<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>放大镜</title>
<style>
*{
margin:0px;
padding:0px;
}
#box{
width:430px;
height:430px;
margin:100px;
margin-left:17%;
position:relative;//这里使用相对定位，好让其他的元素能依靠这个元素定位
}
#move{
background-color:green;
width:220px;
height:220px;
position:absolute;
left:0px;
top:0px;
display:none;//先让他隐藏，用js使其显示
}
#bimg{
width:430px;
height:430px;
overflow:hidden;
position:absolute;
top:0px;
left:450px;
display:none;//先让他隐藏，用js使其显示
}
#bimg img{
width:800px;
height:800px;
position:absolute;
top:0px;
left:0px;
}
</style>
</head>
<body onload="bigimg()">
<div id="box">
<img src="img/4.jpg" alt="#">
<div id="move"></div>
<div id="bimg">
<img id="b_bimg" src="img/4.jpg" alt="#">
</div>
</div>
<script>
function bigimg(){
var bbox = document.getElementById("box");
var bmove = document.getElementById("move");
var bbimg = document.getElementById("bimg");
var b_bimg = document.getElementById("b_bimg");
bbox.onmouseover = function(){//鼠标移动到box上显示大图片和选框
bbimg.style.display = "block";
bmove.style.display="block";
}
bbox.onmouseout = function(){//鼠标移开box不显示大图片和选框
bbimg.style.display = "none";
bmove.style.display="none";
}
bbox.onmousemove = function(e){//获取鼠标位置
var x = e.clientX;//鼠标相对于视口的位置
var y = e.clientY;
var t = bbox.offsetTop;//box相对于视口的位置
var l = bbox.offsetLeft;
var _left = x - l - bmove.offsetWidth/2;//计算move的位置
var _top = y - t -bmove.offsetHeight/2;
if(_top<=0)//滑到box的最顶部
_top = 0;
else if(_top>=bbox.offsetHeight-bmove.offsetHeight)//滑到box的最底部
_top = bbox.offsetHeight-bmove.offsetHeight ;
if(_left<=0)//滑到box的最左边
_left=0;
else if(_left>=bbox.offsetWidth-bmove.offsetWidth)//滑到box的最右边
_left=bbox.offsetWidth-bmove.offsetWidth ;
bmove.style.top = _top +"px";//设置move的位置
bmove.style.left = _left + "px";
var w = _left/(bbox.offsetWidth-bmove.offsetWidth);//计算移动的比例
var h = _top/(bbox.offsetHeight-bmove.offsetHeight);
var b_bimg_top = (b_bimg.offsetHeight-bbimg.offsetHeight)*h;//计算大图的位置
var b_bimg_left = (b_bimg.offsetWidth-bbimg.offsetWidth)*w;
b_bimg.style.top = -b_bimg_top + "px";//设置大图的位置信息
b_bimg.style.left = -b_bimg_left + "px";
}
}
</script>
</body>
</html>
黑色箭头：
| 12 | var x = e.clientX;var y = e.clientY; |
红色箭头：
| 12 | var t = bbox.offsetTop;var l = bbox.offsetLeft; |
橙色箭头：
| 12 | var _left = x - l - bmove.offsetWidth/2;var _top = y - t -bmove.offsetHeight/2; |
2、bimg块的计算
利用move块在可移动范围内的比例来设置大图的位置
move块的移动范围：
| 1 | bbox.offsetWidth-bmove.offsetWidth |
move块现在的坐标占可移动范围的比例：
| 12 | var w = _left/(bbox.offsetWidth-bmove.offsetWidth);var h = _top/(bbox.offsetHeight-bmove.offsetHeight); |
bimg的移动范围：
| 1 | b_bimg.offsetHeight-bbimg.offsetHeight |
bimg的位置：
| 12 | var b_bimg_top = (b_bimg.offsetHeight-bbimg.offsetHeight)*h;var b_bimg_left = (b_bimg.offsetWidth-bbimg.offsetWidth)*w; |
