本文实例讲述了Js可拖拽放大的层拖动特效实现方法。分享给大家供大家参考。具体实现方法如下：
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>Js实现层拖动效果，还可以拖拽放大</title>
<style>
*{margin:0;padding:0;}
#zhezhao{
width:100%;
height:100%;
background:#f00;
filter:alpha(opacity:0);
opacity:0;
z-index:9999;
position:absolute;
top:0;
left:0;
display:none;
}
#div2{
width:200px;
height:200px;
position:relative;
background:#EEEEEE;
border:1px solid #f00;
}
#div1{
width:15px;
height:15px;
background:#99CC00;
position:absolute;
right:0px;
bottom:0px;
cursor:nw-resize;
overflow:hidden;
font-size:12px;
text-align:center;
line-height:15px;
color:#FFFFFF;
float:right;
z-index:3;
}
#right{
width:15px;
height:100%;
background:#f00;
float:right;
position:absolute;
right:0;
top:0;
cursor:e-resize;
overflow:hidden;
filter:alpha(opacity:0);
opacity:0;
z-index:1;
}
#bottom{
width:100%;
height:15px;
background:#f00;
position:absolute;
left:0;
bottom:0;
cursor:n-resize;
overflow:hidden;
filter:alpha(opacity:0);
opacity:0;
z-index:1;
}
#div2 p{
padding:10px;
line-height:24px;
font-size:13px;
text-indent:24px;
color:#996600;
}
#div2 h2{
width:100%;
height:25px;
line-height:25px;
font-size:14px;
background:#CC9900;
color:#FFFFFF;
text-indent:15px;
cursor:move;
overflow:hidden;
}
</style>
<script type="text/javascript">
window.onload=function()
{
var oDiv=document.getElementById("div1");
var oDiv2=document.getElementById("div2");
var zhezhao=document.getElementById("zhezhao");
var h2=oDiv2.getElementsByTagName("h2")[0];
var right=document.getElementById("right");
var bottom=document.getElementById("bottom");
var mouseStart={};
var divStart={};
var rightStart={};
var bottomStart={};
//往右拽
right.onmousedown=function(ev)
{
var oEvent=ev||event;
mouseStart.x=oEvent.clientX;
mouseStart.y=oEvent.clientY;
rightStart.x=right.offsetLeft;
if(right.setCapture)
{
right.onmousemove=doDrag1;
right.onmouseup=stopDrag1;
right.setCapture();
}
else
{
document.addEventListener("mousemove",doDrag1,true);
document.addEventListener("mouseup",stopDrag1,true);
}
};
function doDrag1(ev)
{
var oEvent=ev||event;
var l=oEvent.clientX-mouseStart.x+rightStart.x;
var w=l+oDiv.offsetWidth;
if(w<oDiv.offsetWidth)
{
w=oDiv.offsetWidth;
}
else if(w>document.documentElement.clientWidth-oDiv2.offsetLeft)
{
w=document.documentElement.clientWidth-oDiv2.offsetLeft-2;
}
oDiv2.style.width=w+"px";
};
function stopDrag1()
{
if(right.releaseCapture)
{
right.onmousemove=null;
right.onmouseup=null;
right.releaseCapture();
}
else
{
document.removeEventListener("mousemove",doDrag1,true);
document.removeEventListener("mouseup",stopDrag1,true);
}
};
//往下拽
bottom.onmousedown=function(ev)
{
var oEvent=ev||event;
mouseStart.x=oEvent.clientX;
mouseStart.y=oEvent.clientY;
bottomStart.y=bottom.offsetTop;
if(bottom.setCapture)
{
bottom.onmousemove=doDrag2;
bottom.onmouseup=stopDrag2;
bottom.setCapture();
}
else
{
document.addEventListener("mousemove",doDrag2,true);
document.addEventListener("mouseup",stopDrag2,true);
}
};
function doDrag2(ev)
{
var oEvent=ev||event;
var t=oEvent.clientY-mouseStart.y+bottomStart.y;
var h=t+oDiv.offsetHeight;
if(h<oDiv.offsetHeight)
{
h=oDiv.offsetHeight;
}
else if(h>document.documentElement.clientHeight-oDiv2.offsetTop)
