﻿(function($) {

    $.fn.pngfix = function(options) {

        // Review the Microsoft IE developer library for AlphaImageLoader reference 
        // http://msdn2.microsoft.com/en-us/library/ms532969(VS.85).aspx

        // ECMA scope fix
        var elements = this;
        var settings = $.extend({
            imageFixSrc: false,
            sizingMethod: false
        }, options);

        if (!$.browser.msie || ($.browser.msie && $.browser.version >= 7)) {
            return (elements);
        }

        function setFilter(el, path, mode) {
            var fs = el.attr("filters");
            var alpha = "DXImageTransform.Microsoft.AlphaImageLoader";
            if (fs[alpha]) {
                fs[alpha].enabled = true;
                fs[alpha].src = path;
                fs[alpha].sizingMethod = mode;
            } else {
                el.css("filter", 'progid:' + alpha + '(enabled="true", sizingMethod="' + mode + '", src="' + path + '")');
            }
        }

        function setDOMElementWidth(el) {
            if (el.css("width") == "auto" & el.css("height") == "auto") {
                el.css("width", el.attr("offsetWidth") + "px");
            }
        }

        return (
			elements.each(function() {

			    // Scope
			    var el = $(this);

			    if (el.attr("tagName").toUpperCase() == "IMG" && (/\.png/i).test(el.attr("src"))) {
			        if (!settings.imageFixSrc) {

			            // Wrap the <img> in a <span> then apply style/filters, 
			            // removing the <img> tag from the final render 
			            el.wrap("<span></span>");
			            var par = el.parent();
			            par.css({
			                height: el.height(),
			                width: el.width(),
			                display: "inline-block"
			            });
			            setFilter(par, el.attr("src"), "scale");
			            el.remove();
			        } else if ((/\.gif/i).test(settings.imageFixSrc)) {

			            // Replace the current image with a transparent GIF
			            // and apply the filter to the background of the 
			            // <img> tag (not the preferred route)
			            setDOMElementWidth(el);
			            setFilter(el, el.attr("src"), "image");
			            el.attr("src", settings.imageFixSrc);
			        }

			    } else {
			        var bg = new String(el.css("backgroundImage"));
			        var matches = bg.match(/^url\("(.*)"\)$/);
			        if (matches && matches.length) {

			            // Elements with a PNG as a backgroundImage have the
			            // filter applied with a sizing method relevant to the 
			            // background repeat type
			            setDOMElementWidth(el);
			            el.css("backgroundImage", "none");

			            // Restrict scaling methods to valid MSDN defintions (or one custom)
			            var sc = "crop";
			            if (settings.sizingMethod) {
			                sc = settings.sizingMethod;
			            }
			            setFilter(el, matches[1], sc);

			            // Fix IE peek-a-boo bug for internal links
			            // within that DOM element
			            el.find("a").each(function() {
			                $(this).css("position", "relative");
			            });
			        }
			    }

			})
		);
    }

})(jQuery)
