Examples
Dynamic styling (32)

Count features in a selected area

package com.mapbox.mapboxandroiddemo.examples.query;
import android.graphics.Color;
import android.graphics.RectF;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Toast;
import com.mapbox.geojson.Feature;
import com.mapbox.geojson.FeatureCollection;
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.layers.FillLayer;
import com.mapbox.mapboxsdk.style.sources.GeoJsonSource;
import java.util.List;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.fillColor;
/**
* Get the feature count inside of a bounding box and highlight all of the buildings in the box.
*/
public class FeatureCountActivity extends AppCompatActivity {
private MapView mapView;
@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 access token is configured.
setContentView(R.layout.activity_query_feature_count);
// Define our views, ones the center box and the others our view container used for the
// snackbar.
final View selectionBox = findViewById(R.id.selection_box);
final View viewContainer = findViewById(R.id.query_feature_count_map_container);
mapView = findViewById(R.id.mapView);
mapView.onCreate(savedInstanceState);
mapView.getMapAsync(new OnMapReadyCallback() {
@Override
public void onMapReady(@NonNull final MapboxMap mapboxMap) {
mapboxMap.setStyle(Style.LIGHT, new Style.OnStyleLoaded() {
@Override
public void onStyleLoaded(@NonNull final Style style) {
style.addSource(new GeoJsonSource("highlighted-shapes-source"));
// add a layer to the map that highlights the maps buildings inside the bounding box.
style.addLayer(
new FillLayer("highlighted-shapes-layer", "highlighted-shapes-source")
.withProperties(fillColor(Color.parseColor("#50667F"))));
// Toast instructing user to tap on the box
Toast.makeText(
FeatureCountActivity.this,
getString(R.string.tap_on_feature_box_instruction),
Toast.LENGTH_LONG
).show();
selectionBox.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// Perform feature query within the selectionBox. The bounding box is
// calculated using the view but you can also use a map bounding box made up
// of latitudes and longitudes.
int top = selectionBox.getTop() - mapView.getTop();
int left = selectionBox.getLeft() - mapView.getLeft();
RectF box = new RectF(left, top, left + selectionBox.getWidth(), top + selectionBox.getHeight());
List<Feature> features = mapboxMap.queryRenderedFeatures(box, "building");
// Show the features count
Snackbar.make(
viewContainer,
String.format(getString(R.string.feature_count_snackbar_feature_size), features.size()),
Snackbar.LENGTH_LONG).show();
GeoJsonSource source = style.getSourceAs("highlighted-shapes-source");
if (source != null) {
source.setGeoJson(FeatureCollection.fromFeatures(features));
}
}
});
}
});
}
});
}
@Override
public void onResume() {
super.onResume();
mapView.onResume();
}
@Override
protected void onStart() {
super.onStart();
mapView.onStart();
}
@Override
protected void onStop() {
super.onStop();
mapView.onStop();
}
@Override
public void onPause() {
super.onPause();
mapView.onPause();
}
@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);
}
}