Zoom control buttons in reader

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

@@ -120,6 +120,12 @@ class ReaderViewModel @Inject constructor(
 		valueProducer = { isWebtoonZoomEnable },
 	)
 
+	val isZoomControlEnabled = settings.observeAsStateFlow(
+		scope = viewModelScope + Dispatchers.Default,
+		key = AppSettings.KEY_READER_ZOOM_BUTTONS,
+		valueProducer = { isReaderZoomButtonsEnabled },
+	)
+
 	val readerSettings = ReaderSettings(
 		parentScope = viewModelScope,
 		settings = settings,

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

@@ -32,6 +32,9 @@ class ReaderSettings(
 	val isPagesNumbersEnabled: Boolean
 		get() = settings.isPagesNumbersEnabled
 
+	val isZoomControlsEnabled: Boolean
+		get() = settings.isReaderZoomButtonsEnabled
+
 	fun applyBackground(view: View) {
 		val bg = settings.readerBackground
 		view.background = bg.resolve(view.context)
@@ -74,6 +77,7 @@ class ReaderSettings(
 				key == AppSettings.KEY_ZOOM_MODE ||
 				key == AppSettings.KEY_PAGES_NUMBERS ||
 				key == AppSettings.KEY_WEBTOON_ZOOM ||
+				key == AppSettings.KEY_READER_ZOOM_BUTTONS ||
 				key == AppSettings.KEY_READER_BACKGROUND
 			) {
 				notifyChanged()

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

@@ -13,7 +13,7 @@ import org.koitharu.kotatsu.reader.ui.config.ReaderSettings
 abstract class BasePageHolder<B : ViewBinding>(
 	protected val binding: B,
 	loader: PageLoader,
-	private val settings: ReaderSettings,
+	protected val settings: ReaderSettings,
 	networkState: NetworkState,
 	exceptionResolver: ExceptionResolver,
 ) : RecyclerView.ViewHolder(binding.root), PageHolderDelegate.Callback {

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

@@ -40,6 +40,12 @@ open class PageHolder(
 		@Suppress("LeakingThis")
 		bindingInfo.buttonErrorDetails.setOnClickListener(this)
 		binding.textViewNumber.isVisible = settings.isPagesNumbersEnabled
+		binding.zoomControl.listener = SsivZoomListener(binding.ssiv)
+	}
+
+	override fun onConfigChanged() {
+		super.onConfigChanged()
+		binding.zoomControl.isVisible = settings.isZoomControlsEnabled
 	}
 
 	@SuppressLint("SetTextI18n")

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

@@ -0,0 +1,28 @@
+package org.koitharu.kotatsu.reader.ui.pager.standard
+
+import android.view.animation.DecelerateInterpolator
+import com.davemorrissey.labs.subscaleview.SubsamplingScaleImageView
+import org.koitharu.kotatsu.core.ui.widgets.ZoomControl
+
+class SsivZoomListener(
+	private val ssiv: SubsamplingScaleImageView,
+) : ZoomControl.ZoomControlListener {
+
+	override fun onZoomIn() {
+		scaleBy(1.2f)
+	}
+
+	override fun onZoomOut() {
+		scaleBy(0.8f)
+	}
+
+	private fun scaleBy(factor: Float) {
+		val center = ssiv.getCenter() ?: return
+		val newScale = ssiv.scale * factor
+		ssiv.animateScaleAndCenter(newScale, center)?.apply {
+			withDuration(ssiv.resources.getInteger(android.R.integer.config_shortAnimTime).toLong())
+			withInterpolator(DecelerateInterpolator())
+			start()
+		}
+	}
+}

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 androidx.core.view.isVisible
 import com.google.android.material.snackbar.Snackbar
 import dagger.hilt.android.AndroidEntryPoint
 import kotlinx.coroutines.async
@@ -45,10 +46,14 @@ class WebtoonReaderFragment : BaseReaderFragment<FragmentReaderWebtoonBinding>()
 			adapter = readerAdapter
 			addOnPageScrollListener(PageScrollListener())
 		}
+		binding.zoomControl.listener = binding.frame
 
 		viewModel.isWebtoonZoomEnabled.observe(viewLifecycleOwner) {
 			binding.frame.isZoomEnable = it
 		}
+		viewModel.isZoomControlEnabled.observe(viewLifecycleOwner) {
+			binding.zoomControl.isVisible = it
+		}
 	}
 
 	override fun onDestroyView() {

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

@@ -18,6 +18,7 @@ import android.widget.FrameLayout
 import android.widget.OverScroller
 import androidx.core.view.GestureDetectorCompat
 import androidx.core.view.ViewConfigurationCompat
+import org.koitharu.kotatsu.core.ui.widgets.ZoomControl
 import org.koitharu.kotatsu.core.util.ext.getAnimationDuration
 
 private const val MAX_SCALE = 2.5f
@@ -27,7 +28,9 @@ class WebtoonScalingFrame @JvmOverloads constructor(
 	context: Context,
 	attrs: AttributeSet? = null,
 	defStyles: Int = 0,
-) : FrameLayout(context, attrs, defStyles), ScaleGestureDetector.OnScaleGestureListener {
+) : FrameLayout(context, attrs, defStyles),
+	ScaleGestureDetector.OnScaleGestureListener,
+	ZoomControl.ZoomControlListener {
 
 	private val targetChild by lazy(LazyThreadSafetyMode.NONE) { getChildAt(0) as WebtoonRecyclerView }
 
@@ -110,14 +113,14 @@ class WebtoonScalingFrame @JvmOverloads constructor(
 			KeyEvent.KEYCODE_ZOOM_IN,
 			KeyEvent.KEYCODE_NUMPAD_ADD,
 			KeyEvent.KEYCODE_PLUS -> {
-				smoothScaleTo(scale * 1.1f)
+				onZoomIn()
 				true
 			}
 
 			KeyEvent.KEYCODE_ZOOM_OUT,
 			KeyEvent.KEYCODE_NUMPAD_SUBTRACT,
 			KeyEvent.KEYCODE_MINUS -> {
-				smoothScaleTo(scale * 0.9f)
+				onZoomOut()
 				true
 			}
 
@@ -151,6 +154,14 @@ class WebtoonScalingFrame @JvmOverloads constructor(
 		halfHeight = h / 2f
 	}
 
+	override fun onZoomIn() {
+		smoothScaleTo(scale * 1.1f)
+	}
+
+	override fun onZoomOut() {
+		smoothScaleTo(scale * 0.9f)
+	}
+
 	private fun invalidateTarget() {
 		adjustBounds()
 		targetChild.run {