Recyclerview selection experiment

app/build.gradle

@@ -79,6 +79,7 @@ dependencies {
 
     implementation "androidx.appcompat:appcompat:$androidx_version"
     implementation "androidx.recyclerview:recyclerview:$androidx_version"
+    implementation "androidx.recyclerview:recyclerview-selection:$androidx_version"
     implementation "com.google.android.material:material:$androidx_version"
     implementation "androidx.browser:browser:$androidx_version"
     implementation "androidx.constraintlayout:constraintlayout:$constraintlayout_version"

app/src/main/java/eu/faircode/email/AdapterMessage.java

@@ -24,6 +24,7 @@ import android.content.Intent;
 import android.graphics.Typeface;
 import android.preference.PreferenceManager;
 import android.text.format.DateUtils;
+import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -41,6 +42,8 @@ import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.Observer;
 import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 import androidx.paging.PagedListAdapter;
+import androidx.recyclerview.selection.ItemDetailsLookup;
+import androidx.recyclerview.selection.SelectionTracker;
 import androidx.recyclerview.widget.DiffUtil;
 import androidx.recyclerview.widget.RecyclerView;
 
@@ -48,6 +51,7 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
     private Context context;
     private LifecycleOwner owner;
     private ViewType viewType;
+    private SelectionTracker selectionTracker;
 
     private boolean debug;
     private DateFormat df = SimpleDateFormat.getDateTimeInstance(SimpleDateFormat.SHORT, SimpleDateFormat.LONG);
@@ -84,12 +88,12 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
 
         private void wire() {
             itemView.setOnClickListener(this);
-            itemView.setOnLongClickListener(this);
+            //itemView.setOnLongClickListener(this);
         }
 
         private void unwire() {
             itemView.setOnClickListener(null);
-            itemView.setOnLongClickListener(null);
+            //itemView.setOnLongClickListener(null);
         }
 
         private void clear() {
@@ -107,6 +111,8 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
         private void bindTo(final TupleMessageEx message) {
             pbLoading.setVisibility(View.GONE);
 
+            itemView.setActivated(selectionTracker.isSelected(message.id));
+
             if (EntityFolder.DRAFTS.equals(message.folderType) ||
                     EntityFolder.OUTBOX.equals(message.folderType) ||
                     EntityFolder.SENT.equals(message.folderType)) {
@@ -209,6 +215,16 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
 
             return true;
         }
+
+        public ItemDetailsLookup.ItemDetails getItemDetails() {
+            Log.i(Helper.TAG, "getItemDetails");
+            return new MyItemDetail(getAdapterPosition(), getItem(getAdapterPosition()).id);
+        }
+    }
+
+    public void setSelectionTracker(SelectionTracker selectionTracker) {
+        Log.i(Helper.TAG, "setSelectionTracker");
+        this.selectionTracker = selectionTracker;
     }
 
     AdapterMessage(Context context, LifecycleOwner owner, ViewType viewType) {
@@ -243,6 +259,7 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
     @Override
     public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
         holder.unwire();
+        Log.i(Helper.TAG, "onBindViewHolder");
 
         TupleMessageEx message = getItem(position);
         if (message == null)

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -28,6 +28,7 @@ import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
+import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ProgressBar;
@@ -46,6 +47,10 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.Observer;
 import androidx.paging.LivePagedListBuilder;
 import androidx.paging.PagedList;
+import androidx.recyclerview.selection.OnDragInitiatedListener;
+import androidx.recyclerview.selection.SelectionPredicates;
+import androidx.recyclerview.selection.SelectionTracker;
+import androidx.recyclerview.selection.StorageStrategy;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
@@ -58,6 +63,7 @@ public class FragmentMessages extends FragmentEx {
 
     private long primary = -1;
     private AdapterMessage adapter;
+    private SelectionTracker selectionTracker;
 
     private static final int PAGE_SIZE = 50;
 
@@ -118,7 +124,14 @@ public class FragmentMessages extends FragmentEx {
     }
 
     @Override
-    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
+    public void onSaveInstanceState(Bundle outState) {
+        super.onSaveInstanceState(outState);
+        if (selectionTracker != null)
+            selectionTracker.onSaveInstanceState(outState);
+    }
+
+    @Override
+    public void onActivityCreated(@Nullable final Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);
 
         // Get arguments
@@ -191,6 +204,53 @@ public class FragmentMessages extends FragmentEx {
                 Log.i(Helper.TAG, "Submit messages=" + messages.size());
                 adapter.submitList(messages);
 
+                selectionTracker = new SelectionTracker.Builder<>(
+                        "messages-selection",
+                        rvMessage,
+                        new MyItemKeyProvider(messages),
+                        new MyItemLookup(rvMessage),
+                        StorageStrategy.createLongStorage())
+                        .withSelectionPredicate(SelectionPredicates.<Long>createSelectAnything())
+                        .withOnDragInitiatedListener(new OnDragInitiatedListener() {
+                            @Override
+                            public boolean onDragInitiated(@NonNull MotionEvent e) {
+                                Log.i(Helper.TAG, "onDragInitiated");
+                                return true;
+                            }
+                        }).build();
+
+
+                adapter.setSelectionTracker(selectionTracker);
+
+                selectionTracker.addObserver(new SelectionTracker.SelectionObserver() {
+                    @Override
+                    public void onItemStateChanged(@NonNull Object key, boolean selected) {
+                        Log.i(Helper.TAG, "onItemStateChanged");
+                        super.onItemStateChanged(key, selected);
+                    }
+
+                    @Override
+                    public void onSelectionRefresh() {
+                        Log.i(Helper.TAG, "onSelectionRefresh");
+                        super.onSelectionRefresh();
+                    }
+
+                    @Override
+                    public void onSelectionChanged() {
+                        Log.i(Helper.TAG, "onSelectionChanged");
+                        super.onSelectionChanged();
+                    }
+
+                    @Override
+                    public void onSelectionRestored() {
+                        Log.i(Helper.TAG, "onSelectionRestored");
+                        super.onSelectionRestored();
+                    }
+                });
+
+                if (savedInstanceState != null)
+                    selectionTracker.onRestoreInstanceState(savedInstanceState);
+
                 pbWait.setVisibility(View.GONE);
                 grpReady.setVisibility(View.VISIBLE);
 

