Experiment: show last selected folder

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

@@ -57,10 +57,12 @@ import androidx.constraintlayout.widget.Group;
 import androidx.core.content.pm.ShortcutInfoCompat;
 import androidx.core.content.pm.ShortcutManagerCompat;
 import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentActivity;
 import androidx.lifecycle.Lifecycle;
 import androidx.lifecycle.LifecycleObserver;
 import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.OnLifecycleEvent;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 import androidx.preference.PreferenceManager;
 import androidx.recyclerview.widget.DiffUtil;
@@ -95,6 +97,7 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
     private Context context;
     private LifecycleOwner owner;
     private LayoutInflater inflater;
+    private ViewModelSelected selectedModel;
 
     private boolean subscriptions;
 
@@ -105,6 +108,7 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
     private int textColorSecondary;
     private int colorUnread;
     private int colorControlNormal;
+    private int colorSeparator;
 
     private String search = null;
     private List<Long> disabledIds = new ArrayList<>();
@@ -226,6 +230,10 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
             view.setEnabled(!disabled);
             view.setAlpha(folder.hide || disabled ? Helper.LOW_LIGHT : 1.0f);
 
+            if (listener == null && selectedModel != null)
+                view.setBackgroundColor(selectedModel.isSelected(folder.id)
+                        ? colorSeparator : Color.TRANSPARENT);
+
             if (textSize != 0)
                 tvName.setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize);
 
@@ -425,6 +433,9 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
                         return;
 
                     if (listener == null) {
+                        if (selectedModel != null)
+                            selectedModel.select(folder.id);
+
                         LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(context);
                         lbm.sendBroadcast(
                                 new Intent(ActivityView.ACTION_VIEW_MESSAGES)
@@ -1154,6 +1165,9 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
         this.context = context;
         this.owner = owner;
         this.inflater = LayoutInflater.from(context);
+        if (context instanceof FragmentActivity)
+            this.selectedModel = new ViewModelProvider((FragmentActivity) context)
+                    .get(ViewModelSelected.class);
 
         SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
         boolean compact = prefs.getBoolean("compact", false);
@@ -1176,6 +1190,7 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
         int colorHighlight = prefs.getInt("highlight_color", Helper.resolveColor(context, R.attr.colorUnreadHighlight));
         this.colorUnread = (highlight_unread ? colorHighlight : Helper.resolveColor(context, R.attr.colorUnread));
         this.colorControlNormal = Helper.resolveColor(context, R.attr.colorControlNormal);
+        this.colorSeparator = Helper.resolveColor(context, R.attr.colorSeparator);
 
         setHasStableIds(true);
 

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

@@ -60,6 +60,7 @@ import androidx.core.view.MenuCompat;
 import androidx.fragment.app.FragmentTransaction;
 import androidx.lifecycle.Lifecycle;
 import androidx.lifecycle.Observer;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.preference.PreferenceManager;
 import androidx.recyclerview.widget.DividerItemDecoration;
 import androidx.recyclerview.widget.LinearLayoutManager;
@@ -408,6 +409,9 @@ public class FragmentFolders extends FragmentBase {
     public void onActivityCreated(@Nullable Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);
 
+        if (BuildConfig.DEBUG)
+            new ViewModelProvider(getActivity()).get(ViewModelSelected.class);
+
         if (savedInstanceState != null)
             searching = savedInstanceState.getString("fair:searching");
         adapter.search(searching);

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

@@ -0,0 +1,40 @@
+package eu.faircode.email;
+
+/*
+    This file is part of FairEmail.
+
+    FairEmail is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    FairEmail is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with FairEmail.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2018-2022 by Marcel Bokhorst (M66B)
+*/
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.ViewModel;
+
+public class ViewModelSelected extends ViewModel {
+    private final MutableLiveData<Long> selectedItem = new MutableLiveData<>();
+
+    public void select(Long selected) {
+        selectedItem.setValue(selected);
+    }
+
+    public LiveData<Long> liveSelected() {
+        return selectedItem;
+    }
+
+    public boolean isSelected(long id) {
+        return Long.valueOf(id).equals(selectedItem.getValue());
+    }
+}