Refactor back button handling to get rid of deprecation warnings.

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/ui/download/activity/TrackDownloadActivity.kt

@@ -96,8 +96,9 @@ class TrackDownloadActivity: BaseActivity() {
         cancel()
     }
 
-    override fun onBackPressed() {
+    override fun onInterceptBackButton(): Boolean {
         confirmCancelDialog()
+        return true
     }
 
     private fun cancel() {

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/ui/shared/activity/BaseActivity.kt

@@ -9,6 +9,7 @@ import android.view.KeyEvent
 import android.view.MenuItem
 import android.view.View
 import android.view.ViewGroup
+import androidx.activity.OnBackPressedCallback
 import androidx.appcompat.app.AppCompatActivity
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentManager
@@ -29,7 +30,7 @@ import io.casey.musikcube.remote.ui.shared.mixin.RunnerMixin
 import io.casey.musikcube.remote.ui.shared.mixin.ViewModelMixin
 import io.reactivex.disposables.CompositeDisposable
 
-abstract class BaseActivity : AppCompatActivity(), ViewModel.Provider, Runner.TaskCallbacks {
+abstract class BaseActivity: AppCompatActivity(), ViewModel.Provider, Runner.TaskCallbacks {
     protected var disposables = CompositeDisposable()
         private set
 
@@ -55,6 +56,7 @@ abstract class BaseActivity : AppCompatActivity(), ViewModel.Provider, Runner.Ta
         prefs = getSharedPreferences(Prefs.NAME, Context.MODE_PRIVATE)
         volumeControlStream = AudioManager.STREAM_MUSIC
         mixins.onCreate(savedInstanceState ?: Bundle())
+        onBackPressedDispatcher.addCallback(this, backHandler)
     }
 
     override fun onStart() {
@@ -97,19 +99,42 @@ abstract class BaseActivity : AppCompatActivity(), ViewModel.Provider, Runner.Ta
         mixins.onDestroy()
     }
 
-    override fun onBackPressed() {
+    override fun onNavigateUp(): Boolean {
+        if (!navigateBack()) {
+            finish()
+        }
+        return true
+    }
+
+    private fun navigateBack(): Boolean {
         (top as? IBackHandler)?.let {
-            if (it.onBackPressed()) {
+            if (it.onInterceptBackButton()) {
-                return
+                return true
             }
         }
 
-        when {
+        if (onInterceptBackButton()) {
-            fm.backStackEntryCount > 1 -> fm.popBackStack()
+            return true
-            else -> super.onBackPressed()
+        }
+
+        if (fm.backStackEntryCount >= 1) {
+            fm.popBackStack()
+            return true
+        }
+
+        return false
+    }
+
+    private val backHandler = object: OnBackPressedCallback(true) {
+        override fun handleOnBackPressed() {
+            if (!navigateBack()) {
+                finish()
+            }
         }
     }
 
+    protected open fun onInterceptBackButton(): Boolean = false
+
     override fun onKeyDown(keyCode: Int, event: KeyEvent): Boolean {
         if (mixin(PlaybackMixin::class.java)?.onKeyDown(keyCode) == true) {
             return true

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/ui/shared/activity/IBackHandler.kt

@@ -1,5 +1,5 @@
 package io.casey.musikcube.remote.ui.shared.activity
 
 interface IBackHandler {
-    fun onBackPressed(): Boolean
+    fun onInterceptBackButton(): Boolean
 }

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/ui/shared/extension/Extensions.kt

@@ -19,6 +19,7 @@ import android.widget.CompoundButton
 import android.widget.EditText
 import android.widget.TextView
 import androidx.appcompat.app.AppCompatActivity
+import androidx.appcompat.content.res.AppCompatResources
 import androidx.appcompat.widget.SearchView
 import androidx.appcompat.widget.Toolbar
 import androidx.core.content.ContextCompat
@@ -276,9 +277,9 @@ inline fun <reified T: BaseFragment> T.withTitleOverride(activity: AppCompatActi
 
 fun BaseFragment.initToolbarIfNecessary(view: View, showFilter: Boolean = true) {
     view.findViewById<Toolbar>(R.id.toolbar)?.let {
-        it.navigationIcon = appCompatActivity.getDrawable(R.drawable.ic_back)
+        it.navigationIcon = AppCompatResources.getDrawable(appCompatActivity, R.drawable.ic_back)
         it.setNavigationOnClickListener {
-            appCompatActivity.onBackPressed()
+            appCompatActivity.onNavigateUp()
         }
         if (showFilter) {
             this.addFilterAction(it.menu, this as? IFilterable)

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/ui/shared/fragment/BaseFragment.kt

@@ -169,7 +169,7 @@ open class BaseFragment: Fragment(), ViewModel.Provider, IBackHandler {
         }
     }
 
-    override fun onBackPressed(): Boolean =
+    override fun onInterceptBackButton(): Boolean =
         toolbar?.collapseActionViewIfExpanded() ?: false
 
     override fun <T: ViewModel<*>> createViewModel(): T? = null

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/ui/tracks/activity/EditPlaylistActivity.kt

@@ -6,6 +6,7 @@ import android.content.Intent
 import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
+import androidx.activity.OnBackPressedCallback
 import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.app.AppCompatActivity
 import androidx.recyclerview.widget.ItemTouchHelper
@@ -45,14 +46,7 @@ class EditPlaylistActivity: BaseActivity() {
         adapter = EditPlaylistAdapter(viewModel, touchHelper, prefs)
         setupDefaultRecyclerView(recycler, adapter)
         setResult(RESULT_CANCELED)
-    }
+        onBackPressedDispatcher.addCallback(this, backHandler)
-
-    override fun onBackPressed() {
-        if (viewModel.modified) {
-            ConfirmDiscardChangesDialog.show(this)
-            return
-        }
-        super.onBackPressed()
     }
 
     override fun onCreateOptionsMenu(menu: Menu): Boolean {
@@ -80,6 +74,16 @@ class EditPlaylistActivity: BaseActivity() {
         ))
     }
 
+    private val backHandler = object: OnBackPressedCallback(true) {
+        override fun handleOnBackPressed() {
+            if (viewModel.modified) {
+                ConfirmDiscardChangesDialog.show(this@EditPlaylistActivity)
+                return
+            }
+            finish()
+        }
+    }
+
     override fun <T: ViewModel<*>> createViewModel(): T {
         @Suppress("unchecked_cast")
         return EditPlaylistViewModel(extras.getLong(EXTRA_PLAYLIST_ID, -1L)) as T