javascript实现类似google和msn space的拖拽

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javascript实现类似google和msn space的拖拽
转自 http://www.cnblogs.com/BlackSoul/archive/2006/03/31/363463.aspx
      最近在网上看到一些朋友到处找类似于google的个性主页和msn space的拖拽实现,在下正好也找到了一个例子.但是问题比较多.我将其改写并完善,建立了一个通用的函数.具体的函数实现如下:

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>BlackSoul的拖拽Demo</title>
<!--
 ____________________________________
|--------Author By BlackSoul---------|
|------------2006.03.30--------------|
|--------BlackSoulylk@gmail.com------|
|------------QQ:9136194--------------|
|------http://blacksoul.cnblogs.cn---|
======================================
-->
<style type="text/css">
body
{
    margin:0px;
}
 
#aim /*设置目标层样式*/
{
    position:absolute;/*控制层的位置所必须的style*/
    width:200px;
    height:30px;
    border:1px solid #666666;
    background-color:#FFCCCC;
}
 
#sourceLayer, #cloneLayer
{
    position:absolute;/*控制层的位置所必须的style*/
    width:300px;
    height:50px;
    border:1px solid #666666;
    background-color:#CCCCCC;
    cursor:move;
}
 
.docked
{
    display:none;
    filter:alpha(opacity=100);
}
 
.actived
{
    display:block;
    filter:alpha(opacity=70);
}
</style>
</head>
 
<body >
 
<div id="aim">放置范围</div>
<div id="sourceLayer" unselectable="off"><img src="http://blacksoul.gamenews.cn/mail.png" alt="拖拽Demo">拖拽Demo源</div>
<div id="cloneLayer" class="docked" unselectable="off"></div>
 
<script type="text/javascript" language="javascript">
<!--
/*
 ====================================
|--------Author By BlackSoul---------|
|------------2006.03.30--------------|
|--------BlackSoulylk@gmail.com------|
|------------QQ:9136194--------------|
|------http://blacksoul.cnblogs.cn---|
 ====================================
*/
//设置层对象
var aim;
var sourceLayer;
var cloneLayer;
 
//定义各个层初始位置
var aimX;
var aimY;
var orgnX;
var orgnY;
 
//拖拽过程中的变量
var draging = false; //是否处于拖拽中
var offsetX = 0;     //X方向左右偏移量
var offsetY = 0;     //Y方向上下偏移量
var back;            //返回动画对象
var thisX ;          //当前clone层的X位置
var thisY ;          //当前clone层的Y位置
var time ;
var stepX ;          //位移速度
var stepY ;          //位移速度
 
//初始化拖拽信息
/*
 initAimX 目标x坐标
 initAimY 目标y坐标
 initOrgnX 拖拽源x坐标
 initOrgnY 拖拽源y坐标
*/
//获得层对象
 
function getLayer(inAim,inSource,inClone)
{
    aim = document.getElementById(inAim);
    sourceLayer = document.getElementById(inSource);
    cloneLayer = document.getElementById(inClone);
}
 
function initDrag(initAimX,initAimY,initOrgnX,initOrgnY)
{
    aimX = initAimX;
    aimY = initAimY;
    orgnX = initOrgnX;
    orgnY = initOrgnY;
    //设置各个开始层的位置
    aim.style.pixelLeft = aimX;
    aim.style.pixelTop = aimY;
    sourceLayer.style.pixelLeft = orgnX;
    sourceLayer.style.pixelTop = orgnY;
    cloneLayer.style.pixelLeft = orgnX;
    cloneLayer.style.pixelTop = orgnY;
}
 
//准备拖拽
function BeforeDrag()
{
    if (event.button != 1)
    {
        return;
    }
    cloneLayer.innerHTML = sourceLayer.innerHTML; //复制拖拽源内容
    offsetX = document.body.scrollLeft + event.clientX - sourceLayer.style.pixelLeft;
    offsetY = document.body.scrollTop + event.clientY - sourceLayer.style.pixelTop;
    cloneLayer.className = "actived";
    draging = true;
}
 
//拖拽中
function OnDrag()
{
    if(!draging)
    {
        return;
    }
    //更新位置
    event.returnValue = false;
    cloneLayer.style.pixelLeft = document.body.scrollLeft + event.clientX - offsetX;
    cloneLayer.style.pixelTop = document.body.scrollTop + event.clientY - offsetY;
}
 
//结束拖拽
function EndDrag()
{
    if (event.button != 1)
    {
       return;
    }
    draging = false;
 
    if (event.clientX >= aim.style.pixelLeft && event.clientX <= (aim.style.pixelLeft + aim.offsetWidth) &&
        event.clientY >= aim.style.pixelTop && event.clientY <= (aim.style.pixelTop + aim.offsetHeight))
    {
        //拖拽层位于目标中,自动定位到目标位置
        sourceLayer.style.pixelLeft = aim.style.pixelLeft;
        sourceLayer.style.pixelTop = aim.style.pixelTop;
         cloneLayer.className = "docked";
         /*
         ** 这里完成之后可以用xml保存当前位置.
         ** 下次用户进入的时候
         ** 就初始化源拖拽层为xml当中的数据了    
         */
    }
    else
    {
    //拖拽位于目标层外,将拖拽源位置复原
     thisX = cloneLayer.style.pixelLeft;
     thisY = cloneLayer.style.pixelTop;
     offSetX = Math.abs(thisX - orgnX);
     offSetY = Math.abs(thisY - orgnY);
     time = 500;//设置动画时间
     stepX = Math.floor((offSetX/time)*20);
     stepY = Math.floor((offSetY/time)*20);
     if(stepX == 0)
         stepX = 2;
     if(stepY == 0)
         stepY = 2;
        
