Fix null pointer exception when presenting latest media thumbnail.

app/src/main/java/org/thoughtcrime/securesms/mediasend/AvatarSelectionActivity.java

@@ -13,7 +13,6 @@ import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.app.AppCompatDelegate;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentTransaction;
-import androidx.lifecycle.LiveData;
 
 import org.signal.imageeditor.core.model.EditorModel;
 import org.thoughtcrime.securesms.R;
@@ -22,13 +21,14 @@ import org.thoughtcrime.securesms.mms.MediaConstraints;
 import org.thoughtcrime.securesms.profiles.AvatarHelper;
 import org.thoughtcrime.securesms.providers.BlobProvider;
 import org.thoughtcrime.securesms.scribbles.ImageEditorFragment;
-import org.thoughtcrime.securesms.util.DefaultValueLiveData;
 import org.thoughtcrime.securesms.util.MediaUtil;
 
 import java.io.FileDescriptor;
 import java.util.Collections;
 import java.util.Optional;
 
+import io.reactivex.rxjava3.core.Flowable;
+
 public class AvatarSelectionActivity extends AppCompatActivity implements CameraFragment.Controller, ImageEditorFragment.Controller, MediaGalleryFragment.Callbacks {
 
   private static final Point AVATAR_DIMENSIONS = new Point(AvatarHelper.AVATAR_DIMENSIONS, AvatarHelper.AVATAR_DIMENSIONS);
@@ -131,8 +131,8 @@ public class AvatarSelectionActivity extends AppCompatActivity implements Camera
   }
 
   @Override
-  public @NonNull LiveData<Optional<Media>> getMostRecentMediaItem() {
+  public @NonNull Flowable<Optional<Media>> getMostRecentMediaItem() {
-    return new DefaultValueLiveData<>(Optional.empty());
+    return Flowable.just(Optional.empty());
   }
 
   @Override

app/src/main/java/org/thoughtcrime/securesms/mediasend/Camera1Fragment.java

@@ -27,7 +27,6 @@ import android.widget.ImageView;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
-import androidx.lifecycle.Observer;
 
 import com.bumptech.glide.Glide;
 import com.bumptech.glide.load.MultiTransformation;
@@ -51,8 +50,8 @@ import org.thoughtcrime.securesms.util.Stopwatch;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
 
 import java.io.ByteArrayOutputStream;
-import java.util.Optional;
 
+import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers;
 import io.reactivex.rxjava3.disposables.Disposable;
 
 /**
@@ -75,8 +74,8 @@ public class Camera1Fragment extends LoggingFragment implements CameraFragment,
   private Camera1Controller.Properties properties;
   private RotationListener             rotationListener;
   private Disposable                   rotationListenerDisposable;
+  private Disposable                   mostRecentItemDisposable = Disposable.disposed();
 
-  private final Observer<Optional<Media>> thumbObserver = this::presentRecentItemThumbnail;
   private boolean isThumbAvailable;
   private boolean isMediaSelected;
 
@@ -192,7 +191,7 @@ public class Camera1Fragment extends LoggingFragment implements CameraFragment,
   @Override
   public void onDestroyView() {
     super.onDestroyView();
-    controller.getMostRecentMediaItem().removeObserver(thumbObserver);
+    mostRecentItemDisposable.dispose();
   }
 
   @Override
@@ -271,19 +270,13 @@ public class Camera1Fragment extends LoggingFragment implements CameraFragment,
     controller.onCameraError();
   }
 
-  private void presentRecentItemThumbnail(Optional<Media> media) {
+  private void presentRecentItemThumbnail(@Nullable Media media) {
-    if (media == null) {
-      isThumbAvailable = false;
-      updateGalleryVisibility();
-      return;
-    }
-
     ImageView thumbnail = controlsContainer.findViewById(R.id.camera_gallery_button);
 
-    if (media.isPresent()) {
+    if (media != null) {
       thumbnail.setVisibility(View.VISIBLE);
       Glide.with(this)
-           .load(new DecryptableUri(media.get().getUri()))
+           .load(new DecryptableUri(media.getUri()))
            .centerCrop()
            .into(thumbnail);
     } else {
@@ -291,7 +284,7 @@ public class Camera1Fragment extends LoggingFragment implements CameraFragment,
       thumbnail.setImageResource(0);
     }
 
