/**
* DD_belatedPNG: Adds IE6 support: PNG images for CSS background-image and HTML <IMG/>.
* Author: Drew Diller
* Email: drew.diller@gmail.com
* URL: http://www.dillerdesign.com/experiment/DD_belatedPNG/
* Version: 0.0.7a
* Licensed under the MIT License: http://dillerdesign.com/experiment/DD_belatedPNG/#license
*
* Example usage:
* DD_belatedPNG.fix('.png_bg'); // argument is a CSS selector
* DD_belatedPNG.fixPng( someNode ); // argument is an HTMLDomElement
**/

/*
PLEASE READ:
Absolutely everything in this script is SILLY.  I know this.  IE's rendering of certain pixels doesn't make sense, so neither does this code!
*/

if ($.browser.msie6) {

    var DD_belatedPNG = {

        ns: 'DD_belatedPNG',
        imgSize: {},

        createVmlNameSpace: function() { /* enable VML */
            if (document.namespaces && !document.namespaces[this.ns]) {
                document.namespaces.add(this.ns, 'urn:schemas-microsoft-com:vml');
            }
            if (window.attachEvent) {
                window.attachEvent('onbeforeunload', function() {
                    DD_belatedPNG = null;
                });
            }
        },

        createVmlStyleSheet: function() { /* style VML, enable behaviors */
            /*
            Just in case lots of other developers have added
            lots of other stylesheets using document.createStyleSheet
            and hit the 31-limit mark, let's not use that method!
            further reading: http://msdn.microsoft.com/en-us/library/ms531194(VS.85).aspx
            */
            var style = document.createElement('style');
            document.documentElement.firstChild.insertBefore(style, document.documentElement.firstChild.firstChild);
            var styleSheet = style.styleSheet;
            styleSheet.addRule(this.ns + '\\:*', '{behavior:url(#default#VML)}');
            styleSheet.addRule(this.ns + '\\:shape', 'position:absolute;');
            styleSheet.addRule('img.' + this.ns + '_sizeFinder', 'behavior:none; border:none; position:absolute; z-index:-1; top:-10000px; visibility:hidden;'); /* large negative top value for avoiding vertical scrollbars for large images, suggested by James O'Brien, http://www.thanatopsic.org/hendrik/ */
            this.styleSheet = styleSheet;
        },

        readPropertyChange: function() {
            var el = event.srcElement;
            if (event.propertyName.search('background') != -1 || event.propertyName.search('border') != -1) {
                DD_belatedPNG.applyVML(el);
            }
            if (event.propertyName == 'style.display') {
                var display = (el.currentStyle.display == 'none') ? 'none' : 'block';
                for (var v in el.vml) {
                    el.vml[v].shape.style.display = display;
                }
            }
            if (event.propertyName.search('filter') != -1) {
                DD_belatedPNG.vmlOpacity(el);
            }
        },

        vmlOpacity: function(el) {
            if (el.currentStyle.filter.search('lpha') != -1) {
                var trans = el.currentStyle.filter;
                trans = parseInt(trans.substring(trans.lastIndexOf('=') + 1, trans.lastIndexOf(')')), 10) / 100;
                el.vml.color.shape.style.filter = el.currentStyle.filter; /* complete guesswork */
                el.vml.image.fill.opacity = trans; /* complete guesswork */
            }
        },

        handlePseudoHover: function(el) {
            setTimeout(function() { /* wouldn't work as intended without setTimeout */
                DD_belatedPNG.applyVML(el);
            }, 1);
        },

        /**
        * This is the method to use in a document.
        * @param {String} selector - REQUIRED - a CSS selector, such as '#doc .container'
        **/
        fix: function(selector) {
            var selectors = selector.split(','); /* multiple selectors supported, no need for multiple calls to this anymore */
            for (var i = 0; i < selectors.length; i++) {
                this.styleSheet.addRule(selectors[i], 'behavior:expression(DD_belatedPNG.fixPng(this))'); /* seems to execute the function without adding it to the stylesheet - interesting... */
            }
        },

        applyVML: function(el) {
            el.runtimeStyle.cssText = '';
            this.vmlFill(el);
            this.vmlOffsets(el);
            this.vmlOpacity(el);
            if (el.isImg) {
                this.copyImageBorders(el);
            }
        },

