Layer and tile API update.

The tile now has responsibility for resolving feature ids and fetching feature data given x, y pixel offsets with getFeatureId and getFeatureData methods.  The layer has corresponding getFeatureId and getFeatureData methods that take a map location, lookup the appropriate tile, and delegate to the tile for the rest of the work.

lib/OpenLayers/Layer/UTFGrid.js

@@ -107,6 +107,9 @@ OpenLayers.Layer.UTFGrid = OpenLayers.Class(OpenLayers.Layer.Grid, {
      */
     initialize: function(name, url, options) {
         OpenLayers.Layer.Grid.prototype.initialize.apply(this, [name, url, {}, options]);
+        this.tileOptions = OpenLayers.Util.extend({
+            utfgridResolution: this.utfgridResolution
+        }, this.tileOptions);
     },
     
     /**
@@ -158,10 +161,12 @@ OpenLayers.Layer.UTFGrid = OpenLayers.Class(OpenLayers.Layer.Grid, {
 
     /**
      * APIProperty: utfgridResolution
-     * {Number} Number of pixels per grid "cell"
-     * Defaults to 4
+     * {Number}
+     * Ratio of the pixel width to the width of a UTFGrid data point.  If an 
+     *     entry in the grid represents a 2x2 block of pixels, the 
+     *     utfgridResolution would be 2.  Default is 4 (specified in 
+     *     <OpenLayers.Tile.UTFGrid>).
      */
-    utfgridResolution: 4,
 
     /** 
      * Method: getTileInfo
@@ -232,8 +237,8 @@ OpenLayers.Layer.UTFGrid = OpenLayers.Class(OpenLayers.Layer.Grid, {
     },
     
     /**
-     * APIProperty: getData
-     * Get tile data associated with a map location.
+     * APIProperty: getFeatureData
+     * Get feature data from UTFGrid associated with a map location.
      *
      * Parameters:
      * location - {<OpenLayers.LonLat>} map location
@@ -241,41 +246,32 @@ OpenLayers.Layer.UTFGrid = OpenLayers.Class(OpenLayers.Layer.Grid, {
      * Returns:
      * {Object} The UTFGrid data corresponding to the given map location.
      */
-    getData: function(location) {
-        var info = this.getTileInfo(location);
-        var tile = info.tile;
+    getFeatureData: function(location) {
         var data;
-        if (tile) {
-            var resolution = this.utfgridResolution;
-            var json = tile.json
-            if (json) {
-                var code = this.resolveCode(json.grid[ 
-                        Math.floor((info.j) / resolution) 
-                    ].charCodeAt(
-                        Math.floor((info.i) / resolution)
-                    ));
-                data = json.data[json.keys[code]];
-            }
+        var info = this.getTileInfo(location);
+        if (info.tile) {
+            data = info.tile.getFeatureData(info.i, info.j);
         }
         return data;
     },
 
     /**
-     * Method: resolveCode
-     * Resolve the UTF-8 encoding stored in grids to simple number values.  
-     *     See the UTFGrid spec for details.
+     * APIMethod: getFeatureId
+     * Get the identifier for the feature associated with a map location.
      *
      * Parameters:
-     * key - {Integer}
+     * location - {<OpenLayers.LonLat>} map location
      *
      * Returns:
-     * {Integer} Adjusted key for non-escaped chars
+     * {Object} The feature identifier corresponding to the given map location.
      */
-    resolveCode: function(key) {
-        if (key >= 93) key--;
-        if (key >= 35) key--;
-        key -= 32;
-        return key;
+    getFeatureId: function(location) {
+        var id;
+        var info = this.getTileInfo(location);
+        if (info.tile) {
+            id = info.tile.getFeatureId(info.i, info.j);
+        }
+        return id;
     },
 
     /**