Optimize Element.Dimension.js

/* 
Script: Element.Dimensions.js
	Contains methods to work with size, scroll, or positioning of Elements and the window object.

License:
	MIT-style license.
	
Credits:
	- Viewport dimensions based on [YUI](http://developer.yahoo.com/yui/) code, [BSD License](http://developer.yahoo.com/yui/license.html).	

*/

(function(){

var quirks, compute = Element.getComputedStyle;

var checkQuirks = function(){
	var temp = document.createElement('div');
	temp.style.cssText = 'position:absolute;width:1px;height:1px;left:0;top:0;margin:0;border:0;visibility:hidden';
	temp.innerHTML = '<div style="position:absolute;width:1px;height:1px;left:0;top:0;margin:0;border:5px solid #000;padding:0"><div></div></div><table style="position:absolute;width:1px;height:1px;top:0;left:0;margin:0;border:5px solid #000;padding:0" cellpadding="0" cellspacing="0"><tr><td></td></tr></table>';
	var body = document.body, bodyCssText = body.style.cssText, inner = temp.firstChild, div = inner.firstChild, td = inner.nextSibling.firstChild.firstChild;
	body.insertBefore(temp, body.firstChild);
	
	Browser.Quirks = quirks = {
		addsBorder: div.offsetType == 5,
		addsBorderForTableAndCells: td.offsetTop == 5,
		supportsFixedPosition: (div.style.cssText = 'position:fixed;top:20px;') && div.offsetTop >= 15,
		substractsBorderForOverflowHidden: (div.style.cssText = 'overflow:hidden;position:relative') && div.offsetTop == -5,
		includesMarginInBody: (body.style.marginTop = '1px') && body.offsetTop == 0
	};
	
	body.style.cssText = bodyCssText;
	body.removeChild(temp);
	checkQuirks = null;
};

var computeFloat = function(element, style){
	return parseFloat(compute(element, style) || 0);
};

var getCompatElement = function(obj){
	var doc = obj.getDocument();
	return doc.compatElement || (doc.compatElement = doc.standardMode ? doc.html : doc.body);
};

var getPosition = document.documentElement.getBoundingClientRect ? function(){
	var box = this.getBoundingClientRect(), scroll = this.getScroll(), pos = {x: box.left + scroll.x, y: box.top + scroll.y};
	if (Browser.ie){
		var doc = this.ownerDocument, std = doc.compatMode == 'CSS1Compat', html = doc.documentElement;
		pos.x -= std ? html.clientLeft : parseInt(html.currentStyle.borderLeftWidth, 10) || 2;
		pos.y -= std ? html.clientTop : parseInt(html.currentStyle.borderTopWidth, 10) || 2;
	}
	return pos;
} : function(){
	var el = this, offsetParent = el.offsetParent, doc = el.ownerDocument, html = doc.documentElement, body = doc.body;
	var defaultView = doc.defaultView, computed = defaultView.getComputedStyle(el, null), x = el.offsetLeft, y = el.offsetTop;
	
	while (!quirks.supportsFixedPosition || computed.position != 'fixed' && (el = el.parentNode) && el !== body && el !== html){
		computed = defaultView.getComputedStyle(el, null);
		x -= el.scrollLeft, y -= el.scrollTop;
		if (el == offsetParent){
			x += el.offsetLeft, y += el.offsetTop;
			if (!quirks.addsBorder && !(quirks.addsBorderForTableAndCells && /^t(able|d|h)$/i.test(el.tagName))){
				x += parseFloat(computed.borderLeftWidth) || 0;
				y += parseFloat(computed.borderTopWidth) || 0;
			}
			offsetParent = el.offsetParent;
		}
		if (quirks.subtractBorderForOverflowHidden && computed.overflow != 'visible'){
			x += parseFloat(computed.borderLeftWidth) || 0;
			y += parseFloat(computed.borderTopWidth) || 0;
		}
	}
	if (/^relative|static$/.test(prevComputed.position)) x += body.offsetLeft, y += body.offsetTop;
	if (quirks.supportsFixedPosition && prevComputed.position == 'fixed'){
		x += Math.max(html.scrollLeft, body.scrollLeft);
		y += Math.max(html.scrollTop, body.scrollTop);
	}
	return {x: x, y: y};
};

var getBodyPosition = function(body){
	if (checkQuirks) checkQuirks();
	var x = body.offsetLeft, y = body.offsetTop;
	if (!Browser.includesMarginInBody) x += computeFloat(body, 'margin-left'), y += computeFloat(body, 'margin-top');
	return {x: x, y: y};
};

Element.implement({

	scrollTo: function(x, y){
		if (this == this.ownerDocument.body){
			this.getWindow().scrollTo(x, y);
		} else {
			this.scrollLeft = x;
			this.scrollTop = y;
		}
		return this;
	},

	getSize: function(){
		return {x: this.offsetWidth, y: this.offsetHeight};
	},

	getScrollSize: function(){
		return {x: this.scrollWidth, y: this.scrollHeight};
	},

	getScroll: function(){		
		return (/^input$/i).test(this.tagName) ? {x: 0, y: 0} : {x: this.scrollLeft, y: this.scrollTop};
	},

	getPosition: function(relative) {
		if (checkQuirks) checkQuirks();
		var position = (this == this.ownerDocument.body) ? getBodyPosition(this) : getPosition.call(this);
		if (relative && (relative = $(relative)) {
			relative = relative.getPosition();
			position.x -= relative.x;
			position.y -= relative.y;
		}
		return {x: position.x, y: position.y};
	},

	getCoordinates: function(element){
		var position = this.getPosition(element), size = this.getSize();
		return {left: position.x, right: position.x + size.x, top: position.y, bottom: position.y + size.y, width: size.x, height: size.y};
	},

	// why this?
	computePosition: function(obj){
		//return {left: obj.x - styleNumber(this, 'margin-left'), top: obj.y - styleNumber(this, 'margin-top')};
	},

	position: function(obj){
		//return this.setStyles(this.computePosition(obj));
	}

});

Document.implement({
	getSize: function(){
		var el = getCompatElement(this), winSize = this.getWindow().getSize();
		return {x: Math.max(el.scrollWidth, winSize.x), y: Math.max(el.scrollHeight, winSize.y)};
	}
});

Window.implement({
	getSize: function(){
		var el = getCompatElement(this);
		return {x: el.clientWidth, y: el.clientHeight};
	}
});

Native.implement([Document, Window], {

	getScrollSize: function(){
		return this.getDocument().getSize();
	},

	getScroll: $defined(window.pageYOffset) ? function(){
		var win = this.getWindow();
		return {x: win.pageXOffset, y: win.pageYOffset};
	} : function(){	
		return $(getCompatElement(this)).getScroll();
	}

}); 

})();

//aliases

Native.implement([Window, Document, Element], {

	getHeight: function(){
		return this.getSize().y;
	},

	getWidth: function(){
		return this.getSize().x;
	},

	getScrollTop: function(){
		return this.getScroll().y;
	},

	getScrollLeft: function(){
		return this.getScroll().x;
	},

	getScrollHeight: function(){
		return this.getScrollSize().y;
	},

	getScrollWidth: function(){
		return this.getScrollSize().x;
	},

	getTop: function(){
		return this.getPosition().y;
	},

	getLeft: function(){
		return this.getPosition().x;
	}

});