/* 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);