/*
* stickyfloat - jQuery plugin for verticaly floating anything in a constrained area
* 
* Example: jQuery('#menu').stickyfloat({duration: 400});
* parameters:
* 		duration 	- the duration of the animation
*		startOffset - the amount of scroll offset after it the animations kicks in
*		offsetY		- the offset from the top when the object is animated
*		lockBottom	- 'true' by default, set to false if you don't want your floating box to stop at parent's bottom
* $Version: 05.16.2009 r1
* Copyright (c) 2009 Yair Even-Or
* vsync.design@gmail.com
*/

// modified to support dynamic height changes of the Obj parent /Eric

$.fn.stickyfloat = function(options, lockBottom) {
	var $obj = this;
	var parentPaddingTop = parseInt($obj.parent().css('padding-top'));
	var startOffset = $obj.parent().offset().top;
	var opts = $.extend({ startOffset: startOffset, offsetY: parentPaddingTop, duration: 200, lockBottom: true }, options);

	$obj.css({ position: 'absolute' });
	$obj.parent().css({ position: 'relative' });

	// add a empty div with the exact same size as the Obj so that the parent div size is correctly calculated
	var emptyDiv = $('<div id="stickyFloatEmptyDiv" generated="true" />');
	emptyDiv.width($obj.outerWidth(true));
	emptyDiv.height($obj.outerHeight(true));
	emptyDiv.appendTo($obj.parent());
	var p = $obj.parent();
	
	if (opts.lockBottom) {
		var bottomPos = $obj.parent().height() - $obj.outerHeight(true) + parentPaddingTop; //get the maximum scrollTop value
		if (bottomPos < 0)
			bottomPos = 0;
	}

	$(window).scroll(function() {
		$obj.stop(); // stop all calculations on scroll event

		// refresh the bottomPos to support client side changes of page content
		if (opts.lockBottom) {
			bottomPos = $obj.parent().height() - $obj.outerHeight(true) + parentPaddingTop; //get the maximum scrollTop value

			if (bottomPos < 0)
				bottomPos = 0;
		}

		var pastStartOffset = $(document).scrollTop() > opts.startOffset; // check if the window was scrolled down more than the start offset declared.
		var objFartherThanTopPos = $obj.offset().top > startOffset; // check if the object is at it's top position (starting point)
		var objBiggerThanWindow = $obj.outerHeight() < $(window).height(); // if the window size is smaller than the Obj size, then do not animate.

		// if window scrolled down more than startOffset OR obj position is greater than
		// the top position possible (+ offsetY) AND window size must be bigger than Obj size
		if ((pastStartOffset || objFartherThanTopPos) && objBiggerThanWindow) {
			var newpos = ($(document).scrollTop() - startOffset + opts.offsetY);
			if (newpos > bottomPos)
				newpos = bottomPos;
			if ($(document).scrollTop() < opts.startOffset) // if window scrolled < starting offset, then reset Obj position (opts.offsetY);
				newpos = parentPaddingTop;

			$obj.animate({ top: newpos }, opts.duration);
		}
	});
};