Double reader integration

app/src/main/kotlin/org/koitharu/kotatsu/core/prefs/AppSettings.kt

@@ -101,6 +101,10 @@ class AppSettings @Inject constructor(@ApplicationContext context: Context) {
 			}
 		}
 
+	var isReaderDoubleOnLandscape: Boolean
+		get() = prefs.getBoolean(KEY_READER_DOUBLE_PAGES, false)
+		set(value) = prefs.edit { putBoolean(KEY_READER_DOUBLE_PAGES, value) }
+
 	val isReaderVolumeButtonsEnabled: Boolean
 		get() = prefs.getBoolean(KEY_READER_VOLUME_BUTTONS, false)
 
@@ -472,6 +476,7 @@ class AppSettings @Inject constructor(@ApplicationContext context: Context) {
 		const val KEY_GRID_SIZE = "grid_size"
 		const val KEY_REMOTE_SOURCES = "remote_sources"
 		const val KEY_LOCAL_STORAGE = "local_storage"
+		const val KEY_READER_DOUBLE_PAGES = "reader_double_pages"
 		const val KEY_READER_ZOOM_BUTTONS = "reader_zoom_buttons"
 		const val KEY_READER_VOLUME_BUTTONS = "reader_volume_buttons"
 		const val KEY_TRACKER_ENABLED = "tracker_enabled"

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

@@ -6,7 +6,6 @@ enum class ReaderMode(val id: Int) {
 	REVERSED(3),
 	VERTICAL(4),
 	WEBTOON(2),
-	DOUBLE(5),
 	;
 
 	companion object {

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

@@ -3,6 +3,7 @@ package org.koitharu.kotatsu.reader.ui
 import android.content.Context
 import android.content.Intent
 import android.net.Uri
+import android.os.Build.VERSION_CODES.R
 import android.os.Bundle
 import android.transition.Fade
 import android.transition.Slide
@@ -108,7 +109,7 @@ class ReaderActivity :
 	override fun onCreate(savedInstanceState: Bundle?) {
 		super.onCreate(savedInstanceState)
 		setContentView(ActivityReaderBinding.inflate(layoutInflater))
-		readerManager = ReaderManager(supportFragmentManager, viewBinding.container)
+		readerManager = ReaderManager(supportFragmentManager, viewBinding.container, settings)
 		supportActionBar?.setDisplayHomeAsUpEnabled(true)
 		touchHelper = TapGridDispatcher(this, this)
 		scrollTimer = scrollTimerFactory.create(this, this)

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/ReaderManager.kt

@@ -1,9 +1,10 @@
 package org.koitharu.kotatsu.reader.ui
 
+import android.content.res.Configuration
 import androidx.fragment.app.FragmentContainerView
 import androidx.fragment.app.FragmentManager
 import androidx.fragment.app.commit
-import org.koitharu.kotatsu.R
+import org.koitharu.kotatsu.core.prefs.AppSettings
 import org.koitharu.kotatsu.core.prefs.ReaderMode
 import org.koitharu.kotatsu.reader.ui.pager.BaseReaderFragment
 import org.koitharu.kotatsu.reader.ui.pager.doublepage.DoubleReaderFragment
@@ -16,13 +17,13 @@ import java.util.EnumMap
 class ReaderManager(
 	private val fragmentManager: FragmentManager,
 	private val container: FragmentContainerView,
+	private val settings: AppSettings,
 ) {
 
 	private val modeMap = EnumMap<ReaderMode, Class<out BaseReaderFragment<*>>>(ReaderMode::class.java)
 
 	init {
-		val isTablet = container.resources.getBoolean(R.bool.is_tablet)
+		modeMap[ReaderMode.STANDARD] = if (useDoublePages()) {
-		modeMap[ReaderMode.STANDARD] = if (isTablet) {
 			DoubleReaderFragment::class.java
 		} else {
 			PagerReaderFragment::class.java
@@ -49,6 +50,9 @@ class ReaderManager(
 		}
 	}
 
