var gNumSlides;
var gCurSlide;
var gSSInterval;
var gRunning = false;
var gOpacity;
var gSSDiv;

function initSlideShow(numSlides) {
	gNumSlides = numSlides;
	gCurSlide = 0;
	gSSDiv = document.getElementById('slideshow');
	playPause();
}

function setOpacity(opac) {
	if (gSSDiv.style.MozOpacity!=null) {  
		/* Mozilla's pre-CSS3 proprietary rule */ 
		gSSDiv.style.MozOpacity = (opac/100) - .001;
	} else if (gSSDiv.style.opac!=null) {
		/* CSS3 compatible */
		gSSDiv.style.opacity = (opac/100) - .001;
	} else if (gSSDiv.style.filter!=null) {
		/* IE's proprietary filter */ 
		if (opac>=100){
			gSSDiv.style.filter = "none;";
		} else {
			gSSDiv.style.filter = "alpha(opacity="+opac+");";
		}
 	}
}

function fadeIn() {
	gOpacity += 10;
	setOpacity(gOpacity);
	if (gOpacity < 100) {
		setTimeout("fadeIn()", 50);
	}
}

function fadeOut() {
	gOpacity -= 10;
	if (gOpacity <= 0) {
		for(i=0; i<gNumSlides; i++) {
			document.getElementById('slide' +i).style.display = 'none';
			document.getElementById('slidenum' +i).className = '';
		}
		document.getElementById('slide' +gCurSlide).style.display = 'block';
		document.getElementById('slidenum' +gCurSlide).className = 'currentslidenum';

		setTimeout("fadeIn()", 50);
		
	} else {
		setOpacity(gOpacity);
		setTimeout("fadeOut()", 50);
	}
}

function showSlide(slideNum) {
	gCurSlide = slideNum;
	gOpacity = 100;
	setTimeout("fadeOut()", 50);
}

function manualShowSlide(slideNum) {
	if (gRunning) {
		playPause();
	}
	showSlide(slideNum);
}

function advanceSlide() {
	gCurSlide++;
	if (gCurSlide >= gNumSlides) {
		gCurSlide = 0;
	}
	showSlide(gCurSlide);
}

function playPause() {
	if (gRunning) {
		gRunning = false;
		clearInterval(gSSInterval);
		document.getElementById('playpauseimg').src = '/elems2/slideplay.gif';
	} else {
		gRunning = true;
		gSSInterval = setInterval("advanceSlide()", 5000);
		document.getElementById('playpauseimg').src = '/elems2/slidepause.gif';
	}
}