/* Copyright (c) 2006-2007 MetaCarta, Inc., published under the BSD licence. * See http://svn.openlayers.org/trunk/openlayers/release-license.txt  * for the full text of the license. *//** * @requires OpenLayers/Layer/Grid.js * * Class: OpenLayers.Layer.TileCache * A read only TileCache layer.  Used to requests tiles cached by TileCache in *     a web accessible cache.  Create a new instance with the *     <OpenLayers.Layer.TileCache> constructor. * * Inherits from: *  - <OpenLayers.Layer.Grid> */OpenLayers.Layer.TileCache = OpenLayers.Class(OpenLayers.Layer.Grid, {    /**      * APIProperty: isBaseLayer     * {Boolean} Treat this layer as a base layer.  Default is true.     */    isBaseLayer: true,        /**     * APIProperty: tileOrigin     * {<OpenLayers.LonLat>} Location of the tile lattice origin.  Default is     *     bottom left of the maxExtent.     */    tileOrigin: null,        /**      * APIProperty: format     * {String} Mime type of the images returned.  Default is image/png.     */    format: 'image/png',    /**     * Constructor: OpenLayers.Layer.TileCache     * Create a new read only TileCache layer.     *     * Parameters:     * name - {String} Name of the layer displayed in the interface     * url - {String} Location of the web accessible cache     * layername - {String} Layer name as defined in the TileCache      *     configuration     * options - {Object} Hashtable of extra options to tag onto the layer     */    initialize: function(name, url, layername, options) {        options = OpenLayers.Util.extend({maxResolution: 180/256}, options);        this.layername = layername;        OpenLayers.Layer.Grid.prototype.initialize.apply(this,                                                         [name, url, {}, options]);        this.extension = this.format.split('/')[1].toLowerCase();        this.extension = (this.extension == 'jpeg') ? 'jpg' : this.extension;    },        /**     * APIMethod: clone     * obj - {Object}      *      * Returns:     * {<OpenLayers.Layer.TileCache>} An exact clone of this      *     <OpenLayers.Layer.TileCache>     */    clone: function (obj) {                if (obj == null) {            obj = new OpenLayers.Layer.TileCache(this.name,                                           this.url,                                           this.options);        }        //get all additions from superclasses        obj = OpenLayers.Layer.Grid.prototype.clone.apply(this, [obj]);        // copy/set any non-init, non-simple values here        return obj;    },            /**     * Method: getURL     *     * Parameters:     * bounds - {<OpenLayers.Bounds>}      *      * Returns:     * {String} A string with the layer's url and parameters and also the      *     passed-in bounds and appropriate tile size specified as parameters.     */    getURL: function(bounds) {        var res = this.map.getResolution();        var bbox = this.maxExtent;        var size = this.tileSize;        var tileX = Math.floor((bounds.left - bbox.left) / (res * size.w));        var tileY = Math.floor((bounds.bottom - bbox.bottom) / (res * size.h));        var tileZ = this.map.zoom;        /**         * Zero-pad a positive integer.         * number - {Int}          * length - {Int}          *         * Returns:         * {String} A zero-padded string         */        function zeroPad(number, length) {            number = String(number);            var zeros = [];            for(var i=0; i<length; ++i) {                zeros.push('0');            }            return zeros.join('').substring(0, length - number.length) + number;        }        var components = [            this.layername,            zeroPad(tileZ, 2),            zeroPad(parseInt(tileX / 1000000), 3),            zeroPad((parseInt(tileX / 1000) % 1000), 3),            zeroPad((parseInt(tileX) % 1000), 3),            zeroPad(parseInt(tileY / 1000000), 3),            zeroPad((parseInt(tileY / 1000) % 1000), 3),            zeroPad((parseInt(tileY) % 1000), 3) + '.' + this.extension        ];        var path = components.join('/');         var url = this.url;        if (url instanceof Array) {            url = this.selectUrl(path, url);        }        url = (url.charAt(url.length - 1) == '/') ? url : url + '/';        return url + path;    },    /**     * Method: addTile     * Create a tile, initialize it, and add it to the layer div.      *     * Parameters:      * bounds - {<OpenLayers.Bounds>}      *     * Returns:     * {<OpenLayers.Tile.Image>} The added <OpenLayers.Tile.Image>     */    addTile:function(bounds, position) {        var url = this.getURL(bounds);        return new OpenLayers.Tile.Image(this, position, bounds,                                              url, this.tileSize);    },    /**      * Method: setMap     * When the layer is added to a map, then we can fetch our origin      *     (if we don't have one.)      *      * Parameters:     * map - {<OpenLayers.Map>}      */    setMap: function(map) {        OpenLayers.Layer.Grid.prototype.setMap.apply(this, arguments);        if (!this.tileOrigin) {             this.tileOrigin = new OpenLayers.LonLat(this.map.maxExtent.left,                                                    this.map.maxExtent.bottom);        }    },    CLASS_NAME: "OpenLayers.Layer.TileCache"});