//
// Generic
// (DHTML-micro API from www.quirksmode.org)
//
var DHTML = (document.getElementById || document.all || document.layers);

function getObj(name) {
	if (document.getElementById) {
		this.obj = document.getElementById(name);
		if (this.obj) {
			this.style = document.getElementById(name).style;
		}
	}
	else if (document.all) {
		this.obj = document.all[name];
		if (this.obj) {
			this.style = document.all[name].style;
		}
	}
	else if (document.layers) {
		 this.obj = document.layers[name];
		 if (this.obj) {
		 	this.style = document.layers[name];
		 }
	}
}


//
// layer scrolling
//
// http://13thparallel.org/archive/dhtml-scrollbars/
var scrollBox;
var scrollClip;
var scrollCtrl;
var scrollTime;
var scrollTout;
var scrollPos;

function init(nameBox, nameClip, nameControl, time) {
	scrollBox = new getObj(nameBox);
	scrollClip = new getObj(nameClip);
	scrollPos = 0;
	scrollTout = time;
	//alert(scrollClip.obj.offsetHeight +':'+ scrollBox.obj.offsetHeight);
	if (scrollClip.obj) {
		if (scrollClip.obj.offsetHeight > scrollBox.obj.offsetHeight) {
			scrollCtrl = new getObj(nameControl);
			scrollCtrl.style.visibility = 'visible';
		}
	}
}

function scroll_layer(move, time) {
	//alert('move:'+move+', scrollPos:'+scrollPos+', scrollBox.offsetHeight:'+scrollBox.obj.offsetHeight);
	if (move > 0) {
		if (scrollPos < 0) {
			scrollClip.style.top = (scrollPos+move) +'px';
			scrollPos = scrollPos+move;
		} else {
			scroll_stop();
		}
	}
	if (move < 0) {
		if (scrollPos+scrollClip.obj.offsetHeight > scrollBox.obj.offsetHeight) {
			scrollClip.style.top = (scrollPos+move) +'px';
			scrollPos = scrollPos+move;
		} else {
			scroll_stop();
		}
	}
	scrollTime = setTimeout('scroll_layer('+move+')', scrollTout);
}

function scroll_stop() {
	if (scrollTime) clearTimeout(scrollTime);
}

//
// image rollovers
//
function newImage(arg) {
	if (DHTML) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function changeImages() {
	if (DHTML) { // && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			var o = new getObj(changeImages.arguments[i]);
			o.obj.src = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;
function preloadImages() {
	if (DHTML) {
		nl1_home_over = newImage("lib/images/navl1/home-over.jpg");
		nl1_margreetpost_over = newImage("lib/images/navl1/margreetpost-over.jpg");
		nl1_particulieren_over = newImage("lib/images/navl1/particulieren-ove.jpg");
		nl1_bedrijven_over = newImage("lib/images/navl1/bedrijven-over.jpg");
		nl1_portfolio_over = newImage("lib/images/navl1/portfolio-over.jpg");
		nl1_contact_over = newImage("lib/images/navl1/contact-over.jpg");
		sctrl_up_over = newImage("lib/images/scroll/up-over.gif");
		sctrl_down_over = newImage("lib/images/scroll/down-over.gif");
		preloadFlag = true;
	}
}

//
// page preload
//
function pagestarter() {
	preloadImages();
	init('scrollbox', 'scrollclip', 'scrollcontrol', 30);
}