Support predictive back, closes #10

Author: nift4

app/src/main/AndroidManifest.xml

@@ -45,18 +45,14 @@
         android:maxSdkVersion="30" />
     <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
 
-    <!-- TODO now that google fixed androidx, for enableOnBackInvokedCallback we need to fix
-        1. bottom sheet hide/show (eg settings)
-        2. bottom sheet -> home
-        3. lyrics -> bottom sheet -->
     <application
         android:name=".logic.GramophoneApplication"
         android:allowBackup="true"
         android:appCategory="audio"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:fullBackupContent="@xml/backup_rules"
         android:icon="@mipmap/ic_launcher"
-        android:enableOnBackInvokedCallback="false"
+        android:enableOnBackInvokedCallback="true"
         android:label="@string/app_name"
         android:requestLegacyExternalStorage="true"
         android:supportsRtl="true"

app/src/main/java/org/akanework/gramophone/ui/MediaControllerViewModel.kt

@@ -121,6 +121,8 @@ class MediaControllerViewModel(application: Application) : AndroidViewModel(appl
         controllerFuture = null
     }
 
+    // TODO reconsider whether onStop is a good place, as getting stopped is quite easy and
+    //  predictive back makes it obvious that we are reconnecting
     override fun onStop(owner: LifecycleOwner) {
         if (controllerFuture?.isDone == true) {
             if (controllerFuture?.isCancelled == false) {

app/src/main/java/org/akanework/gramophone/ui/components/PlayerBottomSheet.kt

@@ -17,7 +17,11 @@
 
 package org.akanework.gramophone.ui.components
 
+import android.animation.Animator
+import android.animation.AnimatorListenerAdapter
+import android.annotation.SuppressLint
 import android.content.Context
+import android.os.Build
 import android.os.Handler
 import android.os.Looper
 import android.util.AttributeSet
@@ -37,6 +41,8 @@ import androidx.core.view.WindowInsetsCompat
 import androidx.core.view.doOnLayout
 import androidx.core.view.doOnNextLayout
 import androidx.core.view.isVisible
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.findFragment
 import androidx.lifecycle.DefaultLifecycleObserver
 import androidx.lifecycle.LifecycleOwner
 import androidx.media3.common.MediaItem
@@ -52,6 +58,7 @@ import coil3.size.Scale
 import com.google.android.material.bottomsheet.BottomSheetBehavior
 import com.google.android.material.bottomsheet.BottomSheetBehavior.BottomSheetCallback
 import com.google.android.material.button.MaterialButton
+import com.google.android.material.motion.MaterialBottomContainerBackHelper
 import org.akanework.gramophone.BuildConfig
 import org.akanework.gramophone.R
 import org.akanework.gramophone.logic.clone
@@ -77,6 +84,8 @@ class PlayerBottomSheet private constructor(
 
     private var lastDisposable: Disposable? = null
     private var standardBottomSheetBehavior: MyBottomSheetBehavior<FrameLayout>? = null
+    @SuppressLint("RestrictedApi")
+    private var lyricsBackHelper: MaterialBottomContainerBackHelper? = null
     private var bottomSheetBackCallback: OnBackPressedCallback? = null
     val fullPlayer: FullBottomSheet
     private val previewPlayer: View
@@ -100,6 +109,8 @@ class PlayerBottomSheet private constructor(
         set(value) {
             if (field != value) {
                 field = value
+                // TODO: this should be animated with predictive back once we switch to a better
+                //  back stack.
                 standardBottomSheetBehavior?.state =
                     if ((instance?.mediaItemCount ?: 0) > 0 && value) {
                         if (standardBottomSheetBehavior?.state
@@ -218,37 +229,51 @@ class PlayerBottomSheet private constructor(
             fullPlayer.minimize = {
                 standardBottomSheetBehavior!!.state = BottomSheetBehavior.STATE_COLLAPSED
             }
+            @SuppressLint("RestrictedApi")
+            lyricsBackHelper = MaterialBottomContainerBackHelper(fullPlayer.bottomSheetFullLyricView)
             bottomSheetBackCallback = object : OnBackPressedCallback(enabled = false) {
                 override fun handleOnBackStarted(backEvent: BackEventCompat) {
                     if (fullPlayer.bottomSheetFullLyricView.isVisible) {
-                        fullPlayer.bottomSheetFullLyricView.fadOutAnimation(FullBottomSheet.LYRIC_FADE_TRANSITION_SEC)
-                        fullPlayer.bottomSheetLyricButton.isChecked = false
+                        @SuppressLint("RestrictedApi")
+                        lyricsBackHelper!!.startBackProgress(backEvent)
                     } else {
                         standardBottomSheetBehavior!!.startBackProgress(backEvent)
                     }
                 }
 
                 override fun handleOnBackProgressed(backEvent: BackEventCompat) {
                     if (fullPlayer.bottomSheetFullLyricView.isVisible) {
-                        // TODO
+                        @SuppressLint("RestrictedApi")
+                        lyricsBackHelper!!.updateBackProgress(backEvent)
                     } else {
                         standardBottomSheetBehavior!!.updateBackProgress(backEvent)
                     }
                 }
 
                 override fun handleOnBackPressed() {
                     if (fullPlayer.bottomSheetFullLyricView.isVisible) {
-                        fullPlayer.bottomSheetFullLyricView.fadOutAnimation(FullBottomSheet.LYRIC_FADE_TRANSITION_SEC)
-                        fullPlayer.bottomSheetLyricButton.isChecked = false
+                        @SuppressLint("RestrictedApi")
+                        val backEvent = lyricsBackHelper!!.onHandleBackInvoked()
+                        if (backEvent == null || backEvent.progress == 0f
+                            || Build.VERSION.SDK_INT < Build.VERSION_CODES.UPSIDE_DOWN_CAKE) {
+                            fullPlayer.bottomSheetFullLyricView.fadOutAnimation(FullBottomSheet.LYRIC_FADE_TRANSITION_SEC)
+                            return
+                        }
+                        @SuppressLint("RestrictedApi")
+                        lyricsBackHelper!!.finishBackProgressNotPersistent(backEvent, object : AnimatorListenerAdapter() {
+                            override fun onAnimationEnd(animation: Animator) {
+                                fullPlayer.bottomSheetFullLyricView.visibility = View.INVISIBLE
+                            }
+                        })
                     } else {
                         standardBottomSheetBehavior!!.handleBackInvoked()
                     }
                 }
 
                 override fun handleOnBackCancelled() {
                     if (fullPlayer.bottomSheetFullLyricView.isVisible) {
-                        fullPlayer.bottomSheetFullLyricView.fadInAnimation(FullBottomSheet.LYRIC_FADE_TRANSITION_SEC)
-                        fullPlayer.bottomSheetLyricButton.isChecked = false
+                        @SuppressLint("RestrictedApi")
+                        lyricsBackHelper!!.cancelBackProgress()
                     } else {
                         standardBottomSheetBehavior!!.cancelBackProgress()
                     }