class="point" style="left:10%; top:10%" @mousedown="pointmousedown"></div>
     </div>
    </div>
   </div>
  </div>
 </div>
</template>
<script>
export default {
 data() {
  return {
   dragcontainer: {
    box: {
     w: 0,
     h: 0
    },
    point: {
     left: 0,
     top: 0
    },
    newpoint: {
     left: 0,
     top: 0
    }
   },
   mousepoint: {
    x: 0,
    y: 0
   },
   imageshowbox: {
    box: {
     w: 0,
     h: 0
    },
    dragcheck: {
     h: true,
     v: true
    }
   }
  };
 },
 updated() {
  let _this = this;
  // 确保dom元素已经渲染成功，然后获取拖拽容器和显示区域的大小
  _this.$nexttick(function() {
   _this.dragcontainer.box = {
    w: _this.$refs.dragcontainer.offsetwidth,
    h: _this.$refs.dragcontainer.offsetheight
   };
   _this.imageshowbox.box = {
    w: _this.$refs.imageshowbox.offsetwidth,
    h: _this.$refs.imageshowbox.offsetheight
   };
   // 判断是否允许拖拽
   _this.imageshowbox.dragcheck = {
    h: _this.imageshowbox.box.w > _this.dragcontainer.box.w ? false : true,
    v: _this.imageshowbox.box.h > _this.dragcontainer.box.h ? false : true
   };
  });
 },
 methods: {
  // 鼠标在拖拽容器中按下时触发
  dragcontainermousedown(e) {
   const _this = this;
   // 记录鼠标点击时的初始坐标
   this.mousepoint = {
    x: e.clientx,
    y: e.clienty
   };
   _this.dragcontainer.point = _this.dragcontainer.newpoint;
   document.body.onmousemove = _this.dragcontainermousemove;
   document.onmouseup = _this.dragcontainermouseup;
   return false;
  },
  // 容器拖拽时触发
  dragcontainermousemove(e) {
   const _this = this;
   // 鼠标偏移量 = 初始坐标 - 当前坐标
   let dx = e.clientx - _this.mousepoint.x;
   let dy = e.clienty - _this.mousepoint.y;
   // 获取拖拽容器移动后的left和top值
   if (_this.imageshowbox.dragcheck.h)
    var newx = dx > 0 ? math.min(0, _this.dragcontainer.point.left + dx) : math.max(- _this.dragcontainer.box.w + _this.imageshowbox.box.w, _this.dragcontainer.point.left + dx );
   if (_this.imageshowbox.dragcheck.v)
    var newy = dy > 0 ? math.min(0, _this.dragcontainer.point.top + dy) : math.max(- _this.dragcontainer.box.h + _this.imageshowbox.box.h, _this.dragcontainer.point.top + dy );
   _this.dragcontainer.newpoint = {
    left: typeof newx != 'undefined' ? newx : _this.dragcontainer.point.left,
    top: typeof newy != 'undefined' ? newy : _this.dragcontainer.point.top
   };
   console.log(_this.dragcontainer.newpoint);
   return false;
  },
  // 移动完成 取消onmousemove和onmouseup事件
  dragcontainermouseup(e) {
   document.body.onmousemove = null;
   document.onmouseup = null;
  },
  pointmousedown(e) {
   //阻止事件冒泡
   e.stoppropagation();
  }
 }
};
</script>

样式表

.page {
 background: #444;
 width: 100%;
 height: 100%;
 position: relative;
 .image-move-wapper {
  position: absolute;
  right: 50px;
  top: 50px;
  background: #fff;
  box-shadow: rgba(255, 255, 255, 0.5);
  padding: 10px;
 }
 .image-show-box {
  height: 400px;
  width: 400px;
  cursor: move;
  overflow: hidden;
  position: relative;
  .drag-container {
   position: absolute;
   left: 0px;
   top: 0;
   /*禁止元素选中*/
   -moz-user-select: none; /*火狐*/
   -webkit-user-select: none; /*webkit浏览器*/
   -ms-user-select: none; /*ie10*/
   -khtml-user-select: none; /*早期浏览器*/
   user-select: none;
   .drag-image-box {
    position: relative;
    .point {
     position: absolute;
     background: red;
     height: 30px;
     width: 30px;
     border-radius: 50%;
    }
   }
  }
 }
} 

总结

以上所述是小编给大家介绍的基于vue实现图片在指定区域内移动的思路详解，希望对大家有所帮助