// IE5.5+ PNG Alpha Fix v2.0 Alpha: Background Tiling Support
// (c) 2008 Angus Turnbull http://www.twinhelix.com
// This is licensed under the GNU LGPL, version 2.1 or later.
// For details, see: http://creativecommons.org/licenses/LGPL/2.1/
var IEPNGFix = window.IEPNGFix || {};
IEPNGFix.tileBG = function(elm, pngSrc, ready) {
 // Params: A reference to a DOM element, the PNG src file pathname, and a
 // hidden "ready-to-run" passed when called back after image preloading.
 var data = this.data[elm.uniqueID],
  elmW = Math.max(elm.clientWidth, elm.scrollWidth),
  elmH = Math.max(elm.clientHeight, elm.scrollHeight),
  bgX = elm.currentStyle.backgroundPositionX,
  bgY = elm.currentStyle.backgroundPositionY,
  bgR = elm.currentStyle.backgroundRepeat;
 // Cache of DIVs created per element, and image preloader/data.
 if (!data.tiles) {
  data.tiles = {
   elm: elm,
   src: '',
   cache: [],
   img: new Image(),
   old: {}
  };
 }
 var tiles = data.tiles,
  pngW = tiles.img.width,
  pngH = tiles.img.height;
 if (pngSrc) {
  if (!ready && pngSrc != tiles.src) {
   // New image? Preload it with a callback to detect dimensions.
   tiles.img.onload = function() {
    this.onload = null;
    IEPNGFix.tileBG(elm, pngSrc, 1);
   };
   return tiles.img.src = pngSrc;
  }
 } else {
  // No image?
  if (tiles.src) ready = 1;
  pngW = pngH = 0;
 }
 tiles.src = pngSrc;
 if (!ready && elmW == tiles.old.w && elmH == tiles.old.h &&
  bgX == tiles.old.x && bgY == tiles.old.y && bgR == tiles.old.r) {
  return;
 }
 // Convert English and percentage positions to pixels.
 var pos = {
   top: '0%',
   left: '0%',
   center: '50%',
   bottom: '100%',
   right: '100%'
  },
  x,
  y,
  pc;
 x = pos[bgX] || bgX;
 y = pos[bgY] || bgY;
 if (pc = x.match(/(\d+)%/)) {
  x = Math.round((elmW - pngW) * (parseInt(pc[1]) / 100));
 }
 if (pc = y.match(/(\d+)%/)) {
  y = Math.round((elmH - pngH) * (parseInt(pc[1]) / 100));
 }
 x = parseInt(x);
 y = parseInt(y);
 // Handle backgroundRepeat.
 var repeatX = { 'repeat': 1, 'repeat-x': 1 }[bgR],
  repeatY = { 'repeat': 1, 'repeat-y': 1 }[bgR];
 if (repeatX) {
  x %= pngW;
  if (x > 0) x -= pngW;
 }
 if (repeatY) {
  y %= pngH;
  if (y > 0) y -= pngH;
 }
 // Go!
 this.hook.enabled = 0;
 if (!({ relative: 1, absolute: 1 }[elm.currentStyle.position])) {
  elm.style.position = 'relative';
 }
 var count = 0,
  xPos,
  maxX = repeatX ? elmW : x + 0.1,
  yPos,
  maxY = repeatY ? elmH : y + 0.1,
  d,
  s,
  isNew;
 if (pngW && pngH) {
  for (xPos = x; xPos < maxX; xPos += pngW) {
   for (yPos = y; yPos < maxY; yPos += pngH) {
    isNew = 0;
    if (!tiles.cache[count]) {
     tiles.cache[count] = document.createElement('div');
     isNew = 1;
    }
    var clipR = (xPos + pngW > elmW ? elmW - xPos : pngW),
     clipB = (yPos + pngH > elmH ? elmH - yPos : pngH);
    d = tiles.cache[count];
    s = d.style;
    s.behavior = 'none';
    s.left = xPos + 'px';
    s.top = yPos + 'px';
    s.width = clipR + 'px';
    s.height = clipB + 'px';
    s.clip = 'rect(' +
     (yPos < 0 ? 0 - yPos : 0) + 'px,' +
     clipR + 'px,' +
     clipB + 'px,' +
     (xPos < 0 ? 0 - xPos : 0) + 'px)';
    s.display = 'block';
    if (isNew) {
     s.position = 'absolute';
     s.zIndex = -999;
     if (elm.firstChild) {
      elm.insertBefore(d, elm.firstChild);
     } else {
      elm.appendChild(d);
     }
    }
    this.fix(d, pngSrc, 0);
    count++;
   }
  }
 }
 while (count < tiles.cache.length) {
  this.fix(tiles.cache[count], '', 0);
  tiles.cache[count++].style.display = 'none';
 }
 this.hook.enabled = 1;
 // Cache so updates are infrequent.
 tiles.old = {
  w: elmW,
  h: elmH,
  x: bgX,
  y: bgY,
  r: bgR
 };
};

IEPNGFix.update = function() {
 // Update all PNG backgrounds.
 for (var i in IEPNGFix.data) {
  var t = IEPNGFix.data[i].tiles;
  if (t && t.elm && t.src) {
   IEPNGFix.tileBG(t.elm, t.src);
  }
 }
};
IEPNGFix.update.timer = 0;
if (window.attachEvent && !window.opera) {
 window.attachEvent('onresize', function() {
  clearTimeout(IEPNGFix.update.timer);
  IEPNGFix.update.timer = setTimeout(IEPNGFix.update, 100);
 });
}