Automatically reload previously selected fragment on orientation change,...

Automatically reload previously selected fragment on orientation change, dynamically set number of category columns on orientation change

app/src/main/java/io/eelo/appinstaller/MainActivity.kt

@@ -18,11 +18,12 @@ import io.eelo.appinstaller.search.SearchFragment
 import io.eelo.appinstaller.settings.SettingsFragment
 import io.eelo.appinstaller.updates.UpdatesFragment
 import io.eelo.appinstaller.utils.Common
+import io.eelo.appinstaller.utils.Constants.CURRENTLY_SELECTED_FRAGMENT_KEY
 import io.eelo.appinstaller.utils.Constants.STORAGE_PERMISSION_REQUEST_CODE
 import kotlinx.android.synthetic.main.activity_main.*
 
 class MainActivity : AppCompatActivity(), BottomNavigationView.OnNavigationItemSelectedListener {
-    private var currentFragment: Fragment? = null
+    private var currentFragmentId = 0
     private val homeFragment = HomeFragment()
     private val categoriesFragment = CategoriesFragment()
     private val searchFragment = SearchFragment()
@@ -38,7 +39,15 @@ class MainActivity : AppCompatActivity(), BottomNavigationView.OnNavigationItemS
             val installManager = installManagerGetter.connectAndGet(this)
             initialiseFragments(installManager)
             // Show the home fragment by default
-            showFragment(homeFragment)
+            if (savedInstanceState != null) {
+                if (selectFragment(savedInstanceState.getInt(CURRENTLY_SELECTED_FRAGMENT_KEY))) {
+                    currentFragmentId = savedInstanceState.getInt(CURRENTLY_SELECTED_FRAGMENT_KEY)
+                }
+            } else {
+                if (selectFragment(R.id.menu_home)) {
+                    currentFragmentId = R.id.menu_home
+                }
+            }
         }
 
         bottom_navigation_view.setOnNavigationItemSelectedListener(this)
@@ -52,24 +61,32 @@ class MainActivity : AppCompatActivity(), BottomNavigationView.OnNavigationItemS
     }
 
     override fun onNavigationItemSelected(item: MenuItem): Boolean {
-        when {
-            item.itemId == R.id.menu_home -> {
+        if (selectFragment(item.itemId)) {
+            currentFragmentId = item.itemId
+            return true
+        }
+        return false
+    }
+
+    private fun selectFragment(fragmentId: Int): Boolean {
+        when (fragmentId) {
+            R.id.menu_home -> {
                 showFragment(homeFragment)
                 return true
             }
-            item.itemId == R.id.menu_categories -> {
+            R.id.menu_categories -> {
                 showFragment(categoriesFragment)
                 return true
             }
-            item.itemId == R.id.menu_search -> {
+            R.id.menu_search -> {
                 showFragment(searchFragment)
                 return true
             }
-            item.itemId == R.id.menu_updates -> {
+            R.id.menu_updates -> {
                 showFragment(updatesFragment)
                 return true
             }
-            item.itemId == R.id.menu_settings -> {
+            R.id.menu_settings -> {
                 showFragment(settingsFragment)
                 return true
             }
@@ -82,7 +99,6 @@ class MainActivity : AppCompatActivity(), BottomNavigationView.OnNavigationItemS
                 .beginTransaction()
                 .replace(R.id.frame_layout, fragment)
                 .commit()
-        currentFragment = fragment
     }
 
     @SuppressLint("RestrictedApi")
@@ -112,6 +128,11 @@ class MainActivity : AppCompatActivity(), BottomNavigationView.OnNavigationItemS
         }
     }
 
+    override fun onSaveInstanceState(outState: Bundle?) {
+        super.onSaveInstanceState(outState)
+        outState?.putInt(CURRENTLY_SELECTED_FRAGMENT_KEY, currentFragmentId)
+    }
+
     override fun onDestroy() {
         super.onDestroy()
         installManagerGetter.disconnect(this)

app/src/main/java/io/eelo/appinstaller/categories/CategoriesFragment.kt

@@ -2,6 +2,7 @@ package io.eelo.appinstaller.categories
 
 import android.arch.lifecycle.Observer
 import android.arch.lifecycle.ViewModelProviders
+import android.content.res.Configuration
 import android.os.Bundle
 import android.support.v4.app.Fragment
 import android.text.TextUtils
@@ -60,6 +61,18 @@ class CategoriesFragment : Fragment() {
         itemParams.marginStart = itemPadding
         itemParams.marginEnd = itemPadding
 
+        // Check device orientation and increase/decrease number of columns
+        val orientation = resources.configuration.orientation
+        if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
+            // In landscape
+            applicationsCategoriesList.columnCount = 3
+            gamesCategoriesList.columnCount = 3
+        } else {
+            // In portrait
+            applicationsCategoriesList.columnCount = 2
+            gamesCategoriesList.columnCount = 2
+        }
+
         // Bind to the list of applications categories
         categoriesViewModel.getApplicationsCategories().observe(this, Observer {
             showApplicationsCategories()

app/src/main/java/io/eelo/appinstaller/utils/Constants.kt

@@ -17,4 +17,7 @@ object Constants {
 
     // Categories
     const val CATEGORY_KEY = "category_key"
+
+    // Home
+    const val CURRENTLY_SELECTED_FRAGMENT_KEY = "currently_selected_fragment"
 }

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

@@ -37,7 +37,6 @@
                 android:layout_height="wrap_content"
                 android:layout_gravity="center_horizontal"
                 android:layout_marginTop="@dimen/layout_margin_medium"
-                android:columnCount="2"
                 app:layout_constraintTop_toBottomOf="@id/applications_categories_title" />
 
             <TextView
@@ -59,7 +58,6 @@
                 android:layout_height="wrap_content"
                 android:layout_gravity="center_horizontal"
                 android:layout_marginTop="@dimen/layout_margin_medium"
-                android:columnCount="2"
                 app:layout_constraintTop_toBottomOf="@id/games_categories_title" />
 
         </LinearLayout>