Webtoon reader improvements

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

@@ -80,26 +80,28 @@ class WebtoonImageView @JvmOverloads constructor(
 		val parentHeight = MeasureSpec.getSize(heightMeasureSpec)
 		val resizeWidth = widthSpecMode != MeasureSpec.EXACTLY
 		val resizeHeight = heightSpecMode != MeasureSpec.EXACTLY
-		var width = parentWidth
-		var height = parentHeight
+		var desiredWidth = parentWidth
+		var desiredHeight = parentHeight
 		if (sWidth > 0 && sHeight > 0) {
 			if (resizeWidth && resizeHeight) {
-				width = sWidth
-				height = sHeight
+				desiredWidth = sWidth
+				desiredHeight = sHeight
 			} else if (resizeHeight) {
-				height = (sHeight.toDouble() / sWidth.toDouble() * width).toInt()
+				desiredHeight = (sHeight.toDouble() / sWidth.toDouble() * desiredWidth).roundToInt()
 			} else if (resizeWidth) {
-				width = (sWidth.toDouble() / sHeight.toDouble() * height).toInt()
+				desiredWidth = (sWidth.toDouble() / sHeight.toDouble() * desiredHeight).roundToInt()
 			}
 		}
-		width = width.coerceAtLeast(suggestedMinimumWidth)
-		height = height.coerceAtLeast(suggestedMinimumHeight).coerceAtMost(parentHeight())
-		setMeasuredDimension(width, height)
+		desiredWidth = desiredWidth.coerceAtLeast(suggestedMinimumWidth)
+		desiredHeight = desiredHeight.coerceAtLeast(suggestedMinimumHeight).coerceAtMost(parentHeight())
+		setMeasuredDimension(desiredWidth, desiredHeight)
 	}
 
 	override fun onDownsamplingChanged() {
 		super.onDownsamplingChanged()
-		adjustScale()
+		post {
+			adjustScale()
+		}
 	}
 
 	override fun onReady() {
@@ -107,15 +109,6 @@ class WebtoonImageView @JvmOverloads constructor(
 		adjustScale()
 	}
 
-	override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
-		super.onSizeChanged(w, h, oldw, oldh)
-		if (oldh != h && oldw != 0 && oldh != 0 && isReady) {
-			ancestors.firstNotNullOfOrNull { it as? WebtoonRecyclerView }?.updateChildrenScroll()
-		} else {
-			return
-		}
-	}
-
 	private fun scrollToInternal(pos: Int) {
 		minScale = width / sWidth.toFloat()
 		maxScale = minScale
@@ -128,6 +121,7 @@ class WebtoonImageView @JvmOverloads constructor(
 		minScale = width / sWidth.toFloat()
 		maxScale = minScale
 		minimumScaleType = SCALE_TYPE_CUSTOM
+		requestLayout()
 	}
 
 	private fun parentHeight(): Int {

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

@@ -5,9 +5,9 @@ import android.util.AttributeSet
 import android.view.View
 import androidx.core.view.ViewCompat.TYPE_TOUCH
 import androidx.core.view.forEach
-import androidx.core.view.iterator
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
+import java.util.Collections
 import java.util.LinkedList
 import java.util.WeakHashMap
 
@@ -17,12 +17,11 @@ class WebtoonRecyclerView @JvmOverloads constructor(
 
 	private var onPageScrollListeners = LinkedList<OnWebtoonScrollListener>()
 	private val scrollDispatcher = WebtoonScrollDispatcher()
-	private val detachedViews = WeakHashMap<View, Unit>()
-	private var isFixingScroll: Boolean = false
+	private val detachedViews = Collections.newSetFromMap(WeakHashMap<View, Boolean>())
 
 	override fun onChildDetachedFromWindow(child: View) {
 		super.onChildDetachedFromWindow(child)
-		detachedViews[child] = Unit
+		detachedViews.add(child)
 	}
 
 	override fun onChildAttachedToWindow(child: View) {
@@ -32,7 +31,7 @@ class WebtoonRecyclerView @JvmOverloads constructor(
 
 	override fun startNestedScroll(axes: Int) = startNestedScroll(axes, TYPE_TOUCH)
 
-	override fun startNestedScroll(axes: Int, type: Int): Boolean = true
+	override fun startNestedScroll(axes: Int, type: Int): Boolean = childCount != 0
 
 	override fun dispatchNestedPreScroll(
 		dx: Int,
@@ -57,13 +56,6 @@ class WebtoonRecyclerView @JvmOverloads constructor(
 		return consumedY != 0 || dy == 0
 	}
 
-	override fun onScrollStateChanged(state: Int) {
-		super.onScrollStateChanged(state)
-		if (state == SCROLL_STATE_IDLE) {
-			updateChildrenScroll()
-		}
-	}
-
 	private fun consumeVerticalScroll(dy: Int): Int {
 		if (childCount == 0) {
 			return 0
@@ -124,43 +116,11 @@ class WebtoonRecyclerView @JvmOverloads constructor(
 		forEach { child ->
 			(child as WebtoonFrameLayout).target.requestLayout()
 		}
-		detachedViews.keys.forEach { child ->
+		detachedViews.forEach { child ->
 			(child as WebtoonFrameLayout).target.requestLayout()
 		}
 	}
 
-	fun updateChildrenScroll() {
-		if (isFixingScroll) {
-			return
-		}
-		isFixingScroll = true
-		for (child in this) {
-			val ssiv = (child as WebtoonFrameLayout).target
-			if (adjustScroll(child, ssiv)) {
-				break
-			}
-		}
-		isFixingScroll = false
-	}
-
-	private fun adjustScroll(child: View, ssiv: WebtoonImageView): Boolean = when {
-		child.bottom < height && ssiv.getScroll() < ssiv.getScrollRange() -> {
-			val distance = minOf(height - child.bottom, ssiv.getScrollRange() - ssiv.getScroll())
-			scrollBy(0, -distance)
-			ssiv.scrollBy(distance)
-			true
-		}
-
-		child.top > 0 && ssiv.getScroll() > 0 -> {
-			val distance = minOf(child.top, ssiv.getScroll())
-			scrollBy(0, distance)
-			ssiv.scrollBy(-distance)
-			true
-		}
-
-		else -> false
-	}
-
 	private class WebtoonScrollDispatcher {
 
 		private var firstPos = NO_POSITION
@@ -178,13 +138,20 @@ class WebtoonRecyclerView @JvmOverloads constructor(
 			if (newFirstPos != firstPos || newLastPos != lastPos) {
 				firstPos = newFirstPos
 				lastPos = newLastPos
-				rv.onPageScrollListeners.forEach { it.onScrollChanged(rv, dy, newFirstPos, newLastPos) }
+				if (newFirstPos != NO_POSITION && newLastPos != NO_POSITION) {
+					rv.onPageScrollListeners.forEach { it.onScrollChanged(rv, dy, newFirstPos, newLastPos) }
+				}
 			}
 		}
 	}
 
 	interface OnWebtoonScrollListener {
 
-		fun onScrollChanged(recyclerView: WebtoonRecyclerView, dy: Int, firstVisiblePosition: Int, lastVisiblePosition: Int)
+		fun onScrollChanged(
+			recyclerView: WebtoonRecyclerView,
+			dy: Int,
+			firstVisiblePosition: Int,
+			lastVisiblePosition: Int,
+		)
 	}
 }