var show='visible';  
var hide='hidden';  

function showLayer(layerName)
{
document.getElementById(layerName).style.visibility = show;
}

function hideLayer(layerName)
{
document.getElementById(layerName).style.visibility = hide;
}

function toggleLayer(layerName)
{
state=document.getElementById(layerName).style.visibility;
if(state==hide) showLayer(layerName);
else hideLayer(layerName);
}

function moveLayerTo(layerName,xx,yy)
{
document.getElementById(layerName).style.left = xx +"px"; 
document.getElementById(layerName).style.top = yy +"px"; 
}

function scaleImage(imageName,xx,yy)
{
img = document.getElementById(imageName);

 img.setAttribute('width', xx);
 img.setAttribute('height', yy);
}