网页窗口拖拽（改变大小/最小化/最大化/还原/关闭）

<!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=utf-8" />
<title>窗口拖拽（改变大小/最小化/最大化/还原/关闭）</title>
<style type="text/css"> 
body,div,h2{margin:0;padding:0;}
body{background:url(/jscss/demoimg/201212/bg222.jpg);font:12px/1.5 \5fae\8f6f\96c5\9ed1;color:#333;}
#drag{position:absolute;top:100px;left:100px;300px;height:160px;background:#e9e9e9;border:1px solid #444;border-radius:5px;box-shadow:0 1px 3px 2px #666;}
#drag .title{position:relative;height:27px;margin:5px;}
#drag .title h2{font-size:14px;height:27px;line-height:24px;border-bottom:1px solid #A1B4B0;}
#drag .title div{position:absolute;height:19px;top:2px;right:0;}
#drag .title a,a.open{float:left;21px;height:19px;display:block;margin-left:5px;background:url(/jscss/demoimg/201212/tool.png) no-repeat;}
a.open{position:absolute;top:10px;left:50%;margin-left:-10px;background-position:0 0;}
a.open:hover{background-position:0 -29px;}
#drag .title a.min{background-position:-29px 0;}
#drag .title a.min:hover{background-position:-29px -29px;}
#drag .title a.max{background-position:-60px 0;}
#drag .title a.max:hover{background-position:-60px -29px;}
#drag .title a.revert{background-position:-149px 0;display:none;}
#drag .title a.revert:hover{background-position:-149px -29px;}
#drag .title a.close{background-position:-89px 0;}
#drag .title a.close:hover{background-position:-89px -29px;}
#drag .content{overflow:auto;margin:0 5px;}
#drag .resizeBR{position:absolute;14px;height:14px;right:0;bottom:0;overflow:hidden;cursor:nw-resize;background:url(/jscss/demoimg/201212/resize.png) no-repeat;}
#drag .resizeL,#drag .resizeT,#drag .resizeR,#drag .resizeB,#drag .resizeLT,#drag .resizeTR,#drag .resizeLB{position:absolute;background:#000;overflow:hidden;opacity:0;filter:alpha(opacity=0);}
#drag .resizeL,#drag .resizeR{top:0;5px;height:100%;cursor:w-resize;}
#drag .resizeR{right:0;}
#drag .resizeT,#drag .resizeB{100%;height:5px;cursor:n-resize;}
#drag .resizeT{top:0;}
#drag .resizeB{bottom:0;}
#drag .resizeLT,#drag .resizeTR,#drag .resizeLB{8px;height:8px;background:#FF0;}
#drag .resizeLT{top:0;left:0;cursor:nw-resize;}
#drag .resizeTR{top:0;right:0;cursor:ne-resize;}
#drag .resizeLB{left:0;bottom:0;cursor:ne-resize;}
</style>
<script type="text/javascript"> 
/*-------------------------- +
  获取id, class, tagName
 +-------------------------- */
var get = {
    byId: function(id) {
        return typeof id === "string" ? document.getElementById(id) : id
    },
    byClass: function(sClass, oParent) {
        var aClass = [];
        var reClass = new RegExp("(^| )" + sClass + "( |$)");
        var aElem = this.byTagName("*", oParent);
        for (var i = 0; i < aElem.length; i++) reClass.test(aElem[i].className) && aClass.push(aElem[i]);
        return aClass
    },
    byTagName: function(elem, obj) {
        return (obj || document).getElementsByTagName(elem)
    }
};
var dragMinWidth = 250;
var dragMinHeight = 124;
/*-------------------------- +
  拖拽函数
 +-------------------------- */
function drag(oDrag, handle)
{
    var disX = dixY = 0;
    var oMin = get.byClass("min", oDrag)[0];
    var oMax = get.byClass("max", oDrag)[0];
    var oRevert = get.byClass("revert", oDrag)[0];
    var oClose = get.byClass("close", oDrag)[0];
    handle = handle || oDrag;
    handle.style.cursor = "move";
    handle.onmousedown = function (event)
    {
        var event = event || window.event;
        disX = event.clientX - oDrag.offsetLeft;
        disY = event.clientY - oDrag.offsetTop;
        
        document.onmousemove = function (event)
        {
            var event = event || window.event;
            var iL = event.clientX - disX;
            var iT = event.clientY - disY;
            var maxL = document.documentElement.clientWidth - oDrag.offsetWidth;
            var maxT = document.documentElement.clientHeight - oDrag.offsetHeight;
            
            iL <= 0 && (iL = 0);
            iT <= 0 && (iT = 0);
            iL >= maxL && (iL = maxL);
            iT >= maxT && (iT = maxT);
            
            oDrag.style.left = iL + "px";
            oDrag.style.top = iT + "px";
            
            return false
        };
        
