Store page scroll position in history

app/src/main/java/org/koitharu/kotatsu/KotatsuApp.kt

@@ -15,6 +15,7 @@ import org.koin.core.context.startKoin
 import org.koin.dsl.module
 import org.koitharu.kotatsu.core.db.MangaDatabase
 import org.koitharu.kotatsu.core.db.migrations.Migration1To2
+import org.koitharu.kotatsu.core.db.migrations.Migration2To3
 import org.koitharu.kotatsu.core.local.CbzFetcher
 import org.koitharu.kotatsu.core.local.PagesCache
 import org.koitharu.kotatsu.core.local.cookies.PersistentCookieJar
@@ -110,5 +111,5 @@ class KotatsuApp : Application() {
 		applicationContext,
 		MangaDatabase::class.java,
 		"kotatsu-db"
-	).addMigrations(Migration1To2)
+	).addMigrations(Migration1To2, Migration2To3)
 }

app/src/main/java/org/koitharu/kotatsu/core/db/HistoryDao.kt

@@ -24,13 +24,13 @@ abstract class HistoryDao {
     @Insert(onConflict = OnConflictStrategy.IGNORE)
     abstract suspend fun insert(entity: HistoryEntity): Long
 
-    @Query("UPDATE history SET page = :page, chapter_id = :chapterId, updated_at = :updatedAt WHERE manga_id = :mangaId")
-    abstract suspend fun update(mangaId: Long, page: Int, chapterId: Long, updatedAt: Long): Int
+    @Query("UPDATE history SET page = :page, chapter_id = :chapterId, scroll = :scroll, updated_at = :updatedAt WHERE manga_id = :mangaId")
+    abstract suspend fun update(mangaId: Long, page: Int, chapterId: Long, scroll: Float, updatedAt: Long): Int
 
     @Query("DELETE FROM history WHERE manga_id = :mangaId")
     abstract suspend fun delete(mangaId: Long)
 
-    suspend fun update(entity: HistoryEntity) = update(entity.mangaId, entity.page, entity.chapterId, entity.updatedAt)
+    suspend fun update(entity: HistoryEntity) = update(entity.mangaId, entity.page, entity.chapterId, entity.scroll, entity.updatedAt)
 
     @Transaction
     open suspend fun upsert(entity: HistoryEntity) {

app/src/main/java/org/koitharu/kotatsu/core/db/MangaDatabase.kt

@@ -8,7 +8,7 @@ import org.koitharu.kotatsu.core.db.entity.*
 	entities = [
 		MangaEntity::class, TagEntity::class, HistoryEntity::class, MangaTagsEntity::class,
 		FavouriteCategoryEntity::class, FavouriteEntity::class, MangaPrefsEntity::class
-	], version = 2
+	], version = 3
 )
 abstract class MangaDatabase : RoomDatabase() {
 

app/src/main/java/org/koitharu/kotatsu/core/db/entity/HistoryEntity.kt

@@ -23,13 +23,15 @@ data class HistoryEntity(
 	@ColumnInfo(name = "created_at") val createdAt: Long = System.currentTimeMillis(),
 	@ColumnInfo(name = "updated_at") val updatedAt: Long,
 	@ColumnInfo(name = "chapter_id") val chapterId: Long,
-	@ColumnInfo(name = "page") val page: Int
+	@ColumnInfo(name = "page") val page: Int,
+	@ColumnInfo(name = "scroll") val scroll: Float
 ) {
 
 	fun toMangaHistory() = MangaHistory(
 		createdAt = Date(createdAt),
 		updatedAt = Date(updatedAt),
 		chapterId = chapterId,
-		page = page
+		page = page,
+		scroll = scroll
 	)
 }

app/src/main/java/org/koitharu/kotatsu/core/db/migrations/Migration2To3.kt

@@ -0,0 +1,11 @@
+package org.koitharu.kotatsu.core.db.migrations
+
+import androidx.room.migration.Migration
+import androidx.sqlite.db.SupportSQLiteDatabase
+
+object Migration2To3 : Migration(2, 3) {
+
+	override fun migrate(database: SupportSQLiteDatabase) {
+		database.execSQL("ALTER TABLE history ADD COLUMN scroll REAL NOT NULL DEFAULT 0")
+	}
+}

app/src/main/java/org/koitharu/kotatsu/core/model/MangaHistory.kt

@@ -9,5 +9,6 @@ data class MangaHistory(
 	val createdAt: Date,
 	val updatedAt: Date,
 	val chapterId: Long,
-	val page: Int
+	val page: Int,
+	val scroll: Float
 ) : Parcelable

app/src/main/java/org/koitharu/kotatsu/domain/history/HistoryRepository.kt

@@ -21,7 +21,7 @@ class HistoryRepository : KoinComponent {
 		return entities.map { it.manga.toManga(it.tags.map(TagEntity::toMangaTag).toSet()) }
 	}
 
