Draft: using ViewModel to store Playable state.

buildSrc/src/main/java/kohii/Dependencies.kt

@@ -155,6 +155,7 @@ object Libs {
       val liveData = "androidx.lifecycle:lifecycle-livedata-ktx:$version"
       val viewModel = "androidx.lifecycle:lifecycle-viewmodel-ktx:$version"
       val service = "androidx.lifecycle:lifecycle-service:$version"
+      val process = "androidx.lifecycle:lifecycle-process:$version"
     }
 
     object Room {

kohii-core/build.gradle

@@ -74,6 +74,7 @@ dependencies {
   implementation Libs.AndroidX.coordinatorLayout
   implementation Libs.AndroidX.Lifecycle.extensions
   implementation Libs.AndroidX.Lifecycle.service
+  implementation Libs.AndroidX.Lifecycle.process
   api Libs.AndroidX.Lifecycle.java8
 
   testImplementation(Libs.Common.junit)

kohii-core/src/main/java/kohii/v1/core/AbstractPlayable.kt

@@ -22,6 +22,7 @@ import kohii.v1.core.MemoryMode.HIGH
 import kohii.v1.core.MemoryMode.INFINITE
 import kohii.v1.core.MemoryMode.LOW
 import kohii.v1.core.MemoryMode.NORMAL
+import kohii.v1.debugOnly
 import kohii.v1.internal.PlayerParametersChangeListener
 import kohii.v1.logInfo
 import kohii.v1.logWarn
@@ -41,7 +42,7 @@ abstract class AbstractPlayable<RENDERER : Any>(
   private var playRequested: Boolean = false
 
   override fun toString(): String {
-    return "Playable([t=$tag][b=$bridge][h=${super.hashCode()}])"
+    return "Playable([t=$tag][b=$bridge][h=${hashCode()}])"
   }
 
   // Ensure the preparation for the playback
@@ -89,6 +90,7 @@ abstract class AbstractPlayable<RENDERER : Any>(
   }
 
   override fun isPlaying(): Boolean {
+    "Playable#isPlaying $this".logInfo()
     return bridge.isPlaying()
   }
 
@@ -102,12 +104,12 @@ abstract class AbstractPlayable<RENDERER : Any>(
       val newManager = field
       if (oldManager === newManager) return
       "Playable#manager $oldManager --> $newManager, $this".logInfo()
+      oldManager?.removePlayable(this)
+      newManager?.addPlayable(this)
+      // Setting Manager to null.
       if (newManager == null) {
         master.trySavePlaybackInfo(this)
-        master.tearDown(
-            playable = this,
-            clearState = if (oldManager is Manager) !oldManager.isChangingConfigurations() else true
-        )
+        master.tearDown(playable = this)
       } else if (oldManager === null) {
         master.tryRestorePlaybackInfo(this)
       }
@@ -120,15 +122,7 @@ abstract class AbstractPlayable<RENDERER : Any>(
       val newPlayback = field
       if (oldPlayback === newPlayback) return
       "Playable#playback $oldPlayback --> $newPlayback, $this".logInfo()
-      if (oldPlayback != null) {
-        bridge.removeErrorListener(oldPlayback)
-        bridge.removeEventListener(oldPlayback)
-        oldPlayback.removeCallback(this)
-        if (oldPlayback.playable === this) oldPlayback.playable = null
-        if (oldPlayback.playerParametersChangeListener === this) {
-          oldPlayback.playerParametersChangeListener = null
-        }
-      }
+      oldPlayback?.let(::detachFromPlayback)
 
       this.manager = if (newPlayback != null) {
         newPlayback.manager
@@ -150,30 +144,50 @@ abstract class AbstractPlayable<RENDERER : Any>(
         }
       }
 
