// IE5.5+ PNG Alpha Fix v2.0 Alpha: Background Tiling Support



// (c) 2008-2009 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 = Math.max(0, xPos + pngW > elmW ? elmW - xPos : pngW),



					clipB = Math.max(0, yPos + pngH > elmH ? elmH - yPos : pngH);



				d = tiles.cache[count];



				s = d.style;



				s.behavior = 'none';



				s.left = (xPos - parseInt(elm.currentStyle.paddingLeft)) + '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);



	});



}