feat: Add Pull Gesture Navigate Chapter

.idea/appInsightsSettings.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="AppInsightsSettings">
+    <option name="tabSettings">
+      <map>
+        <entry key="Firebase Crashlytics">
+          <value>
+            <InsightsFilterSettings>
+              <option name="connection">
+                <ConnectionSetting>
+                  <option name="appId" value="PLACEHOLDER" />
+                  <option name="mobileSdkAppId" value="" />
+                  <option name="projectId" value="" />
+                  <option name="projectNumber" value="" />
+                </ConnectionSetting>
+              </option>
+              <option name="signal" value="SIGNAL_UNSPECIFIED" />
+              <option name="timeIntervalDays" value="THIRTY_DAYS" />
+              <option name="visibilityType" value="ALL" />
+            </InsightsFilterSettings>
+          </value>
+        </entry>
+      </map>
+    </option>
+  </component>
+</project>

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

@@ -488,6 +488,10 @@ class AppSettings @Inject constructor(@ApplicationContext context: Context) {
 		get() = prefs.getBoolean(KEY_WEBTOON_GAPS, false)
 		set(value) = prefs.edit { putBoolean(KEY_WEBTOON_GAPS, value) }
 
+	var isWebtoonPullGestureEnabled: Boolean
+		get() = prefs.getBoolean(KEY_WEBTOON_PULL_GESTURE, false)
+		set(value) = prefs.edit { putBoolean(KEY_WEBTOON_PULL_GESTURE, value) }
+
 	@get:FloatRange(from = 0.0, to = 0.5)
 	val defaultWebtoonZoomOut: Float
 		get() = prefs.getInt(KEY_WEBTOON_ZOOM_OUT, 0).coerceIn(0, 50) / 100f
@@ -748,6 +752,7 @@ class AppSettings @Inject constructor(@ApplicationContext context: Context) {
 		const val KEY_WEBTOON_GAPS = "webtoon_gaps"
 		const val KEY_WEBTOON_ZOOM = "webtoon_zoom"
 		const val KEY_WEBTOON_ZOOM_OUT = "webtoon_zoom_out"
+		const val KEY_WEBTOON_PULL_GESTURE = "webtoon_pull_gesture"
 		const val KEY_PREFETCH_CONTENT = "prefetch_content"
 		const val KEY_APP_LOCALE = "app_locale"
 		const val KEY_SOURCES_GRID = "sources_grid"

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

@@ -157,6 +157,12 @@ class ReaderViewModel @Inject constructor(
 		valueProducer = { isWebtoonGapsEnabled },
 	)
 
+	val isWebtoonPullGestureEnabled = settings.observeAsStateFlow(
+		scope = viewModelScope + Dispatchers.Default,
+		key = AppSettings.KEY_WEBTOON_PULL_GESTURE,
+		valueProducer = { isWebtoonPullGestureEnabled },
+	)
+
 	val defaultWebtoonZoomOut = observeIsWebtoonZoomEnabled().flatMapLatest {
 		if (it) {
 			observeWebtoonZoomOut()
@@ -345,11 +351,14 @@ class ReaderViewModel @Inject constructor(
 				return@launchJob
 			}
 			ensureActive()
-			if (upperPos >= pages.lastIndex - BOUNDS_PAGE_OFFSET) {
-				loadPrevNextChapter(pages.last().chapterId, isNext = true)
-			}
-			if (lowerPos <= BOUNDS_PAGE_OFFSET) {
-				loadPrevNextChapter(pages.first().chapterId, isNext = false)
+			val autoLoadAllowed = readerMode.value != ReaderMode.WEBTOON || !isWebtoonPullGestureEnabled.value
+			if (autoLoadAllowed) {
+				if (upperPos >= pages.lastIndex - BOUNDS_PAGE_OFFSET) {
+					loadPrevNextChapter(pages.last().chapterId, isNext = true)
+				}
+				if (lowerPos <= BOUNDS_PAGE_OFFSET) {
+					loadPrevNextChapter(pages.first().chapterId, isNext = false)
+				}
 			}
 			if (pageLoader.isPrefetchApplicable()) {
 				pageLoader.prefetch(pages.trySublist(upperPos + 1, upperPos + PREFETCH_LIMIT))

