- fixed memory leak while switching between fragments.

- added help button.
- used another graph icon for navigation icons to avoid that the preference tint method is applied to the navigation icon.

android_app/app/src/main/java/com/health/openscale/gui/MainActivity.java

@@ -66,13 +66,13 @@ import java.lang.reflect.Field;
 
 import cat.ereza.customactivityoncrash.config.CaocConfig;
 
-
 public class MainActivity extends AppCompatActivity {
     private static boolean firstAppStart = true;
     private static boolean valueOfCountModified = false;
     private static int bluetoothStatusIcon = R.drawable.ic_bluetooth_disabled;
     private static MenuItem bluetoothStatus;
 
+    private Fragment currentFragment;
     private DrawerLayout drawerLayout;
     private Toolbar toolbar;
     private NavigationView navDrawer;
@@ -95,6 +95,8 @@ public class MainActivity extends AppCompatActivity {
 
         setContentView(R.layout.activity_main);
 
+        currentFragment = null;
+
         // Set a Toolbar to replace the ActionBar.
         toolbar = (Toolbar) findViewById(R.id.toolbar);
         setSupportActionBar(toolbar);
@@ -250,7 +252,6 @@ public class MainActivity extends AppCompatActivity {
 
     public void selectDrawerItem(int menuItemId) {
         // Create a new fragment and specify the fragment to show based on nav item clicked
-        Fragment fragment = null;
         Class fragmentClass;
         String fragmentTitle;
 
@@ -282,22 +283,37 @@ public class MainActivity extends AppCompatActivity {
                 settingsIntent.putExtra(SettingsActivity.EXTRA_TINT_COLOR, navDrawer.getItemTextColor().getDefaultColor());
                 startActivityForResult(settingsIntent, 1);
                 return;
+            case R.id.nav_help:
+                startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("https://github.com/oliexdev/openScale/wiki")));
+                return;
             default:
                 fragmentClass = OverviewFragment.class;
                 fragmentTitle = getResources().getString(R.string.title_overview);
                 prefs.edit().putInt("lastFragmentId", menuItemId).commit();
         }
 
-        try {
-            fragment = (Fragment) fragmentClass.newInstance();
+        FragmentManager fragmentManager = getSupportFragmentManager();
 
+        // hide previous fragment if it available
+        if (currentFragment != null) {
+            fragmentManager.beginTransaction().hide(currentFragment).commit();
+        }
+
+        // try to find selected fragment
+        currentFragment = fragmentManager.findFragmentByTag(""+menuItemId);
+
+        // if fragment not found then add the fragment
+        if (currentFragment == null) {
+            try {
+                currentFragment = (Fragment) fragmentClass.newInstance();
             } catch (Exception e) {
                 e.printStackTrace();
             }
 
-        // Insert the fragment by replacing any existing fragment
-        FragmentManager fragmentManager = getSupportFragmentManager();
-        fragmentManager.beginTransaction().replace(R.id.fragment_content, fragment).commit();
+            fragmentManager.beginTransaction().add(R.id.fragment_content, currentFragment, "" + menuItemId).commit();
+        } else { // otherwise show fragment
+            fragmentManager.beginTransaction().show(currentFragment).commit();
+        }
 
         // Set action bar title
         setTitle(fragmentTitle);
@@ -468,10 +484,10 @@ public class MainActivity extends AppCompatActivity {
                 BottomNavigationItemView item = (BottomNavigationItemView) menuView.getChildAt(i);
                 //noinspection RestrictedApi
                 item.setShiftingMode(false);
-                item.setPadding(0, 15, 0, 0);
+                //item.setPadding(0, 15, 0, 0);
                 // set once again checked value, so view will be updated
                 //noinspection RestrictedApi
-                item.setChecked(item.getItemData().isChecked());
+                //item.setChecked(item.getItemData().isChecked());
             }
         } catch (NoSuchFieldException e) {
             Log.e("BNVHelper", "Unable to get shift mode field", e);

android_app/app/src/main/res/menu/drawer_bottom_view.xml

@@ -1,8 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <menu xmlns:android="http://schemas.android.com/apk/res/android">
-    <group android:id="@+id/menu_top"
-           android:checkableBehavior="single">
-
+    <group android:checkableBehavior="single">
         <item
             android:id="@+id/nav_overview"
             android:icon="@drawable/ic_preferences_home"
@@ -10,7 +8,7 @@
 
         <item
             android:id="@+id/nav_graph"
-            android:icon="@drawable/ic_preferences_graph"
+            android:icon="@drawable/ic_preferences_nav_graph"
             android:title="@string/title_graph" />
 
         <item

android_app/app/src/main/res/menu/drawer_view.xml

@@ -10,7 +10,7 @@
 
         <item
             android:id="@+id/nav_graph"
-            android:icon="@drawable/ic_preferences_graph"
+            android:icon="@drawable/ic_preferences_nav_graph"
             android:title="@string/title_graph" />
 
         <item
@@ -31,5 +31,10 @@
             android:id="@+id/nav_settings"
             android:icon="@drawable/ic_preferences_settings"
             android:title="@string/action_settings" />
+
+        <item
+            android:id="@+id/nav_help"
+            android:icon="@drawable/ic_preferences_help"
+            android:title="@string/label_help" />
         </group>
     </menu>

android_app/app/src/main/res/values-de/strings.xml

@@ -184,4 +184,5 @@
     <string name="info_app_restart_required">Um die Änderungen zu übernehmen, ist ein App Neustart erforderlich</string>
     <string name="label_share">Teilen</string>
     <string name="label_bluetooth_searching_finished">Suche beendet nach Bluetooth Waagen</string>
+    <string name="label_help">Hilfe</string>
 </resources>

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

@@ -189,6 +189,7 @@
     <string name="label_regression_line">Regression weight line</string>
     <string name="label_regression_line_degree">Regression polynom degree</string>
     <string name="label_goal_line">Goal line</string>
+    <string name="label_help">Help</string>
 
     <string name="label_feedback_message_enjoying">Enjoying openScale?</string>
     <string name="label_feedback_message_rate_app">How about a rating on GooglePlay or on GitHub, then?</string>