/* thanks to PPK - http://www.quirksmode.org/viewport/compatibility.html */

function Viewport_Class () {};

Viewport_Class.prototype.getWindowSize = function() {
	// returns innerHeight / innerWidth of window

	if (self.innerHeight) {

		// all except Explorer
		var width = self.innerWidth;
		var height = self.innerHeight;

	} else if (document.documentElement && document.documentElement.clientHeight) {

		// Explorer 6 Strict Mode
		var width = document.documentElement.clientWidth;
		var height = document.documentElement.clientHeight;

	} else if (document.body) {

		// other Explorers
		var width = document.body.clientWidth;
		var height = document.body.clientHeight;

	};

	return { width: width, height: height };
};

Viewport_Class.prototype.getWindowScrollOffset = function() {
	// returns window's scroll offset

	if (typeof window.pageYOffset == 'number') {

		//Netscape compliant
		var x = window.pageXOffset;
		var y = window.pageYOffset;


	} else if (document.body && (document.body.scrollLeft || document.body.scrollTop)) {

		//DOM compliant
		var x = document.body.scrollLeft;
		var y = document.body.scrollTop;


	} else if (document.documentElement &&
	  (document.documentElement.scrollLeft || document.documentElement.scrollTop)) {

		//IE6 standards compliant mode
		var x = document.documentElement.scrollLeft;
		var y = document.documentElement.scrollTop;

	};

	return { x: x||0, y: y||0 };
};

Viewport_Class.prototype.get = function() {
	// returns viewport boundaries and dimensions as top, left, bottom, right, height, width
	var windowSize = this.getWindowSize();
	var scrollOffset = this.getWindowScrollOffset();

	var top = scrollOffset.y;
	var bottom = scrollOffset.y + windowSize.height;

	var left = scrollOffset.x;
	var right = scrollOffset.x + windowSize.width;

	return {
		top: top,
		left: left,
		bottom: bottom,
		right: right,
		width: windowSize.width,
		height: windowSize.height
	};
};

WSDOM.defineClass("Viewport", null, Viewport_Class);
WSDOM.loadSingleton("WSDOM.Viewport.1");