/* ***********************************************************
Dynamic HTML:The Definitive Reference 2nd Edition
by Danny Goodman
Published by O'Reilly & Associates  ISBN 1-56592-494-0
http://www.oreilly.com
Copyright 2002 Danny Goodman.  All Rights Reserved.
************************************************************ */

// Global variables
var isCSS, isW3C, isIE4, isNN4, isIE6CSS;

// initialize upon load to let all browsers establish content objects
function initDHTMLAPI() 
{
    if (document.images) 
    {
        isCSS = (document.body && document.body.style) ? true : false;
        isW3C = (isCSS && document.getElementById) ? true : false;
        isIE4 = (isCSS && document.all) ? true : false;
        isNN4 = (document.layers) ? true : false;
        isIE6CSS = (document.compatMode && document.compatMode.indexOf("CSS1") >= 0) ? true : false;
    }
}
// set event handler to initialize API
//window.onload = initDHTMLAPI;

// Seek nested NN4 layer from string name
function seekLayer(doc, name) {
    var theObj;
    for (var i = 0; i < doc.layers.length; i++) {
        if (doc.layers[i].name == name) {
            theObj = doc.layers[i];
            break;
        }
        // dive into nested layers if necessary
        if (doc.layers[i].document.layers.length > 0) {
            theObj = seekLayer(document.layers[i].document, name);
        }
    }
    return theObj;
}

// Convert object name string or object reference
// into a valid element object reference
function getRawObject(obj) {
    var theObj;
    if (typeof obj == "string") {
        if (isW3C) {
            theObj = document.getElementById(obj);
        } else if (isIE4) {
            theObj = document.all(obj);
        } else if (isNN4) {
            theObj = seekLayer(document, obj);
        }
    } else {
        // pass through object reference
        theObj = obj;
    }
    return theObj;
}

// Convert object name string or object reference
// into a valid style (or NN4 layer) reference
function getObject(obj) {
    var theObj = getRawObject(obj);
    if (theObj && isCSS) {
        theObj = theObj.style;
    }
    return theObj;
}

// Position an object at a specific pixel coordinate
function shiftTo(obj, x, y) {
    var theObj = getObject(obj);
    if (theObj) {
        if (isCSS) {
            // equalize incorrect numeric value type
            var units = (typeof theObj.left == "string") ? "px" : 0;
            theObj.left = x + units;
            theObj.top = y + units;
        } else if (isNN4) {
            theObj.moveTo(x,y)
        }
    }
}

// Move an object by x and/or y pixels
function shiftBy(obj, deltaX, deltaY) {
    var theObj = getObject(obj);
    if (theObj) {
        if (isCSS) {
            // equalize incorrect numeric value type
            var units = (typeof theObj.left == "string") ? "px" : 0;
            theObj.left = getObjectLeft(obj) + deltaX + units;
            theObj.top = getObjectTop(obj) + deltaY + units;
        } else if (isNN4) {
            theObj.moveBy(deltaX, deltaY);
        }
    }
}

// Set the z-order of an object
function setZIndex(obj, zOrder) {
    var theObj = getObject(obj);
    if (theObj) {
        theObj.zIndex = zOrder;
    }
}

// Set the background color of an object
function setBGColor(obj, color) {
    var theObj = getObject(obj);
    if (theObj) {
        if (isNN4) {
            theObj.bgColor = color;
        } else if (isCSS) {
            theObj.backgroundColor = color;
        }
    }
}

// Set the visibility of an object to visible
function show(obj) {
    var theObj = getObject(obj);
    if (theObj) 
    {
        theObj.visibility = "visible";
    }
}

// Set the visibility of an object to hidden
function hide(obj) {
    var theObj = getObject(obj);
    if (theObj) {
        theObj.visibility = "hidden";
    }
}

// Retrieve the x coordinate of a positionable object
function getObjectLeft(obj)  {
    var elem = getRawObject(obj);
    var result = 0;
    if (document.defaultView) {
        var style = document.defaultView;
        var cssDecl = style.getComputedStyle(elem, "");
        result = cssDecl.getPropertyValue("left");
    } else if (elem.currentStyle) {
        result = elem.currentStyle.left;
    } else if (elem.style) {
        result = elem.style.left;
    } else if (isNN4) {
        result = elem.left;
    }
    return parseInt(result);
}