+	private fun useDoublePages() = container.resources.configuration.orientation == Configuration.ORIENTATION_LANDSCAPE
+		&& settings.isReaderDoubleOnLandscape
+
 	/*fun replace(reader: BaseReaderFragment<*>) {
 		fragmentManager.commit {
 			setReorderingAllowed(true)

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/config/ReaderConfigSheet.kt

@@ -1,6 +1,7 @@
 package org.koitharu.kotatsu.reader.ui.config
 
 import android.net.Uri
+import android.os.Build.VERSION_CODES.R
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
@@ -80,7 +81,8 @@ class ReaderConfigSheet :
 		binding.buttonReversed.isChecked = mode == ReaderMode.REVERSED
 		binding.buttonWebtoon.isChecked = mode == ReaderMode.WEBTOON
 		binding.buttonVertical.isChecked = mode == ReaderMode.VERTICAL
-		binding.buttonDouble.isChecked = mode == ReaderMode.DOUBLE
+		binding.switchDoubleReader.isChecked = settings.isReaderDoubleOnLandscape
+		binding.switchDoubleReader.isEnabled = mode == ReaderMode.STANDARD
 
 		binding.checkableGroup.addOnButtonCheckedListener(this)
 		binding.buttonSavePage.setOnClickListener(this)
@@ -89,6 +91,7 @@ class ReaderConfigSheet :
 		binding.buttonColorFilter.setOnClickListener(this)
 		binding.sliderTimer.addOnChangeListener(this)
 		binding.switchScrollTimer.setOnCheckedChangeListener(this)
+		binding.switchDoubleReader.setOnCheckedChangeListener(this)
 
 		settings.observeAsStateFlow(
 			scope = lifecycleScope + Dispatchers.Default,
@@ -140,6 +143,11 @@ class ReaderConfigSheet :
 			R.id.switch_screen_lock_rotation -> {
 				orientationHelper.isLocked = isChecked
 			}
+
+			R.id.switch_double_reader -> {
+				settings.isReaderDoubleOnLandscape = isChecked
+				findCallback()?.onReaderModeChanged(mode)
+			}
 		}
 	}
 
@@ -156,9 +164,9 @@ class ReaderConfigSheet :
 			R.id.button_webtoon -> ReaderMode.WEBTOON
 			R.id.button_reversed -> ReaderMode.REVERSED
 			R.id.button_vertical -> ReaderMode.VERTICAL
-			R.id.button_double -> ReaderMode.DOUBLE
 			else -> return
 		}
+		viewBinding?.switchDoubleReader?.isEnabled = newMode == ReaderMode.STANDARD
 		if (newMode == mode) {
 			return
 		}

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/pager/BasePagerReaderFragment.kt

@@ -1,6 +1,7 @@
 package org.koitharu.kotatsu.reader.ui.pager
 
 import android.os.Build
+import android.os.Build.VERSION_CODES.R
 import android.os.Bundle
 import android.view.InputDevice
 import android.view.KeyEvent
@@ -75,7 +76,7 @@ abstract class BasePagerReaderFragment : BaseReaderFragment<FragmentReaderPagerB
 
 		viewModel.pageAnimation.observe(viewLifecycleOwner) {
 			val transformer = when (it) {
-				ReaderAnimation.NONE -> NoAnimPageTransformer()
+				ReaderAnimation.NONE -> NoAnimPageTransformer(binding.pager.orientation)
 				ReaderAnimation.DEFAULT -> null
 				ReaderAnimation.ADVANCED -> onCreateAdvancedTransformer()
 			}

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/pager/doublepage/DoublePageLayoutManager.kt

@@ -16,4 +16,10 @@ class DoublePageLayoutManager(
 		lp?.width = width / 2
 		return super.checkLayoutParams(lp)
 	}
+
+	override fun calculateExtraLayoutSpace(state: RecyclerView.State, extraLayoutSpace: IntArray) {
+		val offscreenSpace = width / 2
+		extraLayoutSpace[0] = offscreenSpace
+		extraLayoutSpace[1] = offscreenSpace
+	}
 }

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/pager/doublepage/DoubleReaderFragment.kt

