Boostrap GML2 serializers

- Add writeFeatureElement (copied and adapted from ol.format.GML3)
- Add writeGeometryElement (copied and adapted from ol.format.GML3)
- Add related constants (GEOMETRY_SERIALIZERS_, GEOMETRY_NODE_FACTORY_)
- Add empty serialization methods

src/ol/format/gml2.js

@@ -2,8 +2,10 @@ goog.provide('ol.format.GML2');
 
 goog.require('ol');
 goog.require('ol.extent');
+goog.require('ol.format.Feature');
 goog.require('ol.format.GMLBase');
 goog.require('ol.format.XSD');
+goog.require('ol.obj');
 goog.require('ol.proj');
 goog.require('ol.xml');
 
@@ -204,3 +206,235 @@ ol.format.GML2.prototype.GEOMETRY_PARSERS_ = {
     'Box': ol.xml.makeReplacer(ol.format.GML2.prototype.readBox_)
   }
 };
+
+
+/**
+ * @const
+ * @param {*} value Value.
+ * @param {Array.<*>} objectStack Object stack.
+ * @param {string=} opt_nodeName Node name.
+ * @return {Node|undefined} Node.
+ * @private
+ */
+ol.format.GML2.prototype.GEOMETRY_NODE_FACTORY_ = function(value, objectStack, opt_nodeName) {
+  var context = objectStack[objectStack.length - 1];
+  var multiSurface = context['multiSurface'];
+  var surface = context['surface'];
+  var curve = context['curve'];
+  var multiCurve = context['multiCurve'];
+  var nodeName;
+  if (!Array.isArray(value)) {
+    nodeName = /** @type {ol.geom.Geometry} */ (value).getType();
+    if (nodeName === 'MultiPolygon' && multiSurface === true) {
+      nodeName = 'MultiSurface';
+    } else if (nodeName === 'Polygon' && surface === true) {
+      nodeName = 'Surface';
+    } else if (nodeName === 'LineString' && curve === true) {
+      nodeName = 'Curve';
+    } else if (nodeName === 'MultiLineString' && multiCurve === true) {
+      nodeName = 'MultiCurve';
+    }
+  } else {
+    nodeName = 'Envelope';
+  }
+  return ol.xml.createElementNS('http://www.opengis.net/gml',
+      nodeName);
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.Feature} feature Feature.
+ * @param {Array.<*>} objectStack Node stack.
+ */
+ol.format.GML2.prototype.writeFeatureElement = function(node, feature, objectStack) {
+  var fid = feature.getId();
+  if (fid) {
+    node.setAttribute('fid', fid);
+  }
+  var context = /** @type {Object} */ (objectStack[objectStack.length - 1]);
+  var featureNS = context['featureNS'];
+  var geometryName = feature.getGeometryName();
+  if (!context.serializers) {
+    context.serializers = {};
+    context.serializers[featureNS] = {};
+  }
+  var properties = feature.getProperties();
+  var keys = [], values = [];
+  for (var key in properties) {
+    var value = properties[key];
+    if (value !== null) {
+      keys.push(key);
+      values.push(value);
+      if (key == geometryName || value instanceof ol.geom.Geometry) {
+        if (!(key in context.serializers[featureNS])) {
+          context.serializers[featureNS][key] = ol.xml.makeChildAppender(
+              this.writeGeometryElement, this);
+        }
+      } else {
+        if (!(key in context.serializers[featureNS])) {
+          context.serializers[featureNS][key] = ol.xml.makeChildAppender(
+              ol.format.XSD.writeStringTextNode);
+        }
+      }
+    }
+  }
+  var item = ol.obj.assign({}, context);
+  item.node = node;
+  ol.xml.pushSerializeAndPop(/** @type {ol.XmlNodeStackItem} */
+      (item), context.serializers,
+      ol.xml.makeSimpleNodeFactory(undefined, featureNS),
+      values,
+      objectStack, keys);
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.geom.Geometry|ol.Extent} geometry Geometry.
+ * @param {Array.<*>} objectStack Node stack.
+ */
+ol.format.GML2.prototype.writeGeometryElement = function(node, geometry, objectStack) {
+  var context = /** @type {olx.format.WriteOptions} */ (objectStack[objectStack.length - 1]);
+  var item = ol.obj.assign({}, context);
+  item.node = node;
+  var value;
+  if (Array.isArray(geometry)) {
+    if (context.dataProjection) {
+      value = ol.proj.transformExtent(
