Added multiple selection

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

@@ -94,6 +94,8 @@ 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.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
@@ -109,6 +111,8 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
     private boolean compact;
     private boolean debug;
 
+    private SelectionTracker<Long> selectionTracker = null;
+
     private DateFormat df = SimpleDateFormat.getDateTimeInstance(SimpleDateFormat.LONG, SimpleDateFormat.LONG);
 
     enum ViewType {UNIFIED, FOLDER, THREAD, SEARCH}
@@ -159,6 +163,8 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
         private Group grpAttachments;
         private Group grpExpanded;
 
+        private ItemDetailsMessage itemDetails = null;
+
         ViewHolder(View itemView) {
             super(itemView);
 
@@ -251,7 +257,7 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
             grpExpanded.setVisibility(View.GONE);
         }
 
-        private void bindTo(final TupleMessageEx message) {
+        private void bindTo(int position, final TupleMessageEx message) {
             final DB db = DB.getInstance(context);
             final boolean show_expanded = properties.isExpanded(message.id);
             boolean show_headers = properties.showHeaders(message.id);
@@ -458,6 +464,9 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
                             }
                         });
             }
+
+            itemDetails = new ItemDetailsMessage(position, message.id);
+            itemView.setActivated(selectionTracker != null && selectionTracker.isSelected(message.id));
         }
 
         @Override
@@ -1329,6 +1338,10 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
                     .putExtra("action", "reply")
                     .putExtra("reference", data.message.id));
         }
+
+        ItemDetailsLookup.ItemDetails<Long> getItemDetails(@NonNull MotionEvent motionEvent) {
+            return itemDetails;
+        }
     }
 
     AdapterMessage(Context context, LifecycleOwner owner, ViewType viewType, IProperties properties) {
@@ -1380,11 +1393,15 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
         if (message == null)
             holder.clear();
         else {
-            holder.bindTo(message);
+            holder.bindTo(position, message);
             holder.wire();
         }
     }
 
+    void setSelectionTracker(SelectionTracker<Long> selectionTracker) {
+        this.selectionTracker = selectionTracker;
+    }
+
     interface IProperties {
         void setExpanded(long id, boolean expand);
 

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

@@ -61,6 +61,8 @@ import androidx.lifecycle.ViewModelProviders;
 import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 import androidx.paging.LivePagedListBuilder;
 import androidx.paging.PagedList;
+import androidx.recyclerview.selection.SelectionTracker;
+import androidx.recyclerview.selection.StorageStrategy;
 import androidx.recyclerview.widget.ItemTouchHelper;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
@@ -95,6 +97,8 @@ public class FragmentMessages extends FragmentEx {
     private AdapterMessage.ViewType viewType;
     private LiveData<PagedList<TupleMessageEx>> messages = null;
 
+    private SelectionTracker<Long> selectionTracker;
+
     private int autoCount = 0;
     private boolean autoExpand = true;
     private List<Long> expanded = new ArrayList<>();
@@ -229,6 +233,22 @@ public class FragmentMessages extends FragmentEx {
         });
         rvMessage.setAdapter(adapter);
 
+        selectionTracker = new SelectionTracker.Builder<>(
+                "messages-selection",
+                rvMessage,
+                new ItemKeyProviderMessage(rvMessage),
+                new ItemDetailsLookupMessage(rvMessage),
+                StorageStrategy.createLongStorage())
+                .withSelectionPredicate(new SelectionPredicateMessage())
+                .build();
+        adapter.setSelectionTracker(selectionTracker);
+
+        selectionTracker.addObserver(new SelectionTracker.SelectionObserver() {
+            @Override
+            public void onSelectionChanged() {
+            }
+        });
+
         new ItemTouchHelper(new ItemTouchHelper.Callback() {
             @Override
             public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
@@ -515,6 +535,7 @@ public class FragmentMessages extends FragmentEx {
         outState.putLongArray("expanded", Helper.toLongArray(expanded));
         outState.putLongArray("headers", Helper.toLongArray(headers));
         outState.putLongArray("images", Helper.toLongArray(images));
+        selectionTracker.onSaveInstanceState(outState);
     }
 
