/* Copyright (c) 2006-2011 by OpenLayers Contributors (see authors.txt for 
 * full list of contributors). Published under the Clear BSD license.  
 * See http://svn.openlayers.org/trunk/openlayers/license.txt for the
 * full text of the license. */

/**
 * @requires OpenLayers/BaseTypes/Class.js
 * @requires OpenLayers/Util.js
 * @requires OpenLayers/Events.js
 * @requires OpenLayers/Tween.js
 * @requires OpenLayers/Console.js
 * @requires OpenLayers/Lang.js
 */

/**
 * Class: OpenLayers.Map
 * Instances of OpenLayers.Map are interactive maps embedded in a web page.
 * Create a new map with the <OpenLayers.Map> constructor.
 * 
 * On their own maps do not provide much functionality.  To extend a map
 * it's necessary to add controls (<OpenLayers.Control>) and 
 * layers (<OpenLayers.Layer>) to the map. 
 */
OpenLayers.Map = OpenLayers.Class({
    
    /**
     * Constant: Z_INDEX_BASE
     * {Object} Base z-indexes for different classes of thing 
     */
    Z_INDEX_BASE: {
        BaseLayer: 100,
        Overlay: 325,
        Feature: 725,
        Popup: 750,
        Control: 1000
    },

    /**
     * Constant: EVENT_TYPES
     * {Array(String)} Supported application event types.  Register a listener
     *     for a particular event with the following syntax:
     * (code)
     * map.events.register(type, obj, listener);
     * (end)
     *
     * Listeners will be called with a reference to an event object.  The
     *     properties of this event depends on exactly what happened.
     *
     * All event objects have at least the following properties:
     *  - *object* {Object} A reference to map.events.object.
     *  - *element* {DOMElement} A reference to map.events.element.
     *
     * Browser events have the following additional properties:
     *  - *xy* {<OpenLayers.Pixel>} The pixel location of the event (relative
     *      to the the map viewport).
     *  - other properties that come with browser events
     *
     * Supported map event types:
     *  - *preaddlayer* triggered before a layer has been added.  The event
     *      object will include a *layer* property that references the layer  
     *      to be added. When a listener returns "false" the adding will be 
     *      aborted.
     *  - *addlayer* triggered after a layer has been added.  The event object
     *      will include a *layer* property that references the added layer.
     *  - *preremovelayer* triggered before a layer has been removed. The event
     *      object will include a *layer* property that references the layer  
     *      to be removed. When a listener returns "false" the removal will be 
     *      aborted.
     *  - *removelayer* triggered after a layer has been removed.  The event
     *      object will include a *layer* property that references the removed
     *      layer.
     *  - *changelayer* triggered after a layer name change, order change,
     *      opacity change, params change, visibility change (due to resolution
     *      thresholds) or attribution change (due to extent change). Listeners
     *      will receive an event object with *layer* and *property* properties.
     *      The *layer* property will be a reference to the changed layer. The
     *      *property* property will be a key to the changed property (name,
     *      order, opacity, params, visibility or attribution).
     *  - *movestart* triggered after the start of a drag, pan, or zoom
     *  - *move* triggered after each drag, pan, or zoom
     *  - *moveend* triggered after a drag, pan, or zoom completes
     *  - *zoomend* triggered after a zoom completes
     *  - *mouseover* triggered after mouseover the map
     *  - *mouseout* triggered after mouseout the map
     *  - *mousemove* triggered after mousemove the map
     *  - *changebaselayer* triggered after the base layer changes
     */
    EVENT_TYPES: [ 
        "preaddlayer", "addlayer","preremovelayer", "removelayer", 
        "changelayer", "movestart",
        "move", "moveend", "zoomend", "popupopen", "popupclose",
        "addmarker", "removemarker", "clearmarkers", "mouseover",
        "mouseout", "mousemove", "dragstart", "drag", "dragend",
        "changebaselayer"],

    /**
     * Property: id
     * {String} Unique identifier for the map
     */
    id: null,
    
    /**
     * Property: fractionalZoom
     * {Boolean} For a base layer that supports it, allow the map resolution
     *     to be set to a value between one of the values in the resolutions
     *     array.  Default is false.
     *
     * When fractionalZoom is set to true, it is possible to zoom to
     *     an arbitrary extent.  This requires a base layer from a source
     *     that supports requests for arbitrary extents (i.e. not cached
     *     tiles on a regular lattice).  This means that fractionalZoom
     *     will not work with commercial layers (Google, Yahoo, VE), layers
     *     using TileCache, or any other pre-cached data sources.
     *
     * If you are using fractionalZoom, then you should also use
     *     <getResolutionForZoom> instead of layer.resolutions[zoom] as the
     *     former works for non-integer zoom levels.
     */
    fractionalZoom: false,
    
    /**
     * APIProperty: events
     * {<OpenLayers.Events>} An events object that handles all 
     *                       events on the map
     */
    events: null,
    
    /**
     * APIProperty: allOverlays
     * {Boolean} Allow the map to function with "overlays" only.  Defaults to
     *     false.  If true, the lowest layer in the draw order will act as
     *     the base layer.  In addition, if set to true, all layers will
     *     have isBaseLayer set to false when they are added to the map.
     *
     * Note:
     * If you set map.allOverlays to true, then you *cannot* use
     *     map.setBaseLayer or layer.setIsBaseLayer.  With allOverlays true,
     *     the lowest layer in the draw layer is the base layer.  So, to change
     *     the base layer, use <setLayerIndex> or <raiseLayer> to set the layer
     *     index to 0.
     */
    allOverlays: false,

    /**
     * APIProperty: div
     * {DOMElement|String} The element that contains the map (or an id for
     *     that element).  If the <OpenLayers.Map> constructor is called
     *     with two arguments, this should be provided as the first argument.
     *     Alternatively, the map constructor can be called with the options
     *     object as the only argument.  In this case (one argument), a
     *     div property may or may not be provided.  If the div property
     *     is not provided, the map can be rendered to a container later
     *     using the <render> method.
     *     
     * Note:
     * If you are calling <render> after map construction, do not use
     *     <maxResolution>  auto.  Instead, divide your <maxExtent> by your
     *     maximum expected dimension.
     */
    div: null,
    
    /**
     * Property: dragging
     * {Boolean} The map is currently being dragged.
     */
    dragging: false,

    /**
     * Property: size
     * {<OpenLayers.Size>} Size of the main div (this.div)
     */
    size: null,
    
    /**
     * Property: viewPortDiv
     * {HTMLDivElement} The element that represents the map viewport
     */
    viewPortDiv: null,

    /**
     * Property: layerContainerOrigin
     * {<OpenLayers.LonLat>} The lonlat at which the later container was
     *                       re-initialized (on-zoom)
     */
    layerContainerOrigin: null,

    /**
     * Property: layerContainerDiv
     * {HTMLDivElement} The element that contains the layers.
     */
    layerContainerDiv: null,

    /**
     * APIProperty: layers
     * {Array(<OpenLayers.Layer>)} Ordered list of layers in the map
     */
    layers: null,

    /**
     * Property: controls
     * {Array(<OpenLayers.Control>)} List of controls associated with the map.
     *
     * If not provided in the map options at construction, the map will
     *     be given the following controls by default:
     *  - <OpenLayers.Control.Navigation>
     *  - <OpenLayers.Control.PanZoom>
     *  - <OpenLayers.Control.ArgParser>
     *  - <OpenLayers.Control.Attribution>
     */
    controls: null,

    /**
     * Property: popups
     * {Array(<OpenLayers.Popup>)} List of popups associated with the map
     */
    popups: null,

    /**
     * APIProperty: baseLayer
     * {<OpenLayers.Layer>} The currently selected base layer.  This determines
     * min/max zoom level, projection, etc.
     */
    baseLayer: null,
    
    /**
     * Property: center
     * {<OpenLayers.LonLat>} The current center of the map
     */
    center: null,

    /**
     * Property: resolution
     * {Float} The resolution of the map.
     */
    resolution: null,

    /**
     * Property: zoom
     * {Integer} The current zoom level of the map
     */
    zoom: 0,    

    /**
     * Property: panRatio
     * {Float} The ratio of the current extent within
     *         which panning will tween.
     */
    panRatio: 1.5,    

    /**
     * Property: viewRequestID
     * {String} Used to store a unique identifier that changes when the map 
     *          view changes. viewRequestID should be used when adding data 
     *          asynchronously to the map: viewRequestID is incremented when 
     *          you initiate your request (right now during changing of 
     *          baselayers and changing of zooms). It is stored here in the 
     *          map and also in the data that will be coming back 
     *          asynchronously. Before displaying this data on request 
     *          completion, we check that the viewRequestID of the data is 
     *          still the same as that of the map. Fix for #480
     */
    viewRequestID: 0,

  // Options

    /**
     * APIProperty: tileSize
     * {<OpenLayers.Size>} Set in the map options to override the default tile
     *                     size for this map.
     */
    tileSize: null,

    /**
     * APIProperty: projection
     * {String} Set in the map options to override the default projection 
     *          string this map - also set maxExtent, maxResolution, and 
     *          units if appropriate.  Default is "EPSG:4326".
     */
    projection: "EPSG:4326",    
        
    /**
     * APIProperty: units
     * {String} The map units.  Defaults to 'degrees'.  Possible values are
     *          'degrees' (or 'dd'), 'm', 'ft', 'km', 'mi', 'inches'.
     */
    units: 'degrees',

    /**
     * APIProperty: resolutions
     * {Array(Float)} A list of map resolutions (map units per pixel) in 
     *     descending order.  If this is not set in the layer constructor, it 
     *     will be set based on other resolution related properties 
     *     (maxExtent, maxResolution, maxScale, etc.).
     */
    resolutions: null,

