//*****************************************************************************
// Do not remove this notice.
//
// Copyright 2001 by Mike Hall.
// See http://www.brainjar.com for terms of use.
//*****************************************************************************

// Determine browser and version.

function Browser() {

var ua, s, i;

this.isIE    = false;
this.isNS    = false;
this.version = null;

ua = navigator.userAgent;

s = "MSIE";
if ((i = ua.indexOf(s)) >= 0) {
this.isIE = true;
this.version = parseFloat(ua.substr(i + s.length));
return;
}

s = "Netscape6/";
if ((i = ua.indexOf(s)) >= 0) {
this.isNS = true;
this.version = parseFloat(ua.substr(i + s.length));
return;
}

// Treat any other "Gecko" browser as NS 6.1.

s = "Gecko";
if ((i = ua.indexOf(s)) >= 0) {
this.isNS = true;
this.version = 6.1;
return;
}
}

var browser = new Browser();

// Global object to hold drag information.

var dragObj = new Object();
dragObj.zIndex = 0;

function dragStart(event, id) {

var el;
var x, y;

// If an element id was given, find it. Otherwise use the element being
// clicked on.

if (id)
dragObj.elNode = document.getElementById(id);
else {
if (browser.isIE)
  dragObj.elNode = window.event.srcElement;
if (browser.isNS)
  dragObj.elNode = event.target;

// If this is a text node, use its parent element.

if (dragObj.elNode.nodeType == 3)
  dragObj.elNode = dragObj.elNode.parentNode;
}

// Get cursor position with respect to the page.

if (browser.isIE) {
x = window.event.clientX + document.documentElement.scrollLeft
  + document.body.scrollLeft;
y = window.event.clientY + document.documentElement.scrollTop
  + document.body.scrollTop;
}
if (browser.isNS) {
x = event.clientX + window.scrollX;
y = event.clientY + window.scrollY;
}

// Save starting positions of cursor and element.

dragObj.cursorStartX = x;
dragObj.cursorStartY = y;
dragObj.elStartLeft  = parseInt(dragObj.elNode.style.left, 10);
dragObj.elStartTop   = parseInt(dragObj.elNode.style.top,  10);

if (isNaN(dragObj.elStartLeft)) dragObj.elStartLeft = 0;
if (isNaN(dragObj.elStartTop))  dragObj.elStartTop  = 0;

// Update element's z-index.

dragObj.elNode.style.zIndex = ++dragObj.zIndex;

// Capture mousemove and mouseup events on the page.

if (browser.isIE) {
document.attachEvent("onmousemove", dragGo);
document.attachEvent("onmouseup",   dragStop);
window.event.cancelBubble = true;
window.event.returnValue = false;
}
if (browser.isNS) {
document.addEventListener("mousemove", dragGo,   true);
document.addEventListener("mouseup",   dragStop, true);
event.preventDefault();
}
}

function dragGo(event) {

var x, y;

// Get cursor position with respect to the page.

if (browser.isIE) {
x = window.event.clientX + document.documentElement.scrollLeft
  + document.body.scrollLeft;
y = window.event.clientY + document.documentElement.scrollTop
  + document.body.scrollTop;
}
if (browser.isNS) {
x = event.clientX + window.scrollX;
y = event.clientY + window.scrollY;
}

// Move drag element by the same amount the cursor has moved.

dragObj.elNode.style.left = (dragObj.elStartLeft + x - dragObj.cursorStartX) + "px";
dragObj.elNode.style.top  = (dragObj.elStartTop  + y - dragObj.cursorStartY) + "px";

if (browser.isIE) {
window.event.cancelBubble = true;
window.event.returnValue = false;
}
if (browser.isNS)
event.preventDefault();
}

function dragStop(event) {

// Stop capturing mousemove and mouseup events.

if (browser.isIE) {
document.detachEvent("onmousemove", dragGo);
document.detachEvent("onmouseup",   dragStop);
}
if (browser.isNS) {
document.removeEventListener("mousemove", dragGo,   true);
document.removeEventListener("mouseup",   dragStop, true);
}
}