From 4aa8f5a201bb9649b6348c311d049a0e5da39dc6 Mon Sep 17 00:00:00 2001
From: Cuong-Tran <cuongtran.tm@gmail.com>
Date: Mon, 15 Sep 2025 11:45:32 +0700
Subject: [PATCH] fix(webtoon-scale): Improve webtoon scale type handling &
 listener (#1150)

* fix(webtoon): improve webtoon scale type handling and listener invocation

* fix(webtoon): streamline webtoon scale type handling and improve listener invocation

* add retry

* qualifier

* remove listener on destroy to avoid memory leaks

* using an object expression for the listener

* ensure listener is removed only if viewTreeObserver is alive

* refactor layout listener to improve retry logic and ensure proper removal

* using doOnLayout

* use doOnLayout for scaling logic to ensure proper execution after view is laid out
---
 .../ui/reader/viewer/webtoon/WebtoonViewer.kt | 36 ++++++++++---------
 1 file changed, 19 insertions(+), 17 deletions(-)

diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt
index c0154e68f..835749f09 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt
@@ -9,6 +9,7 @@ import android.view.ViewGroup.LayoutParams.MATCH_PARENT
 import android.view.animation.LinearInterpolator
 import androidx.annotation.ColorInt
 import androidx.core.app.ActivityCompat
+import androidx.core.view.doOnLayout
 import androidx.core.view.isGone
 import androidx.core.view.isVisible
 import androidx.recyclerview.widget.RecyclerView
@@ -21,7 +22,6 @@ import eu.kanade.tachiyomi.ui.reader.model.ViewerChapters
 import eu.kanade.tachiyomi.ui.reader.setting.ReaderPreferences
 import eu.kanade.tachiyomi.ui.reader.viewer.Viewer
 import eu.kanade.tachiyomi.ui.reader.viewer.ViewerNavigation.NavigationRegion
-import exh.util.nullIfZero
 import kotlinx.coroutines.MainScope
 import kotlinx.coroutines.cancel
 import tachiyomi.core.common.util.system.logcat
@@ -40,7 +40,7 @@ class WebtoonViewer(
     val isContinuous: Boolean = true,
     private val tapByPage: Boolean = false,
     // KMK -->
-    @ColorInt private val seedColor: Int? = null,
+    @param:ColorInt private val seedColor: Int? = null,
     private val readerPreferences: ReaderPreferences = Injekt.get(),
     // KMK <--
 ) : Viewer {
@@ -182,24 +182,26 @@ class WebtoonViewer(
             if (!isContinuous && !readerPreferences.longStripGapSmartScale().get()) return@f
 
             recycler.post {
-                if (scaleType == ReaderPreferences.WebtoonScaleType.FIT) {
-                    recycler.scaleTo(1f)
-                    return@post
-                }
+                recycler.doOnLayout doOnLayout@{
+                    val currentWidth = recycler.width
+                    val currentHeight = recycler.originalHeight
+                    if (currentWidth <= 0 || currentHeight <= 0) return@doOnLayout
 
-                // Call `scaleTo` after the view is loaded and visible
-                val currentWidth = recycler.width.takeIf { it > 0 } ?: activity.window.decorView.width.nullIfZero() ?: return@post
-                val currentHeight = recycler.originalHeight.takeIf { it > 0 } ?: activity.window.decorView.height.nullIfZero() ?: return@post
+                    if (scaleType == ReaderPreferences.WebtoonScaleType.FIT) {
+                        recycler.scaleTo(1f)
+                        return@doOnLayout
+                    }
 
-                val desiredRatio = scaleType.ratio
-                val screenRatio = currentWidth.toFloat() / currentHeight
-                val desiredWidth = currentHeight * desiredRatio
-                val desiredScale = desiredWidth / currentWidth
+                    val desiredRatio = scaleType.ratio
+                    val screenRatio = currentWidth.toFloat() / currentHeight
+                    val desiredWidth = currentHeight * desiredRatio
+                    val desiredScale = desiredWidth / currentWidth
 
-                if (screenRatio > desiredRatio) {
-                    recycler.scaleTo(desiredScale)
-                } else {
-                    recycler.scaleTo(1f)
+                    if (screenRatio > desiredRatio) {
+                        recycler.scaleTo(desiredScale)
+                    } else {
+                        recycler.scaleTo(1f)
+                    }
                 }
             }
         }