Missing tiles

[git-bone]

hi,

i've been playing around with the mapsforge samples, which in general work great.

However, generating tiles while zooming, panning or rotating shows a lot of white blocks instead. For instance, when I zoom in, I see no map, when I zoom out to the previous zoom level, the map there again. Sometimes when zooming in again, the tiles are generated, but most of the time the tiles never appear. When rotating it is even worse. Happens on emulators and recent android phones. Am I missing something, maybe there are possibilities to improve this behavior?

thanks!

[devemux86]

@git-bone Thanks for the report.

Do you see this with the Mapsforge Android samples? What sample exactly?
Have you changed the samples code? What map file do you use?

Can you post a video to see what you mean?

---

When scroll / zoom / rotate, the new map areas appear empty until their map tiles are rendered on screen.
With offline map files, the map tiles are rendered in real time.
With online maps, the map tiles must be downloaded.

[git-bone]

thanks for your fast response!
map file is Netherlands, but the issue occurs on every map file.

not sure how to make a video but i did make some screenshots. It mostly happens after rotation. Once the map is rotated, panning the map does generate most of the new tiles, but not all of them.

I'm using the GettingStarted example from your repo, with enabled rotation gesture:

https://github.com/mapsforge/mapsforge/blob/master/mapsforge-samples-android/src/main/java/org/mapsforge/samples/android/GettingStarted.java

[devemux86]

@git-bone

with enabled rotation gesture

If you use the map rotation gesture or API, you must adapt your code according to the samples that use map rotation:

• LabelLayerUsingLabelCacheMapViewer
• LabelLayerUsingMapDataStoreMapViewer
• OverlayMapViewer
• RotationMapViewer

[git-bone]

Ok, implemented that, but it really makes no difference. After rotation, there are lots of missing tiles during panning the map.

private fun openMap(uri: Uri?) {
        try {
            /*
             * We then make some simple adjustments, such as showing a scale bar and zoom controls.
             */
            mapView?.mapScaleBar?.isVisible = true
            mapView?.setBuiltInZoomControls(true)
            mapView?.touchGestureHandler?.isRotationEnabled = true
            Parameters.FRACTIONAL_ZOOM = true
            Parameters.ELASTIC_ZOOM = true

            mapView?.model?.frameBufferModel?.setOverdrawFactor(2.0)

            val tileCache: TileCache? = mapView?.model?.displayModel?.tileSize?.let {
                mapView?.model?.frameBufferModel?.overdrawFactor?.let { it1 ->
                    AndroidUtil.createTileCache(
                        this, "mapcache",
                        it, 1f,
                        it1
                    )
                }
            }

            val fis = contentResolver.openInputStream(uri!!) as FileInputStream?
            val mapDataStore: MapDataStore = MapFile(fis)

            val tileRendererLayer = AndroidUtil.createTileRendererLayer(
                tileCache,
                mapView!!.model.mapViewPosition,
                mapDataStore,
                MapsforgeThemes.DEFAULT,
                false,
                false,
                true
            )

            mapView!!.layerManager.layers.add(tileRendererLayer)

            val labelStore: MapDataStoreLabelStore = CachedMapDataStoreLabelStore(
                mapDataStore,
                tileRendererLayer.renderThemeFuture,
                tileRendererLayer.textScale,
                tileRendererLayer.displayModel,
                AndroidGraphicFactory.INSTANCE
            )
            val labelLayer: LabelLayer = ThreadedLabelLayer(AndroidGraphicFactory.INSTANCE, labelStore)
            mapView!!.layerManager.layers.add(labelLayer)

            mapView?.setCenter(LatLong(52.0, 5.0))
            mapView?.setZoomLevel(12.toByte())

        } catch (e: Exception) {
            /*
             * In case of map file errors avoid crash, but developers should handle these cases!
             */
            e.printStackTrace()
        }
    }```

[devemux86]

LabelLayerUsingLabelCacheMapViewer sample works, better check its code.

Just need to set a larger getScreenRatio.

[git-bone]

hm. I set the screenratio to 2, that seems to help a lot. however, after a minute of panning and zooming an exception occurs:

`2025-02-08 16:40:10.691 1936-2836 AndroidRuntime com.example.mapsforgesample E FATAL EXCEPTION: pool-6-thread-4 (Ask Gemini)
Process: com.example.mapsforgesample, PID: 1936
java.lang.OutOfMemoryError: Failed to allocate a 24 byte allocation with 172368 free bytes and 167KB until OOM, target footprint 268435456, growth limit 268435456; giving up on allocation because <1% of heap free after GC.
at org.mapsforge.map.reader.MapFile.decodeWayNodesSingleDelta(MapFile.java:469)
at org.mapsforge.map.reader.MapFile.processWayDataBlock(MapFile.java:779)
at org.mapsforge.map.reader.MapFile.processWays(MapFile.java:879)
at org.mapsforge.map.reader.MapFile.processBlock(MapFile.java:555)
at org.mapsforge.map.reader.MapFile.processBlocks(MapFile.java:662)
at org.mapsforge.map.reader.MapFile.readMapData(MapFile.java:971)
at org.mapsforge.map.reader.MapFile.readMapData(MapFile.java:932)
at org.mapsforge.map.layer.renderer.DatabaseRenderer.executeJob(DatabaseRenderer.java:96)
at org.mapsforge.map.layer.renderer.MapWorkerPool$MapWorker.run(MapWorkerPool.java:172)