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

@@ -86,6 +86,8 @@ class ReaderConfigSheet :
 		binding.buttonVertical.isChecked = mode == ReaderMode.VERTICAL
 		binding.switchDoubleReader.isChecked = settings.isReaderDoubleOnLandscape
 		binding.switchDoubleReader.isEnabled = mode == ReaderMode.STANDARD || mode == ReaderMode.REVERSED
+		binding.switchPullGesture.isChecked = settings.isWebtoonPullGestureEnabled
+		binding.switchPullGesture.isEnabled = mode == ReaderMode.WEBTOON
 
 		binding.checkableGroup.addOnButtonCheckedListener(this)
 		binding.buttonSavePage.setOnClickListener(this)
@@ -96,6 +98,7 @@ class ReaderConfigSheet :
 		binding.buttonScrollTimer.setOnClickListener(this)
 		binding.buttonBookmark.setOnClickListener(this)
 		binding.switchDoubleReader.setOnCheckedChangeListener(this)
+		binding.switchPullGesture.setOnCheckedChangeListener(this)
 
 		viewModel.isBookmarkAdded.observe(viewLifecycleOwner) {
 			binding.buttonBookmark.setText(if (it) R.string.bookmark_remove else R.string.bookmark_add)
@@ -172,6 +175,10 @@ class ReaderConfigSheet :
 				settings.isReaderDoubleOnLandscape = isChecked
 				findParentCallback(Callback::class.java)?.onDoubleModeChanged(isChecked)
 			}
+
+			R.id.switch_pull_gesture -> {
+				settings.isWebtoonPullGestureEnabled = isChecked
+			}
 		}
 	}
 
@@ -191,6 +198,7 @@ class ReaderConfigSheet :
 			else -> return
 		}
 		viewBinding?.switchDoubleReader?.isEnabled = newMode == ReaderMode.STANDARD || newMode == ReaderMode.REVERSED
+		viewBinding?.switchPullGesture?.isEnabled = newMode == ReaderMode.WEBTOON
 		if (newMode == mode) {
 			return
 		}

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

@@ -4,6 +4,7 @@ import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.ViewGroup
 import android.view.animation.DecelerateInterpolator
+import android.widget.TextView
 import androidx.recyclerview.widget.RecyclerView
 import com.google.android.material.snackbar.Snackbar
 import dagger.hilt.android.AndroidEntryPoint
@@ -46,6 +47,8 @@ class WebtoonReaderFragment : BaseReaderFragment<FragmentReaderWebtoonBinding>()
 
 	override fun onViewBindingCreated(binding: FragmentReaderWebtoonBinding, savedInstanceState: Bundle?) {
 		super.onViewBindingCreated(binding, savedInstanceState)
+		var canGoPrev = true
+		var canGoNext = true
 		with(binding.recyclerView) {
 			setHasFixedSize(true)
 			adapter = readerAdapter
@@ -53,6 +56,40 @@ class WebtoonReaderFragment : BaseReaderFragment<FragmentReaderWebtoonBinding>()
 			recyclerLifecycleDispatcher = RecyclerViewLifecycleDispatcher().also {
 				addOnScrollListener(it)
 			}
+			setOnPullGestureListener(object : WebtoonRecyclerView.OnPullGestureListener {
+				override fun onPullProgressTop(progress: Float) {
+					if (canGoPrev) {
+						binding.feedbackTop.setText(R.string.pull_to_prev_chapter)
+					} else {
+						binding.feedbackTop.setText(R.string.pull_top_no_prev)
+					}
+					updateFeedback(binding.feedbackTop, progress)
+				}
+				override fun onPullProgressBottom(progress: Float) {
+					if (canGoNext) {
+						binding.feedbackBottom.setText(R.string.pull_to_next_chapter)
+					} else {
+						binding.feedbackBottom.setText(R.string.pull_bottom_no_next)
+					}
+					updateFeedback(binding.feedbackBottom, progress)
+				}
+				override fun onPullTriggeredTop() {
+					fadeOut(binding.feedbackTop)
+					if (canGoPrev) {
+						viewModel.switchChapterBy(-1)
+					}
+				}
+				override fun onPullTriggeredBottom() {
+					fadeOut(binding.feedbackBottom)
+					if (canGoNext) {
+						viewModel.switchChapterBy(1)
+					}
+				}
+				override fun onPullCancelled() {
+					fadeOut(binding.feedbackTop)
+					fadeOut(binding.feedbackBottom)
+				}
+			})
 		}
 		viewModel.isWebtoonZooEnabled.observe(viewLifecycleOwner) {
 			binding.frame.isZoomEnable = it
@@ -70,6 +107,21 @@ class WebtoonReaderFragment : BaseReaderFragment<FragmentReaderWebtoonBinding>()
 		viewModel.readerSettingsProducer.observe(viewLifecycleOwner) {
 			it.applyBackground(binding.root)
 		}
+		viewModel.readerMode.observe(viewLifecycleOwner) { mode ->
+			binding.recyclerView.isPullGestureEnabled = (mode == org.koitharu.kotatsu.core.prefs.ReaderMode.WEBTOON) && viewModel.isWebtoonPullGestureEnabled.value
+		}
+		viewModel.isWebtoonPullGestureEnabled.observe(viewLifecycleOwner) { enabled ->
+			binding.recyclerView.isPullGestureEnabled = (viewModel.readerMode.value == org.koitharu.kotatsu.core.prefs.ReaderMode.WEBTOON) && enabled
+		}
+		viewModel.uiState.observe(viewLifecycleOwner) { state ->
+			if (state != null) {
+				canGoPrev = state.chapterIndex > 0
+				canGoNext = state.chapterIndex < state.chaptersTotal - 1
+			} else {
+				canGoPrev = true
+				canGoNext = true
+			}
+		}
 	}
 
