Add ol.reader.GeoJSON

src/ol/reader/geojson/geojson.js

@@ -0,0 +1,139 @@
+// FIXME coordinate order
+// FIXME reprojection
+// FIXME support other geometry types
+
+goog.provide('ol.reader.GeoJSON');
+
+goog.require('goog.asserts');
+goog.require('goog.json');
+goog.require('ol.Feature');
+goog.require('ol.geom.LineString');
+goog.require('ol.geom.Point');
+goog.require('ol.geom.Polygon');
+
+
+
+/**
+ * @constructor
+ */
+ol.reader.GeoJSON = function() {
+};
+
+
+/**
+ * @param {GeoJSONGeometry} geometry Geometry.
+ * @private
+ * @return {ol.geom.Point} Point.
+ */
+ol.reader.GeoJSON.readPointGeometry_ = function(geometry) {
+  goog.asserts.assert(geometry.type == 'Point');
+  return new ol.geom.Point(geometry.coordinates);
+};
+
+
+/**
+ * @param {GeoJSONGeometry} geometry Geometry.
+ * @private
+ * @return {ol.geom.LineString} LineString.
+ */
+ol.reader.GeoJSON.readLineStringGeometry_ = function(geometry) {
+  goog.asserts.assert(geometry.type == 'LineString');
+  return new ol.geom.LineString(geometry.coordinates);
+};
+
+
+/**
+ * @param {GeoJSONGeometry} geometry Geometry.
+ * @private
+ * @return {ol.geom.Polygon} Polygon.
+ */
+ol.reader.GeoJSON.readPolygonGeometry_ = function(geometry) {
+  goog.asserts.assert(geometry.type == 'Polygon');
+  return new ol.geom.Polygon(geometry.coordinates);
+};
+
+
+/**
+ * @param {GeoJSONFeature} feature Feature.
+ * @param {function(ol.Feature): *} callback Callback.
+ * @private
+ * @return {*} Callback result.
+ */
+ol.reader.GeoJSON.readFeature_ = function(feature, callback) {
+  goog.asserts.assert(feature.type == 'Feature');
+  var geometryReader =
+      ol.reader.GeoJSON.GEOMETRY_READERS_[feature.geometry.type];
+  goog.asserts.assert(goog.isDef(geometryReader));
+  var geometry = geometryReader(feature.geometry);
+  var f = new ol.Feature(geometry);
+  if (goog.isDef(feature.properties)) {
+    f.setValues(feature.properties);
+  }
+  return callback(f);
+};
+
+
+/**
+ * @param {GeoJSONFeatureCollection} featureCollection Feature collection.
+ * @param {function(ol.Feature): *} callback Callback.
+ * @private
+ * @return {*} Callback result.
+ */
+ol.reader.GeoJSON.readFeatureCollection_ =
+    function(featureCollection, callback) {
+  goog.asserts.assert(featureCollection.type == 'FeatureCollection');
+  var features = featureCollection.features;
+  var i, ii;
+  for (i = 0, ii = features.length; i < ii; ++i) {
+    var result = ol.reader.GeoJSON.readFeature_(features[i], callback);
+    if (result) {
+      return result;
+    }
+  }
+  return undefined;
+};
+
+
+/**
+ * @param {GeoJSONObject} object Object.
+ * @param {function(ol.Feature): *} callback Callback.
+ * @return {*} Callback result.
+ */
+ol.reader.GeoJSON.readObject = function(object, callback) {
+  var objectReader = ol.reader.GeoJSON.OBJECT_READERS_[object.type];
+  goog.asserts.assert(goog.isDef(objectReader));
+  return objectReader(object, callback);
+};
+
+
+/**
+ * @param {string} string String.
+ * @param {function(ol.Feature): *} callback Callback.
+ * @return {*} Callback result.
+ */
+ol.reader.GeoJSON.readString = function(string, callback) {
+  var object = goog.json.parse(string);
+  return ol.reader.GeoJSON.readObject(
+      /** @type {GeoJSONObject} */ (object), callback);
+};
+
+
+/**
+ * @private
+ * @type {Object.<string, function(GeoJSONGeometry): ol.geom.Geometry>}
+ */
+ol.reader.GeoJSON.GEOMETRY_READERS_ = {
+  'Point': ol.reader.GeoJSON.readPointGeometry_,
+  'LineString': ol.reader.GeoJSON.readLineStringGeometry_,
+  'Polygon': ol.reader.GeoJSON.readPolygonGeometry_
+};
+
+
+/**
+ * @private
+ * @type {Object.<string, function(*, function(ol.Feature): *): *>}
+ */
+ol.reader.GeoJSON.OBJECT_READERS_ = {
+  'Feature': ol.reader.GeoJSON.readFeature_,
+  'FeatureCollection': ol.reader.GeoJSON.readFeatureCollection_
+};