        document.onmouseup = function ()
        {
            document.onmousemove = null;
            document.onmouseup = null;
            this.releaseCapture && this.releaseCapture()
        };
        this.setCapture && this.setCapture();
        return false
    };    
    //最大化按钮
    oMax.onclick = function ()
    {
        oDrag.style.top = oDrag.style.left = 0;
        oDrag.style.width = document.documentElement.clientWidth - 2 + "px";
        oDrag.style.height = document.documentElement.clientHeight - 2 + "px";
        this.style.display = "none";
        oRevert.style.display = "block";
    };
    //还原按钮
    oRevert.onclick = function ()
    {        
        oDrag.style.width = dragMinWidth + "px";
        oDrag.style.height = dragMinHeight + "px";
        oDrag.style.left = (document.documentElement.clientWidth - oDrag.offsetWidth) / 2 + "px";
        oDrag.style.top = (document.documentElement.clientHeight - oDrag.offsetHeight) / 2 + "px";
        this.style.display = "none";
        oMax.style.display = "block";
    };
    //最小化按钮
    oMin.onclick = oClose.onclick = function ()
    {
        oDrag.style.display = "none";
        var oA = document.createElement("a");
        oA.className = "open";
        oA.href = "javascript:;";
        oA.title = "还原";
        document.body.appendChild(oA);
        oA.onclick = function ()
        {
            oDrag.style.display = "block";
            document.body.removeChild(this);
            this.onclick = null;
        };
    };
    //阻止冒泡
    oMin.onmousedown = oMax.onmousedown = oClose.onmousedown = function (event)
    {
        this.onfocus = function () {this.blur()};
        (event || window.event).cancelBubble = true    
    };
}
/*-------------------------- +
  改变大小函数
 +-------------------------- */
function resize(oParent, handle, isLeft, isTop, lockX, lockY)
{
    handle.onmousedown = function (event)
    {
        var event = event || window.event;
        var disX = event.clientX - handle.offsetLeft;
        var disY = event.clientY - handle.offsetTop;    
        var iParentTop = oParent.offsetTop;
        var iParentLeft = oParent.offsetLeft;
        var iParentWidth = oParent.offsetWidth;
        var iParentHeight = oParent.offsetHeight;
        
        document.onmousemove = function (event)
        {
            var event = event || window.event;
            
            var iL = event.clientX - disX;
            var iT = event.clientY - disY;
            var maxW = document.documentElement.clientWidth - oParent.offsetLeft - 2;
            var maxH = document.documentElement.clientHeight - oParent.offsetTop - 2;            
            var iW = isLeft ? iParentWidth - iL : handle.offsetWidth + iL;
            var iH = isTop ? iParentHeight - iT : handle.offsetHeight + iT;
            
            isLeft && (oParent.style.left = iParentLeft + iL + "px");
            isTop && (oParent.style.top = iParentTop + iT + "px");
            
            iW < dragMinWidth && (iW = dragMinWidth);
            iW > maxW && (iW = maxW);
            lockX || (oParent.style.width = iW + "px");
            
            iH < dragMinHeight && (iH = dragMinHeight);
            iH > maxH && (iH = maxH);
            lockY || (oParent.style.height = iH + "px");
            
            if((isLeft && iW == dragMinWidth) || (isTop && iH == dragMinHeight)) document.onmousemove = null;
            
            return false;    
        };
        document.onmouseup = function ()
        {
            document.onmousemove = null;
            document.onmouseup = null;
        };
        return false;
    }
};
window.onload = window.onresize = function ()
{
    var oDrag = document.getElementById("drag");
    var oTitle = get.byClass("title", oDrag)[0];
    var oL = get.byClass("resizeL", oDrag)[0];
    var oT = get.byClass("resizeT", oDrag)[0];
    var oR = get.byClass("resizeR", oDrag)[0];
    var oB = get.byClass("resizeB", oDrag)[0];
    var oLT = get.byClass("resizeLT", oDrag)[0];
    var oTR = get.byClass("resizeTR", oDrag)[0];
    var oBR = get.byClass("resizeBR", oDrag)[0];
    var oLB = get.byClass("resizeLB", oDrag)[0];
    
    drag(oDrag, oTitle);
    //四角
    resize(oDrag, oLT, true, true, false, false);
    resize(oDrag, oTR, false, true, false, false);
    resize(oDrag, oBR, false, false, false, false);
    resize(oDrag, oLB, true, false, false, false);
    //四边
    resize(oDrag, oL, true, false, false, true);
    resize(oDrag, oT, false, true, true, false);
    resize(oDrag, oR, false, false, false, true);
    resize(oDrag, oB, false, false, true, false);
    
    oDrag.style.left = (document.documentElement.clientWidth - oDrag.offsetWidth) / 2 + "px";
    oDrag.style.top = (document.documentElement.clientHeight - oDrag.offsetHeight) / 2 + "px";
}
</script>
</head>
<body>
<div id="drag">
    <div class="title">
        <h2>这是一个可以拖动的窗口</h2>
        <div>
            <a class="min" href="javascript:;" title="最小化"></a>
            <a class="max" href="javascript:;" title="最大化"></a>
            <a class="revert" href="javascript:;" title="还原"></a>
            <a class="close" href="javascript:;" title="关闭"></a>
        </div>
    </div>
    <div class="resizeL"></div>
    <div class="resizeT"></div>
    <div class="resizeR"></div>
    <div class="resizeB"></div>
    <div class="resizeLT"></div>
    <div class="resizeTR"></div>
    <div class="resizeBR"></div>
    <div class="resizeLB"></div>
    <div class="content">
        ① 窗口可以拖动；<br />
        ② 窗口可以通过八个方向改变大小；<br />
        ③ 窗口可以最小化、最大化、还原、关闭；<br />
        ④ 限制窗口最小宽度/高度。
    </div>    
</div>
</body>
</html>
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原文地址：https://www.cnblogs.com/weihengblogs/p/2825281.html