请教拖拽图片的实现思路

就是控制鼠标事件，mousedown,mouseup,mouseover
在鼠标按下事件中设置“开始移动了”，在鼠标抬起事件中设置“不进行移动”。
在鼠标移动事件中判断是否“开始移动了”，是的话就取鼠标XY位置来动态设置图片的位置实现拖拽图片效果。
另外，在鼠标抬起事件中判断是否可以放下，如果可以放下，就把图片的位置设为目标的位置即可，反之则还原图片原来的位置。

事件是图片对象的。而且图片对象的CSS应该设为绝对定位，这样才能移动。

是不是说将图片放入一个div中，而这个div要设为绝对定位？
关于坐标的话，可否以父层的div左上角来作为坐标计算的原点？

图片对象的CSS应该设为绝对定位，图片的CSS应该设为绝对定位

如果你想这样实现的话那就需要鼠标的 down和up事件要放在div上而不是图片上了父层div position:relative;图片所在div position:absolute;

<body>
<div id="div" style='height:100px;width:100px;border:1px solid #000;position:absolute'></div>
<script type="text/javascript">
function bind()
{
    if (!Function.prototype.bind)
    {
        Function.prototype.bind = function(obj)
        {
            var owner = this,
            args = Array.prototype.slice.call(arguments),
            callobj = Array.prototype.shift.call(args);
            return function(e)
            {
                e = e || top.window.event || window.event;
                owner.apply(callobj, args.concat([e]));
            };
        };
    }
}
var drag = function()
{
    var startX , startY , objX , objY , moveX , moveY;
    var parent = this;
    bind()
    var down = function(e)
    {
        e = e || window.event;
        startX = e.clientX;
        startY = e.clientY;
        objX = parent.offsetLeft;
        objY = parent.offsetTop;
        moveX = startX - objX;
        moveY = startY - objY;
        if(!document.addEventListener) this.setCapture();

        document.onmousemove = move;
        document.onmouseup = up.bind(this)

        if(e.stopPropagation) e.stopPropagation()
            else e.cancelBubble = true
        if(e.preventDefault) e.preventDefault()
            else e.returnValue = false
    }

    var move = function(e)
    {
         e = e || window.event;
         startX = e.clientX;
         startY = e.clientY;
         parent.style.left = startX - moveX + "px";
         parent.style.top = startY - moveY + "px";

        if(e.stopPropagation) e.stopPropagation()
            else e.cancelBubble = true
        if(e.preventDefault) e.preventDefault()
            else e.returnValue = false
    }

    var up = function(e)
    {
        document.onmousemove = null;
        if(!document.addEventListener) this.releaseCapture();

        if(e.stopPropagation) e.stopPropagation()
            else e.cancelBubble = true
        if(e.preventDefault) e.preventDefault()
            else e.returnValue = false
    }

    this.onmousedown = down;
}this.drag.call(document.getElementById("div"))
</script>
</body>

gogogo
#23 效果

尤溪，very good 呀

参数一为要拖拽的元素，二为事件function(elementToDrag,event){
var startX=event.clientX,startY=event.clientY;var origX=elementToDrag.offsetLeft,origY=elementToDrag.offsetTop;var deltaX=startX-origX,deltaY=startY-origY;
if(document.addEventListener){
document.addEventListener("mousemove",moveHandler,true);
document.addEventListener("mouseup",upHandler,true);
}
else if(document.attachEvent){
elementToDrag.attachEvent("onmousemove",moveHandler);
elementToDrag.attachEvent("onmouseup",upHandler);
//事件捕获失败的时候调用upHandler方法
elementToDrag.attachEvent("onlosecapture",upHandler);
}
else{
document.onmousemove=moveHandler;
document.onmouseup=upHandler;
}if(event.stopPropagation) event.stopPropagation();
else event.cacelBubble=true;if(event.preventDefault) event.preventDefault();
else event.returnValue=false;
function moveHandler(e){
if(!e) e=window.event;
elementToDrag.style.left=(e.clientX-deltaX)+"px";
elementToDrag.style.top=(e.clientY-deltaY)+"px";if(e.stopPropagation) e.stopPropagation();
else e.cancelBubble =true;
}function upHandler(e){
if(!e) e=window.event;
if(document.removeEventListener){document.removeEventListener("mouseup",upHandler,true);
document.removeEventListener("mousemove"moveHandler,true);
}
else if(document.detachEvent){
elementToDrag.detachEvent("onlosecapture",upHandler);
elementToDrag.detachEvent("onmouseup",upHandler);
elementToDrag.detachEvent("onmousemove",moveHandler);
elementToDrag.releaseCapture;
}
else{
document.onmouseup=olduphandler;
document.onmousemove=oldmovehandler;
}
if(e.stopPropagation) e.stopPropagation();
else e.cancelBubble=true;}}