-	suspend fun addOrUpdate(manga: Manga, chapterId: Long, page: Int) {
+	suspend fun addOrUpdate(manga: Manga, chapterId: Long, page: Int, scroll: Float) {
 		val tags = manga.tags.map(TagEntity.Companion::fromMangaTag)
 		db.tagsDao().upsert(tags)
 		db.mangaDao().upsert(MangaEntity.from(manga), tags)
@@ -31,7 +31,8 @@ class HistoryRepository : KoinComponent {
 				createdAt = System.currentTimeMillis(),
 				updatedAt = System.currentTimeMillis(),
 				chapterId = chapterId,
-				page = page
+				page = page,
+				scroll = scroll
 			)
 		)
 		notifyHistoryChanged()
@@ -43,7 +44,8 @@ class HistoryRepository : KoinComponent {
 				createdAt = Date(it.createdAt),
 				updatedAt = Date(it.updatedAt),
 				chapterId = it.chapterId,
-				page = it.page
+				page = it.page,
+				scroll = it.scroll
 			)
 		}
 	}

app/src/main/java/org/koitharu/kotatsu/ui/main/MainPresenter.kt

@@ -26,7 +26,7 @@ class MainPresenter : BasePresenter<MainView>() {
 					val history = repo.getOne(manga) ?: throw EmptyHistoryException()
 					ReaderState(
 						MangaProviderFactory.create(manga.source).getDetails(manga),
-						history.chapterId, history.page
+						history.chapterId, history.page, history.scroll
 					)
 				}
 				viewState.onOpenReader(state)

app/src/main/java/org/koitharu/kotatsu/ui/reader/ReaderActivity.kt

@@ -195,8 +195,8 @@ class ReaderActivity : BaseFullscreenActivity(), ReaderView, ChaptersDialog.OnCh
 		else -> super.onOptionsItemSelected(item)
 	}
 
-	override fun saveState(chapterId: Long, page: Int) {
-		state = state.copy(chapterId = chapterId, page = page)
+	override fun saveState(chapterId: Long, page: Int, scroll: Float) {
+		state = state.copy(chapterId = chapterId, page = page, scroll = scroll)
 		ReaderPresenter.saveState(state)
 	}
 
@@ -293,7 +293,8 @@ class ReaderActivity : BaseFullscreenActivity(), ReaderView, ChaptersDialog.OnCh
 	override fun onChapterChanged(chapter: MangaChapter) {
 		state = state.copy(
 			chapterId = chapter.id,
-			page = 0
+			page = 0,
+			scroll = 0f
 		)
 		reader?.updateState(chapterId = chapter.id)
 	}
@@ -371,7 +372,8 @@ class ReaderActivity : BaseFullscreenActivity(), ReaderView, ChaptersDialog.OnCh
 				manga = manga,
 				chapterId = if (chapterId == -1L) manga.chapters?.firstOrNull()?.id
 					?: -1 else chapterId,
-				page = 0
+				page = 0,
+				scroll = 0f
 			)
 		)
 
@@ -383,7 +385,8 @@ class ReaderActivity : BaseFullscreenActivity(), ReaderView, ChaptersDialog.OnCh
 					context, ReaderState(
 						manga = manga,
 						chapterId = history.chapterId,
-						page = history.page
+						page = history.page,
+						scroll = history.scroll
 					)
 				)
 			}

app/src/main/java/org/koitharu/kotatsu/ui/reader/ReaderListener.kt

@@ -7,5 +7,5 @@ interface ReaderListener : BaseMvpView {
 
 	fun onPageChanged(chapter: MangaChapter, page: Int, total: Int)
 
