Add a transform method to geometries

This accepts CRS identifiers for source and destination, transforms the geometry in place, and returns a reference to the geometry.

src/ol/geom/geometry.js

@@ -4,6 +4,7 @@ goog.provide('ol.geom.GeometryType');
 goog.require('goog.asserts');
 goog.require('goog.functions');
 goog.require('ol.Observable');
+goog.require('ol.proj');
 
 
 /**
@@ -166,6 +167,24 @@ ol.geom.Geometry.prototype.getType = goog.abstractMethod;
 ol.geom.Geometry.prototype.applyTransform = goog.abstractMethod;
 
 
+/**
+ * Transform a geometry from one coordinate reference system to another.
+ * Modifies the geometry in place.
+ *
+ * @param {ol.proj.ProjectionLike} source The current projection.  Can be a
+ *     string identifier or a {@link ol.proj.Projection} object.
+ * @param {ol.proj.ProjectionLike} destination The desired projection.  Can be a
+ *     string identifier or a {@link ol.proj.Projection} object.
+ * @return {ol.geom.Geometry} This geometry.  Note that original geometry is
+ *     modified in place.
+ * @todo api
+ */
+ol.geom.Geometry.prototype.transform = function(source, destination) {
+  this.applyTransform(ol.proj.getTransform(source, destination));
+  return this;
+};
+
+
 /**
  * @typedef {ol.Coordinate}
  */

test/spec/ol/geom/geometrycollection.test.js

@@ -139,6 +139,35 @@ describe('ol.geom.GeometryCollection', function() {
 
   });
 
+  describe('#transform()', function() {
+
+    var line, multi, point;
+    beforeEach(function() {
+      point = new ol.geom.Point([10, 20]);
+      line = new ol.geom.LineString([[10, 20], [30, 40]]);
+      multi = new ol.geom.GeometryCollection([point, line]);
+    });
+
+    it('transforms all geometries', function() {
+      multi.transform('EPSG:4326', 'EPSG:3857');
+
+      var geometries = multi.getGeometries();
+      expect(geometries[0]).to.be.a(ol.geom.Point);
+      expect(geometries[1]).to.be.a(ol.geom.LineString);
+
+      var coords = geometries[0].getCoordinates();
+      expect(coords[0]).to.roughlyEqual(1113194.90, 1e-2);
+      expect(coords[1]).to.roughlyEqual(2273030.92, 1e-2);
+
+      coords = geometries[1].getCoordinates();
+      expect(coords[0][0]).to.roughlyEqual(1113194.90, 1e-2);
+      expect(coords[0][1]).to.roughlyEqual(2273030.92, 1e-2);
+      expect(coords[1][0]).to.roughlyEqual(3339584.72, 1e-2);
+      expect(coords[1][1]).to.roughlyEqual(4865942.27, 1e-2);
+    });
+
+  });
+
 });
 
 

test/spec/ol/geom/multipoint.test.js

@@ -230,6 +230,25 @@ describe('ol.geom.MultiPoint', function() {
 
   });
 
+  describe('#transform()', function() {
+
+    it('transforms a geometry given CRS identifiers', function() {
+      var multi = new ol.geom.MultiPoint([[-111, 45], [111, -45]]).transform(
+          'EPSG:4326', 'EPSG:3857');
+
+      expect(multi).to.be.a(ol.geom.MultiPoint);
+
+      var coords = multi.getCoordinates();
+
+      expect(coords[0][0]).to.roughlyEqual(-12356463.47, 1e-2);
+      expect(coords[0][1]).to.roughlyEqual(5621521.48, 1e-2);
+
+      expect(coords[1][0]).to.roughlyEqual(12356463.47, 1e-2);
+      expect(coords[1][1]).to.roughlyEqual(-5621521.48, 1e-2);
+    });
+
+  });
+
 });
 
 

test/spec/ol/geom/point.test.js

@@ -142,6 +142,31 @@ describe('ol.geom.Point', function() {
 
   });
 
+  describe('#transform()', function() {
+
+    it('transforms a geometry given CRS identifiers', function() {
+      var point = new ol.geom.Point([-111, 45]).transform(
+          'EPSG:4326', 'EPSG:3857');
+
+      expect(point).to.be.a(ol.geom.Point);
+
+      var coords = point.getCoordinates();
+
+      expect(coords[0]).to.roughlyEqual(-12356463.47, 1e-2);
+      expect(coords[1]).to.roughlyEqual(5621521.48, 1e-2);
+    });
+
+    it('modifies the original', function() {
+      var point = new ol.geom.Point([-111, 45]);
+      point.transform('EPSG:4326', 'EPSG:3857');
+      var coords = point.getCoordinates();
+
+      expect(coords[0]).to.roughlyEqual(-12356463.47, 1e-2);
+      expect(coords[1]).to.roughlyEqual(5621521.48, 1e-2);
+    });
+
+  });
+
 });