Stickers in image editor.

src/org/thoughtcrime/securesms/scribbles/ImageEditorFragmentViewModel.java

@@ -0,0 +1,65 @@
+package org.thoughtcrime.securesms.scribbles;
+
+import android.app.Application;
+import android.database.ContentObserver;
+import android.os.Handler;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.ViewModel;
+import androidx.lifecycle.ViewModelProvider;
+
+import org.thoughtcrime.securesms.database.DatabaseContentProviders;
+import org.thoughtcrime.securesms.stickers.StickerSearchRepository;
+import org.thoughtcrime.securesms.util.Throttler;
+
+public final class ImageEditorFragmentViewModel extends ViewModel {
+
+  private final Application              application;
+  private final StickerSearchRepository  repository;
+  private final MutableLiveData<Boolean> stickersAvailable;
+  private final Throttler                availabilityThrottler;
+  private final ContentObserver          packObserver;
+
+  private ImageEditorFragmentViewModel(@NonNull Application application, @NonNull StickerSearchRepository repository) {
+    this.application           = application;
+    this.repository            = repository;
+    this.stickersAvailable     = new MutableLiveData<>();
+    this.availabilityThrottler = new Throttler(500);
+    this.packObserver          = new ContentObserver(new Handler()) {
+      @Override
+      public void onChange(boolean selfChange) {
+        availabilityThrottler.publish(() -> repository.getStickerFeatureAvailability(stickersAvailable::postValue));
+      }
+    };
+
+    application.getContentResolver().registerContentObserver(DatabaseContentProviders.StickerPack.CONTENT_URI, true, packObserver);
+  }
+
+  @NonNull LiveData<Boolean> getStickersAvailability() {
+    repository.getStickerFeatureAvailability(stickersAvailable::postValue);
+    return stickersAvailable;
+  }
+
+  @Override
+  protected void onCleared() {
+    application.getContentResolver().unregisterContentObserver(packObserver);
+  }
+
+  static class Factory extends ViewModelProvider.NewInstanceFactory {
+    private final Application             application;
+    private final StickerSearchRepository repository;
+
+    public Factory(@NonNull Application application, @NonNull StickerSearchRepository repository) {
+      this.application = application;
+      this.repository  = repository;
+    }
+
+    @Override
+    public @NonNull <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
+      //noinspection ConstantConditions
+      return modelClass.cast(new ImageEditorFragmentViewModel(application, repository));
+    }
+  }
+}