/**
* 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: 0.0.8a
* 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.Engine.name == "trident" && Browser.Engine.version < 5) {
	
	var DD_belatedPNG = {
		ns: 'DD_belatedPNG',
		imgSize: {},
		delay: 0,
		nodesFixed: 0,
		createVmlNameSpace: function(){ /* enable VML */
			if (document.namespaces && !document.namespaces[this.ns]) {
				document.namespaces.add(this.ns, 'urn:schemas-microsoft-com:vml');
			}
		},
		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 screenStyleSheet, printStyleSheet;
			screenStyleSheet = document.createElement('style');
			screenStyleSheet.setAttribute('media', 'screen');
			document.documentElement.firstChild.insertBefore(screenStyleSheet, document.documentElement.firstChild.firstChild);			
			if (screenStyleSheet.styleSheet) {
				screenStyleSheet = screenStyleSheet.styleSheet;
				screenStyleSheet.addRule(this.ns + '\\:*', '{behavior:url(#default#VML)}');
				screenStyleSheet.addRule(this.ns + '\\:shape', 'position:absolute;');
				screenStyleSheet.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.screenStyleSheet = screenStyleSheet;
				
				/* Add a print-media stylesheet, for preventing VML artifacts from showing up in print (including preview). */
				/* Thanks to Rémi Prévost for automating this! */
				printStyleSheet = document.createElement('style');
				printStyleSheet.setAttribute('media', 'print');
				document.documentElement.firstChild.insertBefore(printStyleSheet, document.documentElement.firstChild.firstChild);
				printStyleSheet = printStyleSheet.styleSheet;
				printStyleSheet.addRule(this.ns + '\\:*', '{display: none !important;}');
				printStyleSheet.addRule('img.' + this.ns + '_sizeFinder', '{display: none !important;}');
			}
		},
		readPropertyChange: function(){
			var el, display, v;
			el = event.srcElement;
			if (!el.vmlInitiated) {
				return;
			}
			if (event.propertyName.search('background') != -1 || event.propertyName.search('border') != -1) {
				DD_belatedPNG.applyVML(el);
			}
			if (event.propertyName == 'style.display') {
				display = (el.currentStyle.display == 'none') ? 'none' : 'block';
				for (v in el.vml) {
					if (el.vml.hasOwnProperty(v)) {
						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){
			if (this.screenStyleSheet) {
				var selectors, i;
				selectors = selector.split(','); /* multiple selectors supported, no need for multiple calls to this anymore */
				for (i = 0; i < selectors.length; i++) {
					this.screenStyleSheet.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, handlers, handler, moreForAs, a, h;
			self = this;
			handlers = {
				resize: 'vmlOffsets',
				move: 'vmlOffsets'
			};
			if (el.nodeName == 'A') {
				moreForAs = {
					mouseleave: 'handlePseudoHover',
					mouseenter: 'handlePseudoHover',
					focus: 'handlePseudoHover',
					blur: 'handlePseudoHover'
				};
				for (a in moreForAs) {
					if (moreForAs.hasOwnProperty(a)) {
						handlers[a] = moreForAs[a];
					}
				}
			}
			for (h in handlers) {
				if (handlers.hasOwnProperty(h)) {
					handler = function(){
						self[handlers[h]](el);
					};
					el.attachEvent('on' + h, handler);
				}
			}
			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, s;
			styles = {
				'borderStyle': true,
				'borderWidth': true,
				'borderColor': true
			};
			for (s in styles) {
				if (styles.hasOwnProperty(s)) {
					el.vml.color.shape.style[s] = el.currentStyle[s];
				}
			}
		},
		vmlFill: function(el){
			if (!el.currentStyle) {
				return;
			}
			else {
				var elStyle, noImg, lib, v, img, imgLoaded;
				elStyle = el.currentStyle;
			}
			for (v in el.vml) {
				if (el.vml.hasOwnProperty(v)) {
