Load tiles and downsample images from server if needed

In that version you can provide a protocol in the file pattern like

    mapView.addZoomLevel(1024, 1024, "http://localhost:8080/tiles/256/0/%col%-%row%.png","http://localhost:8080/downsample.png", 256, 256);

and the MapView loads them over http. If you provide no protocol, it loads the files as assets. Now it would be possible to add more protocol implementations like ftp etc...