/**
* 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!
*/

/*
Copyright (c) 2008 Drew Diller

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

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();