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/* Copyright (c) 2006-2013 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the 2-clause BSD license.
* See license.txt in the OpenLayers distribution or repository for the
* full text of the license. */
/**
* @requires OpenLayers/Layer/XYZ.js
* @requires OpenLayers/Tile/UTFGrid.js
*/
/**
* Class: OpenLayers.Layer.UTFGrid
* This Layer reads from UTFGrid tiled data sources. Since UTFGrids are
* essentially JSON-based ASCII art with attached attributes, they are not
* visibly rendered. In order to use them in the map, you must add a
* <OpenLayers.Control.UTFGrid> control as well.
*
* Example:
*
* (start code)
* var world_utfgrid = new OpenLayers.Layer.UTFGrid({
* url: "/tiles/world_utfgrid/${z}/${x}/${y}.json",
* utfgridResolution: 4,
* displayInLayerSwitcher: false
* );
* map.addLayer(world_utfgrid);
*
* var control = new OpenLayers.Control.UTFGrid({
* layers: [world_utfgrid],
* handlerMode: 'move',
* callback: function(dataLookup) {
* // do something with returned data
* }
* })
* (end code)
*
*
* Inherits from:
* - <OpenLayers.Layer.XYZ>
*/
OpenLayers.Layer.UTFGrid = OpenLayers.Class(OpenLayers.Layer.XYZ, {
/**
* APIProperty: isBaseLayer
* Default is false, as UTFGrids are designed to be a transparent overlay layer.
*/
isBaseLayer: false,
/**
* APIProperty: projection
* {<OpenLayers.Projection>}
* Source projection for the UTFGrids. Default is "EPSG:900913".
*/
projection: new OpenLayers.Projection("EPSG:900913"),
/**
* Property: useJSONP
* {Boolean}
* Should we use a JSONP script approach instead of a standard AJAX call?
*
* Set to true for using utfgrids from another server.
* Avoids same-domain policy restrictions.
* Note that this only works if the server accepts
* the callback GET parameter and dynamically
* wraps the returned json in a function call.
*
* Default is false
*/
useJSONP: false,
/**
* APIProperty: url
* {String}
* URL tempate for UTFGrid tiles. Include x, y, and z parameters.
* E.g. "/tiles/${z}/${x}/${y}.json"
*/
/**
* APIProperty: utfgridResolution
* {Number}
* Ratio of the pixel width to the width of a UTFGrid data point. If an
* entry in the grid represents a 4x4 block of pixels, the
* utfgridResolution would be 4. Default is 2 (specified in
* <OpenLayers.Tile.UTFGrid>).
*/
/**
* Property: tileClass
* {<OpenLayers.Tile>} The tile class to use for this layer.
* Defaults is <OpenLayers.Tile.UTFGrid>.
*/
tileClass: OpenLayers.Tile.UTFGrid,
/**
* Constructor: OpenLayers.Layer.UTFGrid
* Create a new UTFGrid layer.
*
* Parameters:
* config - {Object} Configuration properties for the layer.
*
* Required configuration properties:
* url - {String} The url template for UTFGrid tiles. See the <url> property.
*/
initialize: function(options) {
OpenLayers.Layer.Grid.prototype.initialize.apply(
this, [options.name, options.url, {}, options]
);
this.tileOptions = OpenLayers.Util.extend({
utfgridResolution: this.utfgridResolution
}, this.tileOptions);
},
/**
* Method: createBackBuffer
* The UTFGrid cannot create a back buffer, so this method is overriden.
*/
createBackBuffer: function() {},
/**
* APIMethod: clone
* Create a clone of this layer
*
* Parameters:
* obj - {Object} Only used by a subclass of this layer.
*
* Returns:
* {<OpenLayers.Layer.UTFGrid>} An exact clone of this OpenLayers.Layer.UTFGrid
*/
clone: function (obj) {
if (obj == null) {
obj = new OpenLayers.Layer.UTFGrid(this.getOptions());
}
// get all additions from superclasses
obj = OpenLayers.Layer.Grid.prototype.clone.apply(this, [obj]);
return obj;
},
/**
* APIProperty: getFeatureInfo
* Get details about a feature associated with a map location. The object
* returned will have id and data properties. If the given location
* doesn't correspond to a feature, null will be returned.
*
* Parameters:
* location - {<OpenLayers.LonLat>} map location
*
* Returns:
* {Object} Object representing the feature id and UTFGrid data
* corresponding to the given map location. Returns null if the given
* location doesn't hit a feature.
*/
getFeatureInfo: function(location) {
var info = null;
var tileInfo = this.getTileData(location);
if (tileInfo && tileInfo.tile) {
info = tileInfo.tile.getFeatureInfo(tileInfo.i, tileInfo.j);
}
return info;
},
/**
* APIMethod: getFeatureId
* Get the identifier for the feature associated with a map location.
*
* Parameters:
* location - {<OpenLayers.LonLat>} map location
*
* Returns:
* {String} The feature identifier corresponding to the given map location.
* Returns null if the location doesn't hit a feature.
*/
getFeatureId: function(location) {
var id = null;
var info = this.getTileData(location);
if (info.tile) {
id = info.tile.getFeatureId(info.i, info.j);
}
return id;
},
CLASS_NAME: "OpenLayers.Layer.UTFGrid"
});
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