2025-02-08 16:40:10.691 1936-2836 AndroidRuntime com.example.mapsforgesample E FATAL EXCEPTION: pool-6-thread-4 (Ask Gemini)
Process: com.example.mapsforgesample, PID: 1936
java.lang.OutOfMemoryError: Failed to allocate a 24 byte allocation with 172368 free bytes and 167KB until OOM, target footprint 268435456, growth limit 268435456; giving up on allocation because <1% of heap free after GC.
at org.mapsforge.map.reader.MapFile.decodeWayNodesSingleDelta(MapFile.java:469)
at org.mapsforge.map.reader.MapFile.processWayDataBlock(MapFile.java:779)
at org.mapsforge.map.reader.MapFile.processWays(MapFile.java:879)
at org.mapsforge.map.reader.MapFile.processBlock(MapFile.java:555)
at org.mapsforge.map.reader.MapFile.processBlocks(MapFile.java:662)
at org.mapsforge.map.reader.MapFile.readMapData(MapFile.java:971)
at org.mapsforge.map.reader.MapFile.readMapData(MapFile.java:932)
at org.mapsforge.map.layer.renderer.DatabaseRenderer.executeJob(DatabaseRenderer.java:96)
at org.mapsforge.map.layer.renderer.MapWorkerPool$MapWorker.run(MapWorkerPool.java:172)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:644)
at java.lang.Thread.run(Thread.java:1012)
`

[devemux86]

@git-bone Does it happens with Mapsforge samples?

[git-bone]

Out of mem happens a lot after a couple of minutes zooming, panning and rotating. It happens less when I dont add the labellayer. Code is from above in my previous reply, which is a combo some of the mapsforge examples. I create the labelstore and labellayer like this:

val labelStore: MapDataStoreLabelStore = CachedMapDataStoreLabelStore( mapDataStore, tileRendererLayer.renderThemeFuture, tileRendererLayer.textScale, tileRendererLayer.displayModel, AndroidGraphicFactory.INSTANCE ) val labelLayer: LabelLayer = ThreadedLabelLayer(AndroidGraphicFactory.INSTANCE, labelStore) mapView!!.layerManager.layers.add(labelLayer)

and add it after the tilerenderlayer.

[devemux86]

@git-bone Try the label layer as it is in LabelLayerUsingLabelCacheMapViewer.

The ThreadedLabelLayer should be more heavy.

[devemux86]

@git-bone Try also with another large map to see if having the same result.

Netherlands has complex water polygons, leading to some heavy rendering.

[git-bone]

this indeed seems to help a bit for the out of mem error:
val labelLayer = LabelLayer(AndroidGraphicFactory.INSTANCE, tileRendererLayer.labelStore)

I also tested Germany NRW map. Also same issue there with map rotation and missing tiles. What also seems to happen, is that the map gesture for rotation becomes kind of unresponsive after the first rotation?

about the missing tiles, what I just noticed, is that a lot of missing tiles have on-off effect. Just slightly move the map where you keep the missing tile within the screen boundaries, then the missing tile appears for a second to disappear again:

[devemux86]

@git-bone But Mapsforge samples work correctly with map rotation.

Perhaps there is a problem in your implementation?

Follow the code in LabelLayerUsingLabelCacheMapViewer or RotationMapViewer without changes and see how it works.

[devemux86]

@git-bone Also it's better to open the maps as regular files for best speed.

Android scoped storage and its streams is known to have performance issues.

[git-bone]

So I followed your advice, cloned the latest master and installed the samples app on my phone with the Berlin map. During the example of MapsforgeMapViewer it crashed with this error (i'll only copy the first few lines as the complete error is very long:
2025-02-08 19:51:30.217 6021-6696 Bitmap org.mapsforge.samples.android A Error, cannot access an invalid/free'd bitmap here! 2025-02-08 19:51:30.494 6021-6696 samples.android org.mapsforge.samples.android A runtime.cc:708] Runtime aborting... runtime.cc:708] Dumping all threads without mutator lock held runtime.cc:708] All threads: runtime.cc:708] DALVIK THREADS (23): runtime.cc:708] "main" prio=10 tid=1 Native

Not sure how to reproduce, as it only happened once till now...

But after that, I tried a different implementation of the tilecache and this seems to work a bit better:

val tileCache = AndroidUtil.createTileCache( this, "test", mapView!!.model.displayModel.tileSize, 2f, mapView!!.model.frameBufferModel.overdrawFactor, true )