First experiment with on-scrolling pagination on track list by genre

app/src/main/java/com/cappielloantonio/play/helper/recyclerview/PaginationScrollListener.java

@@ -0,0 +1,36 @@
+package com.cappielloantonio.play.helper.recyclerview;
+
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+
+
+public abstract class PaginationScrollListener extends RecyclerView.OnScrollListener {
+    private static final String TAG = "PaginationScrollListener";
+
+    private LinearLayoutManager layoutManager;
+
+    protected PaginationScrollListener(LinearLayoutManager layoutManager) {
+        this.layoutManager = layoutManager;
+    }
+
+    @Override
+    public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
+        super.onScrolled(recyclerView, dx, dy);
+
+        int visibleItemCount = layoutManager.getChildCount();
+        int totalItemCount = layoutManager.getItemCount();
+        int firstVisibleItemPosition = layoutManager.findFirstVisibleItemPosition();
+
+        if (!isLoading()) {
+            if (firstVisibleItemPosition >= 0 && (visibleItemCount + firstVisibleItemPosition) >= totalItemCount) {
+                loadMoreItems();
+            }
+        }
+    }
+
+    protected abstract void loadMoreItems();
+
+    public abstract boolean isLoading();
+
+}

app/src/main/java/com/cappielloantonio/play/repository/SongRepository.java

@@ -11,7 +11,6 @@ import com.cappielloantonio.play.subsonic.models.Child;
 
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.LinkedHashSet;
 import java.util.List;
 
 import retrofit2.Call;
@@ -171,27 +170,19 @@ public class SongRepository {
                 });
     }
 
-    public MutableLiveData<List<Child>> getSongsByGenre(String id) {
+    public MutableLiveData<List<Child>> getSongsByGenre(String id, int page) {
         MutableLiveData<List<Child>> songsByGenre = new MutableLiveData<>();
 
+        Log.d(TAG, "onScrolled PAGE: " + page);
+
         App.getSubsonicClientInstance(false)
                 .getAlbumSongListClient()
-                .getSongsByGenre(id, 500, 0)
+                .getSongsByGenre(id, 100, 100 * page)
                 .enqueue(new Callback<ApiResponse>() {
                     @Override
                     public void onResponse(@NonNull Call<ApiResponse> call, @NonNull Response<ApiResponse> response) {
                         if (response.isSuccessful() && response.body() != null && response.body().getSubsonicResponse().getSongsByGenre() != null) {
-                            List<Child> newSongs = response.body().getSubsonicResponse().getSongsByGenre().getSongs();
+                            songsByGenre.setValue(response.body().getSubsonicResponse().getSongsByGenre().getSongs());
-                            List<Child> songs = songsByGenre.getValue();
-
-                            if (songs == null) songs = new ArrayList<>();
-                            songs.addAll(newSongs);
-                            Collections.shuffle(songs);
-
-                            LinkedHashSet<Child> hashSet = new LinkedHashSet<>(songs);
-                            ArrayList<Child> songsWithoutDuplicates = new ArrayList<>(hashSet);
-
-                            songsByGenre.setValue(songsWithoutDuplicates);
                         }
                     }
 

app/src/main/java/com/cappielloantonio/play/ui/fragment/SongListPageFragment.java

@@ -18,6 +18,7 @@ import androidx.recyclerview.widget.LinearLayoutManager;
 
 import com.cappielloantonio.play.R;
 import com.cappielloantonio.play.databinding.FragmentSongListPageBinding;
+import com.cappielloantonio.play.helper.recyclerview.PaginationScrollListener;
 import com.cappielloantonio.play.interfaces.ClickCallback;
 import com.cappielloantonio.play.service.MediaManager;
 import com.cappielloantonio.play.service.MediaService;
@@ -32,6 +33,8 @@ import java.util.Collections;
 
 @UnstableApi
 public class SongListPageFragment extends Fragment implements ClickCallback {
+    private static final String TAG = "SongListPageFragment";
+
     private FragmentSongListPageBinding bind;
     private MainActivity activity;
     private SongListPageViewModel songListPageViewModel;
@@ -40,6 +43,8 @@ public class SongListPageFragment extends Fragment implements ClickCallback {
 
     private ListenableFuture<MediaBrowser> mediaBrowserListenableFuture;
 
+    private boolean isLoading = true;
+
     @Override
     public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
@@ -163,7 +168,23 @@ public class SongListPageFragment extends Fragment implements ClickCallback {
 
         songHorizontalAdapter = new SongHorizontalAdapter(this, true);
         bind.songListRecyclerView.setAdapter(songHorizontalAdapter);
-        songListPageViewModel.getSongList().observe(getViewLifecycleOwner(), songs -> songHorizontalAdapter.setItems(songs));
+        songListPageViewModel.getSongList().observe(getViewLifecycleOwner(), songs -> {
+            isLoading = false;
+            songHorizontalAdapter.setItems(songs);
+        });
+
+        bind.songListRecyclerView.addOnScrollListener(new PaginationScrollListener((LinearLayoutManager) bind.songListRecyclerView.getLayoutManager()) {
+            @Override
+            protected void loadMoreItems() {
+                isLoading = true;
+                songListPageViewModel.getSongsByPage(getViewLifecycleOwner());
+            }
+
+            @Override
+            public boolean isLoading() {
+                return isLoading;
+            }
+        });
     }
 
     private void initializeMediaBrowser() {

app/src/main/java/com/cappielloantonio/play/viewmodel/SongListPageViewModel.java

@@ -5,6 +5,7 @@ import android.text.TextUtils;
 
 import androidx.annotation.NonNull;
 import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
@@ -48,7 +49,7 @@ public class SongListPageViewModel extends AndroidViewModel {
 
         switch (title) {
             case Constants.MEDIA_BY_GENRE:
-                songList = songRepository.getSongsByGenre(genre.getGenre());
+                songList = songRepository.getSongsByGenre(genre.getGenre(), 0);
                 break;
             case Constants.MEDIA_BY_ARTIST:
                 songList = artistRepository.getTopSongs(artist.getName(), 50);
@@ -67,6 +68,24 @@ public class SongListPageViewModel extends AndroidViewModel {
         return songList;
     }
 
+    public void getSongsByPage(LifecycleOwner owner) {
+        switch (title) {
+            case Constants.MEDIA_BY_GENRE:
+                int page = (songList.getValue() != null ? songList.getValue().size() : 0) / 100;
+                songRepository.getSongsByGenre(genre.getGenre(), page).observe(owner, children -> {
+                    List<Child> currentMedia = songList.getValue();
+                    currentMedia.addAll(children);
+                    songList.setValue(currentMedia);
+                });
+                break;
+            case Constants.MEDIA_BY_ARTIST:
+            case Constants.MEDIA_BY_GENRES:
+            case Constants.MEDIA_BY_YEAR:
+            case Constants.MEDIA_STARRED:
+                break;
+        }
+    }
+
     public String getFiltersTitle() {
         return TextUtils.join(", ", filterNames);
     }