@@ -1,8 +1,10 @@
 package org.koitharu.kotatsu.reader.ui.pager.doublepage
 
+import android.os.Build.VERSION_CODES.R
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.ViewGroup
+import android.view.animation.AccelerateDecelerateInterpolator
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import com.google.android.material.snackbar.Snackbar
@@ -12,16 +14,15 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.yield
 import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.core.os.NetworkState
+import org.koitharu.kotatsu.core.ui.list.lifecycle.RecyclerViewLifecycleDispatcher
 import org.koitharu.kotatsu.core.util.ext.firstVisibleItemPosition
 import org.koitharu.kotatsu.databinding.FragmentReaderDoubleBinding
-import org.koitharu.kotatsu.parsers.util.toIntUp
 import org.koitharu.kotatsu.reader.domain.PageLoader
 import org.koitharu.kotatsu.reader.ui.ReaderState
 import org.koitharu.kotatsu.reader.ui.ReaderViewModel
 import org.koitharu.kotatsu.reader.ui.pager.BaseReaderAdapter
 import org.koitharu.kotatsu.reader.ui.pager.BaseReaderFragment
 import org.koitharu.kotatsu.reader.ui.pager.ReaderPage
-import org.koitharu.kotatsu.reader.ui.pager.standard.PageHolder
 import javax.inject.Inject
 import kotlin.math.absoluteValue
 
@@ -34,6 +35,8 @@ class DoubleReaderFragment : BaseReaderFragment<FragmentReaderDoubleBinding>() {
 	@Inject
 	lateinit var pageLoader: PageLoader
 
+	private var recyclerLifecycleDispatcher: RecyclerViewLifecycleDispatcher? = null
+
 	override fun onCreateViewBinding(
 		inflater: LayoutInflater,
 		container: ViewGroup?,
@@ -46,12 +49,16 @@ class DoubleReaderFragment : BaseReaderFragment<FragmentReaderDoubleBinding>() {
 		super.onViewBindingCreated(binding, savedInstanceState)
 		with(binding.recyclerView) {
 			adapter = readerAdapter
+			recyclerLifecycleDispatcher = RecyclerViewLifecycleDispatcher().also {
+				addOnScrollListener(it)
+			}
 			addOnScrollListener(PageScrollListener(viewModel))
 			DoublePageSnapHelper().attachToRecyclerView(this)
 		}
 	}
 
 	override fun onDestroyView() {
+		recyclerLifecycleDispatcher = null
 		requireViewBinding().recyclerView.adapter = null
 		super.onDestroyView()
 	}
@@ -60,6 +67,9 @@ class DoubleReaderFragment : BaseReaderFragment<FragmentReaderDoubleBinding>() {
 		val items = launch {
 			requireAdapter().setItems(pages)
 			yield()
+			viewBinding?.recyclerView?.let { rv ->
+				recyclerLifecycleDispatcher?.invalidate(rv)
+			}
 		}
 		if (pendingState != null) {
 			var position = pages.indexOfFirst {
@@ -67,7 +77,7 @@ class DoubleReaderFragment : BaseReaderFragment<FragmentReaderDoubleBinding>() {
 			}
 			items.join()
 			if (position != -1) {
-				position = position or 1
+				position = position.toPagePosition()
 				requireViewBinding().recyclerView.firstVisibleItemPosition = position
 				viewModel.onCurrentPageChanged(position, position + 1)
 			} else {
@@ -88,26 +98,34 @@ class DoubleReaderFragment : BaseReaderFragment<FragmentReaderDoubleBinding>() {
 	)
 
 	override fun onZoomIn() {
-		(viewBinding ?: return).recyclerView.pageHolders()
+		(viewBinding ?: return).recyclerView.visiblePageHolders()
 			.forEach { it.onZoomIn() }
 	}
 
 	override fun onZoomOut() {
-		(viewBinding ?: return).recyclerView.pageHolders()
+		(viewBinding ?: return).recyclerView.visiblePageHolders()
 			.forEach { it.onZoomOut() }
 	}
 
