// hold an Image_ID that is showing/blends
var imgHolder = ""; 

function opacity(id, opacStart, opacEnd, millisec) {
	//speed for each frame
	var speed = Math.round(millisec / 100);
	var timer = 0;
	j = 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--) {
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;
		}
	} else if(opacStart < opacEnd) {
		for(i = opacStart; i <= opacEnd; i++)
			{
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;
		}
	}
	
		
}
var j=0;
//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 + ")";
	
	j++;
	if( opacity == 0 && j!=1 ){
        document.getElementById(id).style.display = 'none';
        j=0;
	}
	
}

function shiftOpacity(id, opacStart, opacEnd, millisec) {
    
  if( document.getElementById(id).style.display == 'block' && opacStart == 0 ) {
      return;
  }

  if( imgHolder != "" && imgHolder != id )
  {
      document.getElementById(imgHolder).style.display = 'none';
  }

  if(document.getElementById(id).style.display == 'none') {
     document.getElementById(id).style.opacity = 0;
		 document.getElementById(id).style.display = 'block';
	} 
	
	//if an element is invisible, make it visible, else make it ivisible
	if(document.getElementById(id).style.opacity == 0) {
		opacity(id, opacStart, opacEnd, millisec);
	} else {
		opacity(id, opacStart, opacEnd, millisec);
	}


  // hold an image ID for future use
  imgHolder = id;	

 
}

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)
}