//------------------------------------------------------------------------------
//  JavaScript function for determining the position of the end of the page.
//  and diplaying a "top of page" button if the page is long.
//
//  Irv.Elshoff@wldelft.nl
//  14 oct 03
//
//  Copyright (C) 2003, WL | Delft Hydraulics
//------------------------------------------------------------------------------


function Pos_Init () {
    var endobj = document.getElementById ("endofpage_id");
    var endpos = FindPosTop (endobj);

    if (endpos > topButton) {
	var imgobj = document.getElementsByName ("nav_top")[0];

	Rov_New ('nav_top', '/wl/im/buttons/a1n-0.gif', '/wl/im/buttons/a1n-1.gif');
    	imgobj.src = "/wl/im/buttons/a1n-0.gif";
    	imgobj.style.visibility = "visible";

	endobj.style.top  = endpos - 154;
	}
    }


//------------------------------------------------------------------------------
//  Position functions adopted from http://www.xs4all.nl/~ppk/js/findpos.html


function FindPosTop (obj) {
    var curtop = 0;
    if (obj.offsetParent) {
	while (obj.offsetParent) {
	    curtop += obj.offsetTop
	    obj = obj.offsetParent;
	    }
	}
    else if (obj.y)
    	curtop += obj.y;

    return curtop;
    }


function FindPosLeft (obj) {
    var curleft = 0;
    if (obj.offsetParent) {
	while (obj.offsetParent) {
	    curleft += obj.offsetLeft
	    obj = obj.offsetParent;
	    }
	}
    else if (obj.x)
    	curleft += obj.x;

    return curleft;
    }