-    isThumbAvailable = media.isPresent();
+    isThumbAvailable = media != null;
     updateGalleryVisibility();
   }
 
@@ -331,8 +324,10 @@ public class Camera1Fragment extends LoggingFragment implements CameraFragment,
     View countButton   = requireView().findViewById(R.id.camera_review_button);
     View toggleSpacer  = requireView().findViewById(R.id.toggle_spacer);
 
-    controller.getMostRecentMediaItem().removeObserver(thumbObserver);
+    mostRecentItemDisposable.dispose();
-    controller.getMostRecentMediaItem().observeForever(thumbObserver);
+    mostRecentItemDisposable = controller.getMostRecentMediaItem()
+                                         .observeOn(AndroidSchedulers.mainThread())
+                                         .subscribe(item -> presentRecentItemThumbnail(item.orElse(null)));
 
     if (toggleSpacer != null) {
       if (Stories.isFeatureEnabled()) {

app/src/main/java/org/thoughtcrime/securesms/mediasend/CameraFragment.java

@@ -5,7 +5,6 @@ import android.content.res.Configuration;
 
 import androidx.annotation.NonNull;
 import androidx.fragment.app.Fragment;
-import androidx.lifecycle.LiveData;
 
 import org.thoughtcrime.securesms.mediasend.camerax.CameraXUtil;
 import org.thoughtcrime.securesms.mms.MediaConstraints;
@@ -13,6 +12,8 @@ import org.thoughtcrime.securesms.mms.MediaConstraints;
 import java.io.FileDescriptor;
 import java.util.Optional;
 
+import io.reactivex.rxjava3.core.Flowable;
+
 public interface CameraFragment {
 
   float PORTRAIT_ASPECT_RATIO = 9 / 16f;
@@ -54,7 +55,7 @@ public interface CameraFragment {
     void onVideoCaptureError();
     void onGalleryClicked();
     void onCameraCountButtonClicked();
-    @NonNull LiveData<Optional<Media>> getMostRecentMediaItem();
+    @NonNull Flowable<Optional<Media>> getMostRecentMediaItem();
     @NonNull MediaConstraints getMediaConstraints();
     int getMaxVideoDuration();
   }

app/src/main/java/org/thoughtcrime/securesms/mediasend/CameraXFragment.java

@@ -31,7 +31,6 @@ import androidx.camera.lifecycle.ProcessCameraProvider;
 import androidx.camera.view.PreviewView;
 import androidx.camera.view.SignalCameraView;
 import androidx.core.content.ContextCompat;
-import androidx.lifecycle.Observer;
 
 import com.bumptech.glide.Glide;
 import com.bumptech.glide.util.Executors;
@@ -57,7 +56,9 @@ import org.thoughtcrime.securesms.video.VideoUtil;
 
 import java.io.FileDescriptor;
 import java.io.IOException;
-import java.util.Optional;
+
+import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers;
+import io.reactivex.rxjava3.disposables.Disposable;
 
 /**
  * Camera captured implemented using the CameraX SDK, which uses Camera2 under the hood. Should be
@@ -74,8 +75,8 @@ public class CameraXFragment extends LoggingFragment implements CameraFragment {
   private Controller           controller;
   private View                 selfieFlash;
   private MemoryFileDescriptor videoFileDescriptor;
+  private Disposable           mostRecentItemDisposable = Disposable.disposed();
 
-  private final Observer<Optional<Media>> thumbObserver = this::presentRecentItemThumbnail;
   private boolean isThumbAvailable;
   private boolean isMediaSelected;
 
@@ -161,7 +162,7 @@ public class CameraXFragment extends LoggingFragment implements CameraFragment {
   @Override
   public void onDestroyView() {
     super.onDestroyView();
-    controller.getMostRecentMediaItem().removeObserver(thumbObserver);
+    mostRecentItemDisposable.dispose();
     closeVideoFileDescriptor();
     requireActivity().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
   }
@@ -221,19 +222,13 @@ public class CameraXFragment extends LoggingFragment implements CameraFragment {
     initControls();
   }
 