    //开始返回动画
     moveStart();
    }   
}
 
 
function moveStart()
{
     back = setInterval("MoveLayer();",15);
}
 
//设置返回的动画效果
function MoveLayer()
{
    //位于目标左上
     if(cloneLayer.style.pixelLeft <= orgnX && cloneLayer.style.pixelTop <= orgnY)
     {
         cloneLayer.style.pixelLeft += stepX;
         cloneLayer.style.pixelTop += stepY;
         //如果位移超过目标则设置速度为pix.并向反方向回移.此处实现了弹簧效果.下同
         if(cloneLayer.style.pixelLeft > orgnX)
         {
              stepX = 1;
         }
         if(cloneLayer.style.pixelTop > orgnY)
         {
              stepY = 1;
         }
         //在X或Y轴上坐标相同则不发生位移
         if(cloneLayer.style.pixelLeft == orgnX)
         {
              stepX = 0;
         }
         if(cloneLayer.style.pixelTop == orgnY)
         {
              stepY = 0;
         }
         if(cloneLayer.style.pixelLeft == orgnX && cloneLayer.style.pixelTop == orgnY)
         {
              EndMove();
         }
     }
    
     //位于目标左下
     else if(cloneLayer.style.pixelLeft <= orgnX && cloneLayer.style.pixelTop >= orgnY)
     {
         cloneLayer.style.pixelLeft += stepX;
         cloneLayer.style.pixelTop -= stepY;
         if(cloneLayer.style.pixelLeft > orgnX)
         {
              stepX = 1;
         }
         if(cloneLayer.style.pixelTop < orgnY)
         {
              stepY = 1;
         }
         if(cloneLayer.style.pixelLeft == orgnX)
         {
              stepX = 0;
         }
         if(cloneLayer.style.pixelTop == orgnY)
         {
              stepY = 0;
         }
         if(cloneLayer.style.pixelLeft == orgnX && cloneLayer.style.pixelTop == orgnY)
         {
              EndMove();
         }
     }
    
     //位于目标右上
     else if(cloneLayer.style.pixelLeft >= orgnX && cloneLayer.style.pixelTop <= orgnY)
     {
         cloneLayer.style.pixelLeft -= stepX;
         cloneLayer.style.pixelTop += stepY;
         if(cloneLayer.style.pixelLeft < orgnX)
         {
              stepX = 1;
         }
         if(cloneLayer.style.pixelTop > orgnY)
         {
              stepY = 1;
         }
         if(cloneLayer.style.pixelLeft == orgnX)
         {
              stepX = 0;
         }
         if(cloneLayer.style.pixelTop == orgnY)
         {
              stepY = 0;
         }
         if(cloneLayer.style.pixelLeft == orgnX && cloneLayer.style.pixelTop == orgnY)
         {
              EndMove();
         }
     }
    
     //位于目标右上
     else if(cloneLayer.style.pixelLeft >= orgnX && cloneLayer.style.pixelTop >= orgnY)
     {
         cloneLayer.style.pixelLeft -= stepX;
         cloneLayer.style.pixelTop -= stepY;
         if(cloneLayer.style.pixelLeft < orgnX)
         {
              stepX = 1;
         }
         if(cloneLayer.style.pixelTop < orgnY)
         {
              stepY = 1;
         }
         if(cloneLayer.style.pixelLeft == orgnX)
         {
              stepX = 0;
         }
         if(cloneLayer.style.pixelTop == orgnY)
         {
              stepY = 0;
         }
         if(cloneLayer.style.pixelLeft == orgnX && cloneLayer.style.pixelTop == orgnY)
         {
              EndMove();
         }
     }
    
     //到达目标
     else
     {
         EndMove();
     }
}
 
//停止返回动画
function EndMove()
{
         sourceLayer.style.pixelLeft = orgnX;
         sourceLayer.style.pixelTop = orgnY;
         cloneLayer.style.pixelLeft = orgnX;
         cloneLayer.style.pixelTop = orgnY;
         cloneLayer.className = "docked";
         clearInterval(back);
}
 
//主拖拽函数
function startDraging(inAim,inSource,inClone,initAimX,initAimY,initOrgnX,initOrgnY)
{
    getLayer(inAim,inSource,inClone)
    initDrag(initAimX,initAimY,initOrgnX,initOrgnY);
    sourceLayer.onmousedown = BeforeDrag;
    document.onmousemove = OnDrag; //这里如果用cloneLayer,在拖拽中会选中cloneLayer里面内容,进而出现一些bug...
    cloneLayer.onmouseup = EndDrag;   
}
 
//调用
startDraging("aim","sourceLayer","cloneLayer",300,200,20,20);
//-->
</script>
</body>
</html>

需要注意的是:
一.html里面对于div的定义需要有三个. 三个层都必须定义style的position为absolute,以便控制位置
    1.目标层(aim),主要作用是定义拖拽生效的位置.
    2.拖拽源(sourceLayer).注意设置属性unselectable = "off"(这里比较奇怪,设置成on范围会在拖拽过程中选中层内容)
    3.用于复制的层(cloneLayer).
二.函数的调用
    startDraging参数解释:
    initAim   目标层名称     initSource  拖拽源名称    initClone 用于复制的层的名称  
    initAimX  目标层x轴坐标  initAimY    目标层y轴坐标 initOrgnX 拖拽源x坐标        initOrgnY 拖拽源Y轴坐标

    仅IE里面测试通过.代码里面添加了注释.可以在拖拽源到达目标之后添加写xml的操作.进而记录用户自定义页面排版的数据.对于返回动画的算法还不是很满意.希望各位多多提些建议.以便完善.小弟当前致力于开发一套基于asp.net2.0的ajax控件.希望多多交流.
 
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