Examples
Dynamic styling (32)

Join local JSON data with vector tile geometries

package com.mapbox.mapboxandroiddemo.examples.dds;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import com.mapbox.mapboxandroiddemo.R;
import com.mapbox.mapboxsdk.Mapbox;
import com.mapbox.mapboxsdk.maps.MapView;
import com.mapbox.mapboxsdk.maps.MapboxMap;
import com.mapbox.mapboxsdk.maps.OnMapReadyCallback;
import com.mapbox.mapboxsdk.maps.Style;
import com.mapbox.mapboxsdk.style.expressions.Expression;
import com.mapbox.mapboxsdk.style.layers.FillLayer;
import com.mapbox.mapboxsdk.style.sources.VectorSource;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.InputStream;
import java.lang.ref.WeakReference;
import java.util.Scanner;
import timber.log.Timber;
import static com.mapbox.mapboxsdk.style.expressions.Expression.get;
import static com.mapbox.mapboxsdk.style.expressions.Expression.match;
import static com.mapbox.mapboxsdk.style.expressions.Expression.rgba;
import static com.mapbox.mapboxsdk.style.expressions.Expression.stop;
import static com.mapbox.mapboxsdk.style.expressions.Expression.toNumber;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.fillColor;
/**
* Style a choropleth map by merging local JSON data with vector tile geometries
*/
public class ChoroplethJsonVectorMixActivity extends AppCompatActivity implements OnMapReadyCallback {
private static final String STATE_UNEMPLOYMENT_INFO_JSON_FILE = "state_unemployment_info.json";
private static final String VECTOR_SOURCE_NAME = "states";
private static final String DATA_MATCH_PROP = "STATE_ID";
private static final String DATA_STYLE_UNEMPLOYMENT_PROP = "unemployment";
private MapView mapView;
private MapboxMap mapboxMap;
private JSONArray statesArray;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Mapbox access token is configured here. This needs to be called either in your application
// object or in the same activity which contains the mapview.
Mapbox.getInstance(this, getString(R.string.access_token));
// This contains the MapView in XML and needs to be called after the account manager
setContentView(R.layout.activity_choropleth_json_vector_mix);
mapView = findViewById(R.id.mapView);
mapView.onCreate(savedInstanceState);
mapView.getMapAsync(this);
}
@Override
public void onMapReady(@NonNull final MapboxMap map) {
this.mapboxMap = map;
map.setStyle(Style.LIGHT, new Style.OnStyleLoaded() {
@Override
public void onStyleLoaded(@NonNull Style style) {
// Add Mapbox-hosted vector source for state polygons
style.addSource(new VectorSource(VECTOR_SOURCE_NAME, "mapbox://mapbox.us_census_states_2015"));
new LoadJson(ChoroplethJsonVectorMixActivity.this).execute();
}
});
}
/**
* Create layer from the vector tile source with data-driven style
*
* @param stops the array of stops to use in the FillLayer
*/
private void addDataToMap(@NonNull Expression.Stop[] stops) {
FillLayer statesJoinLayer = new FillLayer("states-join", VECTOR_SOURCE_NAME);
statesJoinLayer.setSourceLayer(VECTOR_SOURCE_NAME);
statesJoinLayer.withProperties(
fillColor(match(toNumber(get(DATA_MATCH_PROP)),
rgba(0, 0, 0, 1), stops))
);
// Add layer to map below the "waterway-label" layer
if (mapboxMap != null) {
mapboxMap.getStyle(style -> style.addLayerAbove(statesJoinLayer, "waterway-label"));
}
}
private static class LoadJson extends AsyncTask<Void, Void, Expression.Stop[]> {
private WeakReference<ChoroplethJsonVectorMixActivity> weakReference;
private static final String TAG = "ChJSonVectorMix";
LoadJson(ChoroplethJsonVectorMixActivity activity) {
this.weakReference = new WeakReference<>(activity);
}
@Override
protected Expression.Stop[] doInBackground(Void... voids) {
try {
ChoroplethJsonVectorMixActivity activity = weakReference.get();
if (activity != null) {
InputStream inputStream = activity.getAssets().open(STATE_UNEMPLOYMENT_INFO_JSON_FILE);
activity.statesArray = new JSONArray(convertStreamToString(inputStream));
// Create stops array
Expression.Stop[] stops = new Expression.Stop[activity.statesArray.length()];
for (int x = 0; x < activity.statesArray.length(); x++) {
try {
// Generate green color value for each state/stop
JSONObject singleState = activity.statesArray.getJSONObject(x);
double green = singleState.getDouble(DATA_STYLE_UNEMPLOYMENT_PROP) / 14 * 255;
// Add new stop to array of stops
stops[x] = stop(
Double.parseDouble(singleState.getString(DATA_MATCH_PROP)),
rgba(0, green, 0, 1)
);
} catch (JSONException exception) {
throw new RuntimeException(exception);
}
}
return stops;
}
} catch (Exception exception) {
Timber.d("Exception Loading GeoJSON: %s", exception.toString());
}
return null;
}
static String convertStreamToString(InputStream is) {
Scanner scanner = new Scanner(is).useDelimiter("\\A");
return scanner.hasNext() ? scanner.next() : "";
}
@Override
protected void onPostExecute(@Nullable Expression.Stop[] stopsArray) {
super.onPostExecute(stopsArray);
ChoroplethJsonVectorMixActivity activity = weakReference.get();
if (activity != null && stopsArray != null) {
activity.addDataToMap(stopsArray);
}
}
}
@Override
protected void onStart() {
super.onStart();
mapView.onStart();
}
@Override
public void onResume() {
super.onResume();
mapView.onResume();
}
@Override
public void onPause() {
super.onPause();
mapView.onPause();
}
@Override
protected void onStop() {
super.onStop();
mapView.onStop();
}
@Override
public void onLowMemory() {
super.onLowMemory();
mapView.onLowMemory();
}
@Override
protected void onDestroy() {
super.onDestroy();
mapView.onDestroy();
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
mapView.onSaveInstanceState(outState);
}
}
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