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js实现用滚动条来放大缩小图片的代码

时间：2021-07-01 10:21:17 帮助过：69人阅读

这段时间比较闲，就搞了这么一个功能来练练手。
因为没有系统的学习过javascript，很多东西都是现学现用。请大家多提宝贵意见，谢谢

<!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=gb2312" /> 
<title>无标题文档</title> 
<style type="text/css"> 
 
</style> 
<script language="javascript" type="text/javascript"> 
//---------------------------------------------------------------------------------------------- 
//    功能说明：用于放大图片的滚动条，可放大至图片的原始大小。在ie6,ie7,ff1.5下可用 
//    使用方法：在图片代码里加上resizeable=1，同时在onload事件里加上createResizeScroll函数 
//    code by: blues[2007-7-17] 
//---------------------------------------------------------------------------------------------- 
//始初化变量 
var oScroll=null,sScrollState=null,iScrollPos=0,iBrowser; 
//------------------------------------------------------------------------------------------------ 
//页面初始化函数 
//------------------------------------------------------------------------------------------------ 
function winInit(){ 
    //检测浏览器类型 
    var __Agt = navigator.userAgent.toLowerCase(); 
    var __If = /(firefox|netscape|opera).?[\/| ](.)\.([^;\)]+|[^\)]+\))$/.exec(__Agt); 
    if(!__If) __If = /(msie) (.)\.[^;]+;/.exec(__Agt); 
    var _Br=__If[1], _Ver=__If[2]; 
    __Agt=null,__If=null; 
    if(_Br=="msie"){iBrowser=0;} 
    else if(_Br=="firefox"){iBrowser=1;} 
    else{iBrowser=2;} 
} 
//------------------------------------------------------------------------------------------------ 
//加上滚动条 
//------------------------------------------------------------------------------------------------ 
function createResizeScroll(){ 
    var objs=getByTag("IMG"); 
    var i,endi=objs.length; 
    var oFunc; 
    for(i=0;i<endi;i++){ 
        if(objs[i].getAttribute("resizeable")=="1"){ 
            var oFuncBox=document.createElement("DIV");//滚动条框 
            var oFuncLine=document.createElement("DIV");//滚动条背景 
            var oFuncBut=document.createElement("P");//滚动条本体 
            oFuncBut.style.marginLeft="5px"; 
            oFuncBut._forobj=objs[i]; 
            oFuncBut.onmousedown=readyMoveScrollBut; 
            oFuncBut.onmouseup=doneMoveScrollBut; 
            oFuncBox.className="scrollX"; 
            oFuncBox.style.display="none"; 
            oFuncBox.onmouseover=function(){this.style.display='block';}; 
            oFuncBox.onmouseout=function(){this.style.display='none';}; 
            oFuncBox.onselectstart=oFuncLine.onselectstart=oFuncBut.onselectstart=function(){return false;};//防止被选中 
            oFuncBox._type=oFuncLine._type=oFuncBut._type="ScrollX";//给滚动条框加上标志，鼠标移出滚动条框后就要中止 
            oFuncLine.appendChild(oFuncBut); 
            oFuncBox.appendChild(oFuncLine); 
            objs[i].parentNode.insertBefore(oFuncBox,objs[i]); 
            objs[i]._width=objs[i].width; 
            objs[i]._height=objs[i].height; 
            objs[i].onmouseover=function(){this.parentNode.childNodes[0].style.display="block";}; 
            objs[i].onmouseout=function(){this.parentNode.childNodes[0].style.display="none";}; 
        } 
    } 
} 
//------------------------------------------------------------------------------------------------ 
//准备移动 
//------------------------------------------------------------------------------------------------ 
function readyMoveScrollBut(e){ 
    oScroll=this; 
    sScrollState="move"; 
    iScrollPos=getPostion("x",e);//获取鼠标坐标并保存 
    this._left=parseInt(this.style.marginLeft); 
    var img=this._forobj; 
    var oImg=new Image; 
    oImg.src=img.src; 
    //滚动条的移动范围是200像素 
    //这里计算出宽高的换算比例并保存 
    img._wbl=(oImg.width-img._width)/200; 
    img._hbl=(oImg.height-img._height)/200; 
} 
//------------------------------------------------------------------------------------------------ 
//完成并清除全局变量 
//------------------------------------------------------------------------------------------------ 
function doneMoveScrollBut(e){ 
