// JavaScript Document for revolving images

function scale(id, initialWidth, finalWidth, finalFont){
	var obj = document.getElementById(id);
	var objWidth=initialWidth;
	var objHeight = parseInt(obj.style.height);
	var fontSize= parseInt(obj.style.fontSize);
	
	 objWidth = (objWidth+35);
	 objHeight = (objHeight+40);
	 obj.style.width=objWidth;
	 obj.style.height=objHeight;
	if (fontSize < finalFont) {obj.style.fontSize=(fontSize+1)};
	 
	 var theFunction = "scale('" + id + "', " + objWidth + "," + finalWidth + "," + finalFont + ")";
	 
	if (parseInt(objWidth) < parseInt(finalWidth)) {setTimeout(theFunction, 5)}
}

var logos = [];
logos[0]="../../images/logos/contracts/icraf_square.jpg";
logos[1]="../../images/logos/contracts/duke_square.jpg";
logos[2]="../../images/logos/contracts/presa_square.jpg";
logos[3]="../../images/logos/contracts/ft_square.jpg";

var logo_links = [];
logo_links[0]='http://www.worldagroforestry.org/af/index.php';
logo_links[1]='http://www.law.duke.edu';
logo_links[2]='http://presa.worldagroforestry.org';
logo_links[3]='http://www.forest-trends.org';

function scroll_logos(next_logo){
	var logo_frame = document.getElementById('logo_frame');
	var logo_image = document.getElementById('logo_image');
	var logo_link = document.getElementById('logo_link');
	
	var current_image_opacity = parseInt(get_layer_opacity(logo_image));
	
	if (current_image_opacity<=0){
		logo_image.src=logos[next_logo];
		fade_in_image(logo_image,next_logo);
		logo_link.href=logo_links[next_logo];
	} else {
		logo_frame.style.backgroundImage='url('+logos[next_logo]+')';
		fade_out_image(logo_image,next_logo);
		logo_link.href=logo_links[next_logo];
	}
}

function fade_out_image(logo_image,current_logo){
	var current_image_opacity = get_layer_opacity(logo_image);
	if (current_image_opacity>0){
		set_layer_opacity(logo_image, (current_image_opacity-10));
		setTimeout(function(){fade_out_image(logo_image,current_logo)},100);
	} else {
		var next_logo = current_logo+1;
		if (next_logo >= logos.length){
			next_logo=0;
		}
		setTimeout(function(){scroll_logos(next_logo);},3500);
	}
}			  
										  
function fade_in_image(logo_image,current_logo){
	var current_image_opacity = get_layer_opacity(logo_image);
	if (current_image_opacity<100){
		set_layer_opacity(logo_image, (current_image_opacity+10));
		setTimeout(function(){fade_in_image(logo_image,current_logo)},100);
	} else {
		var next_logo = current_logo+1;
		if (next_logo >= logos.length){
			next_logo=0;
		}
		setTimeout(function(){scroll_logos(next_logo);},3500);
	}
}

function get_layer_opacity(theLayer){
	var CurrentOpacity;	
	if (theLayer.style.MozOpacity) 
	{
		CurrentOpacity = parseInt(theLayer.style.MozOpacity * 100)
	} 
	else if (theLayer.style.opacity)
	{
		CurrentOpacity = parseInt(theLayer.style.opacity * 100)
	}
    else 
	{
		CurrentOpacity = theLayer.filters.alpha.opacity
	}
	return (CurrentOpacity);
}

function set_layer_opacity(theLayer, newValue){
	var CurrentOpacity;	
	if (theLayer.style.MozOpacity) 
	{
		theLayer.style.MozOpacity = parseFloat(newValue/100);
		
	} 
	else if (theLayer.style.opacity)
	{
		theLayer.style.opacity = parseFloat(newValue/100);
	}
    else 
	{
		theLayer.filters.alpha.opacity = parseInt(newValue);
	}
}