js放大镜功能 class类方法封装

84 阅读 0 评论 56 点赞

我是靠谱客的博主爱听歌硬币，最近开发中收集的这篇文章主要介绍js放大镜功能 class类方法封装，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

放大镜功能，原生js书写，move遮罩层盒子宽高按比例获取，设置小盒子宽高，以及大盒子宽高，计算比例

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            /* 怪异异盒模型 解决盒子边框1px的问题  */
            /* box-sizing: border-box; */
        }

        .small {
            width: 100px;
            height: 100px;
            border: 1px solid #000;
            position: relative;
            /* margin-left: 20px; */
            margin: 0 auto;
            /* background: url("./images/small.jpg")no-repeat 0 0;
            background-image: */
        }
        .small img{
            width: 100%;
            height: 100%;
        }
        .bigbox {
            width: 400px;
            height: 400px;
            border: 1px solid #000;
            position: relative;
            margin: 0 auto;
            overflow: hidden;
            display: none;
        }

        .bigbox>img {
            position: absolute;
        }

        .move {
            background-color: rgba(25, 25, 25, 0.5);
            position: absolute;
            left: 0;
            top: 0;
            display: none;
        }

        .move:hover {
            cursor: move;
        }
    </style>
</head>

<body>
    <div class="small">
        <img src="https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fimg.alicdn.com%2Fi1%2F2575559575%2FTB2zKznh93PL1JjSZFxXXcBBVXa_%21%212575559575.jpg&refer=http%3A%2F%2Fimg.alicdn.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=auto?sec=1652961453&t=5c170d9d3e29e3b144f08d099116c83e" alt="">
        <div class="move"></div>
    </div>
    <div class="bigbox">
        <img src="https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fimg.alicdn.com%2Fi1%2F2575559575%2FTB2zKznh93PL1JjSZFxXXcBBVXa_%21%212575559575.jpg&refer=http%3A%2F%2Fimg.alicdn.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=auto?sec=1652961453&t=5c170d9d3e29e3b144f08d099116c83e" alt="" class="smallImg">
    </div>
    <script>
        class Zoom {
            constructor(smallbox, move, bigbox, moveImg) {
                this.smallbox = smallbox
                this.move = move
                this.bigbox = bigbox
                this.moveImg = moveImg
                this.maxMoveSizeX = 0
                this.maxMoveSizeY = 0
                this.init()     
            }
            init(){
                this.zoomMoveOut()
                this.zoomMove()
            }
            setMoveSize(){
                // 移动盒子的大小 = 大盒子/图片大小*小盒子
                this.move.style.width = this.bigbox.clientWidth/this.moveImg.clientWidth*this.smallbox.clientWidth + "px"
                this.move.style.height = this.bigbox.clientHeight/this.moveImg.clientHeight*this.smallbox.clientHeight + "px"
                this.maxMoveSizeX = this.smallbox.clientWidth - this.move.clientWidth 
                this.maxMoveSizeY = this.smallbox.clientHeight - this.move.clientHeight
            }
            zoomMoveOut(){
                // 初始化 移入遮罩层
                this.smallbox.onmouseenter = () => {
                    this.move.style.display = "block"
                    this.bigbox.style.display = "block"
                    this.setMoveSize()
                }
                
                this.smallbox.onmouseleave = () => {
                    this.move.style.display = "none"
                    this.bigbox.style.display = "none"
                }
            }
            zoomMove(){
                // 给移动那个的盒子加移动事件
                this.smallbox.onmousemove = (e) => {
                    e = e || window.event
                    /* // 获取鼠标在小盒子里面的位置
                    let moveX = e.clientX - this.smallbox.offsetLeft
                    let moveY = e.clientY - this.smallbox.offsetTop
                    // 在事件中移动鼠标控制移动的盒子位置改变
                    // 鼠标在move中心点的位置
                    let centerX = this.move.clientWidth / 2
                    let centerY = this.move.clientHeight / 2 */
                    // 鼠标在遮罩层里面的位置
                    let targetX = e.clientX - this.smallbox.offsetLeft - this.move.clientWidth / 2
                    let targetY = e.clientY - this.smallbox.offsetTop - this.move.clientHeight / 2
                    /* // 区间判断 全局变量 不会在拖拽时变化，抽取为全局
                    let maxMoveSizeX = this.smallbox.clientWidth - 2 - this.move.clientWidth
                    let maxMoveSizeY = this.smallbox.clientHeight - 2 - this.move.clientHeight */
                    if (targetX < 0) targetX = 0
                    if (targetY < 0) targetY = 0
                    if (targetX > this.maxMoveSizeX) targetX = this.maxMoveSizeX
                    if (targetY > this.maxMoveSizeY) targetY = this.maxMoveSizeY
                    this.move.style.left = targetX + "px"
                    this.move.style.top = targetY + "px"
                    //同时控制大盒子里面的图片坐标变化（图片相对于盒子移动所以要乘以-1）
                    this.moveImg.style.left = targetX * this.moveImg.clientWidth / this.smallbox.clientWidth * -1  +"px"
                    this.moveImg.style.top = targetY * this.moveImg.clientHeight / this.smallbox.clientHeight * -1 + "px"
                    // console.log(smallbox.clientWidth / move.clientWidth)
                }
            }
        }
        // 获取小盒子
        let smallbox = document.getElementsByClassName('small')[0]
        // 获取移动的盒子
        let move = document.getElementsByClassName('move')[0]
        // 获取大盒子
        let bigbox = document.getElementsByClassName('bigbox')[0]
        // 获取大盒子里面的图片
        let moveImg = document.querySelector('.bigbox>img')
        let p = new Zoom(smallbox, move, bigbox, moveImg)
        // 给小盒子移入事件 移动的盒子显示
        
    </script>
</body>

</html>