-      if (newPlayback != null) {
-        newPlayback.playable = this
-        newPlayback.playerParametersChangeListener = this
-        newPlayback.addCallback(this)
-        newPlayback.config.callbacks.forEach { callback -> newPlayback.addCallback(callback) }
-
-        bridge.addEventListener(newPlayback)
-        bridge.addErrorListener(newPlayback)
-
-        if (newPlayback.tag != Master.NO_TAG) {
-          if (newPlayback.config.controller != null) {
-            master.plannedManualPlayables.add(newPlayback.tag)
-          } else {
-            master.plannedManualPlayables.remove(newPlayback.tag)
-          }
-        }
-      }
+      newPlayback?.let(::attachToPlayback)
 
       master.notifyPlaybackChanged(this, oldPlayback, newPlayback)
     }
 
   override val playerState: Int
     get() = bridge.playerState
 
+  private fun attachToPlayback(playback: Playback) {
+    playback.playable = this
+    playback.playerParametersChangeListener = this
+    playback.addCallback(this)
+    playback.config.callbacks.forEach { callback -> playback.addCallback(callback) }
+
+    bridge.addEventListener(playback)
+    bridge.addErrorListener(playback)
+
+    if (playback.tag != Master.NO_TAG) {
+      if (playback.config.controller != null) {
+        master.plannedManualPlayables.add(playback.tag)
+      } else {
+        master.plannedManualPlayables.remove(playback.tag)
+      }
+    }
+  }
+
+  private fun detachFromPlayback(playback: Playback) {
+    bridge.removeErrorListener(playback)
+    bridge.removeEventListener(playback)
+    playback.removeCallback(this)
+    debugOnly {
+      check(playback.playable === this) {
+        """
+          Old playback of this playable ($this) is 
+          bound to a different playable: ${playback.playable}
+        """.trimIndent()
+      }
+    }
+    if (playback.playable === this) playback.playable = null
+    if (playback.playerParametersChangeListener === this) {
+      playback.playerParametersChangeListener = null
+    }
+  }
+
   // Playback.Callback
 
   override fun onActive(playback: Playback) {

kohii-core/src/main/java/kohii/v1/core/Binder.kt

@@ -86,7 +86,7 @@ class Binder(
       if (cache.config != config /* equals */) {
         // Scenario: client bind a Video of same tag/media but different Renderer type or Config.
         cache.playback = null // will also set Manager to null
-        engine.master.tearDown(cache, true)
+        engine.master.tearDown(cache)
         cache = null
       }
     }

kohii-core/src/main/java/kohii/v1/core/Bridge.kt

@@ -56,7 +56,11 @@ interface Bridge<RENDERER : Any> {
    */
   fun prepare(loadSource: Boolean)
 
-  // Ensure resource is ready to play. PlaybackDispatcher will require this for manual playback.
+  /**
+   * Ensure the resources is ready to play.
+   *
+   * Note: PlaybackDispatcher will require this for manual playback.
+   */
   fun ready()
 
   fun play()

kohii-core/src/main/java/kohii/v1/core/CompatHelper.kt

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2021 Nam Nguyen, [email protected]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kohii.v1.core
+
+import androidx.annotation.MainThread
+
+object CompatHelper {
+
+  private val defaultConfig: CompatConfig = CompatConfig()
+  private var customConfig: CompatConfig? = null
+
+  val compatConfig: CompatConfig get() = customConfig ?: defaultConfig
+
+  @MainThread
+  fun setCompatConfig(compatConfig: CompatConfig) {
+    check(customConfig == null || customConfig == compatConfig) {
+      "Another CompatConfig is already set."
+    }
+    customConfig = compatConfig
+  }
+}
+
+data class CompatConfig(
+  val useLegacyPlaybackInfoStore: Boolean = false
+)

kohii-core/src/main/java/kohii/v1/core/Engine.kt

@@ -27,12 +27,14 @@ import androidx.fragment.app.FragmentActivity
 import androidx.lifecycle.Lifecycle.State
 import androidx.lifecycle.Lifecycle.State.STARTED
 import androidx.lifecycle.LifecycleOwner
+import androidx.lifecycle.ViewModelProvider
 import kohii.v1.core.Binder.Options
 import kohii.v1.core.MemoryMode.LOW
 import kohii.v1.core.Scope.BUCKET
 import kohii.v1.core.Scope.GROUP
 import kohii.v1.core.Scope.MANAGER
 import kohii.v1.core.Scope.PLAYBACK
+import kohii.v1.internal.ManagerViewModel
 import kohii.v1.media.Media
 import kohii.v1.media.MediaItem
 import kohii.v1.media.VolumeInfo
@@ -47,9 +49,7 @@ abstract class Engine<RENDERER : Any> constructor(
     playableCreator: PlayableCreator<RENDERER>
   ) : this(Master[context], playableCreator)
 
