Reversed reader mode #15

app/src/main/java/org/koitharu/kotatsu/core/prefs/ReaderMode.kt

@@ -4,7 +4,8 @@ enum class ReaderMode(val id: Int) {
 
 	UNKNOWN(0),
 	STANDARD(1),
-	WEBTOON(2);
+	WEBTOON(2),
+	REVERSED(3);
 
 	companion object {
 

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

@@ -38,6 +38,7 @@ import org.koitharu.kotatsu.core.prefs.AppSettings
 import org.koitharu.kotatsu.core.prefs.ReaderMode
 import org.koitharu.kotatsu.ui.base.BaseFullscreenActivity
 import org.koitharu.kotatsu.ui.reader.base.AbstractReader
+import org.koitharu.kotatsu.ui.reader.reversed.ReversedReaderFragment
 import org.koitharu.kotatsu.ui.reader.standard.PagerReaderFragment
 import org.koitharu.kotatsu.ui.reader.thumbnails.OnPageSelectListener
 import org.koitharu.kotatsu.ui.reader.thumbnails.PagesThumbnailsSheet
@@ -121,6 +122,11 @@ class ReaderActivity : BaseFullscreenActivity(), ReaderView, ChaptersDialog.OnCh
 					replace(R.id.container, WebtoonReaderFragment.newInstance(state))
 				}
 			}
+			ReaderMode.REVERSED -> if (currentReader !is ReversedReaderFragment) {
+				supportFragmentManager.commit {
+					replace(R.id.container, ReversedReaderFragment.newInstance(state))
+				}
+			}
 			else -> if (currentReader !is PagerReaderFragment) {
 				supportFragmentManager.commit {
 					replace(R.id.container, PagerReaderFragment.newInstance(state))
@@ -130,6 +136,7 @@ class ReaderActivity : BaseFullscreenActivity(), ReaderView, ChaptersDialog.OnCh
 		toolbar_bottom.menu.findItem(R.id.action_reader_mode).setIcon(
 			when (mode) {
 				ReaderMode.WEBTOON -> R.drawable.ic_script
+				ReaderMode.REVERSED -> R.drawable.ic_read_reversed
 				else -> R.drawable.ic_book_page
 			}
 		)
@@ -159,6 +166,7 @@ class ReaderActivity : BaseFullscreenActivity(), ReaderView, ChaptersDialog.OnCh
 				supportFragmentManager, when (reader) {
 					is PagerReaderFragment -> ReaderMode.STANDARD
 					is WebtoonReaderFragment -> ReaderMode.WEBTOON
+					is ReversedReaderFragment -> ReaderMode.REVERSED
 					else -> ReaderMode.UNKNOWN
 				}
 			)

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

@@ -32,10 +32,12 @@ class ReaderConfigDialog : AlertDialogFragment(R.layout.dialog_reader_config),
 	override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
 		super.onViewCreated(view, savedInstanceState)
 		button_standard.isChecked = mode == ReaderMode.STANDARD
+		button_reversed.isChecked = mode == ReaderMode.REVERSED
 		button_webtoon.isChecked = mode == ReaderMode.WEBTOON
 
 		button_ok.setOnClickListener(this)
 		button_standard.setOnClickListener(this)
+		button_reversed.setOnClickListener(this)
 		button_webtoon.setOnClickListener(this)
 	}
 
@@ -48,6 +50,7 @@ class ReaderConfigDialog : AlertDialogFragment(R.layout.dialog_reader_config),
 			}
 			R.id.button_standard -> mode = ReaderMode.STANDARD
 			R.id.button_webtoon -> mode = ReaderMode.WEBTOON
+			R.id.button_reversed -> mode = ReaderMode.REVERSED
 		}
 	}
 

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

@@ -5,7 +5,7 @@ import androidx.recyclerview.widget.RecyclerView
 import org.koitharu.kotatsu.core.model.MangaPage
 import org.koitharu.kotatsu.ui.base.list.BaseViewHolder
 
-abstract class BaseReaderAdapter(private val pages: GroupedList<Long, MangaPage>) :
+abstract class BaseReaderAdapter(protected val pages: GroupedList<Long, MangaPage>) :
 	RecyclerView.Adapter<BaseViewHolder<MangaPage, Unit>>() {
 
 	init {
@@ -18,25 +18,25 @@ abstract class BaseReaderAdapter(private val pages: GroupedList<Long, MangaPage>
 		holder.bind(item, Unit)
 	}
 
