Add a method to scale geometries

src/ol/geom/flat/transformflatgeom.js

@@ -60,6 +60,39 @@ ol.geom.flat.transform.rotate = function(flatCoordinates, offset, end, stride, a
 };
 
 
+/**
+ * Scale the coordinates.
+ * @param {Array.<number>} flatCoordinates Flat coordinates.
+ * @param {number} offset Offset.
+ * @param {number} end End.
+ * @param {number} stride Stride.
+ * @param {number} sx Scale factor in the x-direction.
+ * @param {number} sy Scale factor in the y-direction.
+ * @param {Array.<number>} anchor Scale anchor point.
+ * @param {Array.<number>=} opt_dest Destination.
+ * @return {Array.<number>} Transformed coordinates.
+ */
+ol.geom.flat.transform.scale = function(flatCoordinates, offset, end, stride, sx, sy, anchor, opt_dest) {
+  var dest = opt_dest ? opt_dest : [];
+  var anchorX = anchor[0];
+  var anchorY = anchor[1];
+  var i = 0;
+  for (var j = offset; j < end; j += stride) {
+    var deltaX = flatCoordinates[j] - anchorX;
+    var deltaY = flatCoordinates[j + 1] - anchorY;
+    dest[i++] = anchorX + sx * deltaX;
+    dest[i++] = anchorY + sy * deltaY;
+    for (var k = j + 2; k < j + stride; ++k) {
+      dest[i++] = flatCoordinates[k];
+    }
+  }
+  if (opt_dest && dest.length != i) {
+    dest.length = i;
+  }
+  return dest;
+};
+
+
 /**
  * @param {Array.<number>} flatCoordinates Flat coordinates.
  * @param {number} offset Offset.

src/ol/geom/geometry.js

@@ -180,6 +180,20 @@ ol.geom.Geometry.prototype.getExtent = function(opt_extent) {
 ol.geom.Geometry.prototype.rotate = function(angle, anchor) {};
 
 
+/**
+ * Scale the geometry (with an optional origin).  This modifies the geometry
+ * coordinates in place.
+ * @abstract
+ * @param {number} sx The scaling factor in the x-direction.
+ * @param {number=} opt_sy The scaling factor in the y-direction (defaults to
+ *     sx).
+ * @param {ol.Coordinate=} opt_anchor The scale origin (defaults to the center
+ *     of the geometry extent).
+ * @api
+ */
+ol.geom.Geometry.prototype.scale = function(sx, opt_sy, opt_anchor) {};
+
+
 /**
  * Create a simplified version of this geometry.  For linestrings, this uses
  * the the {@link

src/ol/geom/geometrycollection.js

@@ -244,6 +244,19 @@ ol.geom.GeometryCollection.prototype.rotate = function(angle, anchor) {
 };
 
 
+/**
+ * @inheritDoc
+ * @api
+ */
+ol.geom.GeometryCollection.prototype.scale = function(sx, opt_sy, opt_anchor) {
+  var geometries = this.geometries_;
+  for (var i = 0, ii = geometries.length; i < ii; ++i) {
+    geometries[i].scale(sx, opt_sy, opt_anchor);
+  }
+  this.changed();
+};
+
+
 /**
  * Set the geometries that make up this geometry collection.
  * @param {Array.<ol.geom.Geometry>} geometries Geometries.

src/ol/geom/simplegeometry.js

@@ -278,6 +278,30 @@ ol.geom.SimpleGeometry.prototype.rotate = function(angle, anchor) {
 };
 
 
+/**
+ * @inheritDoc
+ * @api
+ */
+ol.geom.SimpleGeometry.prototype.scale = function(sx, opt_sy, opt_anchor) {
+  var sy = opt_sy;
+  if (sy === undefined) {
+    sy = sx;
+  }
+  var anchor = opt_anchor;
+  if (!anchor) {
+    anchor = ol.extent.getCenter(this.getExtent());
+  }
+  var flatCoordinates = this.getFlatCoordinates();
+  if (flatCoordinates) {
+    var stride = this.getStride();
+    ol.geom.flat.transform.scale(
+        flatCoordinates, 0, flatCoordinates.length,
+        stride, sx, sy, anchor, flatCoordinates);
+    this.changed();
+  }
+};
+
+
 /**
  * @inheritDoc
  * @api stable

test/spec/ol/geom/linestring.test.js

@@ -242,6 +242,31 @@ describe('ol.geom.LineString', function() {
 
   });
 
