/* Copyright (c) 2006 Brandon Aaron (http://brandonaaron.net)

 * Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php)

 * and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.

 *

 * $LastChangedDate: 2007-07-21 18:44:59 -0500 (Sat, 21 Jul 2007) $

 * $Rev: 2446 $

 *

 * Version 2.1.1

 */

(function($){

/**

 * The bgiframe is chainable and applies the iframe hack to get

 * around zIndex issues in IE6. It will only apply itself in IE6

 * and adds a class to the iframe called 'bgiframe'. The iframe

 * is appeneded as the first child of the matched element(s)

 * with a tabIndex and zIndex of -1.

 *

 * By default the plugin will take borders, sized with pixel units,

 * into account. If a different unit is used for the border's width,

 * then you will need to use the top and left settings as explained below.

 *

 * NOTICE: This plugin has been reported to cause perfromance problems

 * when used on elements that change properties (like width, height and

 * opacity) a lot in IE6. Most of these problems have been caused by

 * the expressions used to calculate the elements width, height and

 * borders. Some have reported it is due to the opacity filter. All

 * these settings can be changed if needed as explained below.

 *

 * @example $('div').bgiframe();

 * @before <div><p>Paragraph</p></div>

 * @result <div><iframe class="bgiframe".../><p>Paragraph</p></div>

 *

 * @param Map settings Optional settings to configure the iframe.

 * @option String|Number top The iframe must be offset to the top

 * 		by the width of the top border. This should be a negative

 *      number representing the border-top-width. If a number is

 * 		is used here, pixels will be assumed. Otherwise, be sure

 *		to specify a unit. An expression could also be used.

 * 		By default the value is "auto" which will use an expression

 * 		to get the border-top-width if it is in pixels.

 * @option String|Number left The iframe must be offset to the left

 * 		by the width of the left border. This should be a negative

 *      number representing the border-left-width. If a number is

 * 		is used here, pixels will be assumed. Otherwise, be sure

 *		to specify a unit. An expression could also be used.

 * 		By default the value is "auto" which will use an expression

 * 		to get the border-left-width if it is in pixels.

 * @option String|Number width This is the width of the iframe. If

 *		a number is used here, pixels will be assume. Otherwise, be sure

 * 		to specify a unit. An experssion could also be used.

 *		By default the value is "auto" which will use an experssion

 * 		to get the offsetWidth.

 * @option String|Number height This is the height of the iframe. If

 *		a number is used here, pixels will be assume. Otherwise, be sure

 * 		to specify a unit. An experssion could also be used.

 *		By default the value is "auto" which will use an experssion

 * 		to get the offsetHeight.

 * @option Boolean opacity This is a boolean representing whether or not

 * 		to use opacity. If set to true, the opacity of 0 is applied. If

 *		set to false, the opacity filter is not applied. Default: true.

 * @option String src This setting is provided so that one could change

 *		the src of the iframe to whatever they need.

 *		Default: "javascript:false;"

 *

 * @name bgiframe

 * @type jQuery

 * @cat Plugins/bgiframe

 * @author Brandon Aaron (brandon.aaron@gmail.com || http://brandonaaron.net)

 */

$.fn.bgIframe = $.fn.bgiframe = function(s) {

	// This is only for IE6

	if ( $.browser.msie && /6.0/.test(navigator.userAgent) ) {

		s = $.extend({

			top     : 'auto', // auto == .currentStyle.borderTopWidth

			left    : 'auto', // auto == .currentStyle.borderLeftWidth

			width   : 'auto', // auto == offsetWidth

			height  : 'auto', // auto == offsetHeight

			opacity : true,

			src     : 'javascript:false;'

		}, s || {});

		var prop = function(n){return n&&n.constructor==Number?n+'px':n;},

		    html = '<iframe class="bgiframe"frameborder="0"tabindex="-1"src="'+s.src+'"'+

		               'style="display:block;position:absolute;z-index:-1;'+

			               (s.opacity !== false?'filter:Alpha(Opacity=\'0\');':'')+

					       'top:'+(s.top=='auto'?'expression(((parseInt(this.parentNode.currentStyle.borderTopWidth)||0)*-1)+\'px\')':prop(s.top))+';'+

					       'left:'+(s.left=='auto'?'expression(((parseInt(this.parentNode.currentStyle.borderLeftWidth)||0)*-1)+\'px\')':prop(s.left))+';'+

					       'width:'+(s.width=='auto'?'expression(this.parentNode.offsetWidth+\'px\')':prop(s.width))+';'+

					       'height:'+(s.height=='auto'?'expression(this.parentNode.offsetHeight+\'px\')':prop(s.height))+';'+

					'"/>';

		return this.each(function() {

			if ( $('> iframe.bgiframe', this).length == 0 )

				this.insertBefore( document.createElement(html), this.firstChild );

		});

	}

	return this;

};

})(jQuery);