(function($) {

    /**
     * helper variables and function
     */
    $.ifixpng = function(customPixel) {
        $.ifixpng.pixel = customPixel;
    };
    
    $.ifixpng.getPixel = function() {
        return $.ifixpng.pixel || 'images/spacer.gif';
    };
    
    var hack = {
        ltie7  : $.browser.msie && $.browser.version < 7,
        filter : function(src) {
            return "progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled=true,sizingMethod=crop,src='"+src+"')";
        }
    };
    
    /**
     * Applies ie png hack to selected dom elements
     *
     * $('img[@src$=.png]').ifixpng();
     * @desc apply hack to all images with png extensions
     *
     * $('#panel, img[@src$=.png]').ifixpng();
     * @desc apply hack to element #panel and all images with png extensions
     *
     * @name ifixpng
     */
     
    $.fn.ifixpng = hack.ltie7 ? function() {
        return this.each(function() {
            var $$ = $(this);
            // in case rewriting urls
            var base = $('base').attr('href');
            if (base) {
                // remove anything after the last '/'
                base = base.replace(/\/[^\/]+$/,'/');
            }
            if ($$.is('img') || $$.is('input')) { // hack image tags present in dom
                if ($$.attr('src')) {
                    if ($$.attr('src').match(/.*\.png([?].*)?$/i)) { // make sure it is png image
                        // use source tag value if set 
                        var source = (base && $$.attr('src').search(/^(\/|http:)/i)) ? base + $$.attr('src') : $$.attr('src');
                        // apply filter

                        $$.css({filter:hack.filter(source), width:$$.width(), height:$$.height()})
                          .attr({src:$.ifixpng.getPixel()})
                          .positionFix();
                    }
                }
            } else { // hack png css properties present inside css
                var image = $$.css('backgroundImage');
                if (image.match(/^url\(["']?(.*\.png([?].*)?)["']?\)$/i)) {
                    image = RegExp.$1;
                    image = (base && image.substring(0,1)!='/') ? base + image : image;
                    $$.css({backgroundImage:'none', filter:hack.filter(image)})
                      .children().children().positionFix();
                }
            }
        });
    } : function() { return this; };
    
    /**
     * Removes any png hack that may have been applied previously
     *
     * $('img[@src$=.png]').iunfixpng();
     * @desc revert hack on all images with png extensions
     *
     * $('#panel, img[@src$=.png]').iunfixpng();
     * @desc revert hack on element #panel and all images with png extensions
     *
     * @name iunfixpng
     */
     
    $.fn.iunfixpng = hack.ltie7 ? function() {
        return this.each(function() {
            var $$ = $(this);
            var src = $$.css('filter');
            if (src.match(/src=["']?(.*\.png([?].*)?)["']?/i)) { // get img source from filter
                src = RegExp.$1;
                if ($$.is('img') || $$.is('input')) {
                    $$.attr({src:src}).css({filter:''});
                } else {
                    $$.css({filter:'', background:'url('+src+')'});
                }
            }
        });
    } : function() { return this; };
    
    /**
     * positions selected item relatively
     */
     
    $.fn.positionFix = function() {
        return this.each(function() {
            var $$ = $(this);
            var position = $$.css('position');
            if (position != 'absolute' && position != 'relative') {
                $$.css({position:'relative'});
            }
        });
    };

})(jQuery);