如何实现一个拖动层可以跟随屏幕移动


<script>
var x,y,z,down=false,obj;
function init()
{
    obj=event.srcElement;
    obj.setCapture();
    z=obj.style.zIndex;
    obj.style.zIndex=100;
    x=event.offsetX;
    y=event.offsetY;
    down=true;
} 
function moveit()
{
    if(down&&event.srcElement==obj)
    {
        with(obj.style)
        {
            obj.style.posLeft=document.body.scrollLeft+event.x-x;
            obj.style.posTop=document.body.scrollTop+event.y-y;
        }
    }
}
function stopdrag()
{
    down=false;
    obj.style.zIndex=z;
    obj.releaseCapture();
}
</script>
<body>
<div onmousedown="init()" onmousemove="moveit()" onmouseup="stopdrag()" style="position:absolute;left:10;top:50;width:100;height:150;border:1px solid #000000;z-index:1;background:#eeeeee">Layer 1</div>

解决方案 »

  1.   

    <style>
    #div1 
    { 
    position: absolute;  
    left:10;top:50;width:100;height:150;
    border:1px   solid   #000000;
    z-index:1;
    background:#eeeeee;
    } 
    </style>
    <script>
    var   x,y,z,down=false,obj;
    var scrollTop1=0;
    var scrollLeft1=0;
    window.onload=aaa;
    function   init()
    {
            obj=event.srcElement;
            obj.setCapture();
            z=obj.style.zIndex;
            obj.style.zIndex=100;
            x=event.offsetX;
            y=event.offsetY;
            down=true;

    }  
    function   moveit()
    {
            if(down&&event.srcElement==obj)
            {
                    with(obj.style)
                    {
                            obj.style.posLeft=document.body.scrollLeft+event.x-x;
                            obj.style.posTop=document.body.scrollTop+event.y-y;
                    }
            }
    }
    function   stopdrag()
    {
            down=false;
            obj.style.zIndex=z;
            obj.releaseCapture();
    }function aaa()
    {
    if(down==false){
    top1=document.getElementById("div1").offsetTop;
    left1=document.getElementById("div1").offsetLeft;
    document.getElementById("div1").style.top=document.body.scrollTop-scrollTop1+top1;
    document.getElementById("div1").style.left=document.body.scrollLeft-scrollLeft1+left1;
    scrollTop1=document.body.scrollTop
    scrollLeft1=document.body.scrollLeft
    }
    setTimeout("aaa()",50);
    }
    </script>
    <body>
    <div  id="div1"  onmousedown="init()"   onmousemove="moveit()"   onmouseup="stopdrag()" > Layer   1 </div>
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