/*
 Makes 32 bit PNG's transparency work in Internet Explorer 6
 * Dependent on "Prototype JavaScript framework (1.6.0)":http://www.prototypejs.org/2007/8/15/prototype-1-6-0-release-candidate
 * Works on *img elements* and on *background images of elements*
 * PNG's can be used as backgrounds. However, *image tiling will not work*
 * *Safe to use* - You don't have to make an exception or write separate code for IE6
 * Background PNG's used in :hover's might need another application of the method
 Example Usages:

 $('yourPNG').pngHack();
 $$('div#fixMe', 'img#andMe', 'img.andUsTo').invoke('pngHack');

 */


Element.addMethods({
    pngHack: function(el) {
        var el = $(el);
        if ( !(Prototype.Browser.IE && parseInt(navigator.userAgent.substring(navigator.userAgent.indexOf("MSIE")+5))<7) ) {
            return el;
        }
        var gif = 'images/px.gif';
        if ( (el.match('img') || el.match('input')) && el.src.include('png') ) {
            var alphaImgSrc = el.src;
            var sizingMethod = 'scale';
            el.src = gif;
        } else if (el.getStyle('backgroundImage').include('png')) {
            var bgc = el.getStyle('backgroundColor') || '';
            var alphaImgSrc = el.getStyle('backgroundImage').gsub(/url\(|\)|'|"/, '');
            var sizingMethod = 'crop';
            el.setStyle({
                background:[bgc,' url(',gif,') no-repeat'] .join('')
            });
        } else {
            return el;
        }
        el.runtimeStyle.filter = 'progid:DXImageTransform.Microsoft.AlphaImageLoader(src="#{al}",sizingMethod="#{sz}")'.interpolate({
            al: alphaImgSrc,
            sz: sizingMethod
        });
        return el;
    }
});