Tag: NavController

Navigation Listener

An example of using a Navigation Listener would be to limit the screens on which your Navigation Drawer will be available. In this instance the drawer is locked on all screens other than the start destination (the opening Fragment):

import ...
class MainActivity : AppCompatActivity() {
    lateinit var drawerLayout: DrawerLayout
    lateinit var navController: NavController
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        @Suppress("UNUSED_VARIABLE")
        val binding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
        navController = this.findNavController(R.id.myNavHostFragment)
        drawerLayout = binding.drawerLayout
        NavigationUI.setupActionBarWithNavController(this, navController, drawerLayout)

        // Add a listener which will determine if the destination is the start destination. If not, the nav drawer will be locked
        navController.addOnNavigatedListener { nc: NavController, nd: NavDestination -> // This currently doesn't work with Navigation version above 1.0.0-alpha07
            if (nd.id == nc.graph.startDestination) {
                drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED)
            } else {
                drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED)
            }
        }

        NavigationUI.setupWithNavController(binding.navView, navController)
    }

    override fun onSupportNavigateUp(): Boolean {
//        return navController.navigateUp()
        return NavigationUI.navigateUp(navController, drawerLayout)
    }
}

 

Navigation Drawer (with Navigation component?)

Add dependency:

dependencies {
    ...
    implementation "com.google.android.material:material:$version_supportlib" // Add version number to build.gradle also
}

Make sure any Fragments you wish to navigate to have been added to the Navigation Design window.

Create a new menu (e.g. navdrawer_menu.xml) in the res/menu folder.

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"> // All of this can be done through the GUI also

    <item
        android:id="@+id/firstFragment"
        android:icon="@drawable/first"
        android:title="@string/first" />
    <item
        android:id="@+id/secondFragment"
        android:icon="@drawable/second"
        android:title="@string/second" />
</menu>

In your main Activity layout file:

<?xml version="1.0" encoding="utf-8"?><!--

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    
    <androidx.drawerlayout.widget.DrawerLayout // Wrap the main ViewGroup in the DrawerLayout tag and give it an id
        android:id="@+id/drawerLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">
            <fragment
                android:id="@+id/myNavHostFragment"
                android:name="androidx.navigation.fragment.NavHostFragment"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                app:defaultNavHost="true"
                app:navGraph="@navigation/navigation" />
        </LinearLayout>
        
        <com.google.android.material.navigation.NavigationView // Create the NavDrawer element and give it an id
            android:id="@+id/navView"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_gravity="start" // Aligns it to the left of the screen for LtR languages
            app:headerLayout="@layout/nav_header" // Point to a layout file to define a custom header for your menu
            app:menu="@menu/navdrawer_menu" /> // Point it at the menu resource we just created

    </androidx.drawerlayout.widget.DrawerLayout>

</layout>

And in the main Activity file:

import ...

class MainActivity : AppCompatActivity() {
    lateinit var drawerLayout: DrawerLayout
    lateinit var navController: NavController
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        @Suppress("UNUSED_VARIABLE")
        val binding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
        navController = this.findNavController(R.id.myNavHostFragment)
        drawerLayout = binding.drawerLayout // Get the DrawerLayout
        NavigationUI.setupActionBarWithNavController(this, navController, drawerLayout) // Add the DrawerLayout to the ActionBar
        NavigationUI.setupWithNavController(binding.navView, navController) // Link the navigation view with the UI
    }

    override fun onSupportNavigateUp(): Boolean {
//        return navController.navigateUp() // Get rid of this return statement
        return NavigationUI.navigateUp(navController, drawerLayout) // Use this instead which includes the DrawerLayout
    }
}