/******************************************************************************
 * Utility functions
 * author:      Kersing Huang <kh295@cornell.edu>
 * modified:    23 Jan 2009 
 *****************************************************************************/

/**
 * Highlights the main navigation link that corresponds to the current page
 */
function selectNav(id){
    var elem = document.getElementById(id);
    if(elem != null){
        elem.style.borderTop = "solid 5px #CCCCCC";
    }
}

/**
 * Displays id and hides prev.
 */
function showHide(id, prevId){
    var elem = document.getElementById(id);
    var prevElem = document.getElementById(prevId);
    if(elem != null && prevElem != null && elem != prevElem){
        prevElem.style.display = "none";
        elem.style.display = "block";
        return id;
    }
	else if(prevId == ""){
		elem.style.display = "block";
		return id;
	}
    else{
        return prevId;
    }
}

/**
 * Sets the background of the banner to img and embeds a link to the
 * full version in the upper right of the block.
 */
function setBanner(img){
    var banner = document.getElementById("banner");
    if(banner != null){
        banner.style.background = "url(" + img + ") no-repeat";
        banner.style.textAlign = "right";
        banner.innerHTML = "<a href=\""+img+"\">Enlarge [+]</a>";
    }
}