openlayers/lib/OpenLayers/Tile/WFS.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/Tile.js
   8  * @requires OpenLayers/Request/XMLHttpRequest.js
   9  */
  10
  11 /**
  12  * Class: OpenLayers.Tile.WFS
  13  * Instances of OpenLayers.Tile.WFS are used to manage the image tiles
  14  * used by various layers.  Create a new image tile with the
  15  * <OpenLayers.Tile.WFS> constructor.
  16  *
  17  * Inherits from:
  18  *  - <OpenLayers.Tile>
  19  */
  20 OpenLayers.Tile.WFS = OpenLayers.Class(OpenLayers.Tile, {
  21
  22     /**
  23      * Property: features
  24      * {Array(<OpenLayers.Feature>)} list of features in this tile
  25      */
  26     features: null,
  27
  28     /**
  29      * Property: url
  30      * {String}
  31      */
  32     url: null,
  33
  34     /**
  35      * Property: request
  36      * {<OpenLayers.Request.XMLHttpRequest>}
  37      */
  38     request: null,
  39
  40     /** TBD 3.0 - reorder the parameters to the init function to put URL
  41      *             as last, so we can continue to call tile.initialize()
  42      *             without changing the arguments.
  43      *
  44      * Constructor: OpenLayers.Tile.WFS
  45      * Constructor for a new <OpenLayers.Tile.WFS> instance.
  46      *
  47      * Parameters:
  48      * layer - {<OpenLayers.Layer>} layer that the tile will go in.
  49      * position - {<OpenLayers.Pixel>}
  50      * bounds - {<OpenLayers.Bounds>}
  51      * url - {<String>}
  52      * size - {<OpenLayers.Size>}
  53      */
  54     initialize: function(layer, position, bounds, url, size) {
  55         OpenLayers.Tile.prototype.initialize.apply(this, arguments);
  56         this.url = url;
  57         this.features = [];
  58     },
  59
  60     /**
  61      * APIMethod: destroy
  62      * nullify references to prevent circular references and memory leaks
  63      */
  64     destroy: function() {
  65         OpenLayers.Tile.prototype.destroy.apply(this, arguments);
  66         this.destroyAllFeatures();
  67         this.features = null;
  68         this.url = null;
  69         if(this.request) {
  70             this.request.abort();
  71             //this.request.destroy();
  72             this.request = null;
  73         }
  74     },
  75
  76     /**
  77      * Method: clear
  78      *  Clear the tile of any bounds/position-related data so that it can
  79      *   be reused in a new location.
  80      */
  81     clear: function() {
  82         this.destroyAllFeatures();
  83     },
  84
  85     /**
  86      * Method: draw
  87      * Check that a tile should be drawn, and load features for it.
  88      */
  89     draw:function() {
  90         if (OpenLayers.Tile.prototype.draw.apply(this, arguments)) {
  91             if (this.isLoading) {
  92                 //if already loading, send 'reload' instead of 'loadstart'.
  93                 this.events.triggerEvent("reload");
  94             } else {
  95                 this.isLoading = true;
  96                 this.events.triggerEvent("loadstart");
  97             }
  98             this.loadFeaturesForRegion(this.requestSuccess);
  99         }
 100     },
 101
 102     /**
 103     * Method: loadFeaturesForRegion
 104     * Abort any pending requests and issue another request for data.
 105     *
 106     * Input are function pointers for what to do on success and failure.
 107     *
 108     * Parameters:
 109     * success - {function}
 110     * failure - {function}
 111     */
 112     loadFeaturesForRegion:function(success, failure) {
 113         if(this.request) {
 114             this.request.abort();
 115         }
 116         this.request = OpenLayers.Request.GET({
 117             url: this.url,
 118             success: success,
 119             failure: failure,
 120             scope: this
 121         });
 122     },
 123
 124     /**
 125     * Method: requestSuccess
 126     * Called on return from request succcess. Adds results via
 127     * layer.addFeatures in vector mode, addResults otherwise.
 128     *
 129     * Parameters:
 130     * request - {<OpenLayers.Request.XMLHttpRequest>}
 131     */
 132     requestSuccess:function(request) {
 133         if (this.features) {
 134             var doc = request.responseXML;
 135             if (!doc || !doc.documentElement) {
 136                 doc = request.responseText;
 137             }
 138             if (this.layer.vectorMode) {
 139                 this.layer.addFeatures(this.layer.formatObject.read(doc));
 140             } else {
 141                 var xml = new OpenLayers.Format.XML();
 142                 if (typeof doc == "string") {
 143                     doc = xml.read(doc);
 144                 }
 145                 var resultFeatures = xml.getElementsByTagNameNS(
 146                     doc, "http://www.opengis.net/gml", "featureMember"
 147                 );
 148                 this.addResults(resultFeatures);
 149             }
 150         }
 151         if (this.events) {
 152             this.events.triggerEvent("loadend");
 153         }
 154
 155         //request produced with success, we can delete the request object.
 156         //this.request.destroy();
 157         this.request = null;
 158     },
 159
 160     /**
 161      * Method: addResults
 162      * Construct new feature via layer featureClass constructor, and add to
 163      * this.features.
 164      *
 165      * Parameters:
 166      * results - {Object}
 167      */
 168     addResults: function(results) {
 169         for (var i=0; i < results.length; i++) {
 170             var feature = new this.layer.featureClass(this.layer,
 171                                                       results[i]);
 172             this.features.push(feature);
 173         }
 174     },
 175
 176
 177     /**
 178      * Method: destroyAllFeatures
 179      * Iterate through and call destroy() on each feature, removing it from
 180      *   the local array
 181      */
 182     destroyAllFeatures: function() {
 183         while(this.features.length > 0) {
 184             var feature = this.features.shift();
 185             feature.destroy();
 186         }
 187     },
 188
 189     CLASS_NAME: "OpenLayers.Tile.WFS"
 190   }
 191 );