Secondary tile overlay does not always display tiles

I’m using osmdoird 5.6.5 in my Android application. I’m using a custom baselayer, and I add a second layer above it in this way:

baselayer:

final MapTileProviderBasic tileProvider = new MapTileProviderBasic(getApplicationContext());
        final ITileSource tileSource = new XYTileSource(getResources().getString(R.string.rp_cachemap), 6, 17, 256, ".png", tileserver);
        tileProvider.setTileSource(tileSource);
        final TilesOverlay tilesOverlay = new TilesOverlay(tileProvider, this.getBaseContext());
        tilesOverlay.setLoadingBackgroundColor(Color.TRANSPARENT);

overlay:

final MapTileProviderBasic anotherTileProvider = new MapTileProviderBasic(getApplicationContext());
        final ITileSource tileSource2 = new XYTileSource("tile_overlay_3",6, 17, 256, ".png", new String[]{"https://geoserver2.nodemapp.com/geoserver/"})
        {
            @Override
            public String getTileURLString(MapTile aTile) {
                String hello= getBaseUrl() + "gwc/service/gmaps?layers=nodemapp-public-mobile-with-cache&zoom=" + aTile.getZoomLevel() + "&x=" + aTile.getX() + "&y=" + aTile.getY() + "&format=image/png&viewparams=kind:hike;groupid:1&version=1";
                System.out.println(hello);
                return hello;
            }
        };
        anotherTileProvider.setTileSource(tileSource2);
        final TilesOverlay secondTilesOverlay = new TilesOverlay(anotherTileProvider, this.getBaseContext());
        secondTilesOverlay.setLoadingBackgroundColor(Color.TRANSPARENT);

set tiles on map:

osmMap.setTileSource(tileSource);
osmMap.getOverlays().add(secondTilesOverlay);
osmMap.invalidate();

Eveything is working fine, but when scrolling the map, sometimes there are some tiles not showing properly in the second overlay. When scrolling a little bit further, they are loaded. Is this a known bug?

[monsieurtanuki]

@conej730

it does seem less than optimal to have to invalidate the map every time a new tile is downloaded?

According to Android docs about invalidate:

If the view is visible, onDraw(android.graphics.Canvas) will be called at some point in the future.

In short: invalidate is not sync, and it’s safe to call several times as Android will refresh the display potentially only once. At some point.

Back to the current issue.

We have async tile downloads, and a MapView. How do new tiles refresh the MapView: only because whenever a tile is successfully downloaded, it calls (by default) a Handler of class SimpleInvalidationHandler, that explicitly calls MapView.invalidate. Another way to refresh the MapView is to move/pinch the map.

And the problem so far with the secondary tile provider is that you have to explicitly tell your provider how to behave when a tile is successfully downloaded. If not you just ask it to download tiles into the cache, regardless of the display. And you don’t have to do it explicitly for the primary tile provider because it’s done in MapView.setTileProvider.

Therefore you should add something like

anotherTileProvider.setTileRequestCompleteHandler(mMapView.getTileRequestCompleteHandler());

in your code.

In the meanwhile I’m fixing the “Sample with tiles overlay and secondary tile overlay” demo that doesn’t work for the same reasons - I will PR within an hour.

Tell me if it works.

[monsieurtanuki]

@conej730 Excellent!