    /**
     * APIProperty: maxResolution
     * {Float} Default max is 360 deg / 256 px, which corresponds to
     *          zoom level 0 on gmaps.  Specify a different value in the map 
     *          options if you are not using a geographic projection and 
     *          displaying the whole world.
     */
    maxResolution: 1.40625,

    /**
     * APIProperty: minResolution
     * {Float}
     */
    minResolution: null,

    /**
     * APIProperty: maxScale
     * {Float}
     */
    maxScale: null,

    /**
     * APIProperty: minScale
     * {Float}
     */
    minScale: null,

    /**
     * APIProperty: maxExtent
     * {<OpenLayers.Bounds>} The maximum extent for the map.  Defaults to the
     *                       whole world in decimal degrees 
     *                       (-180, -90, 180, 90).  Specify a different
     *                        extent in the map options if you are not using a 
     *                        geographic projection and displaying the whole 
     *                        world.
     */
    maxExtent: null,
    
    /**
     * APIProperty: minExtent
     * {<OpenLayers.Bounds>}
     */
    minExtent: null,
    
    /**
     * APIProperty: restrictedExtent
     * {<OpenLayers.Bounds>} Limit map navigation to this extent where possible.
     *     If a non-null restrictedExtent is set, panning will be restricted
     *     to the given bounds.  In addition, zooming to a resolution that
     *     displays more than the restricted extent will center the map
     *     on the restricted extent.  If you wish to limit the zoom level
     *     or resolution, use maxResolution.
     */
    restrictedExtent: null,

    /**
     * APIProperty: numZoomLevels
     * {Integer} Number of zoom levels for the map.  Defaults to 16.  Set a
     *           different value in the map options if needed.
     */
    numZoomLevels: 16,

    /**
     * APIProperty: theme
     * {String} Relative path to a CSS file from which to load theme styles.
     *          Specify null in the map options (e.g. {theme: null}) if you 
     *          want to get cascading style declarations - by putting links to 
     *          stylesheets or style declarations directly in your page.
     */
    theme: null,
    
    /** 
     * APIProperty: displayProjection
     * {<OpenLayers.Projection>} Requires proj4js support.Projection used by
     *     several controls to display data to user. If this property is set,
     *     it will be set on any control which has a null displayProjection
     *     property at the time the control is added to the map. 
     */
    displayProjection: null,

    /**
     * APIProperty: fallThrough
     * {Boolean} Should OpenLayers allow events on the map to fall through to
     *           other elements on the page, or should it swallow them? (#457)
     *           Default is to fall through.
     */
    fallThrough: true,
    
    /**
     * Property: panTween
     * {OpenLayers.Tween} Animated panning tween object, see panTo()
     */
    panTween: null,

    /**
     * APIProperty: eventListeners
     * {Object} If set as an option at construction, the eventListeners
     *     object will be registered with <OpenLayers.Events.on>.  Object
     *     structure must be a listeners object as shown in the example for
     *     the events.on method.
     */
    eventListeners: null,

    /**
     * APIProperty: panMethod
     * {Function} The Easing function to be used for tweening.  Default is
     * OpenLayers.Easing.Expo.easeOut. Setting this to 'null' turns off
     * animated panning.
     */
    panMethod: OpenLayers.Easing.Expo.easeOut,
    
    /**
     * Property: panDuration
     * {Integer} The number of steps to be passed to the
     * OpenLayers.Tween.start() method when the map is
     * panned.
     * Default is 50.
     */
    panDuration: 50,
    
    /**
     * Property: paddingForPopups
     * {<OpenLayers.Bounds>} Outside margin of the popup. Used to prevent 
     *     the popup from getting too close to the map border.
     */
    paddingForPopups : null,
    
    /**
     * Property: minPx
     * {<OpenLayers.Pixel>} Lower left of maxExtent in viewport pixel space.
     *     Used to verify in moveByPx that the new location we're moving to
     *     is valid. It is also used in the getLonLatFromViewPortPx function
     *     of Layer.
     */
    minPx: null,
    
    /**
     * Property: maxPx
     * {<OpenLayers.Pixel>} Top right of maxExtent in viewport pixel space.
     *     Used to verify in moveByPx that the new location we're moving to
     *     is valid.
     */
    maxPx: null,
    
    /**
     * Constructor: OpenLayers.Map
     * Constructor for a new OpenLayers.Map instance.  There are two possible
     *     ways to call the map constructor.  See the examples below.
     *
     * Parameters:
     * div - {DOMElement|String}  The element or id of an element in your page
     *     that will contain the map.  May be omitted if the <div> option is
     *     provided or if you intend to call the <render> method later.
     * options - {Object} Optional object with properties to tag onto the map.
     *
     * Examples:
     * (code)
     * // create a map with default options in an element with the id "map1"
     * var map = new OpenLayers.Map("map1");
     *
     * // create a map with non-default options in an element with id "map2"
     * var options = {
     *     maxExtent: new OpenLayers.Bounds(-200000, -200000, 200000, 200000),
     *     maxResolution: 156543,
     *     units: 'm',
     *     projection: "EPSG:41001"
     * };
     * var map = new OpenLayers.Map("map2", options);
     *
     * // map with non-default options - same as above but with a single argument
     * var map = new OpenLayers.Map({
     *     div: "map_id",
     *     maxExtent: new OpenLayers.Bounds(-200000, -200000, 200000, 200000),
     *     maxResolution: 156543,
     *     units: 'm',
     *     projection: "EPSG:41001"
     * });
     *
     * // create a map without a reference to a container - call render later
     * var map = new OpenLayers.Map({
     *     maxExtent: new OpenLayers.Bounds(-200000, -200000, 200000, 200000),
     *     maxResolution: 156543,
     *     units: 'm',
     *     projection: "EPSG:41001"
     * });
     * (end)
     */    
    initialize: function (div, options) {
        
        // If only one argument is provided, check if it is an object.
        if(arguments.length === 1 && typeof div === "object") {
            options = div;
            div = options && options.div;
        }

        // Simple-type defaults are set in class definition. 
        //  Now set complex-type defaults 
        this.tileSize = new OpenLayers.Size(OpenLayers.Map.TILE_WIDTH,
                                            OpenLayers.Map.TILE_HEIGHT);
        
        this.maxExtent = new OpenLayers.Bounds(-180, -90, 180, 90);
        
        this.paddingForPopups = new OpenLayers.Bounds(15, 15, 15, 15);

        this.theme = OpenLayers._getScriptLocation() + 
                             'theme/default/style.css'; 

        // now override default options 
        OpenLayers.Util.extend(this, options);

        // initialize layers array
        this.layers = [];

        this.id = OpenLayers.Util.createUniqueID("OpenLayers.Map_");

        this.div = OpenLayers.Util.getElement(div);
        if(!this.div) {
            this.div = document.createElement("div");
            this.div.style.height = "1px";
            this.div.style.width = "1px";
        }
        
        OpenLayers.Element.addClass(this.div, 'olMap');

        // the viewPortDiv is the outermost div we modify
        var id = this.id + "_OpenLayers_ViewPort";
        this.viewPortDiv = OpenLayers.Util.createDiv(id, null, null, null,
                                                     "relative", null,
                                                     "hidden");
        this.viewPortDiv.style.width = "100%";
        this.viewPortDiv.style.height = "100%";
        this.viewPortDiv.className = "olMapViewport";
        this.div.appendChild(this.viewPortDiv);

        // the eventsDiv is where we listen for all map events
        var eventsDiv = document.createElement("div");
        eventsDiv.id = this.id + "_events";
        eventsDiv.style.position = "absolute";
        eventsDiv.style.width = "100%";
        eventsDiv.style.height = "100%";
        eventsDiv.style.zIndex = this.Z_INDEX_BASE.Control - 1;
        this.viewPortDiv.appendChild(eventsDiv);
        this.eventsDiv = eventsDiv;
        this.events = new OpenLayers.Events(
            this, this.eventsDiv, this.EVENT_TYPES, this.fallThrough, 
            {includeXY: true}
        );

        // the layerContainerDiv is the one that holds all the layers
        id = this.id + "_OpenLayers_Container";
        this.layerContainerDiv = OpenLayers.Util.createDiv(id);
        this.layerContainerDiv.style.zIndex=this.Z_INDEX_BASE['Popup']-1;
        
        this.eventsDiv.appendChild(this.layerContainerDiv);

        this.updateSize();
        if(this.eventListeners instanceof Object) {
            this.events.on(this.eventListeners);
        }
 
        // update the map size and location before the map moves
        this.events.register("movestart", this, this.updateSize);

        // Because Mozilla does not support the "resize" event for elements 
        // other than "window", we need to put a hack here. 
        if (OpenLayers.String.contains(navigator.appName, "Microsoft")) {
            // If IE, register the resize on the div
            this.events.register("resize", this, this.updateSize);
        } else {
            // Else updateSize on catching the window's resize
            //  Note that this is ok, as updateSize() does nothing if the 
            //  map's size has not actually changed.
            this.updateSizeDestroy = OpenLayers.Function.bind(this.updateSize, 
                this);
            OpenLayers.Event.observe(window, 'resize',
                            this.updateSizeDestroy);
        }
        
        // only append link stylesheet if the theme property is set
        if(this.theme) {
            // check existing links for equivalent url
            var addNode = true;
            var nodes = document.getElementsByTagName('link');
            for(var i=0, len=nodes.length; i<len; ++i) {
                if(OpenLayers.Util.isEquivalentUrl(nodes.item(i).href,
                                                   this.theme)) {
                    addNode = false;
                    break;
                }
            }
            // only add a new node if one with an equivalent url hasn't already
            // been added
            if(addNode) {
                var cssNode = document.createElement('link');
                cssNode.setAttribute('rel', 'stylesheet');
                cssNode.setAttribute('type', 'text/css');
                cssNode.setAttribute('href', this.theme);
                document.getElementsByTagName('head')[0].appendChild(cssNode);
            }
        }
        
        if (this.controls == null) {
            if (OpenLayers.Control != null) { // running full or lite?
                this.controls = [ new OpenLayers.Control.Navigation(),
                                  new OpenLayers.Control.PanZoom(),
                                  new OpenLayers.Control.ArgParser(),
                                  new OpenLayers.Control.Attribution()
                                ];
            } else {
                this.controls = [];
            }
        }

        for(var i=0, len=this.controls.length; i<len; i++) {
            this.addControlToMap(this.controls[i]);
        }

        this.popups = [];

        this.unloadDestroy = OpenLayers.Function.bind(this.destroy, this);
        

