Get projection and axis order from GML data

To make tests pass, the winding order of the coordinates in the
test data had to be reversed to conform to common gml practice.

src/ol/parser/ogc/gml.js

@@ -14,6 +14,7 @@ goog.require('ol.geom.Point');
 goog.require('ol.geom.Polygon');
 goog.require('ol.parser.StringFeatureParser');
 goog.require('ol.parser.XML');
+goog.require('ol.proj');
 
 
 
@@ -41,6 +42,20 @@ ol.parser.ogc.GML = function(opt_options) {
       options.multiSurface : true;
   this.srsName = goog.isDef(options.srsName) ?
       options.srsName : null;
+
+  /**
+   * @private
+   * @type {string|undefined}
+   */
+  this.srsName_ = goog.isNull(this.srsName) ? undefined : this.srsName;
+
+  /**
+   * @private
+   * @type {string|undefined}
+   */
+  this.axisOrientation_ = goog.isNull(this.srsName) ? undefined :
+      ol.proj.get(this.srsName).getAxisOrientation();
+
   if (goog.isDef(options.schemaLocation)) {
     this.schemaLocation = options.schemaLocation;
   }
@@ -197,7 +212,7 @@ ol.parser.ogc.GML = function(opt_options) {
         var points = new Array(numPoints);
         for (var i = 0; i < numPoints; ++i) {
           coords = goog.array.map(pointList[i].split(cs), parseFloat);
-          if (this.axisOrientation.substr(0, 2) === 'en') {
+          if (this.getAxisOrientation().substr(0, 2) === 'en') {
             points[i] = coords;
           } else {
             if (coords.length === 2) {
@@ -302,6 +317,27 @@ ol.parser.ogc.GML = function(opt_options) {
       if (!this.geometryName) {
         this.geometryName = node.nodeName.split(':').pop();
       }
+      // TODO: Deal with GML documents that do not have the same SRS for all
+      // geometries.
+      if (!goog.isDef(this.srsName_)) {
+        for (var i = node.childNodes.length - 1; i >= 0; --i) {
+          var child = node.childNodes[i];
+          if (child.nodeType == 1) {
+            var srsName = child.getAttribute('srsName');
+            if (goog.isDef(srsName)) {
+              this.srsName_ = srsName.replace(ol.parser.ogc.GML.regExes.epsg,
+                  'EPSG:');
+              if (!goog.isDef(this.axisOrientation_)) {
+                var projection = ol.proj.get(this.srsName_);
+                if (!goog.isNull(projection)) {
+                  this.axisOrientation_ = projection.getAxisOrientation();
+                }
+              }
+            }
+            break;
+          }
+        }
+      }
       this.readChildNodes(node, obj);
     },
     '_attribute': function(node, obj) {
@@ -453,6 +489,26 @@ ol.parser.ogc.GML = function(opt_options) {
 goog.inherits(ol.parser.ogc.GML, ol.parser.XML);
 
 
+/**
+ * Constants for regExes.
+ * @enum {RegExp}
+ */
+ol.parser.ogc.GML.regExes = {
+  epsg: new RegExp('(http:\/\/www\.opengis\.net\/gml\/srs\/epsg.xml#|' +
+      'urn:x-ogc:def:crs:EPSG:)', 'i')
+};
+
+
+/**
+ * @return {string?} Axis orientation of the data that is currently being
+ * parsed.
+ */
+ol.parser.ogc.GML.prototype.getAxisOrientation = function() {
+  return goog.isDef(this.axisOrientation_) ?
+      this.axisOrientation_ : this.axisOrientation;
+};
+
+
 /**
  * @param {string|Document|Element|Object} data Data to read.
  * @return {ol.parser.ReadFeaturesResult} An object representing the document.
@@ -464,8 +520,12 @@ ol.parser.ogc.GML.prototype.read = function(data) {
   if (data && data.nodeType == 9) {
     data = data.documentElement;
   }
-  var obj = {features: [], metadata: {projection: null}};
+  var obj = /** @type {ol.parser.ReadFeaturesResult} */
+      ({features: [], metadata: {}});
   this.readNode(data, obj, true);
+  obj.metadata.projection = this.srsName_;
+  this.srsName_ = goog.isNull(this.srsName) ? undefined : this.srsName;
+  delete this.axisOrientation_;
   return obj;
 };