function validate_checkboxes(field)
{
	var valid = false;

	for(i = 0; i < field.length; i++) {

			if(field[i].checked == true) {

				valid = true;

			}

	}

	if(valid == false) {

		alert('Nothing is selected!');
		return false;

	} else {

		return true;

	}

}

//function hide_details()
function hide_details(str,opposite_str)
{
/*
	var httpRequest;

	if(window.XMLHttpRequest) {

		httpRequest = new XMLHttpRequest();

	} else if(window.ActiveXObject) {

		httpRequest = new ActiveXObject('Msxml2.XMLHTTP');

	}

	httpRequest.open('GET', 'set_session_var.php?var=details&val=0', true);

	httpRequest.onreadystatechange = function (evt) {

		if(httpRequest.readyState == 4) {
		}

	};

	httpRequest.send(null);
*/

	document.getElementById('exif_data').style.display = 'none';
	document.getElementById('exif_toggle').innerHTML   = '<a accesskey="d" href="javascript:void(0);" onclick="show_details(\'' + opposite_str + '\',\'' + str + '\');">' + opposite_str + '</a>';
//	document.getElementById('exif_toggle').innerHTML = '<a accesskey="d" href="javascript:void(0);" onclick="show_details();">Show details</a>';
}

//function show_details()
function show_details(str,opposite_str)
{
/*
	var httpRequest;

	if(window.XMLHttpRequest) {

		httpRequest = new XMLHttpRequest();

	} else if(window.ActiveXObject) {

		httpRequest = new ActiveXObject('Msxml2.XMLHTTP');

	}

	httpRequest.open('GET', 'set_session_var.php?var=details&val=1', true);

	httpRequest.onreadystatechange = function (evt) {

		if(httpRequest.readyState == 4) {
		}

	};

	httpRequest.send(null);
*/

	document.getElementById('exif_data').style.display = '';
	document.getElementById('exif_toggle').innerHTML   = '<a accesskey="d" href="javascript:void(0);" onclick="hide_details(\'' + opposite_str + '\',\'' + str + '\');">' + opposite_str + '</a>';
//	document.getElementById('exif_toggle').innerHTML = '<a accesskey="d" href="javascript:void(0);" onclick="hide_details();">Hide details</a>';

}

function display_overlay(img, content)
{
	// change position of overlay div
	// move to upper left hand corner of image

	// only display overlay if more than one comment
	if(parseInt(content) > 0) {

		var main_pos = getElementPosition('conteneur_general');
		var img_pos  = getElementPosition(img);
		var top_pos  = img_pos.top  - main_pos.top;
		var left_pos = img_pos.left - main_pos.left;

		if(navigator.userAgent.indexOf("MSIE") != -1) {

			left_pos = left_pos - 0;
//			left_pos = left_pos - 135;

		}

		var overlay = document.getElementById('overlay');

		overlay.style.position = 'absolute';
		overlay.style.visibility = 'hidden';
		overlay.innerHTML = content;
		overlay.style.left = left_pos + "px";
		overlay.style.top  = top_pos + "px";
		overlay.style.visibility = 'visible';
//		overlay.style.width = document.getElementById(img).width + "px";
//		alert(document.getElementById(img).width);
//		overlay.style.zIndex = 100;
		overlay.style.zIndex = document.getElementById(img).style.zIndex + 1;

	}

}

function hide_overlay()
{
	document.getElementById('overlay').style.visibility = 'hidden';
}

function getElementPosition(elemID)
{
	var offsetTrail = document.getElementById(elemID);
	var offsetLeft  = 0;
	var offsetTop   = 0;

	while(offsetTrail) {

		offsetLeft += offsetTrail.offsetLeft;
		offsetTop  += offsetTrail.offsetTop;
		offsetTrail = offsetTrail.offsetParent;

	}

	if(navigator.userAgent.indexOf("Mac") != -1 && typeof document.body.leftMargin != "undefined") {

		offsetLeft += document.body.leftMargin;
		offsetTop  += document.body.topMargin;

	}

	return {left:offsetLeft, top:offsetTop};

}