        // always call map.destroy()
        OpenLayers.Event.observe(window, 'unload', this.unloadDestroy);
        
        // add any initial layers
        if (options && options.layers) {
            /** 
             * If you have set options.center, the map center property will be
             * set at this point.  However, since setCenter has not been caleld,
             * addLayers gets confused.  So we delete the map center in this 
             * case.  Because the check below uses options.center, it will
             * be properly set below.
             */
            delete this.center;
            this.addLayers(options.layers);        
            // set center (and optionally zoom)
            if (options.center) {
                // zoom can be undefined here
                this.setCenter(options.center, options.zoom);
            }
        }
    },
    
    /**
     * APIMethod: render
     * Render the map to a specified container.
     * 
     * Parameters:
     * div - {String|DOMElement} The container that the map should be rendered
     *     to. If different than the current container, the map viewport
     *     will be moved from the current to the new container.
     */
    render: function(div) {
        this.div = OpenLayers.Util.getElement(div);
        OpenLayers.Element.addClass(this.div, 'olMap');
        this.viewPortDiv.parentNode.removeChild(this.viewPortDiv);
        this.div.appendChild(this.viewPortDiv);
        this.updateSize();
    },

    /**
     * Method: unloadDestroy
     * Function that is called to destroy the map on page unload. stored here
     *     so that if map is manually destroyed, we can unregister this.
     */
    unloadDestroy: null,
    
    /**
     * Method: updateSizeDestroy
     * When the map is destroyed, we need to stop listening to updateSize
     *    events: this method stores the function we need to unregister in 
     *    non-IE browsers.
     */
    updateSizeDestroy: null,

    /**
     * APIMethod: destroy
     * Destroy this map.
     *    Note that if you are using an application which removes a container
     *    of the map from the DOM, you need to ensure that you destroy the
     *    map *before* this happens; otherwise, the page unload handler
     *    will fail because the DOM elements that map.destroy() wants
     *    to clean up will be gone. (See 
     *    http://trac.osgeo.org/openlayers/ticket/2277 for more information).
     *    This will apply to GeoExt and also to other applications which
     *    modify the DOM of the container of the OpenLayers Map.
     */
    destroy:function() {
        // if unloadDestroy is null, we've already been destroyed
        if (!this.unloadDestroy) {
            return false;
        }
        
        // make sure panning doesn't continue after destruction
        if(this.panTween) {
            this.panTween.stop();
            this.panTween = null;
        }

        // map has been destroyed. dont do it again!
        OpenLayers.Event.stopObserving(window, 'unload', this.unloadDestroy);
        this.unloadDestroy = null;

        if (this.updateSizeDestroy) {
            OpenLayers.Event.stopObserving(window, 'resize', 
                                           this.updateSizeDestroy);
        } else {
            this.events.unregister("resize", this, this.updateSize);
        }    
        
        this.paddingForPopups = null;    

        if (this.controls != null) {
            for (var i = this.controls.length - 1; i>=0; --i) {
                this.controls[i].destroy();
            } 
            this.controls = null;
        }
        if (this.layers != null) {
            for (var i = this.layers.length - 1; i>=0; --i) {
                //pass 'false' to destroy so that map wont try to set a new 
                // baselayer after each baselayer is removed
                this.layers[i].destroy(false);
            } 
            this.layers = null;
        }
        if (this.viewPortDiv) {
            this.div.removeChild(this.viewPortDiv);
        }
        this.viewPortDiv = null;

        if(this.eventListeners) {
            this.events.un(this.eventListeners);
            this.eventListeners = null;
        }
        this.events.destroy();
        this.events = null;

    },

    /**
     * APIMethod: setOptions
     * Change the map options
     *
     * Parameters:
     * options - {Object} Hashtable of options to tag to the map
     */
    setOptions: function(options) {
        var updatePxExtent = this.minPx &&
            options.restrictedExtent != this.restrictedExtent;
        OpenLayers.Util.extend(this, options);
        // force recalculation of minPx and maxPx
        updatePxExtent && this.moveTo(this.getCachedCenter(), this.zoom, {
            forceZoomChange: true
        });
    },

    /**
     * APIMethod: getTileSize
     * Get the tile size for the map
     *
     * Returns:
     * {<OpenLayers.Size>}
     */
     getTileSize: function() {
         return this.tileSize;
     },


    /**
     * APIMethod: getBy
     * Get a list of objects given a property and a match item.
     *
     * Parameters:
     * array - {String} A property on the map whose value is an array.//map装某类对象的属性
     * property - {String} A property on each item of the given array. //某类对象的属性名称
     * match - {String | Object} A string to match.  Can also be a regular  //匹配条件，可以是字符串，也可以是带有test方法的对象
     *     expression literal or object.  In addition, it can be any object
     *     with a method named test.  For reqular expressions or other, if
     *     match.test(map[array][i][property]) evaluates to true, the item will
     *     be included in the array returned.  If no items are found, an empty
     *     array is returned.
     *
     * Returns:
     * {Array} An array of items where the given property matches the given
     *     criteria.
     */
    getBy: function(array, property, match) {
        var test = (typeof match.test == "function");
        var found = OpenLayers.Array.filter(this[array], function(item) {
            return item[property] == match || (test && match.test(item[property]));
        });
        return found;
    },

    /**
     * APIMethod: getLayersBy
     * Get a list of layers with properties matching the given criteria.
     *
     * Parameter:
     * property - {String} A layer property to be matched.
     * match - {String | Object} A string to match.  Can also be a regular
     *     expression literal or object.  In addition, it can be any object
     *     with a method named test.  For reqular expressions or other, if
     *     match.test(layer[property]) evaluates to true, the layer will be
     *     included in the array returned.  If no layers are found, an empty
     *     array is returned.
     *
     * Returns:
     * {Array(<OpenLayers.Layer>)} A list of layers matching the given criteria.
     *     An empty array is returned if no matches are found.
     */
    getLayersBy: function(property, match) {
        return this.getBy("layers", property, match);
    },

    /**
     * APIMethod: getLayersByName
     * Get a list of layers with names matching the given name.
     *
     * Parameter:
     * match - {String | Object} A layer name.  The name can also be a regular
     *     expression literal or object.  In addition, it can be any object
     *     with a method named test.  For reqular expressions or other, if
     *     name.test(layer.name) evaluates to true, the layer will be included
     *     in the list of layers returned.  If no layers are found, an empty
     *     array is returned.
     *
     * Returns:
     * {Array(<OpenLayers.Layer>)} A list of layers matching the given name.
     *     An empty array is returned if no matches are found.
     */
    getLayersByName: function(match) {
        return this.getLayersBy("name", match);
    },

    /**
     * APIMethod: getLayersByClass
     * Get a list of layers of a given class (CLASS_NAME).
     *
     * Parameter:
     * match - {String | Object} A layer class name.  The match can also be a
     *     regular expression literal or object.  In addition, it can be any
     *     object with a method named test.  For reqular expressions or other,
     *     if type.test(layer.CLASS_NAME) evaluates to true, the layer will
     *     be included in the list of layers returned.  If no layers are
     *     found, an empty array is returned.
     *
     * Returns:
     * {Array(<OpenLayers.Layer>)} A list of layers matching the given class.
     *     An empty array is returned if no matches are found.
     */
    getLayersByClass: function(match) {
        return this.getLayersBy("CLASS_NAME", match);
    },

    /**
     * APIMethod: getControlsBy
     * Get a list of controls with properties matching the given criteria.
     *
     * Parameter:
     * property - {String} A control property to be matched.
     * match - {String | Object} A string to match.  Can also be a regular
     *     expression literal or object.  In addition, it can be any object
     *     with a method named test.  For reqular expressions or other, if
     *     match.test(layer[property]) evaluates to true, the layer will be
     *     included in the array returned.  If no layers are found, an empty
     *     array is returned.
     *
     * Returns:
     * {Array(<OpenLayers.Control>)} A list of controls matching the given
     *     criteria.  An empty array is returned if no matches are found.
     */
    getControlsBy: function(property, match) {
        return this.getBy("controls", property, match);
    },

    /**
     * APIMethod: getControlsByClass
     * Get a list of controls of a given class (CLASS_NAME).
     *
     * Parameter:
     * match - {String | Object} A control class name.  The match can also be a
     *     regular expression literal or object.  In addition, it can be any
     *     object with a method named test.  For reqular expressions or other,
     *     if type.test(control.CLASS_NAME) evaluates to true, the control will
     *     be included in the list of controls returned.  If no controls are
     *     found, an empty array is returned.
     *
     * Returns:
     * {Array(<OpenLayers.Control>)} A list of controls matching the given class.
     *     An empty array is returned if no matches are found.
     */
    getControlsByClass: function(match) {
        return this.getControlsBy("CLASS_NAME", match);
    },

  /********************************************************/
  /*                                                      */
  /*                  Layer Functions                     */
  /*                                                      */
  /*     The following functions deal with adding and     */
  /*        removing Layers to and from the Map           */
  /*                                                      */
  /********************************************************/         

    /**
     * APIMethod: getLayer
     * Get a layer based on its id
     *
     * Parameter:
     * id - {String} A layer id
     *
     * Returns:
     * {<OpenLayers.Layer>} The Layer with the corresponding id from the map's 
     *                      layer collection, or null if not found.
     */
    getLayer: function(id) {
        var foundLayer = null;
        for (var i=0, len=this.layers.length; i<len; i++) {
            var layer = this.layers[i];
            if (layer.id == id) {
                foundLayer = layer;
                break;
            }
        }
        return foundLayer;
    },

