js通过八个点 拖动改变div大小的实现方法

代码如下:

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Resize</title>
<style type="text/css">
#rRightDown,#rLeftDown,#rLeftUp,#rRightUp,#rRight,#rLeft,#rUp,#rDown{
position:absolute;background:#C00;width:6px;height:6px;z-index:5;font-size:0;}
#rLeftDown,#rRightUp{cursor:ne-resize;}
#rRightDown,#rLeftUp{cursor:nw-resize;}
#rRight,#rLeft{cursor:e-resize;}
#rUp,#rDown{cursor:n-resize;}
#rRightDown{ bottom:-3px; right:-3px;}
#rLeftDown{ bottom:-3px; left:-3px;}
#rRightUp{ top:-3px; right:-3px;}
#rLeftUp{ top:-3px; left:-3px;}
#rRight{ right:-3px; top:50%}
#rLeft{ left:-3px; top:50%}
#rUp{ top:-3px; left:50%}
#rDown{ bottom:-3px; left:50%}
</style>
</head>
<body>
<div id='ss' style="height:100px; width:100px; border:1px solid #000000; position:absolute; left:200px; top:200px;" >
<div id="rRightDown"> </div>
<div id="rLeftDown"> </div>
<div id="rRightUp"> </div>
<div id="rLeftUp"> </div>
<div id="rRight"> </div>
<div id="rLeft"> </div>
<div id="rUp"> </div>
<div id="rDown"></div>
</div>
<script>
var Sys = (function(ua){
    var s = {};
    s.IE = ua.match(/msie ([\d.]+)/)?true:false;
    s.Firefox = ua.match(/firefox\/([\d.]+)/)?true:false;
    s.Chrome = ua.match(/chrome\/([\d.]+)/)?true:false;
    s.IE6 = (s.IE&&([/MSIE (\d)\.0/i.exec(navigator.userAgent)][0][1] == 6))?true:false;
    s.IE7 = (s.IE&&([/MSIE (\d)\.0/i.exec(navigator.userAgent)][0][1] == 7))?true:false;
    s.IE8 = (s.IE&&([/MSIE (\d)\.0/i.exec(navigator.userAgent)][0][1] == 8))?true:false;
    return s;
})(navigator.userAgent.toLowerCase());

var $ = function (id) {
    return document.getElementById(id);
};

var Css = function(e,o){
    for(var i in o)
    e.style[i] = o[i];
};

var Extend = function(destination, source) {
    for (var property in source) {
        destination[property] = source[property];
    }
};

var Bind = function(object, fun) {
    var args = Array.prototype.slice.call(arguments).slice(2);
    return function() {
        return fun.apply(object, args);
    }
};

var BindAsEventListener = function(object, fun) {
    var args = Array.prototype.slice.call(arguments).slice(2);
    return function(event) {
        return fun.apply(object, [event || window.event].concat(args));
    }
};

var CurrentStyle = function(element){
    return element.currentStyle || document.defaultView.getComputedStyle(element, null);
};

function addListener(element,e,fn){
    element.addEventListener?element.addEventListener(e,fn,false):element.attachEvent("on" + e,fn);
};
function removeListener(element,e,fn){
    element.removeEventListener?element.removeEventListener(e,fn,false):element.detachEvent("on" + e,fn)
};

var Class = function(properties){
    var _class = function(){return (arguments[0] !== null && this.initialize && typeof(this.initialize) == 'function') ? this.initialize.apply(this, arguments) : this;};
    _class.prototype = properties;
    return _class;
};

var Resize =new Class({
    initialize : function(obj){
        this.obj = obj;
        this.resizeelm = null;
        this.fun = null; //记录触发什么事件的索引
        this.original = []; //记录开始状态的数组
        this.width = null;
        this.height = null;
        this.fR = BindAsEventListener(this,this.resize);
        this.fS = Bind(this,this.stop);    
    },
    set : function(elm,direction){
        if(!elm)return;
        this.resizeelm = elm;
        addListener(this.resizeelm,'mousedown',BindAsEventListener(this, this.start, this[direction]));
        return this;
    },
    start : function(e,fun){
        this.fun = fun;
        this.original = [parseInt(CurrentStyle(this.obj).width),parseInt(CurrentStyle(this.obj).height),parseInt(CurrentStyle(this.obj).left),parseInt(CurrentStyle(this.obj).top)];
        this.width = (this.original[2]||0) + this.original[0];
        this.height = (this.original[3]||0) + this.original[1];
        addListener(document,"mousemove",this.fR);
        addListener(document,'mouseup',this.fS);
    },
    resize : function(e){
        this.fun(e);
        Sys.IE?(this.resizeelm.onlosecapture=function(){this.fS()}):(this.resizeelm.onblur=function(){this.fS()})
    },
    stop : function(){
        removeListener(document, "mousemove", this.fR);
        removeListener(document, "mousemove", this.fS);
        window.getSelection ? window.getSelection().removeAllRanges() : document.selection.empty();    
    },
    up : function(e){
        this.height>e.clientY?Css(this.obj,{top:e.clientY + "px",height:this.height-e.clientY + "px"}):this.turnDown(e);
    },
    down : function(e){
        e.clientY>this.original[3]?Css(this.obj,{top:this.original[3]+'px',height:e.clientY-this.original[3]+'px'}):this.turnUp(e);    
    },
    left : function(e){
        e.clientX<this.width?Css(this.obj,{left:e.clientX +'px',width:this.width-e.clientX + "px"}):this.turnRight(e);        
    },
    right : function(e){
        e.clientX>this.original[2]?Css(this.obj,{left:this.original[2]+'px',width:e.clientX-this.original[2]+"px"}):this.turnLeft(e)    ;
    },
    leftUp:function(e){
        this.up(e);this.left(e);
    },
    leftDown:function(e){
        this.left(e);this.down(e);
    },
    rightUp:function(e){
        this.up(e);this.right(e);
    },
    rightDown:function(e){
        this.right(e);this.down(e);
    },                
    turnDown : function(e){
        Css(this.obj,{top:this.height+'px',height:e.clientY - this.height + 'px'});
    },
    turnUp : function(e){
        Css(this.obj,{top : e.clientY +'px',height : this.original[3] - e.clientY +'px'});
    },
    turnRight : function(e){
        Css(this.obj,{left:this.width+'px',width:e.clientX- this.width +'px'});
    },
    turnLeft : function(e){
        Css(this.obj,{left:e.clientX +'px',width:this.original[2]-e.clientX+'px'});         
    }        
});
window.onload = function(){
    new Resize($('ss')).set($('rUp'),'up').set($('rDown'),'down').set($('rLeft'),'left').set($('rRight'),'right').set($('rLeftUp'),'leftUp').set($('rLeftDown'),'leftDown').set($('rRightDown'),'rightDown').set($('rRightUp'),'rightUp');
}
</script>
</body>
</html>