Optimize opening an EPUB

Don't check for a non-empty content iterator when creating the TTS navigator factory
readium · Oct 5, 2023 · 9d5033c · 9d5033c
1 parent fdfbfd3
commit 9d5033c
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Showing 7 changed files with 38 additions and 24 deletions.
diff --git a/readium/navigator/src/main/java/org/readium/r2/navigator/media3/tts/TtsNavigator.kt b/readium/navigator/src/main/java/org/readium/r2/navigator/media3/tts/TtsNavigator.kt
@@ -76,6 +76,9 @@ public class TtsNavigator<S : TtsEngine.Settings, P : TtsEngine.Preferences<P>,
 
             val contentIterator =
                 TtsUtteranceIterator(publication, tokenizerFactory, initialLocator)
+            if (!contentIterator.hasNext()) {
+                return null
+            }
 
             val ttsEngine =
                 ttsEngineProvider.createEngine(publication, actualInitialPreferences)

diff --git a/readium/navigator/src/main/java/org/readium/r2/navigator/media3/tts/TtsNavigatorFactory.kt b/readium/navigator/src/main/java/org/readium/r2/navigator/media3/tts/TtsNavigatorFactory.kt
@@ -17,7 +17,6 @@ import org.readium.r2.shared.ExperimentalReadiumApi
 import org.readium.r2.shared.publication.Locator
 import org.readium.r2.shared.publication.Publication
 import org.readium.r2.shared.publication.services.content.Content
-import org.readium.r2.shared.publication.services.content.content
 import org.readium.r2.shared.util.Language
 import org.readium.r2.shared.util.tokenizer.DefaultTextContentTokenizer
 import org.readium.r2.shared.util.tokenizer.TextTokenizer
@@ -34,14 +33,14 @@ public class TtsNavigatorFactory<S : TtsEngine.Settings, P : TtsEngine.Preferenc
 ) {
     public companion object {
 
-        public suspend operator fun invoke(
+        public operator fun invoke(
             application: Application,
             publication: Publication,
             tokenizerFactory: (language: Language?) -> TextTokenizer = defaultTokenizerFactory,
             metadataProvider: MediaMetadataProvider = defaultMediaMetadataProvider,
             defaults: AndroidTtsDefaults = AndroidTtsDefaults(),
             voiceSelector: (Language?, Set<AndroidTtsEngine.Voice>) -> AndroidTtsEngine.Voice? = defaultVoiceSelector
-        ): AndroidTtsNavigatorFactory? {
+        ): AndroidTtsNavigatorFactory {
             val engineProvider = AndroidTtsEngineProvider(
                 context = application,
                 defaults = defaults,
@@ -57,44 +56,37 @@ public class TtsNavigatorFactory<S : TtsEngine.Settings, P : TtsEngine.Preferenc
             )
         }
 
-        public suspend operator fun <S : TtsEngine.Settings, P : TtsEngine.Preferences<P>, E : PreferencesEditor<P>,
+        public operator fun <S : TtsEngine.Settings, P : TtsEngine.Preferences<P>, E : PreferencesEditor<P>,
             F : TtsEngine.Error, V : TtsEngine.Voice> invoke(
             application: Application,
             publication: Publication,
             ttsEngineProvider: TtsEngineProvider<S, P, E, F, V>,
             tokenizerFactory: (language: Language?) -> TextTokenizer = defaultTokenizerFactory,
             metadataProvider: MediaMetadataProvider = defaultMediaMetadataProvider
-        ): TtsNavigatorFactory<S, P, E, F, V>? {
-            return createNavigatorFactory(
+        ): TtsNavigatorFactory<S, P, E, F, V> =
+            createNavigatorFactory(
                 application,
                 publication,
                 ttsEngineProvider,
                 tokenizerFactory,
                 metadataProvider
             )
-        }
 
-        private suspend fun <S : TtsEngine.Settings, P : TtsEngine.Preferences<P>, E : PreferencesEditor<P>,
+        private fun <S : TtsEngine.Settings, P : TtsEngine.Preferences<P>, E : PreferencesEditor<P>,
             F : TtsEngine.Error, V : TtsEngine.Voice> createNavigatorFactory(
             application: Application,
             publication: Publication,
             ttsEngineProvider: TtsEngineProvider<S, P, E, F, V>,
             tokenizerFactory: (language: Language?) -> TextTokenizer,
             metadataProvider: MediaMetadataProvider
-        ): TtsNavigatorFactory<S, P, E, F, V>? {
-            publication.content()
-                ?.iterator()
-                ?.takeIf { it.hasNext() }
-                ?: return null
-
-            return TtsNavigatorFactory(
+        ): TtsNavigatorFactory<S, P, E, F, V> =
+            TtsNavigatorFactory(
                 application,
                 publication,
                 ttsEngineProvider,
                 tokenizerFactory,
                 metadataProvider
             )
-        }
 
         /**
          * The default content tokenizer will split the [Content.Element] items into individual sentences.