    /**
    * Method: setLayerZIndex
    * 
    * Parameters:
    * layer - {<OpenLayers.Layer>} 
    * zIdx - {int} 
    */    
    setLayerZIndex: function (layer, zIdx) {
        layer.setZIndex(
            this.Z_INDEX_BASE[layer.isBaseLayer ? 'BaseLayer' : 'Overlay']
            + zIdx * 5 );
    },

    /**
     * Method: resetLayersZIndex
     * Reset each layer's z-index based on layer's array index
     */
    resetLayersZIndex: function() {
        for (var i=0, len=this.layers.length; i<len; i++) {
            var layer = this.layers[i];
            this.setLayerZIndex(layer, i);
        }
    },

    /**
    * APIMethod: addLayer
    *
    * Parameters:
    * layer - {<OpenLayers.Layer>} 
    */    
    addLayer: function (layer) {
        for(var i=0, len=this.layers.length; i <len; i++) {
            if (this.layers[i] == layer) {
                var msg = OpenLayers.i18n('layerAlreadyAdded', 
                                                      {'layerName':layer.name});
                OpenLayers.Console.warn(msg);
                return false;
            }
        }
        if (this.events.triggerEvent("preaddlayer", {layer: layer}) === false) {
            return;
        }
        if(this.allOverlays) {
            layer.isBaseLayer = false;
        }

        
        layer.div.className = "olLayerDiv";
        layer.div.style.overflow = "";
        this.setLayerZIndex(layer, this.layers.length);

        if (layer.isFixed) {
            this.viewPortDiv.appendChild(layer.div);
        } else {
            this.layerContainerDiv.appendChild(layer.div);
        }
        this.layers.push(layer);
        layer.setMap(this);

        if (layer.isBaseLayer || (this.allOverlays && !this.baseLayer))  {
            if (this.baseLayer == null) {
                // set the first baselaye we add as the baselayer
                this.setBaseLayer(layer);
            } else {
                layer.setVisibility(false);
            }
        } else {
            layer.redraw();
        }

        this.events.triggerEvent("addlayer", {layer: layer});
        layer.events.triggerEvent("added", {map: this, layer: layer});
        layer.afterAdd();
    },

    /**
    * APIMethod: addLayers 
    *
    * Parameters:
    * layers - {Array(<OpenLayers.Layer>)} 
    */    
    addLayers: function (layers) {
        for (var i=0, len=layers.length; i<len; i++) {
            this.addLayer(layers[i]);
        }
    },

    /** 
     * APIMethod: removeLayer
     * Removes a layer from the map by removing its visual element (the 
     *   layer.div property), then removing it from the map's internal list 
     *   of layers, setting the layer's map property to null. 
     * 
     *   a "removelayer" event is triggered.
     * 
     *   very worthy of mention is that simply removing a layer from a map
     *   will not cause the removal of any popups which may have been created
     *   by the layer. this is due to the fact that it was decided at some
     *   point that popups would not belong to layers. thus there is no way 
     *   for us to know here to which layer the popup belongs.
     *    
     *     A simple solution to this is simply to call destroy() on the layer.
     *     the default OpenLayers.Layer class's destroy() function
     *     automatically takes care to remove itself from whatever map it has
     *     been attached to. 
     * 
     *     The correct solution is for the layer itself to register an 
     *     event-handler on "removelayer" and when it is called, if it 
     *     recognizes itself as the layer being removed, then it cycles through
     *     its own personal list of popups, removing them from the map.
     * 
     * Parameters:
     * layer - {<OpenLayers.Layer>} 
     * setNewBaseLayer - {Boolean} Default is true
     */
    removeLayer: function(layer, setNewBaseLayer) {
        if (this.events.triggerEvent("preremovelayer", {layer: layer}) === false) {
            return;
        }
        if (setNewBaseLayer == null) {
            setNewBaseLayer = true;
        }

        if (layer.isFixed) {
            this.viewPortDiv.removeChild(layer.div);
        } else {
            this.layerContainerDiv.removeChild(layer.div);
        }
        OpenLayers.Util.removeItem(this.layers, layer);
        layer.removeMap(this);
        layer.map = null;

        // if we removed the base layer, need to set a new one
        if(this.baseLayer == layer) {
            this.baseLayer = null;
            if(setNewBaseLayer) {
                for(var i=0, len=this.layers.length; i<len; i++) {
                    var iLayer = this.layers[i];
                    if (iLayer.isBaseLayer || this.allOverlays) {
                        this.setBaseLayer(iLayer);
                        break;
                    }
                }
            }
        }

        this.resetLayersZIndex();

        this.events.triggerEvent("removelayer", {layer: layer});
        layer.events.triggerEvent("removed", {map: this, layer: layer});
    },

    /**
     * APIMethod: getNumLayers
     * 
     * Returns:
     * {Int} The number of layers attached to the map.
     */
    getNumLayers: function () {
        return this.layers.length;
    },

    /** 
     * APIMethod: getLayerIndex
     *
     * Parameters:
     * layer - {<OpenLayers.Layer>}
     *
     * Returns:
     * {Integer} The current (zero-based) index of the given layer in the map's
     *           layer stack. Returns -1 if the layer isn't on the map.
     */
    getLayerIndex: function (layer) {
        return OpenLayers.Util.indexOf(this.layers, layer);
    },
    
    /** 
     * APIMethod: setLayerIndex
     * Move the given layer to the specified (zero-based) index in the layer
     *     list, changing its z-index in the map display. Use
     *     map.getLayerIndex() to find out the current index of a layer. Note
     *     that this cannot (or at least should not) be effectively used to
     *     raise base layers above overlays.
     *
     * Parameters:
     * layer - {<OpenLayers.Layer>} 
     * idx - {int} 
     */
    setLayerIndex: function (layer, idx) {
        var base = this.getLayerIndex(layer);
        if (idx < 0) {
            idx = 0;
        } else if (idx > this.layers.length) {
            idx = this.layers.length;
        }
        if (base != idx) {
            this.layers.splice(base, 1);
            this.layers.splice(idx, 0, layer);
            for (var i=0, len=this.layers.length; i<len; i++) {
                this.setLayerZIndex(this.layers[i], i);
            }
            this.events.triggerEvent("changelayer", {
                layer: layer, property: "order"
            });
            if(this.allOverlays) {
                if(idx === 0) {
                    this.setBaseLayer(layer);
                } else if(this.baseLayer !== this.layers[0]) {
                    this.setBaseLayer(this.layers[0]);
                }
            }
        }
    },

    /** 
     * APIMethod: raiseLayer
     * Change the index of the given layer by delta. If delta is positive, 
     *     the layer is moved up the map's layer stack; if delta is negative,
     *     the layer is moved down.  Again, note that this cannot (or at least
     *     should not) be effectively used to raise base layers above overlays.
     *
     * Paremeters:
     * layer - {<OpenLayers.Layer>} 
     * delta - {int} 
     */
    raiseLayer: function (layer, delta) {
        var idx = this.getLayerIndex(layer) + delta;
        this.setLayerIndex(layer, idx);
    },
    
    /** 
     * APIMethod: setBaseLayer
     * Allows user to specify one of the currently-loaded layers as the Map's
     *     new base layer.
     * 
     * Parameters:
     * newBaseLayer - {<OpenLayers.Layer>}
     */
    setBaseLayer: function(newBaseLayer) {
        
        if (newBaseLayer != this.baseLayer) {
          
            // ensure newBaseLayer is already loaded
            if (OpenLayers.Util.indexOf(this.layers, newBaseLayer) != -1) {

                // preserve center and scale when changing base layers
                var center = this.getCachedCenter();
                var newResolution = OpenLayers.Util.getResolutionFromScale(
                    this.getScale(), newBaseLayer.units
                );

                // make the old base layer invisible 
                if (this.baseLayer != null && !this.allOverlays) {
                    this.baseLayer.setVisibility(false);
                }

                // set new baselayer
                this.baseLayer = newBaseLayer;
                
                // Increment viewRequestID since the baseLayer is 
                // changing. This is used by tiles to check if they should 
                // draw themselves.
                this.viewRequestID++;
                if(!this.allOverlays || this.baseLayer.visibility) {
                    this.baseLayer.setVisibility(true);
                }

                // recenter the map
                if (center != null) {
                    // new zoom level derived from old scale
                    var newZoom = this.getZoomForResolution(
                        newResolution || this.resolution, true
                    );
                    // zoom and force zoom change
                    this.setCenter(center, newZoom, false, true);
                }

                this.events.triggerEvent("changebaselayer", {
                    layer: this.baseLayer
                });
            }        
        }
    },


  /********************************************************/
  /*                                                      */
  /*                 Control Functions                    */
  /*                                                      */
  /*     The following functions deal with adding and     */
  /*        removing Controls to and from the Map         */
  /*                                                      */
  /********************************************************/         

    /**
     * APIMethod: addControl
     * Add the passed over control to the map. Optionally 
     *     position the control at the given pixel.
     * 
     * Parameters:
     * control - {<OpenLayers.Control>}
     * px - {<OpenLayers.Pixel>}
     */    
    addControl: function (control, px) {
        this.controls.push(control);
        this.addControlToMap(control, px);
    },
    
    /**
     * APIMethod: addControls
     * Add all of the passed over controls to the map. 
     *     You can pass over an optional second array
     *     with pixel-objects to position the controls.
     *     The indices of the two arrays should match and
     *     you can add null as pixel for those controls 
     *     you want to be autopositioned.   
     *     
     * Parameters:
     * controls - {Array(<OpenLayers.Control>)}
     * pixels - {Array(<OpenLayers.Pixel>)}
     */    
    addControls: function (controls, pixels) {
        var pxs = (arguments.length === 1) ? [] : pixels;
        for (var i=0, len=controls.length; i<len; i++) {
            var ctrl = controls[i];
            var px = (pxs[i]) ? pxs[i] : null;
            this.addControl( ctrl, px );
        }
    },