     @Override
@@ -527,6 +548,7 @@ public class FragmentMessages extends FragmentEx {
             expanded = Helper.fromLongArray(savedInstanceState.getLongArray("expanded"));
             headers = Helper.fromLongArray(savedInstanceState.getLongArray("headers"));
             images = Helper.fromLongArray(savedInstanceState.getLongArray("images"));
+            selectionTracker.onRestoreInstanceState(savedInstanceState);
         }
 
         SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());

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

@@ -0,0 +1,29 @@
+package eu.faircode.email;
+
+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 ItemDetailsLookupMessage extends ItemDetailsLookup<Long> {
+    private RecyclerView recyclerView;
+
+    ItemDetailsLookupMessage(RecyclerView recyclerView) {
+        this.recyclerView = recyclerView;
+    }
+
+    @Nullable
+    @Override
+    public ItemDetails<Long> getItemDetails(@NonNull MotionEvent motionEvent) {
+        View view = recyclerView.findChildViewUnder(motionEvent.getX(), motionEvent.getY());
+        if (view != null) {
+            RecyclerView.ViewHolder viewHolder = recyclerView.getChildViewHolder(view);
+            if (viewHolder instanceof AdapterMessage.ViewHolder)
+                return ((AdapterMessage.ViewHolder) viewHolder).getItemDetails(motionEvent);
+        }
+        return null;
+    }
+}

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

@@ -0,0 +1,25 @@
+package eu.faircode.email;
+
+import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.ItemDetailsLookup;
+
+public class ItemDetailsMessage extends ItemDetailsLookup.ItemDetails<Long> {
+    private int pos;
+    private Long key;
+
+    ItemDetailsMessage(int pos, Long id) {
+        this.pos = pos;
+        this.key = id;
+    }
+
+    @Override
+    public int getPosition() {
+        return pos;
+    }
+
+    @Nullable
+    @Override
+    public Long getSelectionKey() {
+        return key;
+    }
+}

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

@@ -0,0 +1,36 @@
+package eu.faircode.email;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.paging.PagedList;
+import androidx.recyclerview.selection.ItemKeyProvider;
+import androidx.recyclerview.widget.RecyclerView;
+
+public class ItemKeyProviderMessage extends ItemKeyProvider<Long> {
+    private RecyclerView recyclerView;
+
+    ItemKeyProviderMessage(RecyclerView recyclerView) {
+        super(ItemKeyProvider.SCOPE_CACHED);
+        this.recyclerView = recyclerView;
+    }
+
+    @Nullable
+    @Override
+    public Long getKey(int pos) {
+        AdapterMessage adapter = (AdapterMessage) recyclerView.getAdapter();
+        return adapter.getCurrentList().get(pos).id;
+    }
+
+    @Override
+    public int getPosition(@NonNull Long key) {
+        AdapterMessage adapter = (AdapterMessage) recyclerView.getAdapter();
+        PagedList<TupleMessageEx> messages = adapter.getCurrentList();
+        if (messages != null)
+            for (int i = 0; i < messages.size(); i++) {
+                TupleMessageEx message = messages.get(i);
+                if (message != null && message.id.equals(key))
+                    return i;
+            }
+        return RecyclerView.NO_POSITION;
+    }
+}

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

@@ -0,0 +1,22 @@
+package eu.faircode.email;
+
+import androidx.annotation.NonNull;
+import androidx.recyclerview.selection.SelectionTracker;
+
+public class SelectionPredicateMessage extends SelectionTracker.SelectionPredicate<Long> {
+
+    @Override
+    public boolean canSetStateForKey(@NonNull Long key, boolean nextState) {
+        return true;
+    }
+
+    @Override
+    public boolean canSetStateAtPosition(int position, boolean nextState) {
+        return true;
+    }
+
+    @Override
+    public boolean canSelectMultiple() {
+        return true;
+    }
+}