vue图片拖拉转放大缩小组件使用详解

<doc>  图片组件 - 用户放大缩小以及拖拽</doc><template>  <div style="width: 100%;position: relative;overflow: hidden;text-align: center;border: 1px solid #f1f2f3;">    <el-button size='mini' @click="toBIgChange" icon="el-icon-zoom-in"      style="position: absolute;top: 2px ;left: 2px;z-index: 999;"></el-button>    <el-button size='mini' @click="toSmallChange" icon="el-icon-zoom-out"      style="position: absolute;top: 2px ;left: 40px;z-index: 999;"></el-button>    <img id="img" :src="src" alt="" @mousedown.prevent="dropImage" :style="{transform:'scale('+multiples+')'}">  </div></template><script>  export default {    props: ['src'],    data() {      return {        multiples: 1,        odiv: null,      }    },    mounted() {      this.dropImage()    },    watch: {      src(newValue, oldValue) {        this.multiples = 1        if (this.odiv !== null) {          this.odiv.style.left = '0px';          this.odiv.style.top = '0px';        }      },    },    methods: {      toBIgChange() {        if (this.multiples >= 2) {          return;        }        this.multiples += 0.25;      },      // 缩小      toSmallChange() {        if (this.multiples <= 1) {          return;        }        this.multiples -= 0.25;      },      // 拖拽      dropImage(e) {        if (e === null) {          return        }        this.odiv = e.target;        //获取目标元素        //算出鼠标相对元素的位置        let disX = e.clientX - this.odiv.offsetLeft;        let disY = e.clientY - this.odiv.offsetTop;        document.onmousemove = (e) => {       //鼠标按下并移动的事件          //用鼠标的位置减去鼠标相对元素的位置，得到元素的位置          let left = e.clientX - disX;          let top = e.clientY - disY;          //绑定元素位置到positionX和positionY上面          this.positionX = top;          this.positionY = left;          //移动当前元素          this.odiv.style.left = left + 'px';          this.odiv.style.top = top + 'px';        };        document.onmouseup = (e) => {          document.onmousemove = null;          document.onmouseup = null;        };      },    }  }</script><style scoped>  img {    width: 100%;    position: relative;  }</style>