public synchronized Viewport getViewport() {
        final Viewport.ContainingViewportBuilder vpBuilder = new Viewport.ContainingViewportBuilder();
        for (Map.Entry<K, Pair<GeoItem, Boolean>> entry : this.itemMap.entrySet()) {
            vpBuilder.add(entry.getValue().first.getViewport());
        }
        return vpBuilder.getViewport();
    }
Gets the overall viewport for all objects in this layer (visible or invisible)
main/src/main/java/cgeo/geocaching/unifiedmap/geoitemlayer/GeoItemLayer.java