					el.vml[v].shape.style.zIndex = elStyle.zIndex;
				}
			}
			el.runtimeStyle.backgroundColor = '';
			el.runtimeStyle.backgroundImage = '';
			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;
				}
				lib = this;
				if (!lib.imgSize[el.vmlBg]) { /* determine size of loaded image */
					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; margin:0; padding:0;'; /* make sure to set behavior to none to prevent accidental matching of the helper elements! */
					imgLoaded = function(){
						this.width = this.offsetWidth; /* weird cache-busting requirement! */
						this.height = this.offsetHeight;
						lib.vmlOffsets(el);
					};
					img.attachEvent('onload', imgLoaded);
					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, size, fudge, makeVisible, bg, bgR, dC, altC, b, c, v;
			thisStyle = el.currentStyle;
			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
			};
			fudge = (size.L + size.bLW == 1) ? 1 : 0;
			/* vml shape, left, top, width, height, origin */
			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);
			bg = {
				'X': 0,
				'Y': 0
			};
			if (el.isImg) {
				bg.X = parseInt(thisStyle.paddingLeft, 10) + 1;
				bg.Y = parseInt(thisStyle.paddingTop, 10) + 1;
			}
			else {
				for (b in bg) {
					if (bg.hasOwnProperty(b)) {
						this.figurePercentage(bg, size, b, thisStyle['backgroundPosition' + b]);
					}
				}
			}
			el.vml.image.fill.position = (bg.X / size.W) + ',' + (bg.Y / size.H);
			bgR = thisStyle.backgroundRepeat;
			dC = {
				'T': 1,
				'R': size.W + fudge,
				'B': size.H,
				'L': 1 + fudge
			}; /* these are defaults for repeat of any kind */
			altC = {
				'X': {
					'b1': 'L',
					'b2': 'R',
					'd': 'W'
				},
				'Y': {
					'b1': 'T',
					'b2': 'B',
					'd': 'H'
				}
			};
			if (bgR != 'repeat' || el.isImg) {
				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 */
					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)';
			}
		},
		figurePercentage: function(bg, size, axis, position){
			var horizontal, fraction;
			fraction = true;
			horizontal = (axis == 'X');
			switch (position) {
				case 'left':
				case 'top':
					bg[axis] = 0;
					break;
				case 'center':
					bg[axis] = 0.5;
					break;
				case 'right':
				case 'bottom':
					bg[axis] = 1;
					break;
				default:
					if (position.search('%') != -1) {
						bg[axis] = parseInt(position, 10) / 100;
					}
					else {
						fraction = false;
					}
			}
			bg[axis] = Math.ceil(fraction ? ((size[horizontal ? 'W' : 'H'] * bg[axis]) - (size[horizontal ? 'w' : 'h'] * bg[axis])) : parseInt(position, 10));
			if (bg[axis] % 2 === 0) {
				bg[axis]++;
			}
			return bg[axis];
		},
		fixPng: function(el){
			el.style.behavior = 'none';
			var lib, els, nodeStr, v, e;
			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;
				}
			lib = DD_belatedPNG;
			el.vml = {
				color: {},
				image: {}
			};
			els = {
				shape: {},
				fill: {}
			};
			for (v in el.vml) {
				if (el.vml.hasOwnProperty(v)) {
					for (e in els) {
						if (els.hasOwnProperty(e)) {
							nodeStr = lib.ns + ':' + e;
							el.vml[v][e] = document.createElement(nodeStr);
						}
					}
					el.vml[v].shape.stroked = false;
					el.vml[v].shape.appendChild(el.vml[v].fill);
					el.parentNode.insertBefore(el.vml[v].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'; /* 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);
			el.vmlInitiated = true;
			lib.applyVML(el); /* Render! */
		}
	};
	try {
		document.execCommand("BackgroundImageCache", false, true); /* TredoSoft Multiple IE doesn't like this, so try{} it */
	} 
	catch (r) {
	}
	DD_belatedPNG.createVmlNameSpace();
	DD_belatedPNG.createVmlStyleSheet();
	
}