Android jetpack navigation custom back button overlapping back arrow on back

1
votes

Using android jetpack navigation in combination with toolbar and drawer is that the root destination has a hamburger menu icon (to toggle the drawer) and in child fragments there is a back button.

Also an animation exists when opening / closing child fragments on the back arrow.

Now the problem: In one of my child fragments I set a custom navigation back button 

toolbar_main.setNavigationIcon(R.drawable.ic_clear)

This also works, but upon closing there is a "glitch" where

  1. The custom icon disappears
  2. The back arrow is visible for a short while (this is the "glitch"
  3. The child closes and the root fragment (with burger icon) is visible again

Question:

Is this "glitch" a bug or do I have to call something other than setNavigationIcon (like ActionBarDrawerToggle or similar) ?

1
androidandroid-toolbarandroid-navigationandroid-jetpack
Navigation doesn't support custom navigation icons as per this still open feature request, so yeah, your custom icon is going to conflict if you're using any of the NavigationUI methods. – ianhanniballake

1 Answers

0
votes

Solution: in each Fragment

override fun onAttach(context: Context) {
    super.onAttach(context)
    val activity = context as BaseActivity
    if (navController.backStack.size > 3) {
        activity.toolbar.setNavigationIcon(getNavigationIcon())
    }
}

more than 3 because:

<navigation
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/navigation"
    app:startDestination="@+id/startFragment"> <----- always +1

    <fragment
        android:id="@+id/startFragment"> <----- startFragment + 1 = 2

    <fragment
        android:id="@+id/fragment_1"> <----- startFragment + 1 = 3

    <fragment
        android:id="@+id/fragment_2"> <----- startFragment + 1 = 3

</navigation>