 	override fun switchPageBy(delta: Int) {
-		switchPageTo((requireViewBinding().recyclerView.currentItem() + delta) or 1, delta.absoluteValue > 1)
+		if (delta.absoluteValue > 1 || !isAnimationEnabled()) {
+			switchPageTo(getCurrentItem() + delta + delta, false)
+			return
+		}
+		val rv = viewBinding?.recyclerView ?: return
+		val distance = rv.width * delta
+		rv.smoothScrollBy(distance, 0, AccelerateDecelerateInterpolator())
 	}
 
 	override fun switchPageTo(position: Int, smooth: Boolean) {
-		requireViewBinding().recyclerView.firstVisibleItemPosition = position or 1
+		val lm = viewBinding?.recyclerView?.layoutManager as? LinearLayoutManager ?: return
+		val targetPosition = position.toPagePosition()
+		lm.scrollToPositionWithOffset(targetPosition, 0)
 	}
 
 	override fun getCurrentState(): ReaderState? = viewBinding?.run {
 		val adapter = recyclerView.adapter as? BaseReaderAdapter<*>
-		val page = adapter?.getItemOrNull(recyclerView.currentItem()) ?: return@run null
+		val page = adapter?.getItemOrNull(getCurrentItem()) ?: return@run null
 		ReaderState(
 			chapterId = page.chapterId,
 			page = page.index,
@@ -115,16 +133,10 @@ class DoubleReaderFragment : BaseReaderFragment<FragmentReaderDoubleBinding>() {
 		)
 	}
 
-	private fun RecyclerView.currentItem(): Int {
+	private fun getCurrentItem() = (requireViewBinding().recyclerView.layoutManager as LinearLayoutManager)
-		val lm = layoutManager as LinearLayoutManager
+		.findFirstCompletelyVisibleItemPosition().toPagePosition()
-		return ((lm.findFirstVisibleItemPosition() + lm.findLastVisibleItemPosition()) / 2f).toIntUp()
-	}
 
-	private fun RecyclerView.pageHolders(): Sequence<PageHolder> {
+	private fun Int.toPagePosition() = this and 1.inv()
-		val lm = layoutManager as? LinearLayoutManager ?: return emptySequence()
-		return (lm.findFirstVisibleItemPosition()..lm.findLastVisibleItemPosition()).asSequence()
-			.mapNotNull { findViewHolderForAdapterPosition(it) as? PageHolder }
-	}
 
 	private class PageScrollListener(
 		private val viewModel: ReaderViewModel,

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/pager/doublepage/Utils.kt

@@ -0,0 +1,18 @@
+package org.koitharu.kotatsu.reader.ui.pager.doublepage
+
+import androidx.core.view.children
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import org.koitharu.kotatsu.reader.ui.pager.standard.PageHolder
+
+fun RecyclerView.visiblePageHolders(): Sequence<PageHolder> {
+	val lm = layoutManager as? LinearLayoutManager ?: return emptySequence()
+	return (lm.findFirstVisibleItemPosition()..lm.findLastVisibleItemPosition()).asSequence()
+		.mapNotNull { findViewHolderForAdapterPosition(it) as? PageHolder }
+}
+
+fun RecyclerView.allPageHolders(): Sequence<PageHolder> {
+	return children.mapNotNull {
+		findContainingViewHolder(it) as? PageHolder
+	}
+}

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/pager/standard/NoAnimPageTransformer.kt

@@ -3,13 +3,22 @@ package org.koitharu.kotatsu.reader.ui.pager.standard
 import android.view.View
 import androidx.viewpager2.widget.ViewPager2
 
-class NoAnimPageTransformer : ViewPager2.PageTransformer {
+class NoAnimPageTransformer(
+	private val orientation: Int
+) : ViewPager2.PageTransformer {
 
 	override fun transformPage(page: View, position: Float) {
 		page.translationX = when {
+			orientation != ViewPager2.ORIENTATION_HORIZONTAL -> 0f
 			position in -0.5f..0.5f -> -position * page.width.toFloat()
 			position > 0 -> page.width.toFloat()
 			else -> -page.width.toFloat()
 		}
+		page.translationY = when {
+			orientation != ViewPager2.ORIENTATION_VERTICAL -> 0f
+			position in -0.5f..0.5f -> -position * page.height.toFloat()
+			position > 0 -> page.height.toFloat()
+			else -> -page.height.toFloat()
+		}
 	}
 }

