Implementing GetFeatureInfo for WMS

src/ol/source/singleimagewmssource.js

@@ -1,8 +1,11 @@
 goog.provide('ol.source.SingleImageWMS');
 
+goog.require('goog.asserts');
+goog.require('goog.uri.utils');
 goog.require('ol.Image');
 goog.require('ol.ImageUrlFunction');
 goog.require('ol.extent');
+goog.require('ol.source.FeatureInfoSource');
 goog.require('ol.source.ImageSource');
 goog.require('ol.source.wms');
 
@@ -11,6 +14,7 @@ goog.require('ol.source.wms');
 /**
  * @constructor
  * @extends {ol.source.ImageSource}
+ * @implements {ol.source.FeatureInfoSource}
  * @param {ol.source.SingleImageWMSOptions} options Options.
  */
 ol.source.SingleImageWMS = function(options) {
@@ -28,6 +32,13 @@ ol.source.SingleImageWMS = function(options) {
     imageUrlFunction: imageUrlFunction
   });
 
+  /**
+   * @private
+   * @type {ol.source.WMSGetFeatureInfoOptions}
+   */
+  this.getFeatureInfoOptions_ = goog.isDef(options.getFeatureInfoOptions) ?
+      options.getFeatureInfoOptions : {};
+
   /**
    * @private
    * @type {ol.Image}
@@ -68,3 +79,30 @@ ol.source.SingleImageWMS.prototype.getImage =
   this.image_ = this.createImage(extent, resolution, size, projection);
   return this.image_;
 };
+
+
+/**
+ * @inheritDoc
+ */
+ol.source.SingleImageWMS.prototype.getFeatureInfoForPixel =
+    function(pixel, map, success, opt_error) {
+  var view2D = map.getView().getView2D(),
+      projection = view2D.getProjection(),
+      size = map.getSize(),
+      bottomLeft = map.getCoordinateFromPixel([0, size[1]]),
+      topRight = map.getCoordinateFromPixel([size[0], 0]),
+      extent = [bottomLeft[0], topRight[0], bottomLeft[1], topRight[1]],
+      x = pixel[0],
+      y = pixel[1],
+      url = this.imageUrlFunction(extent, size, projection);
+  goog.asserts.assert(goog.isDef(url),
+      'ol.source.SingleImageWMS#imageUrlFunction does not return a url');
+  // TODO: X, Y is for WMS 1.1 and I, J for 1.3 - without a closure url
+  // function this could be set conditionally.
+  url = goog.uri.utils.appendParamsFromMap(url, {
+    'X': x, 'I': x,
+    'Y': y, 'J': y
+  });
+  ol.source.wms.getFeatureInfo(url, this.getFeatureInfoOptions_, success,
+      opt_error);
+};

src/ol/source/tiledwmssource.js

@@ -3,10 +3,13 @@
 goog.provide('ol.source.TiledWMS');
 
 goog.require('goog.array');
+goog.require('goog.asserts');
 goog.require('goog.math');
+goog.require('goog.uri.utils');
 goog.require('ol.TileCoord');
 goog.require('ol.TileUrlFunction');
 goog.require('ol.extent');
+goog.require('ol.source.FeatureInfoSource');
 goog.require('ol.source.ImageTileSource');
 goog.require('ol.source.wms');
 
@@ -15,9 +18,11 @@ goog.require('ol.source.wms');
 /**
  * @constructor
  * @extends {ol.source.ImageTileSource}
+ * @implements {ol.source.FeatureInfoSource}
  * @param {ol.source.TiledWMSOptions} options Tiled WMS options.
  */
 ol.source.TiledWMS = function(options) {
+
   var tileGrid;
   if (goog.isDef(options.tileGrid)) {
     tileGrid = options.tileGrid;
@@ -28,6 +33,7 @@ ol.source.TiledWMS = function(options) {
   if (!goog.isDef(urls) && goog.isDef(options.url)) {
     urls = ol.TileUrlFunction.expandUrl(options.url);
   }
+
   if (goog.isDef(urls)) {
     var tileUrlFunctions = goog.array.map(
         urls, function(url) {
@@ -81,5 +87,42 @@ ol.source.TiledWMS = function(options) {
         tileCoordTransform, tileUrlFunction)
   });
 
