Replace RxJava in reader transitions

Co-Authored-By: arkon <4098258+arkon@users.noreply.github.com>

app/src/main/java/eu/kanade/tachiyomi/ui/reader/model/ReaderChapter.kt

@@ -1,23 +1,19 @@
 package eu.kanade.tachiyomi.ui.reader.model
 
-import com.jakewharton.rxrelay.BehaviorRelay
 import eu.kanade.tachiyomi.data.database.models.Chapter
 import eu.kanade.tachiyomi.ui.reader.loader.PageLoader
+import kotlinx.coroutines.flow.MutableStateFlow
 import timber.log.Timber
 
 data class ReaderChapter(val chapter: Chapter) {
 
-    var state: State =
-        State.Wait
+    val stateFlow = MutableStateFlow<State>(State.Wait)
+    var state: State
+        get() = stateFlow.value
         set(value) {
-            field = value
-            stateRelay.call(value)
+            stateFlow.value = value
         }
 
-    private val stateRelay by lazy { BehaviorRelay.create(state) }
-
-    val stateObserver by lazy { stateRelay.asObservable() }
-
     val pages: List<ReaderPage>?
         get() = (state as? State.Loaded)?.pages
 
@@ -25,8 +21,7 @@ data class ReaderChapter(val chapter: Chapter) {
 
     var requestedPage: Int = 0
 
-    var references = 0
-        private set
+    private var references = 0
 
     fun ref() {
         references++

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerTransitionHolder.kt

@@ -17,8 +17,10 @@ import eu.kanade.tachiyomi.ui.reader.model.ReaderChapter
 import eu.kanade.tachiyomi.ui.reader.viewer.ReaderTransitionView
 import eu.kanade.tachiyomi.util.system.dpToPx
 import eu.kanade.tachiyomi.widget.ViewPagerAdapter
-import rx.Subscription
-import rx.android.schedulers.AndroidSchedulers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.MainScope
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.launch
 
 /**
  * View of the ViewPager that contains a chapter transition.
@@ -29,17 +31,15 @@ class PagerTransitionHolder(
     val transition: ChapterTransition,
 ) : LinearLayout(viewer.activity), ViewPagerAdapter.PositionableView {
 
+    private val scope = MainScope()
+    private var stateJob: Job? = null
+
     /**
      * Item that identifies this view. Needed by the adapter to not recreate views.
      */
     override val item: Any
         get() = transition
 
-    /**
-     * Subscription for status changes of the transition page.
-     */
-    private var statusSubscription: Subscription? = null
-
     /**
      * View container of the current status of the transition page. Child views will be added
      * dynamically.
@@ -55,11 +55,13 @@ class PagerTransitionHolder(
         gravity = Gravity.CENTER
         val sidePadding = 64.dpToPx
         setPadding(sidePadding, 0, sidePadding, 0)
+
         val transitionView = ReaderTransitionView(context)
         addView(transitionView)
         addView(pagesContainer)
 
-        transitionView.bind(transition, viewer.downloadManager, viewer.activity.viewModel.state.value.manga)
+        transitionView.bind(transition, viewer.downloadManager, viewer.activity.viewModel.manga)
+
         transition.to?.let { observeStatus(it) }
 
         if (viewer.config.hingeGapSize > 0) {
@@ -74,8 +76,7 @@ class PagerTransitionHolder(
      */
     override fun onDetachedFromWindow() {
         super.onDetachedFromWindow()
-        statusSubscription?.unsubscribe()
-        statusSubscription = null
+        stateJob?.cancel()
     }
 
     /**
@@ -83,18 +84,20 @@ class PagerTransitionHolder(
      * state, the pages container is cleaned up before setting the new state.
      */
     private fun observeStatus(chapter: ReaderChapter) {
-        statusSubscription?.unsubscribe()
-        statusSubscription = chapter.stateObserver
-            .observeOn(AndroidSchedulers.mainThread())
-            .subscribe { state ->
-                pagesContainer.removeAllViews()
-                when (state) {
-                    is ReaderChapter.State.Wait -> {}
-                    is ReaderChapter.State.Loading -> setLoading()
-                    is ReaderChapter.State.Error -> setError(state.error)
-                    is ReaderChapter.State.Loaded -> setLoaded()
+        stateJob?.cancel()
+        stateJob = scope.launch {
+            chapter.stateFlow
+                .collectLatest { state ->
+                    pagesContainer.removeAllViews()
+                    when (state) {
+                        is ReaderChapter.State.Loading -> setLoading()
+                        is ReaderChapter.State.Error -> setError(state.error)
+                        is ReaderChapter.State.Wait, is ReaderChapter.State.Loaded -> {
+                            // No additional view is added
+                        }
+                    }
                 }
-            }
+        }
     }
 
