Implement rotate function for circle geometry

src/ol/geom/Circle.js

@@ -5,6 +5,8 @@ import {createOrUpdate, forEachCorner, intersects} from '../extent.js';
 import GeometryType from './GeometryType.js';
 import SimpleGeometry from './SimpleGeometry.js';
 import {deflateCoordinate} from './flat/deflate.js';
+import {rotate} from './flat/transform.js';
+
 
 /**
  * @classdesc
@@ -212,6 +214,18 @@ class Circle extends SimpleGeometry {
     this.flatCoordinates[this.stride] = this.flatCoordinates[0] + radius;
     this.changed();
   }
+
+  /**
+   * @inheritDoc
+   * @api
+   */
+  rotate(angle, anchor) {
+    const center = this.getCenter();
+    const stride = this.getStride();
+    this.setCenter(rotate(center, 0, center.length, stride, angle, anchor, center));
+    this.changed();
+  }
+
 }
 
 

test/spec/ol/geom/circle.test.js

@@ -263,6 +263,24 @@ describe('ol.geom.Circle', function() {
 
     });
 
+    describe('#rotate', function() {
+
+      it('rotates the center around the anchor', function() {
+        circle.setCenter([1, 0]);
+        circle.rotate(Math.PI / 2, [2, 0]);
+        expect(circle.getCenter()).to.eql([2, -1]);
+        expect(circle.getExtent()).to.eql([1, -2, 3, 0]);
+      });
+
+      it('does not change if the anchor equals the center', function() {
+        const center = [1, 0];
+        circle.setCenter(center);
+        const extent = circle.getExtent();
+        circle.rotate(Math.PI / 2, center);
+        expect(circle.getCenter()).to.eql(center);
+        expect(circle.getExtent()).to.eql(extent);
+      });
+    });
   });
 
 });