    /**
     * Method: addControlToMap
     * 
     * Parameters:
     * 
     * control - {<OpenLayers.Control>}
     * px - {<OpenLayers.Pixel>}
     */    
    addControlToMap: function (control, px) {
        // If a control doesn't have a div at this point, it belongs in the
        // viewport.
        control.outsideViewport = (control.div != null);
        
        // If the map has a displayProjection, and the control doesn't, set 
        // the display projection.
        if (this.displayProjection && !control.displayProjection) {
            control.displayProjection = this.displayProjection;
        }    
        
        control.setMap(this);
        var div = control.draw(px);
        if (div) {
            if(!control.outsideViewport) {
                div.style.zIndex = this.Z_INDEX_BASE['Control'] +
                                    this.controls.length;
                this.viewPortDiv.appendChild( div );
            }
        }
        if(control.autoActivate) {
            control.activate();
        }
    },
    
    /**
     * APIMethod: getControl
     * 
     * Parameters:
     * id - {String} ID of the control to return.
     * 
     * Returns:
     * {<OpenLayers.Control>} The control from the map's list of controls 
     *                        which has a matching 'id'. If none found, 
     *                        returns null.
     */    
    getControl: function (id) {
        var returnControl = null;
        for(var i=0, len=this.controls.length; i<len; i++) {
            var control = this.controls[i];
            if (control.id == id) {
                returnControl = control;
                break;
            }
        }
        return returnControl;
    },
    
    /** 
     * APIMethod: removeControl
     * Remove a control from the map. Removes the control both from the map 
     *     object's internal array of controls, as well as from the map's 
     *     viewPort (assuming the control was not added outsideViewport)
     * 
     * Parameters:
     * control - {<OpenLayers.Control>} The control to remove.
     */    
    removeControl: function (control) {
        //make sure control is non-null and actually part of our map
        if ( (control) && (control == this.getControl(control.id)) ) {
            if (control.div && (control.div.parentNode == this.viewPortDiv)) {
                this.viewPortDiv.removeChild(control.div);
            }
            OpenLayers.Util.removeItem(this.controls, control);
        }
    },

  /********************************************************/
  /*                                                      */
  /*                  Popup Functions                     */
  /*                                                      */
  /*     The following functions deal with adding and     */
  /*        removing Popups to and from the Map           */
  /*                                                      */
  /********************************************************/         

    /** 
     * APIMethod: addPopup
     * 
     * Parameters:
     * popup - {<OpenLayers.Popup>}
     * exclusive - {Boolean} If true, closes all other popups first
     */
    addPopup: function(popup, exclusive) {

        if (exclusive) {
            //remove all other popups from screen
            for (var i = this.popups.length - 1; i >= 0; --i) {
                this.removePopup(this.popups[i]);
            }
        }

        popup.map = this;
        this.popups.push(popup);
        var popupDiv = popup.draw();
        if (popupDiv) {
            popupDiv.style.zIndex = this.Z_INDEX_BASE['Popup'] +
                                    this.popups.length;
            this.layerContainerDiv.appendChild(popupDiv);
        }
    },
    
    /** 
    * APIMethod: removePopup
    * 
    * Parameters:
    * popup - {<OpenLayers.Popup>}
    */
    removePopup: function(popup) {
        OpenLayers.Util.removeItem(this.popups, popup);
        if (popup.div) {
            try { this.layerContainerDiv.removeChild(popup.div); }
            catch (e) { } // Popups sometimes apparently get disconnected
                      // from the layerContainerDiv, and cause complaints.
        }
        popup.map = null;
    },

  /********************************************************/
  /*                                                      */
  /*              Container Div Functions                 */
  /*                                                      */
  /*   The following functions deal with the access to    */
  /*    and maintenance of the size of the container div  */
  /*                                                      */
  /********************************************************/     

    /**
     * APIMethod: getSize
     * 
     * Returns:
     * {<OpenLayers.Size>} An <OpenLayers.Size> object that represents the 
     *                     size, in pixels, of the div into which OpenLayers 
     *                     has been loaded. 
     *                     Note - A clone() of this locally cached variable is
     *                     returned, so as not to allow users to modify it.
     */
    getSize: function () {
        var size = null;
        if (this.size != null) {
            size = this.size.clone();
        }
        return size;
    },

    /**
     * APIMethod: updateSize
     * This function should be called by any external code which dynamically
     *     changes the size of the map div (because mozilla wont let us catch 
     *     the "onresize" for an element)
     */
    updateSize: function() {
        // the div might have moved on the page, also
        var newSize = this.getCurrentSize();
        if (newSize && !isNaN(newSize.h) && !isNaN(newSize.w)) {
            this.events.clearMouseCache();
            var oldSize = this.getSize();
            if (oldSize == null) {
                this.size = oldSize = newSize;
            }
            if (!newSize.equals(oldSize)) {
                
                // store the new size
                this.size = newSize;
    
                //notify layers of mapresize
                for(var i=0, len=this.layers.length; i<len; i++) {
                    this.layers[i].onMapResize();                
                }
    
                var center = this.getCachedCenter();
    
                if (this.baseLayer != null && center != null) {
                    var zoom = this.getZoom();
                    this.zoom = null;
                    this.setCenter(center, zoom);
                }
    
            }
        }
    },
    
    /**
     * Method: getCurrentSize
     * 
     * Returns:
     * {<OpenLayers.Size>} A new <OpenLayers.Size> object with the dimensions 
     *                     of the map div
     */
    getCurrentSize: function() {

        var size = new OpenLayers.Size(this.div.clientWidth, 
                                       this.div.clientHeight);

        if (size.w == 0 && size.h == 0 || isNaN(size.w) && isNaN(size.h)) {
            size.w = this.div.offsetWidth;
            size.h = this.div.offsetHeight;
        }
        if (size.w == 0 && size.h == 0 || isNaN(size.w) && isNaN(size.h)) {
            size.w = parseInt(this.div.style.width);
            size.h = parseInt(this.div.style.height);
        }
        return size;
    },

    /** 
     * Method: calculateBounds
     * 
     * Parameters:
     * center - {<OpenLayers.LonLat>} Default is this.getCenter()
     * resolution - {float} Default is this.getResolution() 
     * 
     * Returns:
     * {<OpenLayers.Bounds>} A bounds based on resolution, center, and 
     *                       current mapsize.
     */
    calculateBounds: function(center, resolution) {

        var extent = null;
        
        if (center == null) {
            center = this.getCachedCenter();
        }                
        if (resolution == null) {
            resolution = this.getResolution();
        }
    
        if ((center != null) && (resolution != null)) {

            var size = this.getSize();
            var w_deg = size.w * resolution;
            var h_deg = size.h * resolution;
        
            extent = new OpenLayers.Bounds(center.lon - w_deg / 2,
                                           center.lat - h_deg / 2,
                                           center.lon + w_deg / 2,
                                           center.lat + h_deg / 2);
        
        }

        return extent;
    },


  /********************************************************/
  /*                                                      */
  /*            Zoom, Center, Pan Functions               */
  /*                                                      */
  /*    The following functions handle the validation,    */
  /*   getting and setting of the Zoom Level and Center   */
  /*       as well as the panning of the Map              */
  /*                                                      */
  /********************************************************/
    /**
     * APIMethod: getCenter
     * 
     * Returns:
     * {<OpenLayers.LonLat>}
     */
    getCenter: function () {
        var center = null;
        var cachedCenter = this.getCachedCenter();
        if (cachedCenter) {
            center = cachedCenter.clone();
        }
        return center;
    },

    /**
     * Method: getCachedCenter
     *
     * Returns:
     * {<OpenLayers.LonLat>}
     */
    getCachedCenter: function() {
        if (!this.center && this.size) {
            this.center = this.getLonLatFromViewPortPx(
                new OpenLayers.Pixel(this.size.w / 2, this.size.h / 2)
            );
        }
        return this.center;
    },

    /**
     * APIMethod: getZoom
     * 
     * Returns:
     * {Integer}
     */
    getZoom: function () {
        return this.zoom;
    },
    
    /** 
     * APIMethod: pan
     * Allows user to pan by a value of screen pixels
     * 
     * Parameters:
     * dx - {Integer}
     * dy - {Integer}
     * options - {Object} Options to configure panning:
     *  - *animate* {Boolean} Use panTo instead of setCenter. Default is true.
     *  - *dragging* {Boolean} Call setCenter with dragging true.  Default is
     *    false.
     */
    pan: function(dx, dy, options) {
        options = OpenLayers.Util.applyDefaults(options, {
            animate: true,
            dragging: false
        });
        if (options.dragging) {
            if (dx != 0 || dy != 0) {
                this.moveByPx(dx, dy);
            }
        } else {
            // getCenter
            var centerPx = this.getViewPortPxFromLonLat(this.getCachedCenter());

            // adjust
            var newCenterPx = centerPx.add(dx, dy);

            if (this.dragging || !newCenterPx.equals(centerPx)) {
                var newCenterLonLat = this.getLonLatFromViewPortPx(newCenterPx);
                if (options.animate) {
                    this.panTo(newCenterLonLat);
                } else {
                    this.moveTo(newCenterLonLat);
                    this.dragging = false;
                    this.events.triggerEvent("moveend");
                }    
            }
        }        

   },
   
   /** 
     * APIMethod: panTo
     * Allows user to pan to a new lonlat
     * If the new lonlat is in the current extent the map will slide smoothly
     * 
     * Parameters:
     * lonlat - {<OpenLayers.LonLat>}
     */
    panTo: function(lonlat) {
        if (this.panMethod && this.getExtent().scale(this.panRatio).containsLonLat(lonlat)) {
            if (!this.panTween) {
                this.panTween = new OpenLayers.Tween(this.panMethod);
            }
            var center = this.getCachedCenter();