 	override fun onDestroyView() {
@@ -178,3 +230,14 @@ class WebtoonReaderFragment : BaseReaderFragment<FragmentReaderWebtoonBinding>()
 		return getChildAdapterPosition(view)
 	}
 }
+
+private fun updateFeedback(tv: TextView, progress: Float) {
+	val clamped = progress.coerceIn(0f, 1.2f)
+	tv.alpha = clamped.coerceAtMost(1f)
+	tv.scaleX = 0.9f + 0.1f * clamped.coerceAtMost(1f)
+	tv.scaleY = tv.scaleX
+}
+
+private fun fadeOut(tv: TextView) {
+	tv.animate().alpha(0f).setDuration(150L).start()
+}

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

@@ -1,8 +1,10 @@
 package org.koitharu.kotatsu.reader.ui.pager.webtoon
 
 import android.content.Context
+import android.graphics.Canvas
 import android.util.AttributeSet
 import android.view.View
+import android.widget.EdgeEffect
 import androidx.core.view.ViewCompat.TYPE_TOUCH
 import androidx.core.view.forEach
 import androidx.core.view.isEmpty
@@ -23,6 +25,71 @@ class WebtoonRecyclerView @JvmOverloads constructor(
 	private val detachedViews = Collections.newSetFromMap(WeakHashMap<View, Boolean>())
 	private var isFixingScroll = false
 
+	var isPullGestureEnabled: Boolean = false
+	var pullThreshold: Float = 0.3f
+	private var pullProgressTop: Float = 0f
+	private var pullProgressBottom: Float = 0f
+	private var pullListener: OnPullGestureListener? = null
+
+	init {
+		setEdgeEffectFactory(object : EdgeEffectFactory() {
+			override fun createEdgeEffect(view: RecyclerView, direction: Int): EdgeEffect {
+				return object : EdgeEffect(view.context) {
+					override fun onPull(deltaDistance: Float) {
+						val sign = if (direction == DIRECTION_TOP) 1f else if (direction == DIRECTION_BOTTOM) 1f else 0f
+						if (sign != 0f) onPull(deltaDistance, 0.5f)
+					}
+
+					override fun onPull(deltaDistance: Float, displacement: Float) {
+						if (!isPullGestureEnabled) return
+						if (direction == DIRECTION_TOP) {
+							pullProgressTop = (pullProgressTop + deltaDistance).coerceAtLeast(0f)
+							pullListener?.onPullProgressTop(pullProgressTop / pullThreshold)
+						} else if (direction == DIRECTION_BOTTOM) {
+							pullProgressBottom = (pullProgressBottom + deltaDistance).coerceAtLeast(0f)
+							pullListener?.onPullProgressBottom(pullProgressBottom / pullThreshold)
+						}
+					}
+
+					override fun onRelease() {
+						if (!isPullGestureEnabled) {
+							pullProgressTop = 0f
+							pullProgressBottom = 0f
+							return
+						}
+						var triggered = false
+						if (direction == DIRECTION_TOP) {
+							if (pullProgressTop >= pullThreshold) {
+								pullListener?.onPullTriggeredTop()
+								triggered = true
+							}
+							pullProgressTop = 0f
+							pullListener?.onPullProgressTop(0f)
+						} else if (direction == DIRECTION_BOTTOM) {
+							if (pullProgressBottom >= pullThreshold) {
+								pullListener?.onPullTriggeredBottom()
+								triggered = true
+							}
+							pullProgressBottom = 0f
+							pullListener?.onPullProgressBottom(0f)
+						}
+						if (!triggered) {
+							pullListener?.onPullCancelled()
+						}
+					}
+
+					override fun draw(canvas: Canvas?): Boolean {
+						return false
+					}
+				}
+			}
+		})
+	}
+
+	fun setOnPullGestureListener(listener: OnPullGestureListener?) {
+		pullListener = listener
+	}
+
 	override fun onChildDetachedFromWindow(child: View) {
 		super.onChildDetachedFromWindow(child)
 		detachedViews.add(child)
@@ -188,4 +255,12 @@ class WebtoonRecyclerView @JvmOverloads constructor(
 			lastVisiblePosition: Int,
 		)
 	}
+
+	interface OnPullGestureListener {
+		fun onPullProgressTop(progress: Float)
+		fun onPullProgressBottom(progress: Float)
+		fun onPullTriggeredTop()
+		fun onPullTriggeredBottom()
+		fun onPullCancelled()
+	}
 }

