openlayers/lib/OpenLayers/Layer/WorldWind.js

   1 /* Copyright (c) 2006-2008 MetaCarta, Inc., published under the Clear BSD
   2  * license.  See http://svn.openlayers.org/trunk/openlayers/license.txt for the
   3  * full text of the license. */
   4
   5
   6 /**
   7  * @requires OpenLayers/Layer/Grid.js
   8  */
   9
  10 /**
  11  * Class: OpenLayers.Layer.WorldWind
  12  *
  13  * Inherits from:
  14  *  - <OpenLayers.Layer.Grid>
  15  */
  16 OpenLayers.Layer.WorldWind = OpenLayers.Class(OpenLayers.Layer.Grid, {
  17
  18     DEFAULT_PARAMS: {
  19     },
  20
  21     /**
  22      * APIProperty: isBaseLayer
  23      * WorldWind layer is a base layer by default.
  24      */
  25     isBaseLayer: true,
  26
  27
  28     /**
  29      * APIProperty: lzd
  30      * LevelZeroTileSizeDegrees
  31      */
  32     lzd: null,
  33
  34     /**
  35      * APIProperty: zoomLevels
  36      * Number of zoom levels.
  37      */
  38     zoomLevels: null,
  39
  40     /**
  41      * Constructor: OpenLayers.Layer.WorldWind
  42      *
  43      * Parameters:
  44      * name - {String} Name of Layer
  45      * url - {String} Base URL
  46      * lzd - {Float} Level zero tile size degrees
  47      * zoomLevels - {Int} number of zoom levels
  48      * params - {Object} additional parameters
  49      * options - {Object} additional options
  50      */
  51     initialize: function(name, url, lzd, zoomLevels, params, options) {
  52         this.lzd = lzd;
  53         this.zoomLevels = zoomLevels;
  54         var newArguments = [];
  55         newArguments.push(name, url, params, options);
  56         OpenLayers.Layer.Grid.prototype.initialize.apply(this, newArguments);
  57         this.params = OpenLayers.Util.applyDefaults(
  58             this.params, this.DEFAULT_PARAMS
  59         );
  60     },
  61     /**
  62      * Method: addTile
  63      *
  64      * Parameters:
  65      * bounds - {<OpenLayers.Bounds>}
  66      * position - {<OpenLayers.Pixel>}
  67      *
  68      * Returns:
  69      * {<OpenLayers.Tile.Image>} The added OpenLayers.Tile.Image
  70      */
  71     addTile:function(bounds,position) {
  72         return new OpenLayers.Tile.Image(this, position, bounds,
  73                                              null, this.tileSize);
  74     },
  75
  76     /**
  77      * Method: getZoom
  78      * Convert map zoom to WW zoom.
  79      */
  80     getZoom: function () {
  81         var zoom = this.map.getZoom();
  82         var extent = this.map.getMaxExtent();
  83         zoom = zoom - Math.log(this.maxResolution / (this.lzd/512))/Math.log(2);
  84         return zoom;
  85     },
  86
  87     /**
  88      * Method: getURL
  89      *
  90      * Parameters:
  91      * bounds - {<OpenLayers.Bounds>}
  92      *
  93      * Returns:
  94      * {String} A string with the layer's url and parameters and also the
  95      *           passed-in bounds and appropriate tile size specified as
  96      *           parameters
  97      */
  98     getURL: function (bounds) {
  99         bounds = this.adjustBounds(bounds);
 100         var zoom = this.getZoom();
 101         var extent = this.map.getMaxExtent();
 102         var deg = this.lzd/Math.pow(2,this.getZoom());
 103         var x = Math.floor((bounds.left - extent.left)/deg);
 104         var y = Math.floor((bounds.bottom - extent.bottom)/deg);
 105         if (this.map.getResolution() <= (this.lzd/512)
 106             && this.getZoom() <= this.zoomLevels) {
 107             return this.getFullRequestString(
 108               { L: zoom,
 109                 X: x,
 110                 Y: y
 111               });
 112         } else {
 113             return OpenLayers.Util.getImagesLocation() + "blank.gif";
 114         }
 115
 116     },
 117
 118     CLASS_NAME: "OpenLayers.Layer.WorldWind"
 119 });