            // center will not change, don't do nothing
            if (lonlat.equals(center)) {
                return;
            }

            var from = this.getPixelFromLonLat(center);
            var to = this.getPixelFromLonLat(lonlat);
            var vector = { x: to.x - from.x, y: to.y - from.y };
            var last = { x: 0, y: 0 };

            this.panTween.start( { x: 0, y: 0 }, vector, this.panDuration, {
                callbacks: {
                    eachStep: OpenLayers.Function.bind(function(px) {
                        var x = px.x - last.x,
                            y = px.y - last.y;
                        this.moveByPx(x, y);
                        last.x = Math.round(px.x);
                        last.y = Math.round(px.y);
                    }, this),
                    done: OpenLayers.Function.bind(function(px) {
                        this.moveTo(lonlat);
                        this.dragging = false;
                        this.events.triggerEvent("moveend");
                    }, this)
                }
            });
        } else {
            this.setCenter(lonlat);
        }
    },

    /**
     * APIMethod: setCenter
     * Set the map center (and optionally, the zoom level).
     * 
     * Parameters:
     * lonlat - {<OpenLayers.LonLat>} The new center location.
     * zoom - {Integer} Optional zoom level.
     * dragging - {Boolean} Specifies whether or not to trigger 
     *                      movestart/end events
     * forceZoomChange - {Boolean} Specifies whether or not to trigger zoom 
     *                             change events (needed on baseLayer change)
     *
     * TBD: reconsider forceZoomChange in 3.0
     */
    setCenter: function (lonlat, zoom, dragging, forceZoomChange) {
        this.panTween && this.panTween.stop();             
        this.moveTo(lonlat, zoom, {
            'dragging': dragging,
            'forceZosetCenteromChange': forceZoomChange
        });
    },
    
    /** 
     * Method: moveByPx
     * Drag the map by pixels.
     *
     * Parameters:
     * dx - {Number}
     * dy - {Number}
     */
    moveByPx: function(dx, dy) {
        var hw = this.size.w / 2;
        var hh = this.size.h / 2;
        var x = hw + dx;
        var y = hh + dy;
        var wrapDateLine = this.baseLayer.wrapDateLine;
        var xRestriction = 0;
        var yRestriction = 0;
        if (this.restrictedExtent) {
            xRestriction = hw;
            yRestriction = hh;
            // wrapping the date line makes no sense for restricted extents
            wrapDateLine = false;
        }
        dx = wrapDateLine ||
                    x <= this.maxPx.x - xRestriction &&
                    x >= this.minPx.x + xRestriction ? Math.round(dx) : 0;
        dy = y <= this.maxPx.y - yRestriction &&
                    y >= this.minPx.y + yRestriction ? Math.round(dy) : 0;
        var minX = this.minPx.x, maxX = this.maxPx.x;
        if (dx || dy) {
            if (!this.dragging) {
                this.dragging = true;
                this.events.triggerEvent("movestart");
            }
            this.center = null;
            if (dx) {
                this.layerContainerDiv.style.left =
                    parseInt(this.layerContainerDiv.style.left) - dx + "px";
                this.minPx.x -= dx;
                this.maxPx.x -= dx;
                if (wrapDateLine) {
                    if (this.maxPx.x > maxX) {
                        this.maxPx.x -= (maxX - minX);
                    }
                    if (this.minPx.x < minX) {
                        this.minPx.x += (maxX - minX);
                    }
                }
            }
            if (dy) {
                this.layerContainerDiv.style.top =
                    parseInt(this.layerContainerDiv.style.top) - dy + "px";
                this.minPx.y -= dy;
                this.maxPx.y -= dy;
            }
            var layer, i, len;
            for (i=0, len=this.layers.length; i<len; ++i) {
                layer = this.layers[i];
                if (layer.visibility &&
                    (layer === this.baseLayer || layer.inRange)) {
                    layer.moveByPx(dx, dy);
                    layer.events.triggerEvent("move");
                }
            }
            this.events.triggerEvent("move");
        }
    },

    /**
     * Method: moveTo
     *
     * Parameters:
     * lonlat - {<OpenLayers.LonLat>}
     * zoom - {Integer}
     * options - {Object}
     */
    moveTo: function(lonlat, zoom, options) {
        if (!options) { 
            options = {};
        }
        if (zoom != null) {
            zoom = parseFloat(zoom);
            if (!this.fractionalZoom) {
                zoom = Math.round(zoom);
            }
        }
        // dragging is false by default
        var dragging = options.dragging || this.dragging;
        // forceZoomChange is false by default
        var forceZoomChange = options.forceZoomChange;

        if (!this.getCachedCenter() && !this.isValidLonLat(lonlat)) {
            lonlat = this.maxExtent.getCenterLonLat();
            this.center = lonlat.clone();
        }

        if(this.restrictedExtent != null) {
            // In 3.0, decide if we want to change interpretation of maxExtent.
            if(lonlat == null) { 
                lonlat = this.center; 
            }
            if(zoom == null) { 
                zoom = this.getZoom(); 
            }
            var resolution = this.getResolutionForZoom(zoom);
            var extent = this.calculateBounds(lonlat, resolution); 
            if(!this.restrictedExtent.containsBounds(extent)) {
                var maxCenter = this.restrictedExtent.getCenterLonLat(); 
                if(extent.getWidth() > this.restrictedExtent.getWidth()) { 
                    lonlat = new OpenLayers.LonLat(maxCenter.lon, lonlat.lat); 
                } else if(extent.left < this.restrictedExtent.left) {
                    lonlat = lonlat.add(this.restrictedExtent.left -
                                        extent.left, 0); 
                } else if(extent.right > this.restrictedExtent.right) { 
                    lonlat = lonlat.add(this.restrictedExtent.right -
                                        extent.right, 0); 
                } 
                if(extent.getHeight() > this.restrictedExtent.getHeight()) { 
                    lonlat = new OpenLayers.LonLat(lonlat.lon, maxCenter.lat); 
                } else if(extent.bottom < this.restrictedExtent.bottom) { 
                    lonlat = lonlat.add(0, this.restrictedExtent.bottom -
                                        extent.bottom); 
                } 
                else if(extent.top > this.restrictedExtent.top) { 
                    lonlat = lonlat.add(0, this.restrictedExtent.top -
                                        extent.top); 
                } 
            }
        }
        
        var zoomChanged = forceZoomChange || (
                            (this.isValidZoomLevel(zoom)) && 
                            (zoom != this.getZoom()) );

        var centerChanged = (this.isValidLonLat(lonlat)) && 
                            (!lonlat.equals(this.center));

        // if neither center nor zoom will change, no need to do anything
        if (zoomChanged || centerChanged || dragging) {
            dragging || this.events.triggerEvent("movestart");

            if (centerChanged) {
                if (!zoomChanged && this.center) { 
                    // if zoom hasnt changed, just slide layerContainer
                    //  (must be done before setting this.center to new value)
                    this.centerLayerContainer(lonlat);
                }
                this.center = lonlat.clone();
            }

            var res = zoomChanged ?
                this.getResolutionForZoom(zoom) : this.getResolution();
            // (re)set the layerContainerDiv's location
            if (zoomChanged || this.layerContainerOrigin == null) {
                this.layerContainerOrigin = this.getCachedCenter();
                this.layerContainerDiv.style.left = "0px";
                this.layerContainerDiv.style.top  = "0px";
                var maxExtent = this.getMaxExtent({restricted: true});
                var maxExtentCenter = maxExtent.getCenterLonLat();
                var lonDelta = this.center.lon - maxExtentCenter.lon;
                var latDelta = maxExtentCenter.lat - this.center.lat;
                var extentWidth = Math.round(maxExtent.getWidth() / res);
                var extentHeight = Math.round(maxExtent.getHeight() / res);
                var left = (this.size.w - extentWidth) / 2 - lonDelta / res;
                var top = (this.size.h - extentHeight) / 2 - latDelta / res;
                this.minPx = new OpenLayers.Pixel(left, top);
                this.maxPx = new OpenLayers.Pixel(left + extentWidth, top + extentHeight);
            }

            if (zoomChanged) {
                this.zoom = zoom;
                this.resolution = res;
                // zoom level has changed, increment viewRequestID.
                this.viewRequestID++;
            }    
            
            var bounds = this.getExtent();
            
            //send the move call to the baselayer and all the overlays    

            if(this.baseLayer.visibility) {
                this.baseLayer.moveTo(bounds, zoomChanged, options.dragging);
                options.dragging || this.baseLayer.events.triggerEvent(
                    "moveend", {zoomChanged: zoomChanged}
                );
            }
            
            bounds = this.baseLayer.getExtent();
            
            for (var i=this.layers.length-1; i>=0; --i) {
                var layer = this.layers[i];
                if (layer !== this.baseLayer && !layer.isBaseLayer) {
                    var inRange = layer.calculateInRange();
                    if (layer.inRange != inRange) {
                        // the inRange property has changed. If the layer is
                        // no longer in range, we turn it off right away. If
                        // the layer is no longer out of range, the moveTo
                        // call below will turn on the layer.
                        layer.inRange = inRange;
                        if (!inRange) {
                            layer.display(false);
                        }
                        this.events.triggerEvent("changelayer", {
                            layer: layer, property: "visibility"
                        });
                    }
                    if (inRange && layer.visibility) {
                        layer.moveTo(bounds, zoomChanged, options.dragging);
                        options.dragging || layer.events.triggerEvent(
                            "moveend", {zoomChanged: zoomChanged}
                        );
                    }
                }                
            }
            
            this.events.triggerEvent("move");
            dragging || this.events.triggerEvent("moveend");

            if (zoomChanged) {
                //redraw popups
                for (var i=0, len=this.popups.length; i<len; i++) {
                    this.popups[i].updatePosition();
                }
                this.events.triggerEvent("zoomend");
            }
        }
    },