        attachHandlers: function(el) {
            var self = this;
            var handlers = { resize: 'vmlOffsets', move: 'vmlOffsets' };
            if (el.nodeName == 'A') {
                var moreForAs = { mouseleave: 'handlePseudoHover', mouseenter: 'handlePseudoHover', focus: 'handlePseudoHover', blur: 'handlePseudoHover' };
                for (var a in moreForAs) {
                    handlers[a] = moreForAs[a];
                }
            }
            for (var h in handlers) {
                el.attachEvent('on' + h, function() {
                    self[handlers[h]](el);
                });
            }
            el.attachEvent('onpropertychange', this.readPropertyChange);
        },

        giveLayout: function(el) {
            el.style.zoom = 1;
            if (el.currentStyle.position == 'static') {
                el.style.position = 'relative';
            }
        },

        copyImageBorders: function(el) {
            var styles = { 'borderStyle': true, 'borderWidth': true, 'borderColor': true };
            for (var s in styles) {
                el.vml.color.shape.style[s] = el.currentStyle[s];
            }
        },

        vmlFill: function(el) {
            if (!el.currentStyle) {
                return;
            } else {
                var elStyle = el.currentStyle;
            }
            for (var v in el.vml) {
                el.vml[v].shape.style.zIndex = elStyle.zIndex;
            }
            el.runtimeStyle.backgroundColor = '';
            el.runtimeStyle.backgroundImage = '';
            var noColor = (elStyle.backgroundColor == 'transparent');
            var noImg = true;
            if (elStyle.backgroundImage != 'none' || el.isImg) {
                if (!el.isImg) {
                    el.vmlBg = elStyle.backgroundImage;
                    el.vmlBg = el.vmlBg.substr(5, el.vmlBg.lastIndexOf('")') - 5);
                }
                else {
                    el.vmlBg = el.src;
                }
                var lib = this;
                if (!lib.imgSize[el.vmlBg]) { /* determine size of loaded image */
                    var img = document.createElement('img');
                    lib.imgSize[el.vmlBg] = img;
                    img.className = lib.ns + '_sizeFinder';
                    img.runtimeStyle.cssText = 'behavior:none; position:absolute; left:-10000px; top:-10000px; border:none;'; /* make sure to set behavior to none to prevent accidental matching of the helper elements! */
                    img.attachEvent('onload', function() {
                        this.width = this.offsetWidth; /* weird cache-busting requirement! */
                        this.height = this.offsetHeight;
                        lib.vmlOffsets(el);
                    });
                    img.src = el.vmlBg;
                    img.removeAttribute('width');
                    img.removeAttribute('height');
                    document.body.insertBefore(img, document.body.firstChild);
                }
                el.vml.image.fill.src = el.vmlBg;
                noImg = false;
            }
            el.vml.image.fill.on = !noImg;
            el.vml.image.fill.color = 'none';
            el.vml.color.shape.style.backgroundColor = elStyle.backgroundColor;
            el.runtimeStyle.backgroundImage = 'none';
            el.runtimeStyle.backgroundColor = 'transparent';
        },

        /* IE can't figure out what do when the offsetLeft and the clientLeft add up to 1, and the VML ends up getting fuzzy... so we have to push/enlarge things by 1 pixel and then clip off the excess */
        vmlOffsets: function(el) {
            var thisStyle = el.currentStyle;
            var size = { 'W': el.clientWidth + 1, 'H': el.clientHeight + 1, 'w': this.imgSize[el.vmlBg].width, 'h': this.imgSize[el.vmlBg].height, 'L': el.offsetLeft, 'T': el.offsetTop, 'bLW': el.clientLeft, 'bTW': el.clientTop };
            var fudge = (size.L + size.bLW == 1) ? 1 : 0;

            /* vml shape, left, top, width, height, origin */
            var makeVisible = function(vml, l, t, w, h, o) {
                vml.coordsize = w + ',' + h;
                vml.coordorigin = o + ',' + o;
                vml.path = 'm0,0l' + w + ',0l' + w + ',' + h + 'l0,' + h + ' xe';
                vml.style.width = w + 'px';
                vml.style.height = h + 'px';
                vml.style.left = l + 'px';
                vml.style.top = t + 'px';
            };
            makeVisible(el.vml.color.shape, (size.L + (el.isImg ? 0 : size.bLW)), (size.T + (el.isImg ? 0 : size.bTW)), (size.W - 1), (size.H - 1), 0);
            makeVisible(el.vml.image.shape, (size.L + size.bLW), (size.T + size.bTW), (size.W), (size.H), 1);

