Added hint about message synchronization

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

@@ -43,10 +43,12 @@ import androidx.recyclerview.widget.RecyclerView;
 
 public class FragmentFolders extends FragmentEx {
     private ImageButton ibHintActions;
+    private ImageButton ibHintSync;
     private ToggleButton tbShowHidden;
     private RecyclerView rvFolder;
     private ContentLoadingProgressBar pbWait;
     private Group grpHintActions;
+    private Group grpHintSync;
     private Group grpReady;
     private FloatingActionButton fab;
 
@@ -69,16 +71,19 @@ public class FragmentFolders extends FragmentEx {
 
         // Get controls
         ibHintActions = view.findViewById(R.id.ibHintActions);
+        ibHintSync = view.findViewById(R.id.ibHintSync);
         tbShowHidden = view.findViewById(R.id.tbShowHidden);
         rvFolder = view.findViewById(R.id.rvFolder);
         pbWait = view.findViewById(R.id.pbWait);
         grpHintActions = view.findViewById(R.id.grpHintActions);
+        grpHintSync = view.findViewById(R.id.grpHintSync);
         grpReady = view.findViewById(R.id.grpReady);
         fab = view.findViewById(R.id.fab);
 
         // Wire controls
 
         final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
+
         ibHintActions.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
@@ -87,6 +92,14 @@ public class FragmentFolders extends FragmentEx {
             }
         });
 
+        ibHintSync.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                prefs.edit().putBoolean("folder_sync", true).apply();
+                grpHintSync.setVisibility(View.GONE);
+            }
+        });
+
         tbShowHidden.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
@@ -130,6 +143,7 @@ public class FragmentFolders extends FragmentEx {
 
         SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
         grpHintActions.setVisibility(prefs.getBoolean("folder_actions", false) ? View.GONE : View.VISIBLE);
+        grpHintSync.setVisibility(prefs.getBoolean("folder_sync", false) ? View.GONE : View.VISIBLE);
 
         DB db = DB.getInstance(getContext());
 

app/src/main/res/layout/fragment_folders.xml

@@ -37,7 +37,7 @@
             app:layout_constraintTop_toTopOf="@id/tvHintActions" />
 
         <View
-            android:id="@+id/vSeparator"
+            android:id="@+id/vSeparatorActions"
             android:layout_width="match_parent"
             android:layout_height="1dp"
             android:layout_marginTop="6dp"
@@ -45,6 +45,40 @@
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toBottomOf="@id/tvHintActions" />
 
+        <TextView
+            android:id="@+id/tvHintSync"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="6dp"
+            android:layout_marginTop="6dp"
+            android:layout_marginEnd="6dp"
+            android:gravity="center_vertical"
+            android:minHeight="33dp"
+            android:text="@string/title_hint_folder_sync"
+            android:textAppearance="@style/TextAppearance.AppCompat.Small"
+            android:textColor="?android:attr/textColorPrimary"
+            app:layout_constraintEnd_toStartOf="@+id/ibHintSync"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/vSeparatorActions" />
+
+        <ImageButton
+            android:id="@+id/ibHintSync"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:src="@drawable/baseline_close_24"
+            app:layout_constraintBottom_toBottomOf="@id/tvHintSync"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintTop_toTopOf="@id/tvHintSync" />
+
+        <View
+            android:id="@+id/vSeparatorSync"
+            android:layout_width="match_parent"
+            android:layout_height="1dp"
+            android:layout_marginTop="6dp"
+            android:background="?attr/colorSeparator"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/tvHintSync" />
+
         <ToggleButton
             android:id="@+id/tbShowHidden"
             style="@style/buttonStyleSmall"
@@ -56,7 +90,7 @@
             android:textOn="@string/title_hide_folders"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/vSeparator" />
+            app:layout_constraintTop_toBottomOf="@id/vSeparatorSync" />
 
         <androidx.recyclerview.widget.RecyclerView
             android:id="@+id/rvFolder"
@@ -84,7 +118,13 @@
             android:id="@+id/grpHintActions"
             android:layout_width="0dp"
             android:layout_height="0dp"
-            app:constraint_referenced_ids="tvHintActions,ibHintActions,vSeparator" />
+            app:constraint_referenced_ids="tvHintActions,ibHintActions,vSeparatorActions" />
+
+        <androidx.constraintlayout.widget.Group
+            android:id="@+id/grpHintSync"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:constraint_referenced_ids="tvHintSync,ibHintSync,vSeparatorSync" />
 
         <androidx.constraintlayout.widget.Group
             android:id="@+id/grpReady"

app/src/main/res/values/strings.xml

@@ -387,6 +387,7 @@
     <string name="title_legend_download_fetch">Number of message bodies downloaded / headers fetched</string>
 
     <string name="title_hint_folder_actions">Long press for options</string>
+    <string name="title_hint_folder_sync">To limit battery and network usage not all folders and not all messages will be synchronized by default</string>
     <string name="title_hint_support">If you have a question or a problem, please use the support menu to get help</string>
     <string name="title_hint_message_actions">Swipe left to trash; swipe right to archive (if available)</string>
     <string name="title_hint_message_selection">Long press a message to start selecting multiple messages</string>