/**

* 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!

*/



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();



/* EXAMPLE */

DD_belatedPNG.fix('img, #nav li ul li a, div.box1, #tabs .inside, #logo a, ul#idTabs li a.selected, ul#idTabs li a:hover, h3#photos, h3#videos, h3#links, h3#lifestream, h3#links, form#topSearch, form#topSearch p.fields button, #browseFlickr ');



/* string argument can be any CSS selector */

/* .png_bg example is unnecessary */

/* change it to what suits you! */