Android: Multiple MapView's apparently not supported?

[mar-v-in]

I see various issues when having multiple MapView's on Android at the same time:

1. Sometimes, the text is not rendered correctly, there is only a black box where text is supposed to be
2. Sometimes, parts of the map are not rendered (lines and/or areas).
3. Sometimes, wrong symbols are put in place
4. Sometimes, it just crashes.

Is it intended to support multiple map views at the same time?

[devemux86]

Could be due to shared static data among the map views.

If you want to provide a pull request example for Samples, in order to have it live and check it.

[mar-v-in]

Set of screenshots done using the new sample just provided via PR: http://imgur.com/a/2b4TW

[devemux86]

I improved slightly the multi map example with separate preferences.
Note: it keeps crashing on emulator, working with artifacts on device.

[andreynovikov]

MapView on Android uses GLSurfaceView. GLSurfaceViews can not overlap:
https://groups.google.com/forum/#!topic/android-developers/COffLpanlz0

[mathieudebrito]

Hi Andrey, you can use mapview.setZOrderOnTop(true) on the map on the top
to make it work. You can also use mapview.setZOrderMediaOverlay(true);.
I have a working sample.

[devemux86]

@andreynovikov thanks for the info.
So they mention not overlapping, what about having them side by side?

[mathieudebrito]

Hi guys,

I made a working sample of fragments stack showing different mapviews (as previously said, using mapview.setZOrderMediaOverlay(true);).
It works perfectly until you pop a fragment: coming back to the mapview of the previous fragment, it all works fine except labels.

Any ideas ? Where can I find the possible shared data in order to debug ?

[ocsike]

Hi,
Possible solution for black label. It's work for me
onResume event add: mLabelLayer.update();
and onPause event add mLabelLayer.clearLabels(); mMap.render();

Where mLabelLayer is a LabelLayer instance and mMap is a Map

[devemux86]

@ocsike where do you use those statements, have you managed to work with MultiMapActivity example?

[ocsike]

Yes, but is not perfect solution. Black labels are show when move or zoom the map, but not continuous and not all situation.
Here is a code:

public class MultiMapActivity extends Activity {
    private MapView mMapView1, mMapView2;
    private MapPreferences mPrefs1, mPrefs2;
	
	private LabelLayer map1LabelLayer;
	private LabelLayer map2LabelLayer;
	private Map map1; 
	private Map map2;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Tile.SIZE = Tile.calculateTileSize(getResources().getDisplayMetrics().scaledDensity);
        setContentView(R.layout.activity_map_multi);

        setTitle(getClass().getSimpleName());

        // 1st map view
        mMapView1 = (MapView) findViewById(R.id.mapView1);
        map1 = mMapView1.map();
        mPrefs1 = new MapPreferences(MultiMapActivity.class.getName() + "1", this);
        VectorTileLayer baseLayer1 = map1.setBaseMap(new OSciMap4TileSource());
		map1LabelLayer = new LabelLayer(map1, baseLayer1);
        map1.layers().add(new BuildingLayer(map1, baseLayer1));
        map1.layers().add(map1LabelLayer);
        map1.setTheme(VtmThemes.DEFAULT);

        // 2nd map view
        mMapView2 = (MapView) findViewById(R.id.mapView2);
        map2 = mMapView2.map();
        mPrefs2 = new MapPreferences(MultiMapActivity.class.getName() + "2", this);
        VectorTileLayer baseLayer2 = map2.setBaseMap(new OSciMap4TileSource());
		map2LabelLayer = new LabelLayer(map2, baseLayer2);
		
        map2.layers().add(new BuildingLayer(map2, baseLayer2));
        map2.layers().add(map2LabelLayer);
        map2.setTheme(VtmThemes.DEFAULT);
    }

    @Override
    protected void onResume() {
        super.onResume();

        mPrefs1.load(mMapView1.map());
        mMapView1.onResume();

        mPrefs2.load(mMapView2.map());
        mMapView2.onResume();
		
		
		map2LabelLayer.update();
		map1LabelLayer.update();
    }

    @Override
    protected void onPause() {
        super.onPause();

        mMapView1.onPause();
        mPrefs1.save(mMapView1.map());

        mMapView2.onPause();
        mPrefs2.save(mMapView2.map());
		
		map2LabelLayer.clearLabels(); 
		map2.render();
		
		map1LabelLayer.clearLabels(); 
		map1.render();
		
    }
}