//*****************************************************************************
// Do not remove this notice.
//
// Copyright 2001 by Mike Hall.
// See http://www.brainjar.com for terms of use.
// extensive modes by Johan Pingree for Earthbound Corp. 9/08
//*****************************************************************************

// 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;
    } else {
        this.isNS = true;
        this.version = parseFloat(ua.substr(i + s.length));
        return;
    }
}

var browser = new Browser();

// Global object to hold drag information.
var dragObj = new Object();
dragObj.zIndex = 0;

function dragStart(event, id) {
    var el;
    //grab the element that was passed in by id
    dragObj.elNode = $get(id);
    // Save starting positions of cursor and element.
    dragObj.cursorStartX = mouseX(event);
    dragObj.cursorStartY = mouseY(event);
    
    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;
    } else {
        document.addEventListener("mousemove", dragGo, true);
        document.addEventListener("mouseup", dragStop, true);
        event.preventDefault();
    }
}

function dragGo(event) {
    // Move drag element by the same amount the cursor has moved.
    dragObj.elNode.style.left = (dragObj.elStartLeft + mouseX(event) - dragObj.cursorStartX ) + "px";
    dragObj.elNode.style.top = (dragObj.elStartTop + mouseY(event) - dragObj.cursorStartY) + "px";
    
    if (browser.isIE) {
        window.event.cancelBubble = true;
        window.event.returnValue = false;
    } else {
        event.preventDefault();
    }
}

function dragStop(event) {
    // Stop capturing mousemove and mouseup events.
    if (browser.isIE) {
        document.detachEvent("onmousemove", dragGo);
        document.detachEvent("onmouseup", dragStop);
    } else {
        document.removeEventListener("mousemove", dragGo, true);
        document.removeEventListener("mouseup", dragStop, true);
    }
}

function mouseX(evt) {
    if (evt.pageX) return evt.pageX;
    else if (evt.clientX)
        return evt.clientX + (document.documentElement.scrollLeft ? document.documentElement.scrollLeft : document.body.scrollLeft);
    else return null;
}
function mouseY(evt) {
    if (evt.pageY) return evt.pageY;
    else if (evt.clientY)
        return evt.clientY + (document.documentElement.scrollTop ? document.documentElement.scrollTop : document.body.scrollTop);
    else return null;
}