-  internal fun inject(group: Group) {
-    group.managers.forEach { prepare(it) }
-  }
+  internal fun inject(group: Group) = group.managers.forEach(::prepare)
 
   abstract fun prepare(manager: Manager)
 
@@ -103,6 +103,7 @@ abstract class Engine<RENDERER : Any> constructor(
         activity = activity,
         host = fragment,
         managerLifecycleOwner = lifecycleOwner,
+        viewModel = ViewModelProvider(fragment).get(ManagerViewModel::class.java),
         memoryMode = memoryMode,
         activeLifecycleState = activeLifecycleState
     )
@@ -117,6 +118,7 @@ abstract class Engine<RENDERER : Any> constructor(
       activity = activity,
       host = activity,
       managerLifecycleOwner = activity,
+      viewModel = ViewModelProvider(activity).get(ManagerViewModel::class.java),
       memoryMode = memoryMode,
       activeLifecycleState = activeLifecycleState
   )

kohii-core/src/main/java/kohii/v1/core/Group.kt

@@ -18,6 +18,7 @@ package kohii.v1.core
 
 import android.graphics.Rect
 import android.os.Handler
+import android.os.Looper
 import android.os.Message
 import android.view.ViewGroup
 import androidx.collection.arraySetOf
@@ -51,20 +52,21 @@ class Group(
 
   private var stickyManager: Manager? = null
     set(value) {
-      val from = field
+      val prevStickyManager = field
       field = value
-      val to = field
-      if (from === to) return
-      if (to != null) { // a Manager is promoted
-        to.sticky = true
-        managers.push(to)
+      val nextStickyManager = field
+      if (prevStickyManager === nextStickyManager) return
+      if (nextStickyManager != null) { // a Manager is promoted
+        nextStickyManager.sticky = true
+        managers.push(nextStickyManager)
       } else {
-        require(from != null && from.sticky)
-        if (managers.peek() === from) {
-          from.sticky = false
+        require(prevStickyManager != null && prevStickyManager.sticky)
+        if (managers.peek() === prevStickyManager) {
+          prevStickyManager.sticky = false
           managers.pop()
         }
       }
+      onRefresh()
     }
 
   internal var groupVolumeInfo: VolumeInfo = VolumeInfo.DEFAULT_ACTIVE
@@ -83,7 +85,7 @@ class Group(
       managers.forEach { it.lock = value }
     }
 
-  private val handler = Handler(this)
+  private val handler = Handler(/* looper */ Looper.getMainLooper(), /* callback */ this)
   private val dispatcher = PlayableDispatcher(master)
 
   private val playbacks: Collection<Playback>
@@ -157,8 +159,8 @@ class Group(
       toPlay.addAll(canPlay)
       toPause.addAll(canPause)
     } else {
-      managers.forEach {
-        val (canPlay, canPause) = it.splitPlaybacks()
+      for (manager in managers) {
+        val (canPlay, canPause) = manager.splitPlaybacks()
         toPlay.addAll(canPlay)
         toPause.addAll(canPause)
       }
@@ -190,6 +192,7 @@ class Group(
             if (it.host is OnSelectionListener) {
               it.host to (grouped[it] ?: emptyList())
             } else {
+              @Suppress("USELESS_CAST")
               null as Pair<OnSelectionListener, List<Playback>>?
             }
           }
@@ -231,7 +234,6 @@ class Group(
   internal fun onManagerDestroyed(manager: Manager) {
     if (stickyManager === manager) stickyManager = null
     if (managers.remove(manager)) master.onGroupUpdated(this)
-    if (managers.size == 0) master.onLastManagerDestroyed(this)
   }
 
   // This operation should:

kohii-core/src/main/java/kohii/v1/core/Interfaces.kt

@@ -180,6 +180,4 @@ interface DefaultTrackSelectorHolder {
   val trackSelector: DefaultTrackSelector
 }
 
-interface PlayableManager
-
 interface PlayableContainer