// Retrieve the y coordinate of a positionable object
function getObjectTop(obj)  
{
    var elem = getRawObject(obj);
    var result = 0;
 
    if (document.defaultView) 
    {
        var style = document.defaultView;
        var cssDecl = style.getComputedStyle(elem, "");
        result = cssDecl.getPropertyValue("top");
    } 
    else if (elem.currentStyle) 
    {
        result = elem.currentStyle.top;
    } 
    else if (elem.style) 
    {
        result = elem.style.top;
    } 
    else if (isNN4) 
    {
        result = elem.top;
    }
    return parseInt(result);
}

	// Retrieve the rendered width of an element
	function getObjectWidth(obj)  
	{
		var elem = getRawObject(obj);
		var result = 0;
	
		if (elem.offsetWidth) 
		{
			if (elem.scrollWidth && (elem.offsetWidth != elem.scrollWidth)) 
			{
				result = elem.scrollWidth;
			} 
			else 
			{
				result = elem.offsetWidth;
			}
		} 
		else if (elem.clip && elem.clip.width) 
		{
			result = elem.clip.width;
		} 
		else if (elem.style && elem.style.pixelWidth) 
		{
			result = elem.style.pixelWidth;
		}
		return parseInt(result);
	}

	// Retrieve the rendered height of an element
	function getObjectHeight(obj)  
	{
		var elem = getRawObject(obj);
		var result = 0;
		if (elem.offsetHeight) 
		{
			result = elem.offsetHeight;
		} 
		else if (elem.clip && elem.clip.height) 
		{
			result = elem.clip.height;
		} 
		else if (elem.style && elem.style.pixelHeight) 
		{
			result = elem.style.pixelHeight;
		}
		return parseInt(result);
	}


	// Return the available content width space in browser window
	function getInsideWindowWidth() 
	{
		if (window.innerWidth) 
		{
			return window.innerWidth;
		} 
		else if (isIE6CSS) 
		{
			// measure the html element's clientWidth
			return document.body.parentElement.clientWidth;
		} 
		else if (document.body && document.body.clientWidth) 
		{
			return document.body.clientWidth;
		}
		return 0;
	}

	// Return the available content height space in browser window
	function getInsideWindowHeight() 
	{
		if (window.innerHeight) 
		{
			return window.innerHeight;
		} 
		else if (isIE6CSS) 
		{
			// measure the html element's clientHeight
			return document.body.parentElement.clientHeight;
		} 
		else if (document.body && document.body.clientHeight) 
		{
			return document.body.clientHeight;
		}
		return 0;
	}

	// Center a positionable element whose name is passed as 
	// a parameter in the current window/frame, and show it
	function centerOnWindow(elemID) 
	{
		// 'obj' is the positionable object
		var obj = getRawObject(elemID);
		
		// window scroll factors
		var scrollX = 0, scrollY = 0;
		
		if (document.body && typeof document.body.scrollTop != "undefined") 
		{
			scrollX += document.body.scrollLeft;
			scrollY += document.body.scrollTop;
		
			if (document.body.parentNode && typeof document.body.parentNode.scrollTop != "undefined") 
			{
				scrollX += document.body.parentNode.scrollLeft;
				scrollY += document.body.parentNode.scrollTop
			}
		} 
		else if (typeof window.pageXOffset != "undefined") 
		{
			scrollX += window.pageXOffset;
			scrollY += window.pageYOffset;
		}
		
		var x = Math.round((getInsideWindowWidth()/2) - (getObjectWidth(obj)/2)) + scrollX;
		var y = Math.round((getInsideWindowHeight()/2) - (getObjectHeight(obj)/2)) + scrollY;

		//alert('shifting to x[' + x + '] y[' + y + '] width[' + getObjectWidth(obj) + '] height[' + getObjectHeight(obj) + ']');

		shiftTo(obj, x, y);
	}