🔙 Back Navigation

Overview

Back navigation in zMantra follows a single-activity, fragment-back-stack approach.

• All forward navigations push the fragment onto the back stack.
• Pressing Back pops the stack until the root (e.g., Landing page).
• When no fragments remain, the app exits.

Back can be triggered via:

• System Back button / gesture
• Toolbar Up arrow
• In-UI “Go Back” buttons
• Programmatic back after certain flows

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How It’s Wired

Main Activity toolbar + Up navigation

File: app/src/main/java/com/zendalona/zmantra/MainActivity.kt

• Listens for back stack changes to toggle the toolbar Up arrow:

supportFragmentManager.addOnBackStackChangedListener {
    val canGoBack = supportFragmentManager.backStackEntryCount > 0
    supportActionBar?.setDisplayHomeAsUpEnabled(canGoBack)
}

• Delegates toolbar Up → Back:

override fun onSupportNavigateUp(): Boolean {
    onBackPressed()
    return true
}

Navigating forward

Always use the MainActivity helper to ensure proper back stack behavior:

(requireActivity() as MainActivity)
    .loadFragment(MyNextFragment(), MainActivity.TRANSIT_FRAGMENT_OPEN)

This applies: .replace(...).addToBackStack(null).commit()

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Default Back behavior

• Pops the current fragment from the stack.
• If stack is empty (e.g., LandingPageFragment), Back exits the app.

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Fragment-Specific Handling

Score result screen

File: core/utility/common/ScorePageFragment.kt

• Intercepts Back with a lifecycle-aware callback:

requireActivity().onBackPressedDispatcher.addCallback(
    this,
    object : OnBackPressedCallback(true) {
        override fun handleOnBackPressed() {
            goBack() // cleanup + pop
        }
    }
)

• Also handles toolbar Home (Up) in:

override fun onOptionsItemSelected(item: MenuItem): Boolean {
    if (item.itemId == android.R.id.home) {
        goBack()
        return true
    }
    return super.onOptionsItemSelected(item)
}

Hint & User Guide screens

Files:

• presentation/features/hint/HintFragment.kt
• presentation/features/userguide/UserGuideFragment.kt

In-UI “Go Back” button →

requireActivity().onBackPressedDispatcher.onBackPressed()

Auto-back after completing a flow

• Drawing game → auto-return after announcing completion:

requireActivity().onBackPressedDispatcher.onBackPressed()

• EndGame utility → on score completion:

EndScore.endGameWithScore(... onComplete = {
    activity.onBackPressedDispatcher.onBackPressed()
})

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Accessibility

• Toolbar Up arrow has a spoken label:

supportActionBar?.setHomeActionContentDescription(R.string.back_button_label)

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Guidelines for New Screens

✅ Always navigate via MainActivity.loadFragment(...) ✅ Register a back callback if custom cleanup is required ✅ Use in-UI Back buttons sparingly, but wire them via:

backButton.setOnClickListener {
    requireActivity().onBackPressedDispatcher.onBackPressed()
}

✅ For fragments with toolbar menus, handle android.R.id.home locally