Instances of OpenLayers.Tile.UTFGrid are used to manage UTFGrids. This is an unusual tile type in that it doesn’t have a rendered image; only a ‘hit grid’ that can be used to look up feature attributes.
See the OpenLayers.Tile.UTFGrid constructor for details on constructing a new instance.
| OpenLayers. | Instances of OpenLayers.Tile.UTFGrid are used to manage UTFGrids. | 
| Properties | |
| url | {String} The URL of the UTFGrid file being requested. | 
| utfgridResolution | {Number} Ratio of the pixel width to the width of a UTFGrid data point. | 
| json | {Object} Stores the parsed JSON tile data structure. | 
| format | {OpenLayers.Format.JSON} Parser instance used to parse JSON for cross browser support. | 
| Constructor | |
| OpenLayers. | Constructor for a new OpenLayers.Tile.UTFGrid instance. | 
| Functions | |
| destroy | Clean up. | 
| draw | Check that a tile should be drawn, and draw it. | 
| abortLoading | Cancel a pending request. | 
| getFeatureInfo | Get feature information associated with a pixel offset. | 
| getFeatureId | Get the identifier for the feature associated with a pixel offset. | 
| indexFromCharCode | Given a character code for one of the UTFGrid “grid” characters, resolve the integer index for the feature id in the UTFGrid “keys” array. | 
| parseData | Parse the JSON from a request | 
| clear | Delete data stored with this tile. | 
{String} The URL of the UTFGrid file being requested. Provided by the getURL method.
Constructor for a new OpenLayers.Tile.UTFGrid instance.
| layer | {OpenLayers.Layer} layer that the tile will go in. | 
| position | {OpenLayers.Pixel} | 
| bounds | {OpenLayers.Bounds} | 
| url | {String} Deprecated. Remove me in 3.0. | 
| size | {OpenLayers.Size} | 
| options | {Object} | 
getFeatureInfo: function( i, j ) 
Get feature information associated with a pixel offset. If the pixel offset corresponds to a feature, the returned object will have id and data properties. Otherwise, null will be returned.
| i | {Number} X-axis pixel offset (from top left of tile) | 
| j | {Number} Y-axis pixel offset (from top left of tile) | 
{Object} Object with feature id and data properties corresponding to the given pixel offset.
getFeatureId: function( i, j ) 
Get the identifier for the feature associated with a pixel offset.
| i | {Number} X-axis pixel offset (from top left of tile) | 
| j | {Number} Y-axis pixel offset (from top left of tile) | 
{Object} The feature identifier corresponding to the given pixel offset. Returns null if pixel doesn’t correspond to a feature.
Clean up.
destroy: function() 
Check that a tile should be drawn, and draw it.
draw: function() 
Cancel a pending request.
abortLoading: function() 
Get feature information associated with a pixel offset.
getFeatureInfo: function( i, j ) 
Get the identifier for the feature associated with a pixel offset.
getFeatureId: function( i, j ) 
Given a character code for one of the UTFGrid “grid” characters, resolve the integer index for the feature id in the UTFGrid “keys” array.
indexFromCharCode: function( charCode ) 
Parse the JSON from a request
parseData: function( str ) 
Delete data stored with this tile.
clear: function() 
Determine the URL for a tile given the tile bounds.
getURL: function ( bounds )