{
h=document.documentElement.clientHeight-oDiv2.offsetTop-2;
}
oDiv2.style.height=h+"px";
};
function stopDrag2()
{
if(bottom.releaseCapture)
{
bottom.onmousemove=null;
bottom.onmouseup=null;
bottom.releaseCapture();
}
else
{
document.removeEventListener("mousemove",doDrag2,true);
document.removeEventListener("mouseup",stopDrag2,true);
}
};
//往左右同时拽
oDiv.onmousedown=function(ev)
{
var oEvent=ev||event;
mouseStart.x=oEvent.clientX;
mouseStart.y=oEvent.clientY;
divStart.x=oDiv.offsetLeft;
divStart.y=oDiv.offsetTop;
if(oDiv.setCapture)
{
oDiv.onmousemove=doDrag;
oDiv.onmouseup=stopDrag;
oDiv.setCapture();
}
else
{
document.addEventListener("mousemove",doDrag,true);
document.addEventListener("mouseup",stopDrag,true);
}
zhezhao.style.display='block';
};
function doDrag(ev)
{
var oEvent=ev||event;
var l=oEvent.clientX-mouseStart.x+divStart.x;
var t=oEvent.clientY-mouseStart.y+divStart.y;
var w=l+oDiv.offsetWidth;
var h=t+oDiv.offsetHeight;
if(w<oDiv.offsetWidth)
{
w=oDiv.offsetWidth;
}
else if(w>document.documentElement.clientWidth-oDiv2.offsetLeft)
{
w=document.documentElement.clientWidth-oDiv2.offsetLeft-2;
}
if(h<oDiv.offsetHeight)
{
h=oDiv.offsetHeight;
}
else if(h>document.documentElement.clientHeight-oDiv2.offsetTop)
{
h=document.documentElement.clientHeight-oDiv2.offsetTop-2;
}
oDiv2.style.width=w+"px";
oDiv2.style.height=h+"px";
};
function stopDrag()
{
if(oDiv.releaseCapture)
{
oDiv.onmousemove=null;
oDiv.onmouseup=null;
oDiv.releaseCapture();
}
else
{
document.removeEventListener("mousemove",doDrag,true);
document.removeEventListener("mouseup",stopDrag,true);
}
zhezhao.style.display='none';
};
//h2完美拖拽
h2.onmousedown=function(ev)
{
var oEvent=ev||event;
mouseStart.x=oEvent.clientX;
mouseStart.y=oEvent.clientY;
divStart.x=oDiv2.offsetLeft;
divStart.y=oDiv2.offsetTop;
if(h2.setCapture)
{
h2.onmousemove=doDrag3;
h2.onmouseup=stopDrag3;
h2.setCapture();
}
else
{
document.addEventListener("mousemove",doDrag3,true);
document.addEventListener("mouseup",stopDrag3,true);
}
zhezhao.style.display='block';
};
function doDrag3(ev)
{
var oEvent=ev||event;
var l=oEvent.clientX-mouseStart.x+divStart.x;
var t=oEvent.clientY-mouseStart.y+divStart.y;
if(l<0)
{
l=0;
}
else if(l>document.documentElement.clientWidth-oDiv2.offsetWidth)
{
l=document.documentElement.clientWidth-oDiv2.offsetWidth;
}
if(t<0)
{
t=0;
}
else if(t>document.documentElement.clientHeight-oDiv2.offsetHeight)
{
t=document.documentElement.clientHeight-oDiv2.offsetHeight;
}
oDiv2.style.left=l+"px";
oDiv2.style.top=t+"px";
};
function stopDrag3()
{
if(h2.releaseCapture)
{
h2.onmousemove=null;
h2.onmouseup=null;
h2.releaseCapture();
}
else
{
document.removeEventListener("mousemove",doDrag3,true);
document.removeEventListener("mouseup",stopDrag3,true);
}
zhezhao.style.display='none';
}
};
</script>
</head>
<body>
<div id="div2">
<div style="width:100%; height:100%; overflow:hidden;">
<h2>完美的拖拽</h2>
<p>体验不错的JavaScript网页拖动，除了拖动，还可拖动放大，像Windows窗口一样被放大或缩小，只要按住层的右下角，就可以收放自如的放大或缩小。想使用的朋友，可将代码里的Js封装成类，从外部引入想必更合理些。'</p>
<div id="right"></div>
<div id="div1">拖</div>
<div id="bottom"></div>
</div>
</div>
<div id="zhezhao"></div>
</body>
</html>
希望本文所述对大家的javascript程序设计有所帮助。