-	fun getItem(position: Int) = pages[position]
+	open fun getItem(position: Int) = pages[position]
 
-	fun notifyItemsAppended(count: Int) {
+	open fun notifyItemsAppended(count: Int) {
 		notifyItemRangeInserted(pages.size - count, count)
 	}
 
-	fun notifyItemsPrepended(count: Int) {
+	open fun notifyItemsPrepended(count: Int) {
 		notifyItemRangeInserted(0, count)
 	}
 
-	fun notifyItemsRemovedStart(count: Int) {
+	open fun notifyItemsRemovedStart(count: Int) {
 		notifyItemRangeRemoved(0, count)
 	}
 
-	fun notifyItemsRemovedEnd(count: Int) {
+	open fun notifyItemsRemovedEnd(count: Int) {
 		notifyItemRangeRemoved(pages.size - count, count)
 	}
 
-	override fun getItemId(position: Int) = pages[position].id
+	open override fun getItemId(position: Int) = pages[position].id
 
 	final override fun getItemCount() = pages.size
 

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

@@ -0,0 +1,36 @@
+package org.koitharu.kotatsu.ui.reader.reversed
+
+import android.view.View
+import androidx.viewpager2.widget.ViewPager2
+
+class ReversedPageAnimTransformer : ViewPager2.PageTransformer {
+
+	override fun transformPage(page: View, position: Float) {
+		with(page) {
+			val pageWidth = width
+			when {
+				position > 1 -> alpha = 0f
+				position >= 0 -> {
+					alpha = 1f
+					translationX = 0f
+					translationZ = 0f
+					scaleX = 1 + FACTOR * position
+					scaleY = 1f
+				}
+				position >= -1 -> {
+					alpha = 1f
+					translationX = pageWidth * -position
+					translationZ = -1f
+					scaleX = 1f
+					scaleY = 1f
+				}
+				else -> alpha = 0f
+			}
+		}
+	}
+
+	private companion object {
+
+		const val FACTOR = 0.1f
+	}
+}

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

@@ -0,0 +1,47 @@
+package org.koitharu.kotatsu.ui.reader.reversed
+
+import android.view.ViewGroup
+import org.koitharu.kotatsu.core.model.MangaPage
+import org.koitharu.kotatsu.ui.base.list.BaseViewHolder
+import org.koitharu.kotatsu.ui.reader.PageLoader
+import org.koitharu.kotatsu.ui.reader.base.BaseReaderAdapter
+import org.koitharu.kotatsu.ui.reader.base.GroupedList
+import org.koitharu.kotatsu.ui.reader.standard.PageHolder
+
+class ReversedPagesAdapter(
+	pages: GroupedList<Long, MangaPage>,
+	private val loader: PageLoader
+) : BaseReaderAdapter(pages) {
+
+	override fun onCreateViewHolder(parent: ViewGroup) = PageHolder(parent, loader)
+
+	override fun onBindViewHolder(holder: BaseViewHolder<MangaPage, Unit>, position: Int) {
+		super.onBindViewHolder(holder, reversed(position))
+	}
+
+	override fun getItem(position: Int): MangaPage {
+		return super.getItem(reversed(position))
+	}
+
+	override fun getItemId(position: Int): Long {
+		return super.getItemId(reversed(position))
+	}
+
+	override fun notifyItemsAppended(count: Int) {
+		super.notifyItemsPrepended(count)
+	}
+
+	override fun notifyItemsPrepended(count: Int) {
+		super.notifyItemsAppended(count)
+	}
+
+	override fun notifyItemsRemovedStart(count: Int) {
+		super.notifyItemsRemovedEnd(count)
+	}
+
+	override fun notifyItemsRemovedEnd(count: Int) {
+		super.notifyItemsRemovedStart(count)
+	}
+
+	private fun reversed(position: Int) = pages.size - position - 1
+}