+  describe('#scale()', function() {
+
+    it('scales a linestring', function() {
+      var geom = new ol.geom.LineString([[-10, -20], [10, 20]]);
+      geom.scale(10);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([[-100, -200], [100, 200]]);
+    });
+
+    it('accepts sx and sy', function() {
+      var geom = new ol.geom.LineString([[-10, -20], [10, 20]]);
+      geom.scale(2, 3);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([[-20, -60], [20, 60]]);
+    });
+
+    it('accepts an anchor', function() {
+      var geom = new ol.geom.LineString([[-10, -20], [10, 20]]);
+      geom.scale(3, 2, [10, 20]);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([[-50, -60], [10, 20]]);
+    });
+
+  });
+
   describe('with a simple line string', function() {
 
     var lineString;

test/spec/ol/geom/multilinestring.test.js

@@ -313,6 +313,31 @@ describe('ol.geom.MultiLineString', function() {
 
   });
 
+  describe('#scale()', function() {
+
+    it('scales a multi-linestring', function() {
+      var geom = new ol.geom.MultiLineString([[[-10, -20], [10, 20]], [[5, -10], [-5, 10]]]);
+      geom.scale(10);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([[[-100, -200], [100, 200]], [[50, -100], [-50, 100]]]);
+    });
+
+    it('accepts sx and sy', function() {
+      var geom = new ol.geom.MultiLineString([[[-10, -20], [10, 20]], [[5, -10], [-5, 10]]]);
+      geom.scale(2, 3);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([[[-20, -60], [20, 60]], [[10, -30], [-10, 30]]]);
+    });
+
+    it('accepts an anchor', function() {
+      var geom = new ol.geom.MultiLineString([[[-10, -20], [10, 20]], [[5, -10], [-5, 10]]]);
+      geom.scale(3, 2, [10, 20]);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([[[-50, -60], [10, 20]], [[-5, -40], [-35, 0]]]);
+    });
+
+  });
+
   describe('#setLineStrings', function() {
 
     it('sets the line strings', function() {

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

@@ -203,6 +203,31 @@ describe('ol.geom.MultiPoint', function() {
 
   });
 
+  describe('#scale()', function() {
+
+    it('scales a multi-point', function() {
+      var geom = new ol.geom.MultiPoint([[-10, -20], [10, 20]]);
+      geom.scale(10);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([[-100, -200], [100, 200]]);
+    });
+
+    it('accepts sx and sy', function() {
+      var geom = new ol.geom.MultiPoint([[-10, -20], [10, 20]]);
+      geom.scale(2, 3);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([[-20, -60], [20, 60]]);
+    });
+
+    it('accepts an anchor', function() {
+      var geom = new ol.geom.MultiPoint([[-10, -20], [10, 20]]);
+      geom.scale(3, 2, [-10, -20]);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([[-10, -20], [50, 60]]);
+    });
+
+  });
+
   describe('#applyTransform()', function() {
 
     var multi, transform;

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

@@ -129,6 +129,31 @@ describe('ol.geom.Point', function() {
 
   });
 
+  describe('#scale()', function() {
+
+    it('scales a point', function() {
+      var geom = new ol.geom.Point([1, 2]);
+      geom.scale(10e6);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([1, 2]);
+    });
+
+    it('accepts sx and sy', function() {
+      var geom = new ol.geom.Point([1, 2]);
+      geom.scale(1e6, -42);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([1, 2]);
+    });
+
+    it('accepts an anchor', function() {
+      var geom = new ol.geom.Point([1, 2]);
+      geom.scale(10, 15, [0, 0]);
+      var coordinates = geom.getCoordinates();
+      expect(coordinates).to.eql([10, 30]);
+    });
+
+  });
+
   describe('#applyTransform()', function() {
 
     var point, transform;