    /** 
     * Method: centerLayerContainer
     * This function takes care to recenter the layerContainerDiv.
     * 
     * Parameters:
     * lonlat - {<OpenLayers.LonLat>}
     */
    centerLayerContainer: function (lonlat) {
        var originPx = this.getViewPortPxFromLonLat(this.layerContainerOrigin);
        var newPx = this.getViewPortPxFromLonLat(lonlat);

        if ((originPx != null) && (newPx != null)) {
            var oldLeft = parseInt(this.layerContainerDiv.style.left);
            var oldTop = parseInt(this.layerContainerDiv.style.top);
            var newLeft = Math.round(originPx.x - newPx.x);
            var newTop = Math.round(originPx.y - newPx.y);
            this.layerContainerDiv.style.left = newLeft + "px";
            this.layerContainerDiv.style.top  = newTop + "px";
            var dx = oldLeft - newLeft;
            var dy = oldTop - newTop;
            this.minPx.x -= dx;
            this.maxPx.x -= dx;
            this.minPx.y -= dy;
            this.maxPx.y -= dy;
        }        
    },

    /**
     * Method: isValidZoomLevel
     * 
     * Parameters:
     * zoomLevel - {Integer}
     * 
     * Returns:
     * {Boolean} Whether or not the zoom level passed in is non-null and 
     *           within the min/max range of zoom levels.
     */
    isValidZoomLevel: function(zoomLevel) {
        return ( (zoomLevel != null) &&
                 (zoomLevel >= 0) && 
                 (zoomLevel < this.getNumZoomLevels()) );
    },
    
    /**
     * Method: isValidLonLat
     * 
     * Parameters:
     * lonlat - {<OpenLayers.LonLat>}
     * 
     * Returns:
     * {Boolean} Whether or not the lonlat passed in is non-null and within
     *           the maxExtent bounds
     */
    isValidLonLat: function(lonlat) {
        var valid = false;
        if (lonlat != null) {
            var maxExtent = this.getMaxExtent();
            valid = maxExtent.containsLonLat(lonlat);        
        }
        return valid;
    },

  /********************************************************/
  /*                                                      */
  /*                 Layer Options                        */
  /*                                                      */
  /*    Accessor functions to Layer Options parameters    */
  /*                                                      */
  /********************************************************/
    
    /**
     * APIMethod: getProjection
     * This method returns a string representing the projection. In 
     *     the case of projection support, this will be the srsCode which
     *     is loaded -- otherwise it will simply be the string value that
     *     was passed to the projection at startup.
     *
     * FIXME: In 3.0, we will remove getProjectionObject, and instead
     *     return a Projection object from this function. 
     * 
     * Returns:
     * {String} The Projection string from the base layer or null. 
     */
    getProjection: function() {
        var projection = this.getProjectionObject();
        return projection ? projection.getCode() : null;
    },
    
    /**
     * APIMethod: getProjectionObject
     * Returns the projection obect from the baselayer.
     *
     * Returns:
     * {<OpenLayers.Projection>} The Projection of the base layer.
     */
    getProjectionObject: function() {
        var projection = null;
        if (this.baseLayer != null) {
            projection = this.baseLayer.projection;
        }
        return projection;
    },
    
    /**
     * APIMethod: getMaxResolution
     * 
     * Returns:
     * {String} The Map's Maximum Resolution
     */
    getMaxResolution: function() {
        var maxResolution = null;
        if (this.baseLayer != null) {
            maxResolution = this.baseLayer.maxResolution;
        }
        return maxResolution;
    },
        
    /**
     * APIMethod: getMaxExtent
     *
     * Parameters:
     * options - {Object} 
     * 
     * Allowed Options:
     * restricted - {Boolean} If true, returns restricted extent (if it is 
     *     available.)
     *
     * Returns:
     * {<OpenLayers.Bounds>} The maxExtent property as set on the current 
     *     baselayer, unless the 'restricted' option is set, in which case
     *     the 'restrictedExtent' option from the map is returned (if it
     *     is set).
     */
    getMaxExtent: function (options) {
        var maxExtent = null;
        if(options && options.restricted && this.restrictedExtent){
            maxExtent = this.restrictedExtent;
        } else if (this.baseLayer != null) {
            maxExtent = this.baseLayer.maxExtent;
        }        
        return maxExtent;
    },
    
    /**
     * APIMethod: getNumZoomLevels
     * 
     * Returns:
     * {Integer} The total number of zoom levels that can be displayed by the 
     *           current baseLayer.
     */
    getNumZoomLevels: function() {
        var numZoomLevels = null;
        if (this.baseLayer != null) {
            numZoomLevels = this.baseLayer.numZoomLevels;
        }
        return numZoomLevels;
    },

  /********************************************************/
  /*                                                      */
  /*                 Baselayer Functions                  */
  /*                                                      */
  /*    The following functions, all publicly exposed     */
  /*       in the API?, are all merely wrappers to the    */
  /*       the same calls on whatever layer is set as     */
  /*                the current base layer                */
  /*                                                      */
  /********************************************************/

    /**
     * APIMethod: getExtent
     * 
     * Returns:
     * {<OpenLayers.Bounds>} A Bounds object which represents the lon/lat 
     *                       bounds of the current viewPort. 
     *                       If no baselayer is set, returns null.
     */
    getExtent: function () {
        var extent = null;
        if (this.baseLayer != null) {
            extent = this.baseLayer.getExtent();
        }
        return extent;
    },

    /**
     * APIMethod: getResolution
     * 
     * Returns:
     * {Float} The current resolution of the map. 
     *         If no baselayer is set, returns null.
     */
    getResolution: function () {
        var resolution = null;
        if (this.baseLayer != null) {
            resolution = this.baseLayer.getResolution();
        } else if(this.allOverlays === true && this.layers.length > 0) {
            // while adding the 1st layer to the map in allOverlays mode,
            // this.baseLayer is not set yet when we need the resolution
            // for calculateInRange.
            resolution = this.layers[0].getResolution();
        }
        return resolution;
    },

    /**
     * APIMethod: getUnits
     * 
     * Returns:
     * {Float} The current units of the map. 
     *         If no baselayer is set, returns null.
     */
    getUnits: function () {
        var units = null;
        if (this.baseLayer != null) {
            units = this.baseLayer.units;
        }
        return units;
    },

     /**
      * APIMethod: getScale
      * 
      * Returns:
      * {Float} The current scale denominator of the map. 
      *         If no baselayer is set, returns null.
      */
    getScale: function () {
        var scale = null;
        if (this.baseLayer != null) {
            var res = this.getResolution();
            var units = this.baseLayer.units;
            scale = OpenLayers.Util.getScaleFromResolution(res, units);
        }
        return scale;
    },


    /**
     * APIMethod: getZoomForExtent
     * 
     * Parameters: 
     * bounds - {<OpenLayers.Bounds>}
     * closest - {Boolean} Find the zoom level that most closely fits the 
     *     specified bounds. Note that this may result in a zoom that does 
     *     not exactly contain the entire extent.
     *     Default is false.
     * 
     * Returns:
     * {Integer} A suitable zoom level for the specified bounds.
     *           If no baselayer is set, returns null.
     */
    getZoomForExtent: function (bounds, closest) {
        var zoom = null;
        if (this.baseLayer != null) {
            zoom = this.baseLayer.getZoomForExtent(bounds, closest);
        }
        return zoom;
    },

    /**
     * APIMethod: getResolutionForZoom
     * 
     * Parameter:
     * zoom - {Float}
     * 
     * Returns:
     * {Float} A suitable resolution for the specified zoom.  If no baselayer
     *     is set, returns null.
     */
    getResolutionForZoom: function(zoom) {
        var resolution = null;
        if(this.baseLayer) {
            resolution = this.baseLayer.getResolutionForZoom(zoom);
        }
        return resolution;
    },

    /**
     * APIMethod: getZoomForResolution
     * 
     * Parameter:
     * resolution - {Float}
     * closest - {Boolean} Find the zoom level that corresponds to the absolute 
     *     closest resolution, which may result in a zoom whose corresponding
     *     resolution is actually smaller than we would have desired (if this
     *     is being called from a getZoomForExtent() call, then this means that
     *     the returned zoom index might not actually contain the entire 
     *     extent specified... but it'll be close).
     *     Default is false.
     * 
     * Returns:
     * {Integer} A suitable zoom level for the specified resolution.
     *           If no baselayer is set, returns null.
     */
    getZoomForResolution: function(resolution, closest) {
        var zoom = null;
        if (this.baseLayer != null) {
            zoom = this.baseLayer.getZoomForResolution(resolution, closest);
        }
        return zoom;
    },

  /********************************************************/
  /*                                                      */
  /*                  Zooming Functions                   */
  /*                                                      */
  /*    The following functions, all publicly exposed     */
  /*       in the API, are all merely wrappers to the     */
  /*               the setCenter() function               */
  /*                                                      */
  /********************************************************/
  
    /** 
     * APIMethod: zoomTo
     * Zoom to a specific zoom level
     * 
     * Parameters:
     * zoom - {Integer}
     */
    zoomTo: function(zoom) {
        if (this.isValidZoomLevel(zoom)) {
            this.setCenter(null, zoom);
        }
    },
    
    /**
     * APIMethod: zoomIn
     * 
     */
    zoomIn: function() {
        this.zoomTo(this.getZoom() + 1);
    },
    
    /**
     * APIMethod: zoomOut
     * 
     */
    zoomOut: function() {
        this.zoomTo(this.getZoom() - 1);
    },

