var opacity_timer_1 = new Array();
var opacity_timer_2 = new Array();
function opacity(id, opacStart, opacEnd, millisec) {
	//speed for each frame
	var speed = Math.round(millisec / 100);
	var timer = 0;

	//determine the direction for the blending, if start and end are the same nothing happens
	if(opacStart > opacEnd) {
		for(i = opacStart; i >= opacEnd; i= i - 2) {
			opacity_timer_1[i] = setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer= timer + 2;
		}
	} else if(opacStart < opacEnd) {
		for(i = opacStart; i <= opacEnd; i= i + 2)
			{
			opacity_timer_2[i] = setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer= timer + 3;
		}
	}
}

//change the opacity for different browsers
function changeOpac(opacity, id) {

var object = document.getElementById(id).style; 
	object.opacity = (opacity / 100);
	object.MozOpacity = (opacity / 100);
	object.KhtmlOpacity = (opacity / 100);
	object.filter = "alpha(opacity=" + opacity + ")";
	//alert(object.filter);
}

var opacity_fade_timer_1 = 0;
var opacity_fade_timer_2 = 0;
var opacity_fade_1 = 0;
var opacity_fade_2 = 0;
var opacity_fade_3 = 0;
var opacity_fade_4 = 0;
var speed_1 = 0;
var speed_2 = 0;

function opacity_fade(id, opacStart, opacEnd, millisec) {
	//speed for each frame
	
	opacity_fade_timer_1 = -1;
	opacity_fade_timer_2 = -1;
	
	if (opacStart < opacEnd) { 
		speed_1 = Math.round(millisec / 100);
		opacity_fade_1 = opacStart;
		opacity_fade_2 = opacEnd;
		changeOpac_fade_in(opacity_fade_1, id);
	} else {
		speed_2 = Math.round(millisec / 100);
		opacity_fade_3 = opacStart;
		opacity_fade_4 = opacEnd;
		changeOpac_fade_out(opacity_fade_3, id);
	}
}

function changeOpac_fade_in(opacity1, id1) {
		if (opacity1 < opacity_fade_2) {

			opacity_fade_timer_1 = setTimeout("changeOpac_fade_in("+(opacity1+1)+", '"+id1+"')",speed_1);
		} else {
			
		}
		var object = document.getElementById(id1).style; 
		object.opacity = (opacity1 / 100);
		object.MozOpacity = (opacity1 / 100);
		object.KhtmlOpacity = (opacity1 / 100);
		object.filter = "alpha(opacity=" + opacity1 + ")";

}

function changeOpac_fade_out(opacity2, id2) {
	//alert(opacity2);
		if (opacity2 > opacity_fade_4) {

			opacity_fade_timer_2 = setTimeout("changeOpac_fade_out("+(opacity2-1)+", '"+id2+"')",speed_2);
		} else {
			
		}
		var object = document.getElementById(id2).style; 
		object.opacity = (opacity2 / 100);
		object.MozOpacity = (opacity2 / 100);
		object.KhtmlOpacity = (opacity2 / 100);
		object.filter = "alpha(opacity=" + opacity2 + ")";

}




function shiftOpacity(id, millisec) {
	//if an element is invisible, make it visible, else make it ivisible
	if(document.getElementById(id).style.opacity == 0) {
		opacity(id, 0, 100, millisec);
	} else {
		opacity(id, 100, 0, millisec);
	}
}

function blendimage(divid, imageid, imagefile, millisec) {
	var speed = Math.round(millisec / 100);
	var timer = 0;
	
	//set the current image as background
	document.getElementById(divid).style.backgroundImage = "url(" + document.getElementById(imageid).src + ")";
	
	//make image transparent
	changeOpac(0, imageid);
	
	//make new image
	document.getElementById(imageid).src = imagefile;

	//fade in image
	for(i = 0; i <= 100; i++) {
		setTimeout("changeOpac(" + i + ",'" + imageid + "')",(timer * speed));
		timer++;
	}
}

function currentOpac(id, opacEnd, millisec) {
	//standard opacity is 100
	var currentOpac = 100;
	
	//if the element has an opacity set, get it
	if(document.getElementById(id).style.opacity < 100) {
		currentOpac = document.getElementById(id).style.opacity * 100;
	}

	//call for the function that changes the opacity
	opacity(id, currentOpac, opacEnd, millisec)
}