app/src/main/java/eu/faircode/email/MyActionModeController.java

@@ -0,0 +1,38 @@
+package eu.faircode.email;
+
+import android.content.Context;
+import android.view.Menu;
+import android.view.MenuItem;
+
+import androidx.appcompat.view.ActionMode;
+import androidx.recyclerview.selection.SelectionTracker;
+
+public class MyActionModeController implements ActionMode.Callback {
+    private final Context context;
+    private final SelectionTracker selectionTracker;
+
+    public MyActionModeController(Context context, SelectionTracker selectionTracker) {
+        this.context = context;
+        this.selectionTracker = selectionTracker;
+    }
+
+    @Override
+    public boolean onCreateActionMode(ActionMode actionMode, Menu menu) {
+        return false;
+    }
+
+    @Override
+    public boolean onPrepareActionMode(ActionMode actionMode, Menu menu) {
+        return false;
+    }
+
+    @Override
+    public boolean onActionItemClicked(ActionMode actionMode, MenuItem menuItem) {
+        return false;
+    }
+
+    @Override
+    public void onDestroyActionMode(ActionMode actionMode) {
+        selectionTracker.clearSelection();
+    }
+}

app/src/main/java/eu/faircode/email/MyItemDetail.java

@@ -0,0 +1,30 @@
+package eu.faircode.email;
+
+import android.util.Log;
+
+import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.ItemDetailsLookup;
+
+public class MyItemDetail extends ItemDetailsLookup.ItemDetails<Long> {
+    private final int adapterPosition;
+    private final Long selectionKey;
+
+    public MyItemDetail(int adapterPosition, Long selectionKey) {
+        Log.i(Helper.TAG, "MyItemDetail");
+        this.adapterPosition = adapterPosition;
+        this.selectionKey = selectionKey;
+    }
+
+    @Override
+    public int getPosition() {
+        Log.i(Helper.TAG, "MyItemDetail.getPosition=" + adapterPosition);
+        return adapterPosition;
+    }
+
+    @Nullable
+    @Override
+    public Long getSelectionKey() {
+        Log.i(Helper.TAG, "MyItemDetail.getSelectionKey=" + selectionKey);
+        return selectionKey;
+    }
+}

app/src/main/java/eu/faircode/email/MyItemKeyProvider.java

@@ -0,0 +1,37 @@
+package eu.faircode.email;
+
+import android.util.Log;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.paging.PagedList;
+import androidx.recyclerview.selection.ItemKeyProvider;
+import androidx.recyclerview.widget.RecyclerView;
+
+public class MyItemKeyProvider extends ItemKeyProvider<Long> {
+    private final PagedList<TupleMessageEx> messages;
+
+    public MyItemKeyProvider(PagedList<TupleMessageEx> messages) {
+        super(ItemKeyProvider.SCOPE_MAPPED);
+        this.messages = messages;
+        Log.i(Helper.TAG, "MyItemKeyProvider");
+    }
+
+    @Nullable
+    @Override
+    public Long getKey(int position) {
+        Log.i(Helper.TAG, "MyItemKeyProvider.getKey pos=" + position + " key=" + messages.get(position).id);
+        return messages.get(position).id;
+    }
+
+    @Override
+    public int getPosition(@NonNull Long key) {
+        Log.i(Helper.TAG, "MyItemKeyProvider.getPosition key=" + key);
+        int pos = RecyclerView.NO_POSITION;
+        for (int i = 0; i < messages.size(); i++)
+            if (messages.get(i).id.equals(key))
+                pos = i;
+        Log.i(Helper.TAG, "MyItemKeyProvider.getPosition key=" + key + " pos=" + pos);
+        return pos;
+    }
+}

app/src/main/java/eu/faircode/email/MyItemLookup.java

@@ -0,0 +1,35 @@
+package eu.faircode.email;
+
+import android.util.Log;
+import android.view.MotionEvent;
+import android.view.View;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.ItemDetailsLookup;
+import androidx.recyclerview.widget.RecyclerView;
+
+public class MyItemLookup extends ItemDetailsLookup<Long> {
+
+    private final RecyclerView recyclerView;
+
+    public MyItemLookup(RecyclerView recyclerView) {
+        Log.i(Helper.TAG, "MyItemLookup");
+        this.recyclerView = recyclerView;
+    }
+
+    @Nullable
+    @Override
+    public ItemDetails<Long> getItemDetails(@NonNull MotionEvent e) {
+        Log.i(Helper.TAG, "MyItemLookup.getItemDetails");
+        View view = recyclerView.findChildViewUnder(e.getX(), e.getY());
+        if (view != null) {
+            RecyclerView.ViewHolder viewHolder = recyclerView.getChildViewHolder(view);
+            if (viewHolder instanceof AdapterMessage.ViewHolder) {
+                return ((AdapterMessage.ViewHolder) viewHolder).getItemDetails();
+            }
+        }
+
+        return null;
+    }
+}