/*************************

Cross Browser Gradient Backgrounds
v1.0
Last Revision: 11.03.2005
steve@slayeroffice.com

please leave this notice in tact.

should you improve upon this code, please
let me know so that I may update the version
hosted on slayeroffice

--- to use --
reference this file (on your own server) as a javascript src
in the head of your document. give the elements
you want a gradient background applied to a class as such:

class="gradient 000000 ffffff horizontal"

See http://slayeroffice.com/code/gradient/ for more examples.

EDIT (dilari):

* reversed the sorting order for the return array of 'getGradientObjects()', this makes sure every use of this gradient class inside an element that uses it gets processed first and therefor is not overwritten by it's parent.

*************************/

window.addEventListener?window.addEventListener("load",createGradient,false):window.attachEvent("onload",createGradient);
window.addEventListener?window.addEventListener("resize",redrawGradient,false):window.attachEvent("onResize",redrawGradient);

function redrawGradient(){
	if(!document.getElementById('background-gradient'))return;
	var cur = document.getElementById('background-gradient');
	cur.innerHTML = '';
	createGradient();
}

function createGradient() {
	if(!document.getElementById)return;
	
	objArray = getGradientObjects();
	if(!objArray.length) return;
	
	for(i=0;i<objArray.length;i++) {
		params = objArray[i].className.split(" ");
		if(document.all && !window.opera) {
			objArray[i].style.width = objArray[i].offsetWidth + "px";
			params[3] == "horizontal"?gType = 1:gType = 0;
			objArray[i].style.filter = "progid:DXImageTransform.Microsoft.Gradient(GradientType="+gType+",StartColorStr=\"#" + params[1] + "\",EndColorStr=\"#" + params[2] + "\")";
		} else {
			colorArray = createColorPath(params[1],params[2]);
			x=0;y=0;
			if(params[3] == "horizontal") {
				w=Math.round(objArray[i].offsetWidth/colorArray.length);
				if(!w)w=1;
				h = objArray[i].offsetHeight;
			} else {
				//h = Math.round(objArray[i].offsetHeight/colorArray.length);
				h = Math.round(1000/colorArray.length);//NB quickfix!! this disables full element height fill
				if(!h) h =1;
				w = objArray[i].offsetWidth;
			}
			makeGrandParent(objArray[i]);
			tmpDOM = document.createDocumentFragment();
			for(p=0;p<colorArray.length;p++) {
				g = document.createElement("div");
				g.setAttribute("style","position:absolute;z-index:0;top:" + y + "px;left:" + x + "px;height:" + h + "px;width:" + w + "px;background-color:rgb(" + colorArray[p][0] + "," + colorArray[p][1] + "," + colorArray[p][2] + ");");
				params[3] == "horizontal"?x+=w:y+=h;
				tmpDOM.appendChild(g);
				if(y>=objArray[i].offsetHeight || x >= objArray[i].offsetWidth) break;
			}
			objArray[i].appendChild(tmpDOM);
			tmpDOM = null;
		}
	}
}

function getGradientObjects() {
	a = document.getElementsByTagName("*");
	objs = new Array();
	for(i=0;i<a.length;i++) {
		c = a[i].className;
		if(c != "") if(c.indexOf("gradient") == 0) objs[objs.length] = a[i];
	} 
	return objs.reverse();
}
	
function createColorPath(color1,color2) {
	colorPath = new Array();
	colorPercent = 1.0;
	do {
		colorPath[colorPath.length]=setColorHue(longHexToDec(color1),colorPercent,longHexToDec(color2));
		colorPercent-=.01;
	} while(colorPercent>0);
	return colorPath;
}
		
function setColorHue(originColor,opacityPercent,maskRGB) {
	returnColor=new Array();
	for(w=0;w<originColor.length;w++) returnColor[w] = Math.round(originColor[w]*opacityPercent) + Math.round(maskRGB[w]*(1.0-opacityPercent));
	return returnColor;
}

function longHexToDec(longHex) {
	return new Array(toDec(longHex.substring(0,2)),toDec(longHex.substring(2,4)),toDec(longHex.substring(4,6)));	
}

function toDec(hex) {	
	return parseInt(hex,16);
}
	
function makeGrandParent(obj) {
	disp = document.defaultView.getComputedStyle(obj,'').display;
	disp == "block"?nSpan = document.createElement("div"):nSpan = document.createElement("span");
	mHTML = obj.innerHTML;
	obj.innerHTML = "";
	nSpan.innerHTML = mHTML;
	nSpan.setAttribute("style","position:relative;z-index:10;");
	obj.appendChild(nSpan);
}