-	fun saveState(chapterId: Long, page: Int)
+	fun saveState(chapterId: Long, page: Int, scroll: Float)
 }

app/src/main/java/org/koitharu/kotatsu/ui/reader/ReaderPresenter.kt

@@ -1,7 +1,6 @@
 package org.koitharu.kotatsu.ui.reader
 
 import android.content.ContentResolver
-import android.util.Log
 import android.webkit.URLUtil
 import kotlinx.coroutines.*
 import moxy.InjectViewState
@@ -9,7 +8,6 @@ import moxy.presenterScope
 import okhttp3.OkHttpClient
 import okhttp3.Request
 import org.koin.core.get
-import org.koitharu.kotatsu.BuildConfig
 import org.koitharu.kotatsu.core.model.Manga
 import org.koitharu.kotatsu.core.model.MangaPage
 import org.koitharu.kotatsu.core.prefs.ReaderMode
@@ -103,7 +101,8 @@ class ReaderPresenter : BasePresenter<ReaderView>() {
 				HistoryRepository().addOrUpdate(
 					manga = state.manga,
 					chapterId = state.chapterId,
-					page = state.page
+					page = state.page,
+					scroll = state.scroll
 				)
 			}
 		}

app/src/main/java/org/koitharu/kotatsu/ui/reader/ReaderState.kt

@@ -10,7 +10,8 @@ import org.koitharu.kotatsu.core.model.MangaChapter
 data class ReaderState(
 	val manga: Manga,
 	val chapterId: Long,
-	val page: Int
+	val page: Int,
+	val scroll: Float
 ) : Parcelable {
 
 	@IgnoredOnParcel

app/src/main/java/org/koitharu/kotatsu/ui/reader/base/AbstractReader.kt

@@ -58,6 +58,9 @@ abstract class AbstractReader(contentLayoutId: Int) : BaseFragment(contentLayout
 			pages.addLast(state.chapterId, it)
 			adapter?.notifyDataSetChanged()
 			setCurrentItem(state.page, false)
+			if (state.scroll != 0f) {
+				restorePageScroll(state.page, state.scroll)
+			}
 		}
 	}
 
@@ -67,7 +70,8 @@ abstract class AbstractReader(contentLayoutId: Int) : BaseFragment(contentLayout
 			ARG_STATE, ReaderState(
 				manga = manga,
 				chapterId = pages.findGroupByIndex(getCurrentItem()) ?: return,
-				page = pages.getRelativeIndex(getCurrentItem())
+				page = pages.getRelativeIndex(getCurrentItem()),
+				scroll = getCurrentPageScroll()
 			)
 		)
 	}
@@ -174,7 +178,7 @@ abstract class AbstractReader(contentLayoutId: Int) : BaseFragment(contentLayout
 		val chapterId = pages.findGroupByIndex(getCurrentItem()) ?: return
 		val page = pages.getRelativeIndex(getCurrentItem())
 		if (page != -1) {
-			readerListener?.saveState(chapterId, page)
+			readerListener?.saveState(chapterId, page, getCurrentPageScroll())
 		}
 		Log.i(TAG, "saveState(chapterId=$chapterId, page=$page)")
 	}
@@ -217,6 +221,10 @@ abstract class AbstractReader(contentLayoutId: Int) : BaseFragment(contentLayout
 
 	protected abstract fun getCurrentItem(): Int
 
+	protected abstract fun getCurrentPageScroll(): Float
+
+	protected abstract fun restorePageScroll(position: Int, scroll: Float)
+
 	protected abstract fun setCurrentItem(position: Int, isSmooth: Boolean)
 
 	protected abstract fun onCreateAdapter(dataSet: GroupedList<Long, MangaPage>): BaseReaderAdapter

app/src/main/java/org/koitharu/kotatsu/ui/reader/standard/PagerReaderFragment.kt

@@ -5,10 +5,10 @@ import android.view.View
 import kotlinx.android.synthetic.main.fragment_reader_standard.*
 import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.core.model.MangaPage
+import org.koitharu.kotatsu.ui.reader.ReaderState
 import org.koitharu.kotatsu.ui.reader.base.AbstractReader
 import org.koitharu.kotatsu.ui.reader.base.BaseReaderAdapter
 import org.koitharu.kotatsu.ui.reader.base.GroupedList
-import org.koitharu.kotatsu.ui.reader.ReaderState
 import org.koitharu.kotatsu.utils.ext.doOnPageChanged
 import org.koitharu.kotatsu.utils.ext.withArgs
 
