//Variablen

var currentSection = "web_design-bereich"; 
var tabTag = "-knopf";
var bereichTag = "-bereich";



// Werkzeug, dient der Ermittlung der Y-Position eines Elements. Gibt X- und Y-Position als Array aus.

function findElementPos(elemFind)
{
	var elemX = 0;
	var elemY = 0;
	do {
		elemX += elemFind.offsetLeft;
		elemY += elemFind.offsetTop;
	} while ( elemFind = elemFind.offsetParent )
	return Array(elemX, elemY);
}

//Scrollen einer Sektion

function ScrollSection(link, scrollArea, offset)
{

	// Store the last section, and update the current section

	if (currentSection == link) {
		return;
	}
	lastSection = currentSection;
	currentSection = link;
	
	// Change the section highlight.
	// Extract the root section name, and use that to change the background image to 'top', revealing the alt. state

    sectionTab = currentSection.split("-")[0] + tabTag;
    document.getElementById(sectionTab).className = "active";
    if (lastSection) {
	    lastTab = lastSection.split("-")[0] + tabTag;
	    document.getElementById(lastTab).className = "inactive";
	}
    
	// Get the element we want to scroll, get the position of the element to scroll to
	
	theScroll = document.getElementById(scrollArea);
	position = findElementPos(document.getElementById(link));

	// Get the position of the offset div -- the div at the far left.
	// This is the amount we compensate for when scrolling
	
	if (offset != "") {
		offsetPos = findElementPos(document.getElementById(offset));
		position[0] = position[0] - offsetPos[0];
	}

	scrollStart(theScroll, theScroll.scrollLeft, position[0], "horiz");
	// return false;
}

// Scroll the page using the arrows

function ScrollArrow(direction, toolbar, scrollArea, offset) {

	toolbarElem = document.getElementById(toolbar);
	toolbarNames = new Array();
    
	// Find all the <li> elements in the toolbar, and extract their id's into an array.
    
	if (toolbarElem.hasChildNodes())
	{
		var children = toolbarElem.childNodes;
		for (var i = 0; i < children.length; i++) 
		{
			if (toolbarElem.childNodes[i].tagName == "LI") {
				toolbarNames.push(toolbarElem.childNodes[i].id.split("-")[0]);
			}
		}
	}

	// Now iterate through our array of tab names, find matches, and determine where to go.

	for (var i = 0; i < toolbarNames.length; i++) {
		if (toolbarNames[i] == currentSection.split("-")[0]) {
			if (direction == "left") {
				if (i - 1 < 0) {
					gotoTab = toolbarNames[toolbarNames.length - 1];
				} else {
					gotoTab = toolbarNames[i - 1];
				}
			} else {
				if ((i + 1) > (toolbarNames.length - 1)) {
					gotoTab = toolbarNames[0];
				} else {
					gotoTab = toolbarNames[i + 1];
				}
			}
		}
	}
	
	// Go to the section name!
	
	ScrollSection(gotoTab+bereichTag, scrollArea, offset);

}





//Animiertes Scrollen

var scrollanim = {time:0, begin:0, change:0.0, duration:0.0, element:null, timer:null};

function scrollStart(elem, start, end, direction)
{
	//console.log("scrollStart from "+start+" to "+end+" in direction "+direction);

	if (scrollanim.timer != null) {
		clearInterval(scrollanim.timer);
		scrollanim.timer = null;
	}
	scrollanim.time = 0;
	scrollanim.begin = start;
	scrollanim.change = end - start;
	scrollanim.duration = 20;
	scrollanim.element = elem;
	
	if (direction == "horiz") {
		scrollanim.timer = setInterval("scrollHorizAnim();", 15);
	}
	else {
		scrollanim.timer = setInterval("scrollVertAnim();", 15);
	}
}

// Horizontalbewegung

function scrollHorizAnim()
{
	if (scrollanim.time > scrollanim.duration) {
		clearInterval(scrollanim.timer);
		scrollanim.timer = null;
	}
	else {
		move = elastisch(scrollanim.time, scrollanim.begin, scrollanim.change, scrollanim.duration, 0, 1);
		scrollanim.element.scrollLeft = move;
		scrollanim.time++;
	}
}


//Funktion fŸr eine elastische Bewegung, Danke an Robert Penner - http://www.robertpenner.com

function elastisch (t, b, c, d, a, p)
{
		if (t==0) return b;  if ((t/=d/2)==2) return b+c;  if (!p) p=d*(.3*1.5);
		if (!a || a < Math.abs(c)) { a=c; var s=p/4; }
		else var s = p/(2*Math.PI) * Math.asin (c/a);
		if (t < 1) return -.5*(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
		return a*Math.pow(2,-10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )*.5 + c + b;
	}