放大镜效果_react怎么样写放大镜-优快云博客

本文链接：https://blog.youkuaiyun.com/scarsun/article/details/81304770

本文详细介绍了一个基于HTML、CSS和JavaScript的放大镜效果实现方案。通过动态调整遮罩层和大图的位置，用户可以在图片上移动鼠标来查看局部放大的细节。

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首先先写html样式

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>放大镜效果</title>
	<link rel="stylesheet" href="index.css">
</head>
<body>
	<div id="box">
		<div id="large-box">
			<img src="images/1.jpg" id="large-img">
		</div>
		<div id="middle-box">
			<img src="images/1.jpg" id="middle-img">
			<div id="shadow"></div>
		</div>
		<div id="small-box">
			<img src="images/1.jpg" class="active">
			<img src="images/2.jpg">
			<img src="images/3.jpg">
			<img src="images/4.jpg">
		</div>
	</div>
	<script src="index.js"></script>
</body>
</html>

接下来是css部分

* {
	margin: 0;
	padding: 0;
}

body {
	background: #000;
}

img {
	vertical-align: bottom;
}

#box {
	position: relative;
	margin: 10px;
	padding: 10px;
	width: 260px;
	background: #fff;
}
#large-box {
	display: none;
	position: absolute;
	top: 0;
	left: 290px;
	width: 260px;
	height: 260px;
	overflow: hidden;
}
#large-img {
	position: absolute;
	width: 520px;
	height: 520px;
}
#middle-box {
	position: relative;
}
#middle-img {
	width: 100%;
}
#shadow {
	display: none;
	position: absolute;
	left: 0;
	top: 0;
	width: 130px;
	height: 130px;
	background: rgba(255, 0, 0, .4);
	cursor: move;
}
#small-box {
	margin-top: 10px;
	overflow: hidden;
}
#small-box img{
	float: left;
	width: 63px;
	border: 1px solid #fff;
}
#small-box .active {
	border-color: red;
}

js部分


function $(id) {
	return document.getElementById(id);
}

var oBox  	   = $('box');
var oSmallBox  = $('small-box');
var aSmallImg  = Array.from(oSmallBox.children);
var oMiddleBox = $('middle-box');
var oMiddleImg = $('middle-img');
var oLargeBox  = $('large-box');
var oLargeImg  = $('large-img');
var oShadow    = $('shadow');


// 给缩略图添加鼠标进入事件
aSmallImg.forEach( v => {
	v.onmouseover = function () {
		// 先去掉所有的class名
		aSmallImg.forEach(v => v.className = '');

		// 当前img添加class
		this.className = 'active';

		// 改变中型图片的地址
		oMiddleImg.src = this.src;

		// 改变大型图片的地址
		oLargeImg.src = this.src;
	};
});

// 遮罩层最大的left和top值
var maxL = 0;
var maxT = 0;
// 大图片最大的left和top值
var maxLargeImgL  = 0;
var maxLargeImgT  = 0;

// 鼠标进入middle-box
oMiddleBox.onmouseover = function () {
	// 显示遮罩层
	oShadow.style.display = 'block';
	// 显示右侧的盒子
	oLargeBox.style.display = 'block';

	// 获取最大的left和top值
	maxL = oMiddleBox.offsetWidth - oShadow.offsetWidth;
	maxT = oMiddleBox.offsetHeight - oShadow.offsetHeight;

	maxLargeImgL = oLargeImg.offsetWidth - oLargeBox.offsetWidth;
	maxLargeImgT = oLargeImg.offsetHeight - oLargeBox.offsetHeight;
};

// 鼠标离开middle-box
oMiddleBox.onmouseout = function () {
	// 显示遮罩层
	oShadow.style.display = 'none';
	// 显示右侧的盒子
	oLargeBox.style.display = 'none';
};

// 给middle-box添加移动事件
oMiddleBox.onmousemove = function (ev) {
	var e = ev || window.event;
	var iL = e.clientX - oShadow.offsetWidth / 2 - oMiddleBox.offsetLeft - oBox.offsetLeft;
	var iT = e.clientY - oShadow.offsetHeight / 2 - oMiddleBox.offsetTop - oBox.offsetTop;


	// 限定左侧
	if(iL < 0) {
		iL = 0;
	}

	// 限定上侧
	if(iT < 0) {
		iT = 0;
	}

	// 限定右侧
	if(iL > maxL) {
		iL = maxL;
	}

	// 限定下侧
	if(iT > maxT) {
		iT = maxT;
	}
	oShadow.style.left = iL + 'px';
	oShadow.style.top  = iT + 'px';

	// 让大图移动
	oLargeImg.style.left  = - iL * maxLargeImgL / maxL + 'px';
	oLargeImg.style.top   = - iT * maxLargeImgT / maxT + 'px';
};

效果图