-  private void presentRecentItemThumbnail(Optional<Media> media) {
+  private void presentRecentItemThumbnail(@Nullable Media media) {
-    if (media == null) {
-      isThumbAvailable = false;
-      updateGalleryVisibility();
-      return;
-    }
-
     ImageView thumbnail = controlsContainer.findViewById(R.id.camera_gallery_button);
 
-    if (media.isPresent()) {
+    if (media != null) {
       thumbnail.setVisibility(View.VISIBLE);
       Glide.with(this)
-           .load(new DecryptableUri(media.get().getUri()))
+           .load(new DecryptableUri(media.getUri()))
            .centerCrop()
            .into(thumbnail);
     } else {
@@ -241,7 +236,7 @@ public class CameraXFragment extends LoggingFragment implements CameraFragment {
       thumbnail.setImageResource(0);
     }
 
-    isThumbAvailable = media.isPresent();
+    isThumbAvailable = media != null;
     updateGalleryVisibility();
   }
 
@@ -292,8 +287,10 @@ public class CameraXFragment extends LoggingFragment implements CameraFragment {
       }
     }
 
-    controller.getMostRecentMediaItem().removeObserver(thumbObserver);
+    mostRecentItemDisposable.dispose();
-    controller.getMostRecentMediaItem().observeForever(thumbObserver);
+    mostRecentItemDisposable = controller.getMostRecentMediaItem()
+                                         .observeOn(AndroidSchedulers.mainThread())
+                                         .subscribe(item -> presentRecentItemThumbnail(item.orElse(null)));
 
     selfieFlash = requireView().findViewById(R.id.camera_selfie_flash);
 

app/src/main/java/org/thoughtcrime/securesms/mediasend/v2/capture/MediaCaptureFragment.kt

@@ -6,9 +6,9 @@ import android.widget.Toast
 import androidx.activity.OnBackPressedCallback
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.viewModels
-import androidx.lifecycle.LiveData
 import androidx.navigation.fragment.findNavController
 import app.cash.exhaustive.Exhaustive
+import io.reactivex.rxjava3.core.Flowable
 import org.signal.core.util.logging.Log
 import org.thoughtcrime.securesms.R
 import org.thoughtcrime.securesms.mediasend.CameraFragment
@@ -149,7 +149,7 @@ class MediaCaptureFragment : Fragment(R.layout.fragment_container), CameraFragme
     }
   }
 
-  override fun getMostRecentMediaItem(): LiveData<Optional<Media>> {
+  override fun getMostRecentMediaItem(): Flowable<Optional<Media>> {
     return viewModel.getMostRecentMedia()
   }
 

app/src/main/java/org/thoughtcrime/securesms/mediasend/v2/capture/MediaCaptureViewModel.kt

@@ -1,18 +1,18 @@
 package org.thoughtcrime.securesms.mediasend.v2.capture
 
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Transformations
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
+import io.reactivex.rxjava3.core.Flowable
 import org.thoughtcrime.securesms.mediasend.Media
 import org.thoughtcrime.securesms.util.SingleLiveEvent
-import org.thoughtcrime.securesms.util.livedata.Store
+import org.thoughtcrime.securesms.util.rx.RxStore
 import java.io.FileDescriptor
 import java.util.Optional
 
 class MediaCaptureViewModel(private val repository: MediaCaptureRepository) : ViewModel() {
 
-  private val store: Store<MediaCaptureState> = Store(MediaCaptureState())
+  private val store: RxStore<MediaCaptureState> = RxStore(MediaCaptureState())
 
   private val internalEvents: SingleLiveEvent<MediaCaptureEvent> = SingleLiveEvent()
 
@@ -34,8 +34,8 @@ class MediaCaptureViewModel(private val repository: MediaCaptureRepository) : Vi
     repository.renderVideoToMedia(fd, this::onMediaRendered, this::onMediaRenderFailed)
   }
 
-  fun getMostRecentMedia(): LiveData<Optional<Media>> {
+  fun getMostRecentMedia(): Flowable<Optional<Media>> {
-    return Transformations.map(store.stateLiveData) { Optional.ofNullable(it.mostRecentMedia) }
+    return store.stateFlowable.map { Optional.ofNullable(it.mostRecentMedia) }
   }
 
   private fun onMediaRendered(media: Media) {