From b22ea51d15e549dc10ce4b4d64326118b0e82799 Mon Sep 17 00:00:00 2001
From: Semper-Viventem <kostyaxxx8@gmail.com>
Date: Sun, 22 Jul 2018 00:24:56 +0300
Subject: [PATCH] Save menu state

---
 .../backdropview/ui/MainActivity.kt           | 30 +++++++++++++------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/sample/src/main/kotlin/ru/semper_viventem/backdropview/ui/MainActivity.kt b/sample/src/main/kotlin/ru/semper_viventem/backdropview/ui/MainActivity.kt
index 5bd83a4..c771da2 100644
--- a/sample/src/main/kotlin/ru/semper_viventem/backdropview/ui/MainActivity.kt
+++ b/sample/src/main/kotlin/ru/semper_viventem/backdropview/ui/MainActivity.kt
@@ -1,6 +1,7 @@
 package ru.semper_viventem.backdropview.ui
 
 import android.os.Bundle
+import android.support.annotation.IdRes
 import android.support.v4.app.Fragment
 import android.support.v7.app.AppCompatActivity
 import kotlinx.android.synthetic.main.activity_main.*
@@ -14,6 +15,8 @@ import ru.semper_viventem.backdropview.ui.text.TextScreen
 class MainActivity : AppCompatActivity() {
 
     companion object {
+        private const val ARG_LAST_MENU_ITEM = "last_menu_item"
+
         private const val MENU_GALLERY = R.id.menuGallery
         private const val MENU_TEXT = R.id.menuText
         private const val MENU_LIST = R.id.menuList
@@ -23,8 +26,6 @@ class MainActivity : AppCompatActivity() {
         private const val DEFAULT_ITEM = MENU_GALLERY
     }
 
-    private val defaultPage = GalleryScreen()
-
     private lateinit var backdropBehavior: BackdropBehavior
 
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -41,17 +42,14 @@ class MainActivity : AppCompatActivity() {
         }
 
         navigationView.setNavigationItemSelectedListener { item ->
-            when (item.itemId) {
-                MENU_GALLERY -> showPage(GalleryScreen())
-                MENU_TEXT -> showPage(TextScreen())
-                MENU_LIST -> showPage(ListScreen())
-            }
+            checkMenuPosition(item.itemId)
             backdropBehavior.close()
             true
         }
 
-        navigationView.setCheckedItem(DEFAULT_ITEM)
-        showPage(defaultPage)
+        val currentItem = savedInstanceState?.getInt(ARG_LAST_MENU_ITEM) ?: DEFAULT_ITEM
+        navigationView.setCheckedItem(currentItem)
+        checkMenuPosition(navigationView.checkedItem!!.itemId)
     }
 
     override fun onBackPressed() {
@@ -60,6 +58,20 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
+    override fun onSaveInstanceState(outState: Bundle) {
+        outState.putInt(ARG_LAST_MENU_ITEM, navigationView.checkedItem!!.itemId)
+
+        super.onSaveInstanceState(outState)
+    }
+
+    private fun checkMenuPosition(@IdRes menuItemId: Int) {
+        when (menuItemId) {
+            MENU_GALLERY -> showPage(GalleryScreen())
+            MENU_TEXT -> showPage(TextScreen())
+            MENU_LIST -> showPage(ListScreen())
+        }
+    }
+
     private fun showPage(page: Fragment) {
         supportFragmentManager
             .beginTransaction()