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

@@ -0,0 +1,22 @@
+<vector
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	android:width="24dp"
+	android:height="24dp"
+	android:viewportWidth="24"
+	android:viewportHeight="24">
+	<path
+		android:fillColor="#FF000000"
+		android:pathData="M4,4C2.89,4 2,4.89 2,6L2,18C2,19.11 2.89,20 4,20L9,20L9,18L8,18L6,18L4,18L4,6L6,6L8,6L9,6L9,4L4,4zM15,4L15,6L16,6L18,6L20,6L20,18L18,18L16,18L15,18L15,20L20,20C21.1,20 22,19.11 22,18L22,6C22,4.89 21.1,4 20,4L15,4z" />
+	<path
+		android:fillColor="#FF000000"
+		android:pathData="m11,21l-0,-3l2,0l-0,3z" />
+	<path
+		android:fillColor="#FF000000"
+		android:pathData="m13,3l-0,3l-2,0l-0,-3l2,0" />
+	<path
+		android:fillColor="#FF000000"
+		android:pathData="m11,16l-0,-3l2,0l-0,3l-2,0" />
+	<path
+		android:fillColor="#FF000000"
+		android:pathData="m11,11l-0,-3l2,0l-0,3l-2,0" />
+</vector>

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

@@ -119,15 +119,6 @@
 					android:text="@string/webtoon"
 					app:icon="@drawable/ic_script" />
 
-				<com.google.android.material.button.MaterialButton
-					android:id="@+id/button_double"
-					style="@style/Widget.Kotatsu.ToggleButton.Vertical"
-					android:layout_width="0dp"
-					android:layout_height="wrap_content"
-					android:layout_weight="1"
-					android:text="@string/two_pages"
-					app:icon="@drawable/ic_pager_double_ltr" />
-
 			</com.google.android.material.button.MaterialButtonToggleGroup>
 
 			<TextView
@@ -139,7 +130,7 @@
 				android:textAppearance="?attr/textAppearanceBodySmall" />
 
 			<com.google.android.material.materialswitch.MaterialSwitch
-				android:id="@+id/switch_scroll_timer"
+				android:id="@+id/switch_double_reader"
 				android:layout_width="match_parent"
 				android:layout_height="?android:listPreferredItemHeightSmall"
 				android:layout_marginTop="@dimen/margin_normal"
@@ -148,6 +139,20 @@
 				android:paddingStart="?android:listPreferredItemPaddingStart"
 				android:paddingEnd="?android:listPreferredItemPaddingEnd"
 				android:singleLine="true"
+				android:text="@string/use_two_pages_landscape"
+				android:textAppearance="?attr/textAppearanceButton"
+				android:textColor="?colorOnSurfaceVariant"
+				app:drawableStartCompat="@drawable/ic_split_horizontal" />
+
+			<com.google.android.material.materialswitch.MaterialSwitch
+				android:id="@+id/switch_scroll_timer"
+				android:layout_width="match_parent"
+				android:layout_height="?android:listPreferredItemHeightSmall"
+				android:drawablePadding="?android:listPreferredItemPaddingStart"
+				android:ellipsize="end"
+				android:paddingStart="?android:listPreferredItemPaddingStart"
+				android:paddingEnd="?android:listPreferredItemPaddingEnd"
+				android:singleLine="true"
 				android:text="@string/automatic_scroll"
 				android:textAppearance="?attr/textAppearanceButton"
 				android:textColor="?colorOnSurfaceVariant"

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

@@ -582,4 +582,5 @@
 	<string name="long_tap_action">Long tap action</string>
 	<string name="none">None</string>
 	<string name="config_reset_confirm">Reset settings to default values? This action cannot be undone.</string>
+	<string name="use_two_pages_landscape">Use two pages layout on landscape orientation (beta)</string>
 </resources>