9楼写的那个不完整...这个实验通过...function drag(elementToDrag,event){
var startX=event.clientX,startY=event.clientY;var origX=elementToDrag.offsetLeft,origY=elementToDrag.offsetTop;var deltaX=startX-origX,deltaY=startY-origY;
if(document.addEventListener){
document.addEventListener("mousemove",moveHandler,true);
document.addEventListener("mouseup",upHandler,true);
}
else if(document.attachEvent){
elementToDrag.setCapture();
elementToDrag.attachEvent("onmousemove",moveHandler);
elementToDrag.attachEvent("onmouseup",upHandler);
//事件捕获失败的时候调用upHandler方法
elementToDrag.attachEvent("onlosecapture",upHandler);
}
else{
var oldmovehandler =document.onmousemove;
var olduphandler=document.onmouseup;
document.onmousemove=moveHandler;
document.onmouseup=upHandler;
}if(event.stopPropagation) event.stopPropagation();
else event.cacelBubble=true;if(event.preventDefault) event.preventDefault();
else event.returnValue=false;
function moveHandler(e){
if(!e) e=window.event;
elementToDrag.style.left=(e.clientX-deltaX)+"px";
elementToDrag.style.top=(e.clientY-deltaY)+"px";if(e.stopPropagation) e.stopPropagation();
else e.cancelBubble =true;
}function upHandler(e){
if(!e) e=window.event;
if(document.removeEventListener){document.removeEventListener("mouseup",upHandler,true);
document.removeEventListener("mousemove",moveHandler,true);
}
else if(document.detachEvent){
elementToDrag.detachEvent("onlosecapture",upHandler);
elementToDrag.detachEvent("onmouseup",upHandler);
elementToDrag.detachEvent("onmousemove",moveHandler);
elementToDrag.releaseCapture();
}
else{
document.onmouseup=olduphandler;
document.onmousemove=oldmovehandler;
}
if(e.stopPropagation) e.stopPropagation();
else e.cancelBubble=true;}}

<!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>Drag</title>
<style>
* { font-size:12px; font-family:Verdana,宋体; }
html { margin:0px; padding:0px; overflow:auto; }
body { margin:0px; padding:15px; background-color:buttonface; }
#w { position:absolute; width:480px; height:270px; overflow:hidden; border:2px groove #281; cursor:default; -moz-user-select:none; }
#t { line-height:20px; height:20px; width:480px; overflow:hidden; background-color:#27C; color:white; font-weight:bold; border-bottom:1px outset blue; text-align:center; }
#winBody { height:248px; width:480px; overflow-x:hidden; overflow-y:auto; border-top:1px inset blue; padding:10px; text-indent:10px; background-color:white; }
</style>
</head>
<body>
<div id="w">
    <div id="t">Demo Win - Drag me</div>
    <div id="winBody">Hello world</div>
</div>
</body>
<script>
(function(o,s,x,y,d){
    s = o.style;
    d = document;
    o.onselectstart = function(){ return false; }; //阻止选择
    o.onmousedown = function(e){
        e = e||event;
        x = e.clientX-o.offsetLeft;
        y = e.clientY-o.offsetTop;
        d.onmousemove = function(e){
            e = e||event;
            s.left = e.clientX - x + "px";
            s.top = e.clientY - y + "px";
        }
        d.onmouseup = function(){ d.onmouseup = d.onmousemove = ""; }
    }
})(document.getElementById("w"))
</script>
</html>

调试易

请教拖拽图片的实现思路

解决方案 »