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

@@ -0,0 +1,18 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:tint="?attr/colorControlNormal"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:pathData="M12,2A10,10 0 1,0 22,12A10,10 0 0,0 12,2Z"
+        android:strokeColor="@android:color/white"
+        android:strokeWidth="2"
+        android:fillColor="@android:color/transparent"/>
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M12,7l-3,3h2v4h2v-4h2z"/>
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M12,17l3,-3h-2v-4h-2v4h-2z"/>
+</vector>

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

@@ -16,4 +16,30 @@
 		android:orientation="vertical"
 		app:layoutManager="org.koitharu.kotatsu.reader.ui.pager.webtoon.WebtoonLayoutManager" />
 
+	<org.koitharu.kotatsu.reader.ui.ReaderToastView
+		android:id="@+id/feedbackTop"
+		android:layout_width="match_parent"
+		android:layout_height="wrap_content"
+		android:layout_gravity="top"
+		android:gravity="center"
+		android:padding="16dp"
+		android:alpha="0"
+		android:text="@string/pull_to_prev_chapter"
+		android:textAppearance="?textAppearanceBodyLarge"
+		android:background="@drawable/bg_reader_indicator"
+		android:theme="@style/ThemeOverlay.Material3.Dark" />
+
+	<org.koitharu.kotatsu.reader.ui.ReaderToastView
+		android:id="@+id/feedbackBottom"
+		android:layout_width="match_parent"
+		android:layout_height="wrap_content"
+		android:layout_gravity="bottom"
+		android:gravity="center"
+		android:padding="16dp"
+		android:alpha="0"
+		android:text="@string/pull_to_next_chapter"
+		android:textAppearance="?textAppearanceBodyLarge"
+		android:background="@drawable/bg_reader_indicator"
+		android:theme="@style/ThemeOverlay.Material3.Dark" />
+
 </org.koitharu.kotatsu.reader.ui.pager.webtoon.WebtoonScalingFrame>

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

@@ -129,6 +129,20 @@
 				android:textColor="?colorOnSurfaceVariant"
 				app:drawableStartCompat="@drawable/ic_split_horizontal" />
 
+			<com.google.android.material.materialswitch.MaterialSwitch
+				android:id="@+id/switch_pull_gesture"
+				android:layout_width="match_parent"
+				android:layout_height="wrap_content"
+				android:layout_marginTop="@dimen/margin_small"
+				android:drawablePadding="?android:listPreferredItemPaddingStart"
+				android:minHeight="?android:listPreferredItemHeightSmall"
+				android:paddingStart="?android:listPreferredItemPaddingStart"
+				android:paddingEnd="?android:listPreferredItemPaddingEnd"
+				android:text="@string/enable_pull_gesture_title"
+				android:textAppearance="?textAppearanceListItem"
+				android:textColor="?colorOnSurfaceVariant"
+				app:drawableStartCompat="@drawable/ic_gesture" />
+
 			<org.koitharu.kotatsu.core.ui.widgets.ListItemTextView
 				android:id="@+id/button_screen_rotate"
 				android:layout_width="match_parent"

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

@@ -427,6 +427,10 @@
 	<string name="data_and_privacy">Data and privacy</string>
 	<string name="restore_summary">Restore previously created backup</string>
 	<string name="webtoon_zoom_summary">Allow zoom in gesture in webtoon mode</string>
+	<string name="pull_to_prev_chapter">Release to open previous chapter</string>
+	<string name="pull_to_next_chapter">Release to open next chapter</string>
+	<string name="pull_top_no_prev">No previous chapter</string>
+	<string name="pull_bottom_no_next">No next chapter</string>
 	<string name="reader_info_bar_summary">Show the current time and reading progress at the top of the screen</string>
 	<string name="show_pages_numbers_summary">Show page numbers in bottom corner</string>
 	<string name="clear_source_cookies_summary">Clear cookies for specified domain only. In most cases will invalidate authorization</string>
@@ -644,6 +648,8 @@
 	<string name="show_updated">Show updated</string>
 	<string name="webtoon_gaps">Gaps in webtoon mode</string>
 	<string name="webtoon_gaps_summary">Show vertical gaps between pages in webtoon mode</string>
+	<string name="enable_pull_gesture_title">Enable pull gesture</string>
+	<string name="enable_pull_gesture_summary">Use pull gesture to switch chapters in webtoon</string>
 	<string name="less_frequently">Less frequently</string>
 	<string name="more_frequently">More frequently</string>
 	<string name="frequency_of_check">Frequency of check</string>