@Override
    public int size() {
        return mWidth * mHeight;
    }
@Test
    public void testSize() {
        final MapTileArea area = new MapTileArea();
        for (int zoom = 0; zoom <= TileSystem.getMaximumZoomLevel(); zoom++) {
            final int mapTileUpperBound = getMapTileUpperBound(zoom);
            final long size = ((long) mapTileUpperBound) * mapTileUpperBound;
            if (size >= Integer.MAX_VALUE) {
                return;
            }
            setNewWorld(area, zoom);
            Assert.assertEquals(size, area.size());
            Assert.assertTrue(area.iterator().hasNext());
        }
    }