Add scale to ol.Rectangle

src/ol/rectangle.js

@@ -124,3 +124,16 @@ ol.Rectangle.prototype.normalize = function(coordinate) {
 ol.Rectangle.prototype.toString = function() {
   return '(' + [this.minX, this.minY, this.maxX, this.maxY].join(', ') + ')';
 };
+
+
+/**
+ * @param {number} value Value.
+ */
+ol.Rectangle.prototype.scale = function(value) {
+  var deltaX = (this.getWidth() / 2.0) * (value - 1);
+  var deltaY = (this.getHeight() / 2.0) * (value - 1);
+  this.minX -= deltaX;
+  this.minY -= deltaY;
+  this.maxX += deltaX;
+  this.maxY += deltaY;
+};

test/spec/ol/rectangle.test.js

@@ -98,6 +98,17 @@ describe('ol.Rectangle', function() {
     });
   });
 
+  describe('scale', function() {
+    it('scales the extent', function() {
+      var rectangle = new ol.Rectangle(1, 1, 3, 3);
+      rectangle.scale(2);
+      expect(rectangle.minX).toEqual(0);
+      expect(rectangle.minY).toEqual(0);
+      expect(rectangle.maxX).toEqual(4);
+      expect(rectangle.maxY).toEqual(4);
+    });
+  });
+
 });
 
 goog.require('ol.Coordinate');