JavaScript放大镜详解
1.物体随着鼠标移动
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<script>
//offsetLeft 子元素想当父元素的左位移
// offsetTop 子元素想当父元素的上位移
// offsetWidth 盒子本身的宽高 不包括滚动条
// event.clientX 鼠标的X，Y轴相对与整个页面，而非子元素
window.onload = function () {
var box = document.getElementById("box");
var nav = document.getElementById("nav");
box.onmousemove = function (e) {
//兼容ie浏览器
var e = e || window.event
var left = e.clientX - this.offsetLeft - nav.offsetWidth / 2
var top = e.clientY - this.offsetTop - nav.offsetHeight / 2
//控制拖拽物体的范围只能在规定的范围内拖拽,预防出现滚动条
if (left < 0) {
left = 0
} else if (left >= box.offsetWidth - nav.offsetWidth) {
left = box.offsetWidth - nav.offsetWidth
}
if (top < 0) {
top = 0
} else if (top >= box.offsetHeight - nav.offsetHeight) {
top = box.offsetHeight - nav.offsetHeight
}
nav.style.left = left + 'px';
nav.style.top = top + 'px'
}
}
</script>
<style>
*{
margin: 0;
padding: 0;
}
#box{
width: 600px;
height: 400px;
border: 1px solid #aaaaaa;
margin: 20px;
position: relative;
}
#nav{
width: 100px;
height: 100px;
background: red;
position: absolute;
top: 20px;
left: 20px;
cursor: move;
}
</style>
</head>
<body>
<div id="box">
<div id="nav"></div>
</div>
</body>
</html>
2.鼠标拖拽
2.鼠标拖拽
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<script>
//offsetLeft 子元素想当父元素的左位移
// offsetTop 子元素想当父元素的上位移
// offsetWidth 盒子本身的宽高 不包括滚动条
// event.clientX 鼠标的X，Y轴相对与整个页面，而非子元素
window.onload = function () {
var box = document.getElementById("box");
var nav = document.getElementById("nav");
nav.onmousedown = function (e) {
//兼容ie浏览器
var e = e || window.event
var left = e.clientX - this.offsetLeft;
var top = e.clientY - this.offsetTop;
document.onmousemove = function () {
var e = e || window.event
var lefttwo = e.clientX - left
var toptwo = e.clientY - top
//控制拖拽物体的范围只能在规定的范围内拖拽,预防出现滚动条
if (lefttwo < 0) {
lefttwo = 0
} else if (lefttwo >= box.offsetWidth - nav.offsetWidth) {
lefttwo = box.offsetWidth - nav.offsetWidth
}
if (toptwo < 0) {
toptwo = 0
} else if (toptwo >= box.offsetHeight - nav.offsetHeight) {
toptwo = box.offsetHeight - nav.offsetHeight
}
//移动时重新得到改物体的具体位置
nav.style.left = lefttwo + "px";
nav.style.top = toptwo + "px";
}
document.onmouseup = function () {
this.onmousemove = null
this.onmouseup = null
}
}
}
</script>
<style>
*{
margin: 0;
padding: 0;
}
#box{
width: 600px;
height: 400px;
border: 1px solid #aaaaaa;
margin: 20px;
position: relative;
}
#nav{
width: 100px;
height: 100px;
background: red;
position: absolute;
top: 20px;
left: 20px;
cursor: move;
}
</style>
</head>
<body>
<div id="box">
<div id="nav"></div>
</div>
</body>
</html>
3.JavaScript实现放大镜Dome效果
3.JavaScript实现放大镜Dome效果
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<script>
//offsetLeft 子元素想当父元素的左位移
// offsetTop 子元素想当父元素的上位移
// offsetWidth 盒子本身的宽高 不包括滚动条
// event.clientX 鼠标的X，Y轴相对与整个页面，而非子元素
window.onload=function(){
var box=document.getElementById("box");
var big=document.getElementById("big");
var inner=box.getElementsByTagName("div")[0];
var Oimg=big.getElementsByTagName("img")[0];
//鼠标移入的时候显示
box.onmouseover=function(){
big.style.display='block';
inner.style.display='block';
}
//鼠标移动时
box.onmousemove=function(e){
e = e||window.event;
var left=e.clientX-this.offsetLeft-inner.offsetWidth/2
var top=e.clientY-this.offsetTop-inner.offsetHeight/2
//控制拖拽物体的范围只能在规定的范围内拖拽,预防出现滚动条
if(left<=0){
left=0
}else if(left>=this.offsetWidth-inner.offsetWidth){
left=this.offsetWidth-inner.offsetWidth
}
if(top<=0){
top=0
}else if(top>=this.offsetHeight-inner.offsetHeight){
top=this.offsetHeight-inner.offsetHeight
}
//移动时重新得到改物体的具体位置
inner.style.left=left+"px";
inner.style.top=top+"px"
//移动时图片的大小发生改变
Oimg.style.left=left/(box.offsetWidth-inner.offsetWidth)*(big.offsetWidth-Oimg.offsetWidth)+'px';
Oimg.style.top=top/(box.offsetHeight-inner.offsetHeight)*(big.offsetHeight-Oimg.offsetHeight)+'px';
}
box.onmouseout=function(){
big.style.display='none';
inner.style.display='none';
}
}
</script>
<style>
*{
margin: 0;
padding: 0;
}
.box{
width: 400px;
height: 400px;
border: 1px solid #aaa;
position: relative;
}
.inner{
width: 150px;
height: 150px;
background: rgb(228, 218, 218);
border: 1px solid rgba(0, 0, 0, 0.315);
opacity: 0.3;
position: absolute;
left: 0;
top: 0;
cursor: move;
display: none;
}
.big{
width: 500px;
height: 500px;
border: 1px solid #aaa;
position: absolute;
left: 450px;
top: 0;
overflow:hidden;
display: none;
}
.big img{
position: absolute;
width: 230%;
height: 230%;
}
</style>
</head>
<body>
<div id="box" class="box">
<img src="http://img3.imgtn.bdimg.com/it/u=367891043,8441890&fm=11&gp=0.jpg" width="100%" height="100%" alt="图片">
<div class="inner"></div>
</div>
<div id="big" class="big">
<img src="http://img3.imgtn.bdimg.com/it/u=367891043,8441890&fm=11&gp=0.jpg" alt="放大镜">
</div>
</body>
</html>
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