+          geometry, context.featureProjection, context.dataProjection);
+    } else {
+      value = geometry;
+    }
+  } else {
+    value =
+        ol.format.Feature.transformWithOptions(/** @type {ol.geom.Geometry} */ (geometry), true, context);
+  }
+  ol.xml.pushSerializeAndPop(/** @type {ol.XmlNodeStackItem} */
+      (item), ol.format.GML2.GEOMETRY_SERIALIZERS_,
+      this.GEOMETRY_NODE_FACTORY_, [value],
+      objectStack, undefined, this);
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.geom.LineString} geometry LineString geometry.
+ * @param {Array.<*>} objectStack Node stack.
+ * @private
+ */
+ol.format.GML2.prototype.writeCurveOrLineString_ = function(node, geometry, objectStack) {
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.geom.MultiLineString} geometry MultiLineString geometry.
+ * @param {Array.<*>} objectStack Node stack.
+ * @private
+ */
+ol.format.GML2.prototype.writeMultiCurveOrLineString_ = function(node, geometry, objectStack) {
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.geom.Point} geometry Point geometry.
+ * @param {Array.<*>} objectStack Node stack.
+ * @private
+ */
+ol.format.GML2.prototype.writePoint_ = function(node, geometry, objectStack) {
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.geom.MultiPoint} geometry MultiPoint geometry.
+ * @param {Array.<*>} objectStack Node stack.
+ * @private
+ */
+ol.format.GML2.prototype.writeMultiPoint_ = function(node, geometry, objectStack) {
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.geom.LineString} line LineString geometry.
+ * @param {Array.<*>} objectStack Node stack.
+ * @private
+ */
+ol.format.GML2.prototype.writeLineStringOrCurveMember_ = function(node, line, objectStack) {
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.geom.LinearRing} geometry LinearRing geometry.
+ * @param {Array.<*>} objectStack Node stack.
+ * @private
+ */
+ol.format.GML2.prototype.writeLinearRing_ = function(node, geometry, objectStack) {
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.geom.Polygon} geometry Polygon geometry.
+ * @param {Array.<*>} objectStack Node stack.
+ * @private
+ */
+ol.format.GML2.prototype.writeSurfaceOrPolygon_ = function(node, geometry, objectStack) {
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.geom.MultiPolygon} geometry MultiPolygon geometry.
+ * @param {Array.<*>} objectStack Node stack.
+ * @private
+ */
+ol.format.GML2.prototype.writeMultiSurfaceOrPolygon_ = function(node, geometry, objectStack) {
+};
+
+
+/**
+ * @param {Node} node Node.
+ * @param {ol.Extent} extent Extent.
+ * @param {Array.<*>} objectStack Node stack.
+ */
+ol.format.GML2.prototype.writeEnvelope = function(node, extent, objectStack) {
+};
+
+
+/**
+ * @const
+ * @type {Object.<string, Object.<string, ol.XmlSerializer>>}
+ * @private
+ */
+ol.format.GML2.GEOMETRY_SERIALIZERS_ = {
+  'http://www.opengis.net/gml': {
+    'Curve': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeCurveOrLineString_),
+    'MultiCurve': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeMultiCurveOrLineString_),
+    'Point': ol.xml.makeChildAppender(ol.format.GML2.prototype.writePoint_),
+    'MultiPoint': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeMultiPoint_),
+    'LineString': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeCurveOrLineString_),
+    'MultiLineString': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeMultiCurveOrLineString_),
+    'LinearRing': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeLinearRing_),
+    'Polygon': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeSurfaceOrPolygon_),
+    'MultiPolygon': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeMultiSurfaceOrPolygon_),
+    'Surface': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeSurfaceOrPolygon_),
+    'MultiSurface': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeMultiSurfaceOrPolygon_),
+    'Envelope': ol.xml.makeChildAppender(
+        ol.format.GML2.prototype.writeEnvelope)
+  }
+};