    oScroll=null; 
    sScrollState=null; 
    iScrollPos=0; 
} 
//------------------------------------------------------------------------------------------------ 
//鼠标移动 
//------------------------------------------------------------------------------------------------ 
function moveScrollBut(e){ 
    //获取事件源 
    var oEvent=getEvent(e); 
    if(oScroll!=null && sScrollState=="move"){ 
        if(oEvent._type=="ScrollX"){//只有在指定的范围内触发移动 
            var n_x=getPostion("x",e); 
            n_x-=iScrollPos; 
            n_x+=oScroll._left; 
            if(n_x<5)n_x=5; 
            if(n_x>205)n_x=205; 
            oScroll.style.marginLeft=n_x+"px"; 
            //经过计算得出滚动条的marginLeft值（margin-left的取值范围为[5~205]px） 
            n_x-=5; 
            //将滚动条的位置值换算成宽高值（之前已经计算得到了宽高的换算比例），赋给图片 
            var img=oScroll._forobj; 
            img.width=n_x*img._wbl+img._width; 
            img.height=n_x*img._hbl+img._height; 
        }else{doneMoveScrollBut();} 
    } 
} 
//------------------------------------------------------------------------------------------------ 
//给对象的指定事件加上函数功能 
//------------------------------------------------------------------------------------------------ 
function AttachEvent(object,eventName,func,cancelBubble){ 
    var cb=cancelBubble?true:false; 
    eventName=eventName.toLowerCase(); 
    if(document.attachEvent){object.attachEvent(eventName,func);} 
    else{object.addEventListener(eventName.substr(2),func,cb);} 
}    
//------------------------------------------------------------------------------------------------ 
//简写函数 
//------------------------------------------------------------------------------------------------ 
function getById(str){return document.getElementById(str);} 
function getByName(str){return document.getElementsByName(str);} 
function getByTag(str){return document.getElementsByTagName(str);} 
//------------------------------------------------------------------------------------------------ 
//获取鼠标坐标 
//------------------------------------------------------------------------------------------------ 
function getPostion(XorY,e){ 
    if(iBrowser==0){ 
        if(XorY=="x"){return event.x;} 
        else if(XorY=="y"){return event.y;} 
        else{return false;} 
    } 
    else{ 
        if(XorY=="x"){return e.pageX;} 
        else if(XorY=="y"){return e.pageY;} 
        else{return false;} 
    } 
} 
//------------------------------------------------------------------------------------------------ 
//获取事件对象 
//------------------------------------------------------------------------------------------------ 
function getEvent(e){ 
    if(iBrowser==0){return event.srcElement;} 
    else{return e.target;} 
} 
//------------------------------------------------------------------------------------------------ 
//加入事件监听 
//------------------------------------------------------------------------------------------------ 
AttachEvent(window,"onload",winInit,false); 
AttachEvent(window,"onload",createResizeScroll,false); 
AttachEvent(document,"onmousemove",moveScrollBut,false); 
AttachEvent(document,"onmouseup",doneMoveScrollBut,false); 
</script> 
</head> 
<body> 
 
    <img src="https://img.gxlcms.com//Uploads-s/new/2019-09-17-201917/Bluehills.jpg" height="100" resizeable="1" galleryimg="no" /> 
    <img src="https://img.gxlcms.com//Uploads-s/new/2019-09-17-201917/Sunset.jpg" width="300" resizeable="1" galleryimg="no" /> 
    <img src="https://img.gxlcms.com//Uploads-s/new/2019-09-17-201917/Waterlilies.jpg" width="200" resizeable="1" galleryimg="no" /> 
    <img src="https://img.gxlcms.com//Uploads-s/new/2019-09-17-201917/Winter.jpg" width="100" resizeable="1" galleryimg="no" /> 
 
</body> 
</html>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]
另外问大家个问题，像我这样自定义属性的方式行不行的？就是在<img>标签里加上了自定义的 resizeable="1"。在DW里会报警，这样是不是通不过w3c认证的？

js实现用滚动条来放大缩小图片的代码

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