// JavaScript Document
// PNGHandler: Object-Oriented Javascript-based PNG wrapper 
// -------------------------------------------------------- 
// Version 1.1.20031218 
// Code by Scott Schiller - www.schillmania.com 
// -------------------------------------------------------- 
// Description: 
// Provides gracefully-degrading PNG functionality where 
// PNG is supported natively or via filters (Damn you, IE!) 
// Should work with PNGs as images and DIV background images. 
function PNGHandler() { 
var self = this; 
this.na = navigator.appName.toLowerCase(); 
this.nv = navigator.appVersion.toLowerCase(); 
this.isIE = this.na.indexOf('internet explorer')+1?1:0; 
this.isWin = this.nv.indexOf('windows')+1?1:0; 
this.ver = this.isIE?parseFloat(this.nv.split('msie ')[1]):parseFloat(this.nv); 
this.isMac = this.nv.indexOf('mac')+1?1:0; 
this.isOpera = (navigator.userAgent.toLowerCase().indexOf('opera ')+1 || navigator.userAgent.toLowerCase().indexOf('opera/')+1); 
if (this.isOpera) this.isIE = false; // Opera filter catch (which is sneaky, pretending to be IE by default) 
this.transform = null; 
this.getElementsByClassName = function(className,oParent) { 
doc = (oParent||document); 
matches = []; 
nodes = doc.all||doc.getElementsByTagName('*'); 
for (i=0; i<nodes.length; i++) { 
if (nodes[i].className == className || nodes[i].className.indexOf(className)+1 || nodes[i].className.indexOf(className+' ')+1 || nodes[i].className.indexOf(' '+className)+1) { 
matches[matches.length] = nodes[i]; 
} 
} 
return matches; // kids, don't play with fire. ;) 
} 
this.filterMethod = function(oOld) { 
// IE 5.5+ proprietary filter garbage (boo!) 
// Create new element based on old one. Doesn't seem to render properly otherwise (due to filter?) 
// use proprietary "currentStyle" object, so rules inherited via CSS are picked up. 
var o = document.createElement('div','li'); // oOld.nodeName 
var filterID = 'DXImageTransform.Microsoft.AlphaImageLoader'; 
// o.style.width = oOld.currentStyle.width; 
// o.style.height = oOld.currentStyle.height; 
if (oOld.nodeName == 'DIV','LI') { 
var b = oOld.currentStyle.backgroundImage.toString(); // parse out background image URL 
oOld.style.backgroundImage = 'none'; 
// Parse out background image URL from currentStyle object. 
var i1 = b.indexOf('url("')+5; 
var newSrc = b.substr(i1,b.length-i1-2).replace('.gif','.png'); // find first instance of ") after (", chop from string 
o = oOld; 
o.style.writingMode = 'lr-tb'; // Has to be applied so filter "has layout" and is displayed. Seriously. Refer to http://msdn.microsoft.com/workshop/author/filter/reference/filters/alphaimageloader.asp?frame=true 
o.style.filter = "progid:"+filterID+"(src='"+newSrc+"',sizingMethod='crop')"; 
// Replace the old (existing) with the new (just created) element. 
// oOld.parentNode.replaceChild(o,oOld); 
} else if (oOld.nodeName == 'IMG') { 
var newSrc = oOld.getAttribute('src').replace('.gif','.png'); 
// apply filter 
oOld.src = 'none.gif'; // get rid of image 
oOld.style.filter = "progid:"+filterID+"(src='"+newSrc+"',sizingMethod='crop')"; 
oOld.style.writingMode = 'lr-tb'; // Has to be applied so filter "has layout" and is displayed. Seriously. Refer to http://msdn.microsoft.com/workshop/author/filter/reference/filters/alphaimageloader.asp?frame=true 
} 
} 
this.pngMethod = function(o) { 
// Native transparency support. Easy to implement. (woo!) 
bgImage = this.getBackgroundImage(o); 
if (bgImage) { 
// set background image, replacing .gif 
o.style.backgroundImage = 'url('+bgImage.replace('.gif','.png')+')'; 
} else if (o.nodeName == 'IMG') { 
o.src = o.src.replace('.gif','.png'); 
} else if (!this.isMac) { 
// window.status = 'PNGHandler.applyPNG(): Node is not a DIV or IMG.'; 
} 
} 
this.getBackgroundImage = function(o) { 
var b, i1; // background-related variables 
var bgUrl = null; 
if (o.nodeName == 'DIV','LI' && !(this.isIE && this.isMac)) { // ie:mac PNG support broken for DIVs with PNG backgrounds 
if (document.defaultView) { 
if (document.defaultView.getComputedStyle) { 
b = document.defaultView.getComputedStyle(o,'').getPropertyValue('background-image'); 
i1 = b.indexOf('url(')+4; 
bgUrl = b.substr(i1,b.length-i1-1); 
} else { 
// no computed style 
} 
} else { 
// no default view 
} 
} 
return bgUrl; 
} 
this.supportTest = function() { 
// Determine method to use. 
// IE 5.5+/win32: filter 
if (this.isIE && this.isWin && this.ver >= 5.5) { 
// IE proprietary filter method (via DXFilter) 
self.transform = self.filterMethod; 
} else if (!this.isIE && this.ver < 5) { 
self.transform = null; 
// No PNG support or broken support 
// Leave existing content as-is 
} else if (!this.isIE && this.ver >= 5 || (this.isIE && this.isMac && this.ver >= 5)) { // version 5+ browser (not IE), or IE:mac 5+ 
self.transform = self.pngMethod; 
} else { 
// Presumably no PNG support. GIF used instead. 
self.transform = null; 
return false; 
} 
return true; 
} 
this.init = function() { 
if (this.supportTest()) { 
this.elements = this.getElementsByClassName('png'); 
for (var i=0; i<this.elements.length; i++) { 
this.transform(this.elements[i]); 
} 
} 
} 
} 
// Instantiate and initialize PNG Handler 
var pngHandler = new PNGHandler();