Add interface for stretchable image (#314)

* Add interface for stretch image

* Add demo for stretch image api

* Add stretchable image demp

* Update stretchable image test activity.

* Revert change for SymbolLayerActivity

This reverts commit 22bbb798

MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/activity/style/StretchableImageActivity.java

@@ -0,0 +1,198 @@
+package com.mapbox.mapboxsdk.testapp.activity.style;
+
+import android.graphics.Bitmap;
+import android.os.AsyncTask;
+import android.os.Bundle;
+
+import com.mapbox.geojson.Feature;
+import com.mapbox.geojson.FeatureCollection;
+import com.mapbox.geojson.Point;
+import com.mapbox.mapboxsdk.maps.ImageContent;
+import com.mapbox.mapboxsdk.maps.ImageStretches;
+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.SymbolLayer;
+import com.mapbox.mapboxsdk.style.sources.GeoJsonSource;
+import com.mapbox.mapboxsdk.testapp.R;
+import com.mapbox.mapboxsdk.testapp.utils.GeoParseUtil;
+import com.mapbox.mapboxsdk.utils.BitmapUtils;
+
+import java.io.IOException;
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.List;
+
+import androidx.annotation.NonNull;
+import androidx.appcompat.app.AppCompatActivity;
+import timber.log.Timber;
+
+import static com.mapbox.mapboxsdk.style.expressions.Expression.get;
+import static com.mapbox.mapboxsdk.style.layers.Property.ICON_TEXT_FIT_BOTH;
+import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.iconAllowOverlap;
+import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.iconImage;
+import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.iconTextFit;
+import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.textAllowOverlap;
+import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.textField;
+
+/**
+ * Test stretchable image as a background for text..
+ */
+public class StretchableImageActivity extends AppCompatActivity implements OnMapReadyCallback {
+  private static final String NAME_POPUP = "popup";
+  private static final String NAME_POPUP_DEBUG = "popup-debug";
+  private static final String STRETCH_SOURCE = "STRETCH_SOURCE";
+  private static final String STRETCH_LAYER = "STRETCH_LAYER";
+  private static final String ORIGINAL_SOURCE = "ORIGINAL_SOURCE";
+  private static final String ORIGINAL_LAYER = "ORIGINAL_LAYER";
+  private MapboxMap mapboxMap;
+  private MapView mapView;
+
+  @Override
+  public void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    setContentView(R.layout.activity_stretchable_image);
+    mapView = findViewById(R.id.mapView);
+    mapView.onCreate(savedInstanceState);
+    mapView.getMapAsync(this);
+  }
+
+  @Override
+  public void onMapReady(@NonNull MapboxMap mapboxMap) {
+    this.mapboxMap = mapboxMap;
+    mapboxMap.setStyle(Style.MAPBOX_STREETS, style -> {
+      Bitmap popup = BitmapUtils.getBitmapFromDrawable(getResources().getDrawable(R.drawable.popup));
+      Bitmap popupDebug = BitmapUtils.getBitmapFromDrawable(getResources().getDrawable(R.drawable.popup_debug));
+
+      // The two (blue) columns of pixels that can be stretched horizontally:
+      //   - the pixels between x: 25 and x: 55 can be stretched
+      //   - the pixels between x: 85 and x: 115 can be stretched.
+      List<ImageStretches> stretchX = new ArrayList<>();
+      stretchX.add(new ImageStretches(25, 55));
+      stretchX.add(new ImageStretches(85, 115));
+
+      // The one (red) row of pixels that can be stretched vertically:
+      //   - the pixels between y: 25 and y: 100 can be stretched
+      List<ImageStretches> stretchY = new ArrayList<>();
+      stretchY.add(new ImageStretches(25, 100));
+
+      // This part of the image that can contain text ([x1, y1, x2, y2]):
+      ImageContent content = new ImageContent(25, 25, 115, 100);
+
+      style.addImage(NAME_POPUP, popup, stretchX, stretchY, content);
+      style.addImage(NAME_POPUP_DEBUG, popupDebug, stretchX, stretchY, content);
+      new LoadFeatureTask(StretchableImageActivity.this).execute();
+    });
+  }
+
+  private void onFeatureLoaded(String json) {
+    if (json == null) {
+      Timber.e("json is null.");
+      return;
+    }
+
+    Style style = mapboxMap.getStyle();
+    if (style != null) {
+      FeatureCollection featureCollection = FeatureCollection.fromJson(json);
+      GeoJsonSource stretchSource = new GeoJsonSource(STRETCH_SOURCE, featureCollection);
+      SymbolLayer stretchLayer = new SymbolLayer(STRETCH_LAYER, STRETCH_SOURCE)
+        .withProperties(
+          textField(get("name")),
+          iconImage(get("image-name")),
+          iconAllowOverlap(true),
+          textAllowOverlap(true),
+          iconTextFit(ICON_TEXT_FIT_BOTH));
+
+      // the original, unstretched image for comparison
+      Point point = Point.fromLngLat(-70, 0);
+      Feature feature = Feature.fromGeometry(point);
+      FeatureCollection originalCollection = FeatureCollection.fromFeature(feature);
+      GeoJsonSource originalSource = new GeoJsonSource(ORIGINAL_SOURCE, originalCollection);
+      SymbolLayer originalLayer = new SymbolLayer(ORIGINAL_LAYER, ORIGINAL_SOURCE);
+
+      style.addSource(stretchSource);
+      style.addSource(originalSource);
+      style.addLayer(stretchLayer);
+      style.addLayer(originalLayer);
+    }
+  }
+
+  private static class LoadFeatureTask extends AsyncTask<Void, Integer, String> {
+
+    private WeakReference<StretchableImageActivity> activity;
+
+    private LoadFeatureTask(StretchableImageActivity activity) {
+      this.activity = new WeakReference<>(activity);
+    }
+
+    @Override
+    protected String doInBackground(Void... params) {
+      StretchableImageActivity activity = this.activity.get();
+      if (activity != null) {
+        String json = null;
+        try {
+          json = GeoParseUtil.loadStringFromAssets(activity.getApplicationContext(), "stretchable_image.geojson");
+        } catch (IOException exception) {
+          Timber.e(exception, "Could not read feature");
+        }
+
+        return json;
+      }
+      return null;
+    }
+
+    @Override
+    protected void onPostExecute(String json) {
+      super.onPostExecute(json);
+      StretchableImageActivity activity = this.activity.get();
+      if (activity != null) {
+        activity.onFeatureLoaded(json);
+      }
+    }
+  }
+
+
+  @Override
+  protected void onStart() {
+    super.onStart();
+    mapView.onStart();
+  }
+
+  @Override
+  protected void onResume() {
+    super.onResume();
+    mapView.onResume();
+  }
+
+  @Override
+  protected void onPause() {
+    super.onPause();
+    mapView.onPause();
+  }
+
+  @Override
+  protected void onStop() {
+    super.onStop();
+    mapView.onStop();
+  }
+
+  @Override
+  public void onSaveInstanceState(Bundle outState) {
+    super.onSaveInstanceState(outState);
+    mapView.onSaveInstanceState(outState);
+  }
+
+  @Override
+  public void onLowMemory() {
+    super.onLowMemory();
+    mapView.onLowMemory();
+  }
+
+  @Override
+  public void onDestroy() {
+    super.onDestroy();
+    mapView.onDestroy();
+  }
+
+}