    /**
     * APIMethod: zoomToExtent
     * Zoom to the passed in bounds, recenter
     * 
     * Parameters:
     * bounds - {<OpenLayers.Bounds>}
     * closest - {Boolean} Find the zoom level that most closely fits the 
     *     specified bounds. Note that this may result in a zoom that does 
     *     not exactly contain the entire extent.
     *     Default is false.
     * 
     */
    zoomToExtent: function(bounds, closest) {
        var center = bounds.getCenterLonLat();
        if (this.baseLayer.wrapDateLine) {
            var maxExtent = this.getMaxExtent();

            //fix straddling bounds (in the case of a bbox that straddles the 
            // dateline, it's left and right boundaries will appear backwards. 
            // we fix this by allowing a right value that is greater than the
            // max value at the dateline -- this allows us to pass a valid 
            // bounds to calculate zoom)
            //
            bounds = bounds.clone();
            while (bounds.right < bounds.left) {
                bounds.right += maxExtent.getWidth();
            }
            //if the bounds was straddling (see above), then the center point 
            // we got from it was wrong. So we take our new bounds and ask it
            // for the center. Because our new bounds is at least partially 
            // outside the bounds of maxExtent, the new calculated center 
            // might also be. We don't want to pass a bad center value to 
            // setCenter, so we have it wrap itself across the date line.
            //
            center = bounds.getCenterLonLat().wrapDateLine(maxExtent);
        }
        this.setCenter(center, this.getZoomForExtent(bounds, closest));
    },

    /** 
     * APIMethod: zoomToMaxExtent
     * Zoom to the full extent and recenter.
     *
     * Parameters:
     * options - 
     * 
     * Allowed Options:
     * restricted - {Boolean} True to zoom to restricted extent if it is 
     *     set. Defaults to true.
     */
    zoomToMaxExtent: function(options) {
        //restricted is true by default
        var restricted = (options) ? options.restricted : true;

        var maxExtent = this.getMaxExtent({
            'restricted': restricted 
        });
        this.zoomToExtent(maxExtent);
    },

    /** 
     * APIMethod: zoomToScale
     * Zoom to a specified scale 
     * 
     * Parameters:
     * scale - {float}
     * closest - {Boolean} Find the zoom level that most closely fits the 
     *     specified scale. Note that this may result in a zoom that does 
     *     not exactly contain the entire extent.
     *     Default is false.
     * 
     */
    zoomToScale: function(scale, closest) {
        var res = OpenLayers.Util.getResolutionFromScale(scale, 
                                                         this.baseLayer.units);
        var size = this.getSize();
        var w_deg = size.w * res;
        var h_deg = size.h * res;
        var center = this.getCachedCenter();

        var extent = new OpenLayers.Bounds(center.lon - w_deg / 2,
                                           center.lat - h_deg / 2,
                                           center.lon + w_deg / 2,
                                           center.lat + h_deg / 2);
        this.zoomToExtent(extent, closest);
    },
    
  /********************************************************/
  /*                                                      */
  /*             Translation Functions                    */
  /*                                                      */
  /*      The following functions translate between       */
  /*           LonLat, LayerPx, and ViewPortPx            */
  /*                                                      */
  /********************************************************/
      
  //
  // TRANSLATION: LonLat <-> ViewPortPx
  //

    /**
     * Method: getLonLatFromViewPortPx
     * 
     * Parameters:
     * viewPortPx - {<OpenLayers.Pixel>}
     * 
     * Returns:
     * {<OpenLayers.LonLat>} An OpenLayers.LonLat which is the passed-in view 
     *                       port <OpenLayers.Pixel>, translated into lon/lat
     *                       by the current base layer.
     */
    getLonLatFromViewPortPx: function (viewPortPx) {
        var lonlat = null; 
        if (this.baseLayer != null) {
            lonlat = this.baseLayer.getLonLatFromViewPortPx(viewPortPx);
        }
        return lonlat;
    },

    /**
     * APIMethod: getViewPortPxFromLonLat
     * 
     * Parameters:
     * lonlat - {<OpenLayers.LonLat>}
     * 
     * Returns:
     * {<OpenLayers.Pixel>} An OpenLayers.Pixel which is the passed-in 
     *                      <OpenLayers.LonLat>, translated into view port 
     *                      pixels by the current base layer.
     */
    getViewPortPxFromLonLat: function (lonlat) {
        var px = null; 
        if (this.baseLayer != null) {
            px = this.baseLayer.getViewPortPxFromLonLat(lonlat);
        }
        return px;
    },

    
  //
  // CONVENIENCE TRANSLATION FUNCTIONS FOR API
  //

    /**
     * APIMethod: getLonLatFromPixel
     * 
     * Parameters:
     * px - {<OpenLayers.Pixel>}
     *
     * Returns:
     * {<OpenLayers.LonLat>} An OpenLayers.LonLat corresponding to the given
     *                       OpenLayers.Pixel, translated into lon/lat by the 
     *                       current base layer
     */
    getLonLatFromPixel: function (px) {
        return this.getLonLatFromViewPortPx(px);
    },

    /**
     * APIMethod: getPixelFromLonLat
     * Returns a pixel location given a map location.  The map location is
     *     translated to an integer pixel location (in viewport pixel
     *     coordinates) by the current base layer.
     * 
     * Parameters:
     * lonlat - {<OpenLayers.LonLat>} A map location.
     * 
     * Returns: 
     * {<OpenLayers.Pixel>} An OpenLayers.Pixel corresponding to the 
     *     <OpenLayers.LonLat> translated into view port pixels by the current
     *     base layer.
     */
    getPixelFromLonLat: function (lonlat) {
        var px = this.getViewPortPxFromLonLat(lonlat);
        px.x = Math.round(px.x);
        px.y = Math.round(px.y);
        return px;
    },
    
    /**
     * Method: getGeodesicPixelSize
     * 
     * Parameters:
     * px - {<OpenLayers.Pixel>} The pixel to get the geodesic length for. If
     *     not provided, the center pixel of the map viewport will be used.
     * 
     * Returns:
     * {<OpenLayers.Size>} The geodesic size of the pixel in kilometers.
     */
    getGeodesicPixelSize: function(px) {
        var lonlat = px ? this.getLonLatFromPixel(px) : (
            this.getCachedCenter() || new OpenLayers.LonLat(0, 0));
        var res = this.getResolution();
        var left = lonlat.add(-res / 2, 0);
        var right = lonlat.add(res / 2, 0);
        var bottom = lonlat.add(0, -res / 2);
        var top = lonlat.add(0, res / 2);
        var dest = new OpenLayers.Projection("EPSG:4326");
        var source = this.getProjectionObject() || dest;
        if(!source.equals(dest)) {
            left.transform(source, dest);
            right.transform(source, dest);
            bottom.transform(source, dest);
            top.transform(source, dest);
        }
        
        return new OpenLayers.Size(
            OpenLayers.Util.distVincenty(left, right),
            OpenLayers.Util.distVincenty(bottom, top)
        );
    },



  //
  // TRANSLATION: ViewPortPx <-> LayerPx
  //

    /**
     * APIMethod: getViewPortPxFromLayerPx
     * 
     * Parameters:
     * layerPx - {<OpenLayers.Pixel>}
     * 
     * Returns:
     * {<OpenLayers.Pixel>} Layer Pixel translated into ViewPort Pixel 
     *                      coordinates
     */
    getViewPortPxFromLayerPx:function(layerPx) {
        var viewPortPx = null;
        if (layerPx != null) {
            var dX = parseInt(this.layerContainerDiv.style.left);
            var dY = parseInt(this.layerContainerDiv.style.top);
            viewPortPx = layerPx.add(dX, dY);            
        }
        return viewPortPx;
    },
    
    /**
     * APIMethod: getLayerPxFromViewPortPx
     * 
     * Parameters:
     * viewPortPx - {<OpenLayers.Pixel>}
     * 
     * Returns:
     * {<OpenLayers.Pixel>} ViewPort Pixel translated into Layer Pixel 
     *                      coordinates
     */
    getLayerPxFromViewPortPx:function(viewPortPx) {
        var layerPx = null;
        if (viewPortPx != null) {
            var dX = -parseInt(this.layerContainerDiv.style.left);
            var dY = -parseInt(this.layerContainerDiv.style.top);
            layerPx = viewPortPx.add(dX, dY);
            if (isNaN(layerPx.x) || isNaN(layerPx.y)) {
                layerPx = null;
            }
        }
        return layerPx;
    },
    
  //
  // TRANSLATION: LonLat <-> LayerPx
  //

    /**
     * Method: getLonLatFromLayerPx
     * 
     * Parameters:
     * px - {<OpenLayers.Pixel>}
     *
     * Returns:
     * {<OpenLayers.LonLat>}
     */
    getLonLatFromLayerPx: function (px) {
       //adjust for displacement of layerContainerDiv
       px = this.getViewPortPxFromLayerPx(px);
       return this.getLonLatFromViewPortPx(px);         
    },
    
    /**
     * APIMethod: getLayerPxFromLonLat
     * 
     * Parameters:
     * lonlat - {<OpenLayers.LonLat>} lonlat
     *
     * Returns:
     * {<OpenLayers.Pixel>} An OpenLayers.Pixel which is the passed-in 
     *                      <OpenLayers.LonLat>, translated into layer pixels 
     *                      by the current base layer
     */
    getLayerPxFromLonLat: function (lonlat) {
       //adjust for displacement of layerContainerDiv
       var px = this.getPixelFromLonLat(lonlat);
       return this.getLayerPxFromViewPortPx(px);         
    },

    CLASS_NAME: "OpenLayers.Map"
});

/**
 * Constant: TILE_WIDTH
 * {Integer} 256 Default tile width (unless otherwise specified)
 */
OpenLayers.Map.TILE_WIDTH = 256;
/**
 * Constant: TILE_HEIGHT
 * {Integer} 256 Default tile height (unless otherwise specified)
 */
OpenLayers.Map.TILE_HEIGHT = 256;