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

@@ -0,0 +1,93 @@
+package org.koitharu.kotatsu.ui.reader.reversed
+
+import android.content.Context
+import android.content.SharedPreferences
+import android.os.Bundle
+import android.view.View
+import kotlinx.android.synthetic.main.fragment_reader_standard.*
+import org.koin.android.ext.android.inject
+import org.koitharu.kotatsu.R
+import org.koitharu.kotatsu.core.model.MangaPage
+import org.koitharu.kotatsu.core.prefs.AppSettings
+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.PageAnimTransformer
+import org.koitharu.kotatsu.ui.reader.standard.PagerPaginationListener
+import org.koitharu.kotatsu.utils.ext.doOnPageChanged
+import org.koitharu.kotatsu.utils.ext.withArgs
+
+class ReversedReaderFragment : AbstractReader(R.layout.fragment_reader_standard),
+	SharedPreferences.OnSharedPreferenceChangeListener {
+
+	private var paginationListener: PagerPaginationListener? = null
+	private val settings by inject<AppSettings>()
+
+	override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+		super.onViewCreated(view, savedInstanceState)
+		paginationListener = PagerPaginationListener(adapter!!, 2, this)
+		pager.adapter = adapter
+		if (settings.readerAnimation) {
+			pager.setPageTransformer(ReversedPageAnimTransformer())
+		}
+		pager.offscreenPageLimit = 2
+		pager.registerOnPageChangeCallback(paginationListener!!)
+		pager.doOnPageChanged {
+			notifyPageChanged(reversed(it))
+		}
+	}
+
+	override fun onAttach(context: Context) {
+		super.onAttach(context)
+		settings.subscribe(this)
+	}
+
+	override fun onDetach() {
+		settings.unsubscribe(this)
+		super.onDetach()
+	}
+
+	override fun onDestroyView() {
+		paginationListener = null
+		super.onDestroyView()
+	}
+
+	override fun onCreateAdapter(dataSet: GroupedList<Long, MangaPage>): BaseReaderAdapter {
+		return ReversedPagesAdapter(dataSet, loader)
+	}
+
+	override val itemsCount: Int
+		get() = adapter?.itemCount ?: 0
+
+	override fun getCurrentItem() = reversed(pager.currentItem)
+
+	override fun setCurrentItem(position: Int, isSmooth: Boolean) {
+		pager.setCurrentItem(reversed(position), isSmooth)
+	}
+
+	override fun getCurrentPageScroll() = 0
+
+	override fun restorePageScroll(position: Int, scroll: Int) = Unit
+
+	override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences?, key: String?) {
+		when (key) {
+			getString(R.string.key_reader_animation) -> {
+				if (settings.readerAnimation) {
+					pager.setPageTransformer(PageAnimTransformer())
+				} else {
+					pager.setPageTransformer(null)
+				}
+			}
+		}
+	}
+
+	private fun reversed(position: Int) = (itemsCount - position - 1).coerceAtLeast(0)
+
+	companion object {
+
+		fun newInstance(state: ReaderState) = ReversedReaderFragment().withArgs(1) {
+			putParcelable(ARG_STATE, state)
+		}
+	}
+}

app/src/main/res/drawable/ic_read_reversed.xml

@@ -0,0 +1,11 @@
+<vector
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	android:width="24dp"
+	android:height="24dp"
+	android:tint="?colorControlNormal"
+	android:viewportWidth="24"
+	android:viewportHeight="24">
+	<path
+		android:fillColor="#000"
+		android:pathData="M4,21H19A2,2 0 0,0 21,19V13H17V15L13,12L17,9V11H21V5A2,2 0 0,0 19,3H4A2,2 0 0,0 2,5V19A2,2 0 0,0 4,21M4,15H8V17H4V15M4,11H11V13H4V11M4,7H11V9H4V7M21,11H24V13H21V11Z" />
+</vector>

app/src/main/res/layout/dialog_reader_config.xml

@@ -22,6 +22,14 @@
 			android:text="@string/standard"
 			app:icon="@drawable/ic_book_page" />
 
+		<com.google.android.material.button.MaterialButton
+			android:id="@+id/button_reversed"
+			style="@style/AppToggleButton"
+			android:layout_width="match_parent"
+			android:layout_height="wrap_content"
+			android:text="@string/right_to_left"
+			app:icon="@drawable/ic_read_reversed" />
+
 		<com.google.android.material.button.MaterialButton
 			android:id="@+id/button_webtoon"
 			style="@style/AppToggleButton"

app/src/main/res/values-ru/strings.xml

@@ -159,4 +159,5 @@
 	<string name="checking_for_updates">Проверка обновления…</string>
 	<string name="update_check_failed">Ошибка при проверке обновления</string>
 	<string name="no_update_available">Нет доступных обновлений</string>
+	<string name="right_to_left">Справа налево</string>
 </resources>

app/src/main/res/values/strings.xml

@@ -160,4 +160,5 @@
 	<string name="checking_for_updates">Checking for updates…</string>
 	<string name="update_check_failed">Update check failed</string>
 	<string name="no_update_available">No updates available</string>
+	<string name="right_to_left">Right to left</string>
 </resources>