diff --git a/readium/navigator/src/main/java/org/readium/r2/navigator/media3/tts/TtsUtteranceIterator.kt b/readium/navigator/src/main/java/org/readium/r2/navigator/media3/tts/TtsUtteranceIterator.kt
@@ -105,6 +105,19 @@ internal class TtsUtteranceIterator(
     private fun createIterator(locator: Locator?): Content.Iterator =
         contentService.content(locator).iterator()
 
+    suspend fun hasPrevious(): Boolean =
+        hasNextIn(Direction.Backward)
+
+    suspend fun hasNext(): Boolean =
+        hasNextIn(Direction.Forward)
+
+    private suspend fun hasNextIn(direction: Direction): Boolean {
+        if (utterances.isEmpty()) {
+            loadNextUtterances(direction)
+        }
+        return utterances.hasNextIn(direction)
+    }
+
     /**
      * Advances to the previous item and returns it, or null if we reached the beginning.
      */
@@ -217,6 +230,12 @@ internal class TtsUtteranceIterator(
         }
     }
 
+    private fun <E> CursorList<E>.hasNextIn(direction: Direction): Boolean =
+        when (direction) {
+            Direction.Forward -> hasNext()
+            Direction.Backward -> hasPrevious()
+        }
+
     private fun <E> CursorList<E>.nextIn(direction: Direction): E? =
         when (direction) {
             Direction.Forward -> if (hasNext()) next() else null

diff --git a/test-app/src/main/java/org/readium/r2/testapp/reader/ReaderInitData.kt b/test-app/src/main/java/org/readium/r2/testapp/reader/ReaderInitData.kt
@@ -30,14 +30,14 @@ sealed class VisualReaderInitData(
     override val bookId: Long,
     override val publication: Publication,
     val initialLocation: Locator?,
-    val ttsInitData: TtsInitData?
+    val ttsInitData: TtsInitData
 ) : ReaderInitData()
 
 class ImageReaderInitData(
     bookId: Long,
     publication: Publication,
     initialLocation: Locator?,
-    ttsInitData: TtsInitData?
+    ttsInitData: TtsInitData
 ) : VisualReaderInitData(bookId, publication, initialLocation, ttsInitData)
 
 class EpubReaderInitData(
@@ -46,7 +46,7 @@ class EpubReaderInitData(
     initialLocation: Locator?,
     val preferencesManager: PreferencesManager<EpubPreferences>,
     val navigatorFactory: EpubNavigatorFactory,
-    ttsInitData: TtsInitData?
+    ttsInitData: TtsInitData
 ) : VisualReaderInitData(bookId, publication, initialLocation, ttsInitData)
 
 class PdfReaderInitData(
@@ -55,7 +55,7 @@ class PdfReaderInitData(
     initialLocation: Locator?,
     val preferencesManager: PreferencesManager<PdfiumPreferences>,
     val navigatorFactory: PdfiumNavigatorFactory,
-    ttsInitData: TtsInitData?
+    ttsInitData: TtsInitData
 ) : VisualReaderInitData(bookId, publication, initialLocation, ttsInitData)
 
 class TtsInitData(

diff --git a/test-app/src/main/java/org/readium/r2/testapp/reader/ReaderRepository.kt b/test-app/src/main/java/org/readium/r2/testapp/reader/ReaderRepository.kt
@@ -235,13 +235,13 @@ class ReaderRepository(
     private suspend fun getTtsInitData(
         bookId: Long,
         publication: Publication
-    ): TtsInitData? {
+    ): TtsInitData {
         val preferencesManager = AndroidTtsPreferencesManagerFactory(preferencesDataStore)
             .createPreferenceManager(bookId)
         val navigatorFactory = TtsNavigatorFactory(
             application,
             publication
-        ) ?: return null
+        )
         return TtsInitData(mediaServiceFacade, navigatorFactory, preferencesManager)
     }
 

diff --git a/test-app/src/main/java/org/readium/r2/testapp/reader/tts/TtsViewModel.kt b/test-app/src/main/java/org/readium/r2/testapp/reader/tts/TtsViewModel.kt
@@ -59,7 +59,7 @@ class TtsViewModel private constructor(
             viewModelScope: CoroutineScope,
             readerInitData: ReaderInitData
         ): TtsViewModel? {
-            if (readerInitData !is VisualReaderInitData || readerInitData.ttsInitData == null) {
+            if (readerInitData !is VisualReaderInitData) {
                 return null
             }
 

diff --git a/test-app/src/main/res/values/strings.xml b/test-app/src/main/res/values/strings.xml
@@ -136,7 +136,7 @@
     <string name="play_or_pause">Play or pause</string>
     <string name="go_forward_30_seconds">Go forward 30 seconds</string>
 
-    <string name="tts_error_initialization">Failed to initialize the TTS engine</string>
+    <string name="tts_error_initialization">This publication cannot be read aloud</string>
     <string name="tts_error_language_support_incomplete">The language %s requires additional data. Do you want to download it?</string>
     <string name="tts_error_network">A networking error occurred</string>
     <string name="tts_error_other">A TTS error occurred</string>