@@ -43,6 +43,10 @@ class PagerReaderFragment : AbstractReader(R.layout.fragment_reader_standard) {
 		pager.setCurrentItem(position, isSmooth)
 	}
 
+	override fun getCurrentPageScroll() = 0f
+
+	override fun restorePageScroll(position: Int, scroll: Float) = Unit
+
 	companion object {
 
 		fun newInstance(state: ReaderState) = PagerReaderFragment().withArgs(1) {

app/src/main/java/org/koitharu/kotatsu/ui/reader/wetoon/WebtoonHolder.kt

@@ -20,6 +20,7 @@ class WebtoonHolder(parent: ViewGroup, private val loader: PageLoader) :
 	SubsamplingScaleImageView.OnImageEventListener, CoroutineScope by loader {
 
 	private var job: Job? = null
+	private var scrollToRestore = 0f
 
 	init {
 		ssiv.setOnImageEventListener(this)
@@ -34,6 +35,7 @@ class WebtoonHolder(parent: ViewGroup, private val loader: PageLoader) :
 
 	private fun doLoad(data: MangaPage, force: Boolean) {
 		job?.cancel()
+		scrollToRestore = 0f
 		job = launch {
 			layout_error.isVisible = false
 			progressBar.isVisible = true
@@ -51,6 +53,22 @@ class WebtoonHolder(parent: ViewGroup, private val loader: PageLoader) :
 		}
 	}
 
+	fun getScrollY() = ssiv.center?.y ?: 0f
+
+	fun restoreScroll(scroll: Float) {
+		if (ssiv.isReady) {
+			ssiv.setScaleAndCenter(
+				ssiv.scale,
+				PointF(
+					ssiv.sWidth / 2f,
+					scroll
+				)
+			)
+		} else {
+			scrollToRestore = scroll
+		}
+	}
+
 	override fun onReady() {
 		ssiv.maxScale = 2f * ssiv.width / ssiv.sWidth.toFloat()
 		ssiv.setMinimumScaleType(SubsamplingScaleImageView.SCALE_TYPE_CUSTOM)
@@ -59,10 +77,10 @@ class WebtoonHolder(parent: ViewGroup, private val loader: PageLoader) :
 			ssiv.minScale,
 			PointF(
 				ssiv.sWidth / 2f,
-				if (itemView.top < 0) {
-					ssiv.sHeight.toFloat()
-				} else {
-					0f
+				when {
+					scrollToRestore != 0f -> scrollToRestore
+					itemView.top < 0 -> ssiv.sHeight.toFloat()
+					else -> 0f
 				}
 			)
 		)

app/src/main/java/org/koitharu/kotatsu/ui/reader/wetoon/WebtoonReaderFragment.kt

@@ -11,7 +11,6 @@ import org.koitharu.kotatsu.ui.reader.ReaderState
 import org.koitharu.kotatsu.ui.reader.base.AbstractReader
 import org.koitharu.kotatsu.ui.reader.base.BaseReaderAdapter
 import org.koitharu.kotatsu.ui.reader.base.GroupedList
-import org.koitharu.kotatsu.ui.reader.standard.PagerReaderFragment
 import org.koitharu.kotatsu.utils.ext.doOnCurrentItemChanged
 import org.koitharu.kotatsu.utils.ext.findMiddleVisibleItemPosition
 import org.koitharu.kotatsu.utils.ext.firstItem
@@ -56,7 +55,23 @@ class WebtoonReaderFragment : AbstractReader(R.layout.fragment_reader_webtoon) {
 	}
 
 	override fun switchPageBy(delta: Int) {
-		recyclerView.smoothScrollBy(0, (recyclerView.height * 0.9).toInt() * delta, scrollInterpolator)
+		recyclerView.smoothScrollBy(
+			0,
+			(recyclerView.height * 0.9).toInt() * delta,
+			scrollInterpolator
+		)
+	}
+
+	override fun getCurrentPageScroll(): Float {
+		return (recyclerView.findViewHolderForAdapterPosition(getCurrentItem()) as? WebtoonHolder)
+			?.getScrollY() ?: 0f
+	}
+
+	override fun restorePageScroll(position: Int, scroll: Float) {
+		recyclerView.post {
+			val holder = recyclerView.findViewHolderForAdapterPosition(position) ?: return@post
+			(holder as WebtoonHolder).restoreScroll(scroll)
+		}
 	}
 
 	companion object {