JavaScript图片放大技术(放大镜)实现代码分享

代码如下:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>JavaScript图片放大技术(放大镜)实现代码分享 - www.jb51.net</title>
<style type="text/css">
#magnifier{
    width:342px;
    height:420px;
    position:absolute;
    top:100px;
    left:250px;
    font-size:0;
    border:1px solid #000;
}
#img{
    width:342px;
    height:420px;
}
#Browser{
    border:1px solid #000;
    z-index:100;
    position:absolute;
    background:#555;
}
#mag{
    border:1px solid #000;
    overflow:hidden;
    z-index:100;
}
</style>
<script type="text/javascript">
function getEventObject(W3CEvent) {//事件标准化函数
    return W3CEvent || window.event;
}
function getPointerPosition(e) {//兼容浏览器的鼠标x,y获得函数
    e = e || getEventObject(e);
    var x = e.pageX || (e.clientX + (document.documentElement.scrollLeft || document.body.scrollLeft));
    var y = e.pageY || (e.clientY + (document.documentElement.scrollTop || document.body.scrollTop));

return { 'x':x,'y':y };
}
function setOpacity(elem,level) {//兼容浏览器设置透明值
    if(elem.filters) {
        elem.style.filter = 'alpha(opacity=' + level * 100 + ')';
    } else {
        elem.style.opacity = level;
    }
}
function css(elem,prop) {   //css设置函数,可以方便设置css值,并且兼容设置透明值
    for(var i in prop) {
        if(i == 'opacity') {
            setOpacity(elem,prop[i]);
        } else {
            elem.style[i] = prop[i];
        }
    }
    return elem;
}
var magnifier = {
    m : null,

init:function(magni){
        var m = this.m = magni || {
            cont : null,    //装载原始图像的div
            img : null, //放大的图像
            mag : null, //放大框
            scale : 15  //比例值,设置的值越大放大越大,但是这里有个问题就是如果不可以整除时,会产生些很小的白边,目前不知道如何解决
        }

css(m.img,{ 
            'position' : 'absolute',
            'width' : (m.cont.clientWidth * m.scale) + 'px',                //原始图像的宽*比例值    
            'height' : (m.cont.clientHeight * m.scale) + 'px'               //原始图像的高*比例值
            })

css(m.mag,{
            'display' : 'none',
            'width' : m.cont.clientWidth + 'px',    //m.cont为原始图像,与原始图像等宽
            'height' : m.cont.clientHeight + 'px',
            'position' : 'absolute',
            'left' : m.cont.offsetLeft + m.cont.offsetWidth + 10 + 'px',//放大框的位置为原始图像的右方远10px
            'top' : m.cont.offsetTop + 'px'
            })

var borderWid = m.cont.getElementsByTagName('div')[0].offsetWidth - m.cont.getElementsByTagName('div')[0].clientWidth;      //获取border的宽

css(m.cont.getElementsByTagName('div')[0],{         //m.cont.getElementsByTagName('div')[0]为浏览框
            'display' : 'none',                             //开始设置为不可见
            'width' : m.cont.clientWidth / m.scale - borderWid + 'px',          //原始图片的宽/比例值 - border的宽度
            'height' : m.cont.clientHeight / m.scale - borderWid + 'px',//原始图片的高/比例值 - border的宽度
            'opacity' : 0.5//设置透明度
            })

m.img.src = m.cont.getElementsByTagName('img')[0].src;//让原始图像的src值给予放大图像
        m.cont.style.cursor = 'crosshair';

m.cont.onmouseover = magnifier.start;

},

start:function(e){

if(document.all){//只在IE下执行,主要避免IE6的select无法覆盖
            magnifier.createIframe(magnifier.m.img);
        }

this.onmousemove = magnifier.move;//this指向m.cont
        this.onmouseout = magnifier.end;
    },

move:function(e){
        var pos = getPointerPosition(e);        //事件标准化

this.getElementsByTagName('div')[0].style.display = '';

css(this.getElementsByTagName('div')[0],{
            'top' : Math.min(Math.max(pos.y - this.offsetTop - parseInt(this.getElementsByTagName('div')[0].style.height) / 2,0),this.clientHeight - this.getElementsByTagName('div')[0].offsetHeight) + 'px',
            'left' : Math.min(Math.max(pos.x - this.offsetLeft - parseInt(this.getElementsByTagName('div')[0].style.width) / 2,0),this.clientWidth - this.getElementsByTagName('div')[0].offsetWidth) + 'px'            //left=鼠标x - this.offsetLeft - 浏览框宽/2,Math.max和Math.min让浏览框不会超出图像
            })

magnifier.m.mag.style.display = '';

css(magnifier.m.img,{
            'top' : - (parseInt(this.getElementsByTagName('div')[0].style.top) * magnifier.m.scale) + 'px',
            'left' : - (parseInt(this.getElementsByTagName('div')[0].style.left) * magnifier.m.scale) + 'px'
            })

},

end:function(e){
        this.getElementsByTagName('div')[0].style.display = 'none';
        magnifier.removeIframe(magnifier.m.img);        //销毁iframe

magnifier.m.mag.style.display = 'none';
    },

createIframe:function(elem){
        var layer = document.createElement('iframe');
        layer.tabIndex = '-1';
        layer.src = 'javascript:false;';
        elem.parentNode.appendChild(layer);

layer.style.width = elem.offsetWidth + 'px';
        layer.style.height = elem.offsetHeight + 'px';
    },

removeIframe:function(elem){
        var layers = elem.parentNode.getElementsByTagName('iframe');
        while(layers.length >0){
            layers[0].parentNode.removeChild(layers[0]);
        }
    }
}
window.onload = function(){
    magnifier.init({
                   cont : document.getElementById('magnifier'),
                   img : document.getElementById('magnifierImg'),
                   mag : document.getElementById('mag'),
                   scale : 3
                   });
}
</script>
</head>
<body>
<div id="magnifier">
<img src="http://www.jb51.net/images/20091107/fangda.jpg" id="img" />
<div id="Browser"></div>
</div>
<div id="mag"><img id="magnifierImg" /></div>
<select style="position:absolute;top:200px;left:650px;width:100px;">
<option>select测试</option>
<option>是否能覆盖</option>
</select>
</body>
</html>