var tmr = null;
var dir = 1;
var spd = 4;
var x = 0;
var scrollTime = 0;

function scrollInit(id) {
        document.getElementById(id+"_freccie").style.display = 'block';
        document.getElementById(id+"_freccia-su").onmouseover = startScrollDown;
        document.getElementById(id+"_freccia-giu").onmouseover = startScrollUp;
        document.getElementById(id+"_freccia-su").onmouseout = stopScroll;
        document.getElementById(id+"_freccia-giu").onmouseout = stopScroll;
        //this.gallTn = document.getElementById(id+"-scroll");   
}

function startScrollUp(e) {
    document.getElementById("colsx-cont_freccia-giu").style.backgroundImage = "url(img/scroll-gall-giu_on.png)";
	if (!e) var e = window.event;
	var tgt = null;
	if (e.target) {
		tgt = e.target;
	} else {
		tgt = e.srcElement;
	}
    var a = tgt.id.indexOf('_');
    var b = tgt.id.substr(0,a);
	dir = -1;
	spd = 10;
	//scrollTime = 0;
    tmr = setInterval("scroll(\'"+b+ "\')",50);   
	return false;
}

function startScrollDown(e) {
    document.getElementById("colsx-cont_freccia-su").style.backgroundImage = "url(img/scroll-gall-su_on.png)";
	if (!e) var e = window.event;
	var tgt = null;
	if (e.target) {
		tgt = e.target;
	} else {
		tgt = e.srcElement;
	}
    var a = tgt.id.indexOf('_');
    var b = tgt.id.substr(0,a);
	dir = 1;
	spd = 10;
	//scrollTime = 0;
	tmr = setInterval("scroll(\'"+b+ "\')",50);
	return false;
}

function stopScroll(e) {
    document.getElementById("colsx-cont_freccia-su").style.backgroundImage = "url(img/scroll-gall-su.png)";
    document.getElementById("colsx-cont_freccia-giu").style.backgroundImage = "url(img/scroll-gall-giu.png)";
	if (!e) var e = window.event;
	var tgt = null;
	if (e.target) {
		tgt = e.target;
	} else {
		tgt = e.srcElement;
	}
	clearInterval(tmr);
	return false;
}

function scroll(id) {
	var gallTn = document.getElementById(id+"_scroll");
	var pos = gallTn.scrollTop;
	if (gallTn.style.top!="") {
		pos = parseInt(gallTn.style.top);
	}
	var hgt = gallTn.offsetHeight;
	var parHgt = gallTn.parentNode.clientHeight;
	if ((hgt-parHgt)>10) {
		if (((pos<0) && (pos>(parHgt-hgt))) || ((pos==0) && (dir==-1)) || ((pos==(parHgt-hgt)) && (dir==1))) {
			x += dir*spd;
			gallTn.style.top = x+"px";
		} else {
			clearInterval(tmr);
			if (pos>0) {
				x = 0;
				gallTn.style.top = x+"px";
			}
			if (pos<(parHgt-hgt)) {
				x = parHgt-hgt;
				gallTn.style.top = x+"px";
			}
		}
	}
}