            var bg = { 'X': 0, 'Y': 0 };
            var figurePercentage = function(axis, position) {
                var fraction = true;
                switch (position) {
                    case 'left':
                    case 'top':
                        bg[axis] = 0;
                        break;
                    case 'center':
                        bg[axis] = .5;
                        break;
                    case 'right':
                    case 'bottom':
                        bg[axis] = 1;
                        break;
                    default:
                        if (position.search('%') != -1) {
                            bg[axis] = parseInt(position) * .01;
                        }
                        else {
                            fraction = false;
                        }
                }
                var horz = (axis == 'X');
                bg[axis] = Math.ceil(fraction ? ((size[horz ? 'W' : 'H'] * bg[axis]) - (size[horz ? 'w' : 'h'] * bg[axis])) : parseInt(position));
                if (bg[axis] == 0) {
                    bg[axis]++;
                }
            };
            for (var b in bg) {
                figurePercentage(b, thisStyle['backgroundPosition' + b]);
            }

            el.vml.image.fill.position = (bg.X / size.W) + ',' + (bg.Y / size.H);

            var bgR = thisStyle.backgroundRepeat;
            var dC = { 'T': 1, 'R': size.W + fudge, 'B': size.H, 'L': 1 + fudge }; /* these are defaults for repeat of any kind */
            var altC = { 'X': { 'b1': 'L', 'b2': 'R', 'd': 'W' }, 'Y': { 'b1': 'T', 'b2': 'B', 'd': 'H'} };
            if (bgR != 'repeat') {
                var c = { 'T': (bg.Y), 'R': (bg.X + size.w), 'B': (bg.Y + size.h), 'L': (bg.X) }; /* these are defaults for no-repeat - clips down to the image location */
                if (bgR.search('repeat-') != -1) { /* now let's revert to dC for repeat-x or repeat-y */
                    var v = bgR.split('repeat-')[1].toUpperCase();
                    c[altC[v].b1] = 1;
                    c[altC[v].b2] = size[altC[v].d];
                }
                if (c.B > size.H) {
                    c.B = size.H;
                }
                el.vml.image.shape.style.clip = 'rect(' + c.T + 'px ' + (c.R + fudge) + 'px ' + c.B + 'px ' + (c.L + fudge) + 'px)';
            }
            else {
                el.vml.image.shape.style.clip = 'rect(' + dC.T + 'px ' + dC.R + 'px ' + dC.B + 'px ' + dC.L + 'px)';
            }
        },

        fixPng: function(el) {
            el.style.behavior = 'none';
            if (el.nodeName == 'BODY' || el.nodeName == 'TD' || el.nodeName == 'TR') { /* elements not supported yet */
                return;
            }
            el.isImg = false;
            if (el.nodeName == 'IMG') {
                if (el.src.toLowerCase().search(/\.png$/) != -1) {
                    el.isImg = true;
                    el.style.visibility = 'hidden';
                }
                else {
                    return;
                }
            }
            else if (el.currentStyle.backgroundImage.toLowerCase().search('.png') == -1) {
                return;
            }
            var lib = DD_belatedPNG;
            el.vml = { color: {}, image: {} };
            var els = { shape: {}, fill: {} };
            for (var r in el.vml) {
                for (var e in els) {
                    var nodeStr = lib.ns + ':' + e;
                    el.vml[r][e] = document.createElement(nodeStr);
                }
                el.vml[r].shape.stroked = false;
                el.vml[r].shape.appendChild(el.vml[r].fill);
                el.parentNode.insertBefore(el.vml[r].shape, el);
            }
            el.vml.image.shape.fillcolor = 'none'; /* Don't show blank white shapeangle when waiting for image to load. */
            el.vml.image.fill.type = 'tile'; /* Ze magic!! Makes image show up. */
            el.vml.color.fill.on = false; /* Actually going to apply vml element's style.backgroundColor, so hide the whiteness. */

            lib.attachHandlers(el);

            lib.giveLayout(el);
            lib.giveLayout(el.offsetParent);

            /* set up element */
            lib.applyVML(el);
        }

    };
    try {
        document.execCommand("BackgroundImageCache", false, true); /* TredoSoft Multiple IE doesn't like this, so try{} it */
    } catch (r) { }
    DD_belatedPNG.createVmlNameSpace();
    DD_belatedPNG.createVmlStyleSheet();
}