Asynchronous API for map#getFeatureInfo

This change allows us to use feature info services on the
server. It will also be useful for the GetFeature control to
get results from a WFS.

examples/vector-layer.js

@@ -43,12 +43,17 @@ var map = new ol.Map({
 });
 
 map.on('mousemove', function(evt) {
-  var features = map.getFeatureInfoForPixel(evt.getPixel(), [vector]);
+  var features = map.getFeatureInfo({
+    pixel: evt.getPixel(),
+    layers: [vector],
+    success: function(features) {
       var info = [];
       for (var i = 0, ii = features.length; i < ii; ++i) {
         info.push(features[i].get('name'));
       }
       document.getElementById('info').innerHTML = info.join(', ') || '&nbsp;';
+    }
+  });
 });
 
 

src/objectliterals.jsdoc

@@ -5,6 +5,20 @@
  * @property {ol.ProjectionLike} projection Projection.
  */
 
+/**
+ * @typedef {Object} ol.GetFeatureInfoOptions
+ * @property {ol.Pixel} pixel Pixel coordinate relative to the map viewport.
+ * @property {Array.<ol.layer.Layer>|undefined} layers Layers to restrict the
+ *     query to. All layers will be queried if not provided.
+ * @property {function(Array.<ol.Feature|string>)} success Callback for
+ *     successful queries. The passed argument is the resulting feature
+ *     information.  Layers that are able to provide attribute data will put
+ *     ol.Feature instances, other layers will put a string which can either
+ *     be plain text or markup.
+ * @property {function(Object)|undefined} error Callback for unsuccessful
+ *     queries.
+ */
+
 /**
  * Object literal with config options for the map.
  * @typedef {Object} ol.MapOptions

src/ol/map.exports

@@ -2,7 +2,7 @@
 @exportProperty ol.Map.prototype.addLayer
 @exportProperty ol.Map.prototype.addPreRenderFunction
 @exportProperty ol.Map.prototype.addPreRenderFunctions
-@exportProperty ol.Map.prototype.getFeatureInfoForPixel
+@exportProperty ol.Map.prototype.getFeatureInfo
 @exportProperty ol.Map.prototype.getInteractions
 @exportProperty ol.Map.prototype.getRenderer
 @exportProperty ol.Map.prototype.removeLayer

src/ol/map.js

@@ -430,17 +430,13 @@ ol.Map.prototype.getCoordinateFromPixel = function(pixel) {
 /**
  * Get feature information for a pixel on the map.
  *
- * @param {ol.Pixel} pixel Pixel coordinate relative to the map viewport.
- * @param {Array.<ol.layer.Layer>=} opt_layers Layers to restrict the query to.
- *     All layers will be queried if not provided.
- * @return {Array.<ol.Feature|string>} Feature information.  Layers that are
- *     able to return attribute data will return ol.Feature instances, other
- *     layers will return a string which can either be plain text or markup.
+ * @param {ol.GetFeatureInfoOptions} options Options.
  */
-ol.Map.prototype.getFeatureInfoForPixel = function(pixel, opt_layers) {
-  var layers = goog.isDefAndNotNull(opt_layers) ?
-      opt_layers : this.getLayers().getArray();
-  return this.getRenderer().getFeatureInfoForPixel(pixel, layers);
+ol.Map.prototype.getFeatureInfo = function(options) {
+  var layers = goog.isDefAndNotNull(options.layers) ?
+      options.layers : this.getLayers().getArray();
+  this.getRenderer().getFeatureInfoForPixel(
+      options.pixel, layers, options.success, options.error);
 };
 
 

src/ol/renderer/canvas/canvasvectorlayerrenderer.js

@@ -190,10 +190,14 @@ ol.renderer.canvas.VectorLayer.prototype.getTransform = function() {
 
 /**
  * @param {ol.Pixel} pixel Pixel coordinate relative to the map viewport.
- * @return {Array.<ol.Feature>} Features at the pixel location.
+ * @param {function(Array.<ol.Feature|string>)} success Callback for
+ *     successful queries. The passed argument is the resulting feature
+ *     information.  Layers that are able to provide attribute data will put
+ *     ol.Feature instances, other layers will put a string which can either
+ *     be plain text or markup.
  */
 ol.renderer.canvas.VectorLayer.prototype.getFeatureInfoForPixel =
-    function(pixel) {
+    function(pixel, success) {
   // TODO adjust pixel tolerance for applied styles
   var minPixel = new ol.Pixel(pixel.x - 1, pixel.y - 1);
   var maxPixel = new ol.Pixel(pixel.x + 1, pixel.y + 1);
@@ -230,7 +234,7 @@ ol.renderer.canvas.VectorLayer.prototype.getFeatureInfoForPixel =
       result.push(candidate);
     }
   }
-  return result;
+  goog.global.setTimeout(function() { success(result); }, 0);
 };
 
 

src/ol/renderer/maprenderer.js

@@ -106,23 +106,34 @@ ol.renderer.Map.prototype.getCanvas = goog.functions.NULL;
 /**
  * @param {ol.Pixel} pixel Pixel coordinate relative to the map viewport.
  * @param {Array.<ol.layer.Layer>} layers Layers to query.
- * @return {Array.<ol.Feature|string>} Feature information.  Layers that are
- *     able to return attribute data will return ol.Feature instances, other
- *     layers will return a string which can either be plain text or markup.
+ * @param {function(Array.<ol.Feature|string>)} success Callback for
+ *     successful queries. The passed argument is the resulting feature
+ *     information.  Layers that are able to provide attribute data will put
+ *     ol.Feature instances, other layers will put a string which can either
+ *     be plain text or markup.
+ * @param {function(Object)=} opt_error Callback for unsuccessful
+ *     queries.
  */
 ol.renderer.Map.prototype.getFeatureInfoForPixel =
-    function(pixel, layers) {
+    function(pixel, layers, success, opt_error) {
   var layer, layerRenderer;
   var featureInfo = [];
-  for (var i = 0, ii = layers.length; i < ii; ++i) {
+  var numLayers = layers.length;
+  var callback = function(layerFeatureInfo) {
+    featureInfo.push.apply(featureInfo, layerFeatureInfo);
+    --numLayers;
+    if (!numLayers) {
+      success(featureInfo);
+    }
+  };
+
+  for (var i = 0; i < numLayers; ++i) {
     layer = layers[i];
     layerRenderer = this.getLayerRenderer(layer);
     if (goog.isFunction(layerRenderer.getFeatureInfoForPixel)) {
-      featureInfo.push.apply(featureInfo,
-          layerRenderer.getFeatureInfoForPixel(pixel));
+      layerRenderer.getFeatureInfoForPixel(pixel, callback, opt_error);
     }
   }
-  return featureInfo;
 };