[GIS] Visualizing map from Spatialite DB on Mobile

androidmobileofflinespatial-databasespatialite

I am working on an Android application for a school project.

I am converting shapefiles (examples) into SQLite databases using SpatiaLite and performing queries on those databases on the mobile with SpatiaLite-Android.

I am still looking for a way to visually display the map data on Android for user interaction. For example, I would like the user be able to zoom in/out and pan the map around. I also intend show the user her current location with respect to the map.

It would be great if my app can draw maps directly from the SQLite database with SpatiaLite. Can anyone offer tips on this? If this is not possible or not advisable, can anyone suggest alternatives?

NOTE: My app needs to function in offline mode.

Best Answer

You can use a local db create from a .shp using tile format stored in db called .mbtiles and for spatial querys still use spatialite. You can use ESRI sdk for android for maps visibility.

Related Solutions

[GIS] Open source library to display offline shapefiles in Android

In the end we went with: https://developers.arcgis.com/android Here is sample code to get you started...

private Boolean setBaseLayer() {

    File myShapeFilePath = null;
    try {

        if (MyApplication.mPathMaps == null || MyApplication.mPathMaps.length() < 1) {
            File rootDir = new File(Environment.getExternalStorageDirectory().getAbsolutePath(),
                    getApplication().getApplicationInfo().packageName);

            File tmpDir = new File(rootDir, "maps");
            MyApplication.mPathMaps = tmpDir.getAbsolutePath();
        }

        myShapeFilePath = new File(MyApplication.mPathMaps, BASE_LAYER_PATH);
        if (!myShapeFilePath.exists()) {
            displayFatalErrorMsg("Could not locate base map at:\n" + myShapeFilePath.getAbsolutePath());
            return false;
        }

        ShapefileFeatureTable shapefileFeatureTable =
                new ShapefileFeatureTable(myShapeFilePath.toString());
        FeatureLayer featureLayer = new FeatureLayer(shapefileFeatureTable);

        if (MyUVRvalues.getInstance().getBaseLayerColor().isEmpty()) {
            displayFatalErrorMsg("Failed to get config value for 'GIS_BASE_LAYER'");
            return false;
        }

        // int color = Color.argb(255, 84, 110, 122); // a = transparency 0 - 255
        int color = Color.parseColor(MyUVRvalues.getInstance().getBaseLayerColor());
        SimpleFillSymbol simpleFillSymbol = new SimpleFillSymbol(color, SimpleFillSymbol.STYLE.SOLID);
        SimpleRenderer simpleRenderer = new SimpleRenderer(simpleFillSymbol);

        featureLayer.setRenderer(simpleRenderer);
        featureLayer.setVisible(true);

        mMapView.addLayer(featureLayer);

    } catch (FileNotFoundException e) {
        displayFatalErrorMsg("setBaseLayer() Failed, could not locate base map at:\n" + myShapeFilePath.getAbsolutePath()
                + "\n" + e.toString());
        return false;
    }
    return true;
}

private Boolean setFeatureLayer(Boolean visible) {
    File myShapeFilePath = null;
    try {

        myShapeFilePath = new File(MyApplication.mPathMaps, FEATURE_LAYER_PATH);
        if (!myShapeFilePath.exists()) {
            displayFatalErrorMsg("Could not locate feature map at:\n" + myShapeFilePath.getAbsolutePath());
            return false;
        }

        ShapefileFeatureTable shapefileFeatureTable = new ShapefileFeatureTable(myShapeFilePath.toString());
        mFeatureLayer = new FeatureLayer(shapefileFeatureTable);

        mFeatureLayer.setRenderer(getUniqueValueRenderer());
        mFeatureLayer.setSelectionColorWidth(7); // integer in DP(density independent pixels).
        mFeatureLayer.setSelectionColor(Color.YELLOW);

        mFeatureLayer.setVisible(visible); //Only show when zoomed in

        mMapView.addLayer(mFeatureLayer);

    } catch (FileNotFoundException e) {
        displayFatalErrorMsg("Could not locate feature map at:\n" + myShapeFilePath.getAbsolutePath());
        return false;
    } catch (Exception e) {
        displayFatalErrorMsg("setFeatureLayer() caused exception:\n" + e.toString());
        return false;
    }
    return true;
}

private UniqueValueRenderer getUniqueValueRenderer() throws Exception {
    // UniqueValueRenderer used to assign unique values to feature
    UniqueValueRenderer uniqueValueRenderer = new UniqueValueRenderer();

    // setting the field for the unique values
    uniqueValueRenderer.setField1(MyUVRvalues.getInstance().getFieldName());

    // Rendering Type which is used to fill the region
    SimpleFillSymbol defaultsymbol =
            new SimpleFillSymbol(Color.parseColor(MyUVRvalues.getInstance().getDefaultColor()));
    uniqueValueRenderer.setDefaultSymbol(defaultsymbol);

    for (UVRFields field : MyUVRvalues.getInstance().getUVRFields()) {
        UniqueValue uv = new UniqueValue();

        String[] uniqueAttribute = {field.getValue()};
        uv.setValue(uniqueAttribute);

        // The symbol definition for each region
        uv.setSymbol(new SimpleFillSymbol(Color.parseColor(field.getColor())));

        uniqueValueRenderer.addUniqueValue(uv);
    }

    return uniqueValueRenderer;

}