     /**
@@ -112,13 +115,6 @@ class PagerTransitionHolder(
         pagesContainer.addView(textView)
     }
 
-    /**
-     * Sets the loaded state on the pages container.
-     */
-    private fun setLoaded() {
-        // No additional view is added
-    }
-
     /**
      * Sets the error state on the pages container.
      */

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonTransitionHolder.kt

@@ -8,14 +8,17 @@ import android.widget.LinearLayout
 import android.widget.ProgressBar
 import androidx.appcompat.widget.AppCompatButton
 import androidx.appcompat.widget.AppCompatTextView
+import androidx.core.view.isNotEmpty
 import androidx.core.view.isVisible
 import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.ui.reader.model.ChapterTransition
 import eu.kanade.tachiyomi.ui.reader.model.ReaderChapter
 import eu.kanade.tachiyomi.ui.reader.viewer.ReaderTransitionView
 import eu.kanade.tachiyomi.util.system.dpToPx
-import rx.Subscription
-import rx.android.schedulers.AndroidSchedulers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.MainScope
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.launch
 
 /**
  * Holder of the webtoon viewer that contains a chapter transition.
@@ -25,10 +28,8 @@ class WebtoonTransitionHolder(
     viewer: WebtoonViewer,
 ) : WebtoonBaseHolder(layout, viewer) {
 
-    /**
-     * Subscription for status changes of the transition page.
-     */
-    private var statusSubscription: Subscription? = null
+    private val scope = MainScope()
+    private var stateJob: Job? = null
 
     private val transitionView = ReaderTransitionView(context)
 
@@ -64,7 +65,8 @@ class WebtoonTransitionHolder(
      * Binds the given [transition] with this view holder, subscribing to its state.
      */
     fun bind(transition: ChapterTransition) {
-        transitionView.bind(transition, viewer.downloadManager, viewer.activity.viewModel.state.value.manga)
+        transitionView.bind(transition, viewer.downloadManager, viewer.activity.viewModel.manga)
+
         transition.to?.let { observeStatus(it, transition) }
     }
 
@@ -72,7 +74,7 @@ class WebtoonTransitionHolder(
      * Called when the view is recycled and being added to the view pool.
      */
     override fun recycle() {
-        unsubscribeStatus()
+        stateJob?.cancel()
     }
 
     /**
@@ -80,30 +82,21 @@ class WebtoonTransitionHolder(
      * state, the pages container is cleaned up before setting the new state.
      */
     private fun observeStatus(chapter: ReaderChapter, transition: ChapterTransition) {
-        unsubscribeStatus()
-
-        statusSubscription = chapter.stateObserver
-            .observeOn(AndroidSchedulers.mainThread())
-            .subscribe { state ->
-                pagesContainer.removeAllViews()
-                when (state) {
-                    is ReaderChapter.State.Wait -> {}
-                    is ReaderChapter.State.Loading -> setLoading()
-                    is ReaderChapter.State.Error -> setError(state.error, transition)
-                    is ReaderChapter.State.Loaded -> setLoaded()
+        stateJob?.cancel()
+        stateJob = scope.launch {
+            chapter.stateFlow
+                .collectLatest { state ->
+                    pagesContainer.removeAllViews()
+                    when (state) {
+                        is ReaderChapter.State.Loading -> setLoading()
+                        is ReaderChapter.State.Error -> setError(state.error, transition)
+                        is ReaderChapter.State.Wait, is ReaderChapter.State.Loaded -> {
+                            // No additional view is added
+                        }
+                    }
+                    pagesContainer.isVisible = pagesContainer.isNotEmpty()
                 }
-                pagesContainer.isVisible = pagesContainer.childCount > 0
-            }
-
-        addSubscription(statusSubscription)
-    }
-
-    /**
-     * Unsubscribes from the status subscription.
-     */
-    private fun unsubscribeStatus() {
-        removeSubscription(statusSubscription)
-        statusSubscription = null
+        }
     }
 
     /**