+  /**
+   * @private
+   * @type {ol.source.WMSGetFeatureInfoOptions}
+   */
+  this.getFeatureInfoOptions_ = goog.isDef(options.getFeatureInfoOptions) ?
+      options.getFeatureInfoOptions : {};
+
 };
 goog.inherits(ol.source.TiledWMS, ol.source.ImageTileSource);
+
+
+/**
+ * @inheritDoc
+ */
+ol.source.TiledWMS.prototype.getFeatureInfoForPixel =
+    function(pixel, map, success, opt_error) {
+  var coord = map.getCoordinateFromPixel(pixel),
+      view2D = map.getView().getView2D(),
+      projection = view2D.getProjection(),
+      tileGrid = goog.isNull(this.tileGrid) ?
+          ol.tilegrid.getForProjection(projection) : tileGrid,
+      tileCoord = tileGrid.getTileCoordForCoordAndResolution(coord,
+          view2D.getResolution()),
+      tileExtent = tileGrid.getTileCoordExtent(tileCoord),
+      offset = map.getPixelFromCoordinate(ol.extent.getTopLeft(tileExtent)),
+      x = Math.round(pixel[0] - offset[0]),
+      y = Math.round(pixel[1] - offset[1]),
+      url = this.tileUrlFunction(tileCoord, projection);
+  goog.asserts.assert(goog.isDef(url),
+      'ol.source.TiledWMS#tileUrlFunction does not return a url');
+  // TODO: X, Y is for WMS 1.1 and I, J for 1.3 - without a closure url
+  // function this could be set conditionally.
+  url = goog.uri.utils.appendParamsFromMap(url, {
+    'X': x, 'I': x,
+    'Y': y, 'J': y
+  });
+  ol.source.wms.getFeatureInfo(url, this.getFeatureInfoOptions_, success,
+      opt_error);
+};

src/ol/source/wmssource.exports

@@ -0,0 +1 @@
+@exportSymbol ol.source.WMSGetFeatureInfoMethod

src/ol/source/wmssource.js

@@ -1,9 +1,29 @@
+goog.provide('ol.source.WMSGetFeatureInfoMethod');
 goog.provide('ol.source.wms');
 
+goog.require('goog.net.XhrIo');
 goog.require('goog.object');
 goog.require('goog.uri.utils');
 
 
+/**
+ * Method to use to get WMS feature info.
+ * @enum {string}
+ */
+ol.source.WMSGetFeatureInfoMethod = {
+  /**
+   * Load the info in an IFRAME. Only works with 'text/html and 'text/plain' as
+   * `INFO_FORMAT`.
+   */
+  IFRAME: 'iframe',
+  /**
+   * Use an asynchronous GET request. Requires CORS headers or a server at the
+   * same origin as the application script.
+   */
+  XHR_GET: 'xhr_get'
+};
+
+
 /**
  * @param {string} baseUrl WMS base url.
  * @param {Object.<string, string|number>} params Request parameters.
@@ -40,3 +60,43 @@ ol.source.wms.getUrl =
 
   return goog.uri.utils.appendParamsFromMap(baseUrl, baseParams);
 };
+
+
+/**
+ * @param {string} url URL as provided by the url function, with added I, J, X
+ *     and Y params.
+ * @param {Object} options Options as defined in the source.
+ * @param {function(string)} success Callback function for successful queries.
+ * @param {function()=} opt_error Optional callback function for unsuccessful
+ *     queries.
+ */
+ol.source.wms.getFeatureInfo = function(url, options, success, opt_error) {
+  options = goog.isDef(options) ? goog.object.clone(options) : {};
+  goog.object.extend(options, {
+    method: ol.source.WMSGetFeatureInfoMethod.IFRAME,
+    params: {}
+  });
+  var params = {
+    'INFO_FORMAT': 'text/html'
+  };
+  goog.object.extend(params, options.params);
+  url = goog.uri.utils.appendParamsFromMap(url, params);
+  // TODO: This could be done in a smarter way if the url function was not a
+  // closure
+  url = url.replace('REQUEST=GetMap', 'REQUEST=GetFeatureInfo')
+      .replace(/LAYERS=([^&]+)/, 'LAYERS=$1&QUERY_LAYERS=$1');
+  if (options.method == ol.source.WMSGetFeatureInfoMethod.IFRAME) {
+    goog.global.setTimeout(function() {
+      success('<iframe seamless src="' + url + '"></iframe');
+    }, 0);
+  } else if (options.method == ol.source.WMSGetFeatureInfoMethod.XHR_GET) {
+    goog.net.XhrIo.send(url, function(event) {
+      var xhr = event.target;
+      if (xhr.isSuccess()) {
+        success(xhr.getResponseText());
+      } else if (goog.isDef(opt_error)) {
+        opt_error();
+      }
+    });
+  }
+};