function zoom(e) {
	var amount = Event.wheel(e);
	zoom_helper(amount);
	e.stop();
}

function zoom_helper(amount) {
	var delta = 6;

	var new_width = $('large_image').width + (amount * delta);
	if( original_width == 0 ) {
		original_width = $('large_image').width;
	}
	if( new_width >= original_width ) {
		$('large_image').style.width = new_width + 'px';
	}
	if ( zooming == 1 ) {
		window.setTimeout( "zoom_helper(" + amount + ")", 80 );
	}
}

function zoom_reset() {
	stopzoom();
	if( original_width > 0 ) {
		$('large_image').style.width = original_width + 'px';
	}
}

function display_photo (e) {
	var element = Event.element(e);
	var id_arr = element.id.split('/');
	$('large_image').src = '/machinery/database/' + id_arr[1] + '/' + id_arr[2] + '_m.png';
	original_width = 0;
	$$('img.view_thumbnail').each(
		function (i) {
			i.removeClassName('selected');
		}
	);
	element.addClassName('selected');
}

function startzoom(quantity) {
	if ( zooming == 0 ) {
		zooming = 1;
		window.setTimeout( "zoom_helper(" + quantity + ")", 80 );
	}
}

function stopzoom() {
	zooming = 0;
}

function init() {
	$('large_image').observe('mousewheel', zoom);
	$('large_image').observe('DOMMouseScroll', zoom);
	$$('img.view_thumbnail').each(
		function (i) {
			i.observe( 'click', display_photo );
		}
	);
	$('img_zoom_reset').observe('click', zoom_reset);
	//$('img_zoom_in').observe('click', function () { zoom_helper(3); } );
	$('img_zoom_in').observe('mousedown', function (e) { startzoom(2); } );
	$('img_zoom_in').observe('mouseup', function (e) { stopzoom(); } );
	//$('img_zoom_out').observe('click', function () { zoom_helper(-3); } );
	$('img_zoom_out').observe('mousedown', function (e) { startzoom(-2); } );
	$('img_zoom_out').observe('mouseup', function (e) { stopzoom(); } );
}

Object.extend( Event, {
	wheel:function (e){
		var delta = 0;
		if (!e)
			e = window.event;
		if (e.wheelDelta) {
			delta = e.wheelDelta / 120;
			if ( window.opera )
				delta = delta * -1;
		} else if ( e.detail ) {
			delta = (e.detail * -1) / 3;
		}
		return Math.round(delta);
	}
} );

var original_width = 0;
var zooming = 0;
document.observe('dom:loaded', init);