document.onmousemove = mouse_move;
var mouse_pos;
var float_on = '';
var img_cnt = 20;
var curr_img = Math.floor(Math.random() * img_cnt + 1);;

/********************************************************************/
//mouse event handler
function mouse_move(ev) {
	ev        = ev || window.event;
	mouse_pos = mouse_coords(ev);
}

/********************************************************************/
//get mouse coords relative to doc top
function mouse_coords(ev) {
	if(ev.pageX || ev.pageY) {
		return {x:ev.pageX, y:ev.pageY};
	}
	
	return {
		x:ev.clientX + document.documentElement.scrollLeft - document.documentElement.clientLeft,
		y:ev.clientY + document.documentElement.scrollTop  - document.documentElement.clientTop
	};
}

/********************************************************************/
//pick random photo from list
function rand_foto() {
	
	switch(curr_img) {
		case 1: return '/foto/rolling-stones.jpg';
			break;
		case 2: return '/foto/chopok-mist.jpg';
			break;
		case 3: return '/foto/blue-flame.jpg';
			break;	
		case 4: return '/foto/ta3-skokan.jpg';
			break;
		case 5: return '/foto/ta3-pyramida.jpg';
			break;
		case 6: return '/foto/ta3-pyramida2.jpg';
			break;	
		case 7: return '/foto/zima.jpg';
			break;
		case 8: return '/foto/chopok-rotunda.jpg';
			break;
		case 9: return '/foto/mesto.jpg';
			break;	
		case 10: return '/foto/marek-skokan.jpg';
			break;
		case 11: return '/foto/chopok-mist2.jpg';
			break;
		case 12: return '/foto/jesen.jpg';
			break;	
		case 13: return '/foto/mara.jpg';
			break;
		case 14: return '/foto/chopok-ta3.jpg';
			break;		
		case 15: return '/foto/dublin-docks.jpg';
			break;		
		case 16: return '/foto/trencin.jpg';
			break;			
		case 17: return '/foto/vah-strecno.jpg';
			break;		
		case 18: return '/foto/ziar-voda.jpg';
			break;
		case 19: return '/foto/mexico-beetle.jpg';
			break;		
		case 20: return '/foto/mexico-church.jpg';
			break;			
	}//switch

}//func

/********************************************************************/
//rotate top photo
function rotate_foto() {
	
	//get object it
	var photo_style = document.getElementById('photo').style;

	//update top photo
	photo_style.backgroundImage = 'url(' + rand_foto() + ')';
	
	//update
	curr_img = curr_img >= img_cnt ? 1 : curr_img + 1;	
		  
	//call periodically
	setTimeout("rotate_foto()", 12*1000);

}

/********************************************************************/
//hide box
function hide_box(box) {
	var element = document.getElementById(box);
	element.style.display = 'none';
}

/********************************************************************/
//show floating box
function show_float(box) {
	if (float_on == '') {
		var element = document.getElementById(box);
		element.style.top = (mouse_pos.y - 40) + 'px';
		element.style.display = 'block';
		float_on = box;
	}
}

/********************************************************************/
//hide floating box
function hide_float() {
	if (float_on != '') {
		hide_box(float_on);
		float_on = '';
	}
}