如何在 Android 中的 Mapbox 上添加带有标题和描述的自定义标记？

Question

我想为地图上的每个标记添加标题和描述。现在我在地图上添加标记，通过 GET 调用从服务器获取数据并为每个 object 创建标记作为响应。

public void onMapReady(@NonNull final MapboxMap mapboxMap) {

        MainActivity.this.mapboxMap = mapboxMap;

        StringRequest request = new StringRequest(url, new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                try {

                    JSONArray jsonArray = new JSONArray(response);
                    List<Feature> symbolLayerIconFeatureList = new ArrayList<>();

                    for(int i = 0; i < jsonArray.length(); i++){
                        JSONObject crag = jsonArray.getJSONObject(i);

                        String description = crag.getString("descrizione")
                        String name = crag.getString("nome");
                        Double lng = crag.getDouble("longitudine");
                        Double lat = crag.getDouble("latitudine");

                        symbolLayerIconFeatureList.add(Feature.fromGeometry(
                               Point.fromLngLat(lng, lat)));

                    }

                    mapboxMap.setStyle(new Style.Builder().fromUri("mapbox://styles/mapbox/cjf4m44iw0uza2spb3q0a7s41")

                            .withImage(ICON_ID, BitmapFactory.decodeResource(
                                    MainActivity.this.getResources(), R.drawable.icona_falesia))

                            .withSource(new GeoJsonSource(SOURCE_ID,
                                    FeatureCollection.fromFeatures(symbolLayerIconFeatureList)))

                            .withLayer(new SymbolLayer(LAYER_ID, SOURCE_ID)
                                    .withProperties(
                                            iconImage(ICON_ID),
                                            iconAllowOverlap(true),
                                            iconIgnorePlacement(true)
                                    )
                            ), new Style.OnStyleLoaded() {
                        @Override
                        public void onStyleLoaded(@NonNull Style style) {

                        }
                    });
                } catch (JSONException e){
                    e.printStackTrace();
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                error.printStackTrace();
            }
        });

        mQueue.add(request);

    }

这是我的 onMapReady 函数，用于获取数据和创建标记。我怎样才能为每个标记添加标题和一种描述？

Answer 1

您还需要使用 textField()、textOffset()、textIgnorePlacement()、textAllowOverlap() 和 textField() 如果您只想显示SymbolLayer 图标。为每个 Feature 添加名称和描述是使其正常工作的关键。

我修改了https://docs.mapbox.com/android/maps/examples/marker-symbol-layer/ to create the GIF seen at https://i.imgur.com/5LzSzRf.mp4。您可以查看代码中发生的事情，然后调整它以匹配您在 GET onResponse() 回调中的实现。

package com.mapbox.mapboxandroiddemo.examples.styles;

import android.graphics.BitmapFactory;
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import com.mapbox.geojson.Feature;
import com.mapbox.geojson.FeatureCollection;
import com.mapbox.geojson.Point;
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.SymbolLayer;
import com.mapbox.mapboxsdk.style.sources.GeoJsonSource;

import java.util.ArrayList;
import java.util.List;

import static com.mapbox.mapboxsdk.style.expressions.Expression.get;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.iconAllowOverlap;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.iconIgnorePlacement;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.iconImage;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.textAllowOverlap;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.textField;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.textIgnorePlacement;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.textOffset;

/**
 * Display {@link SymbolLayer} icons on the map.
 */
public class BasicSymbolLayerActivity extends AppCompatActivity implements
        OnMapReadyCallback {

  private static final String SOURCE_ID = "SOURCE_ID";
  private static final String ICON_ID = "ICON_ID";
  private static final String LAYER_ID = "LAYER_ID";
  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_style_basic_symbol_layer);

    mapView = findViewById(R.id.mapView);
    mapView.onCreate(savedInstanceState);
    mapView.getMapAsync(this);
  }

  @Override
  public void onMapReady(@NonNull final MapboxMap mapboxMap) {

    List<Feature> symbolLayerIconFeatureList = new ArrayList<>();

    Feature singleFeature = Feature.fromGeometry(Point.fromLngLat(-57.225365, -33.213144));
    singleFeature.addStringProperty("NAME_PROPERTY_KEY", "descrizione 1");
    singleFeature.addStringProperty("DESCRIPTION_PROPERTY_KEY", "nome 1");

    Feature secondFeature = Feature.fromGeometry(Point.fromLngLat(-54.14164, -33.981818));
    secondFeature.addStringProperty("NAME_PROPERTY_KEY", "descrizione 2");
    secondFeature.addStringProperty("DESCRIPTION_PROPERTY_KEY", "nome 2");

    Feature thirdFeature = Feature.fromGeometry(Point.fromLngLat(-56.990533, -30.583266));
    thirdFeature.addStringProperty("NAME_PROPERTY_KEY", "descrizione 3");
    thirdFeature.addStringProperty("DESCRIPTION_PROPERTY_KEY", "nome 3");

    symbolLayerIconFeatureList.add(singleFeature);
    symbolLayerIconFeatureList.add(secondFeature);
    symbolLayerIconFeatureList.add(thirdFeature);

    mapboxMap.setStyle(new Style.Builder().fromUri("mapbox://styles/mapbox/cjf4m44iw0uza2spb3q0a7s41")

            // Add the SymbolLayer icon image to the map style
            .withImage(ICON_ID, BitmapFactory.decodeResource(
                    BasicSymbolLayerActivity.this.getResources(), R.drawable.mapbox_marker_icon_default))

            // Adding a GeoJson source for the SymbolLayer icons.
            .withSource(new GeoJsonSource(SOURCE_ID,
                    FeatureCollection.fromFeatures(symbolLayerIconFeatureList)))

            // Adding the actual SymbolLayer to the map style. An offset is added that the bottom of the red
            // marker icon gets fixed to the coordinate, rather than the middle of the icon being fixed to
            // the coordinate point. This is offset is not always needed and is dependent on the image
            // that you use for the SymbolLayer icon.
            .withLayer(new SymbolLayer(LAYER_ID, SOURCE_ID)
                    .withProperties(
                            iconImage(ICON_ID),
                            iconAllowOverlap(true),
                            iconIgnorePlacement(true),
                            textOffset(new Float[]{0f,-2.5f}),
                            textIgnorePlacement(true),
                            textAllowOverlap(true),
                            textField(Expression.concat(get("NAME_PROPERTY_KEY"), Expression.literal("–"), get("DESCRIPTION_PROPERTY_KEY")))
                    )
            ), new Style.OnStyleLoaded() {
      @Override
      public void onStyleLoaded(@NonNull Style style) {

        // Map is set up and the style has loaded. Now you can add additional data or make other map adjustments.


      }
    });
  }

  @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);
  }
}

如果要创建信息，请参阅 https://docs.mapbox.com/android/maps/examples/symbol-layer-info-window/ window。

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