// PNGHandler: Object-Oriented Javascript-based PNG wrapper
// --------------------------------------------------------
// original code by Scott Schiller - www.schillmania.com
// modified for own purpose by Pascal COURTOIS courtois@linuxfr.org
// --------------------------------------------------------
// 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.transform = null;

  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'); // oOld.nodeName
    var filterID = 'DXImageTransform.Microsoft.AlphaImageLoader';
    o.style.width = oOld.currentStyle.width;
    o.style.height = oOld.currentStyle.height;

    if (oOld.nodeName == 'IMG'|| oOld.nodeName == 'INPUT') {
      var h=oOld.getAttribute('height');
      var w=oOld.getAttribute('width');
      var newSrc = oOld.getAttribute('src');
      // apply filter
      oOld.src = '..//template/auth/icons/none.gif'; // get rid of image
      oOld.style.filter = "progid:"+filterID+"(src='"+newSrc+"',sizingMethod='scale')";
      oOld.width=w;
      oOld.height=h;
      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.supportTest = function() {
    // Determine method to use.
    // IE 5.5+/win32: filter

    if (this.isIE && this.isWin && this.ver >= 5.5) {
      // Support for PNG - milelage may vary
      // window.status = 'IE 5.5+ filter method.';
      self.transform = self.filterMethod;
      return true;

    } 
    return false;

  }

  this.init = function() {
    if (this.supportTest()) {
      this.elements = getElementsByClassName('png');
      for (var i=0; i<this.elements.length; i++) {
        this.transform(this.elements[i]);
      }
    }
  }
}

function getElementsByClassName(className,oParent) {
  var doc = (oParent||document);
  var matches = [];
  var nodes = doc.all||doc.getElementsByTagName('*'); 
  for (var i=0; i<nodes.length; i++) {
    if ((nodes[i].nodeName=="IMG" || (nodes[i].nodeName=="INPUT" && nodes[i].type=="image")) && nodes[i].src.indexOf("png")+1 ){
          matches[matches.length] = nodes[i];
    }
  }
  return matches; // kids, don't play with fire. ;)
}

// Instantiate and initialize PNG Handler

var pngHandler = new PNGHandler();

pngHandler.init();