[android] layout mode transition issues (corruption/gamepad navigation) fixed (#3212)

fellow mike22 pointed out some vulnerabilities related to layout mode transitions. let us give it a go! Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3212 Reviewed-by: Lizzie <lizzie@eden-emu.dev> Reviewed-by: DraVee <dravee@eden-emu.dev> Co-authored-by: xbzk <xbzk@eden-emu.dev> Co-committed-by: xbzk <xbzk@eden-emu.dev>
3 days ago · d76edfc683
2 changed files with 77 additions and 33 deletions
--- a/src/android/app/src/main/java/org/yuzu/yuzu_emu/ui/GamesFragment.kt
+++ b/src/android/app/src/main/java/org/yuzu/yuzu_emu/ui/GamesFragment.kt
@ -186,6 +186,10 @@ class GamesFragment : Fragment() {
            val currentViewType = getCurrentViewType()
            val savedViewType = if (isLandscape || currentViewType != GameAdapter.VIEW_TYPE_CAROUSEL) currentViewType else GameAdapter.VIEW_TYPE_GRID

+            //This prevents Grid/List views from reusing scaled or otherwise modified ViewHolders left over from the carousel.
+            adapter = null
+            recycledViewPool.clear()
+
            gameAdapter.setViewType(savedViewType)
            currentFilter = preferences.getInt(PREF_SORT_TYPE, View.NO_ID)

--- a/src/android/app/src/main/java/org/yuzu/yuzu_emu/views/CarouselRecyclerView.kt
+++ b/src/android/app/src/main/java/org/yuzu/yuzu_emu/views/CarouselRecyclerView.kt
@ -1,9 +1,6 @@
 // SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later

-// SPDX-FileCopyrightText: 2023 yuzu Emulator Project
-// SPDX-License-Identifier: GPL-2.0-or-later
-
 package org.yuzu.yuzu_emu.ui

 import android.content.Context
@ -55,6 +52,24 @@ class CarouselRecyclerView @JvmOverloads constructor(
    private val preferences =
        PreferenceManager.getDefaultSharedPreferences(YuzuApplication.appContext)

+    private val carouselAdapterObserver = object : RecyclerView.AdapterDataObserver() {
+        override fun onChanged() {
+            if (!pendingScrollAfterReload) return
+                doOnNextLayout {
+                    refreshView()
+                    pendingScrollAfterReload = false
+                }
+            }
+        }
+
+    private val isCarouselMode: Boolean
+        get() {
+            val lm = layoutManager as? LinearLayoutManager
+            return lm != null &&
+               lm.orientation == RecyclerView.HORIZONTAL &&
+               lm !is androidx.recyclerview.widget.GridLayoutManager
+    }
+
    var flingMultiplier: Float = 1f

    var pendingScrollAfterReload: Boolean = false
@ -70,6 +85,18 @@ class CarouselRecyclerView @JvmOverloads constructor(
        setChildrenDrawingOrderEnabled(true)
    }

+    override fun setAdapter(adapter: Adapter<*>?) {
+        val oldAdapter = this.adapter as? GameAdapter
+
+        if (oldAdapter !== adapter) {
+            oldAdapter?.unregisterAdapterDataObserver(carouselAdapterObserver)
+        }
+
+        super.setAdapter(adapter)
+
+        (adapter as? GameAdapter)?.registerAdapterDataObserver(carouselAdapterObserver)
+    }
+
    private fun calculateCenter(width: Int, paddingStart: Int, paddingEnd: Int): Int {
        return paddingStart + (width - paddingStart - paddingEnd) / 2
    }
@ -79,14 +106,14 @@ class CarouselRecyclerView @JvmOverloads constructor(
    }

    private fun getLayoutManagerCenter(layoutManager: RecyclerView.LayoutManager): Int {
-        return if (layoutManager is LinearLayoutManager) {
-            calculateCenter(
+        if (isCarouselMode) {
+            return calculateCenter(
                layoutManager.width,
                layoutManager.paddingStart,
                layoutManager.paddingEnd
            )
        } else {
-            width / 2
+            return width / 2
        }
    }

@ -95,6 +122,8 @@ class CarouselRecyclerView @JvmOverloads constructor(
    }

    fun restoreScrollState(position: Int = 0, attempts: Int = 0) {
+        if (!isCarouselMode) return
+
        val lm = layoutManager as? LinearLayoutManager ?: return
        if (lm.findLastVisibleItemPosition() == RecyclerView.NO_POSITION && attempts < 10) {
            post { restoreScrollState(position, attempts + 1) }
@ -104,6 +133,10 @@ class CarouselRecyclerView @JvmOverloads constructor(
    }

    fun getClosestChildPosition(fullRange: Boolean = false): Int {
+        if (!isCarouselMode) {
+            return RecyclerView.NO_POSITION
+        }
+
        val lm = layoutManager as? LinearLayoutManager ?: return RecyclerView.NO_POSITION
        var minDistance = Int.MAX_VALUE
        var closestPosition = RecyclerView.NO_POSITION
@ -203,15 +236,22 @@ class CarouselRecyclerView @JvmOverloads constructor(
    }

    fun refreshView() {
-        updateChildScalesAndAlpha()
-        focusCenteredCard()
+        if (isCarouselMode) {
+            updateChildScalesAndAlpha()
+            focusCenteredCard()
+        }
    }

    fun notifyInsetsReady(newBottomInset: Int) {
        if (bottomInset != newBottomInset) {
            bottomInset = newBottomInset
        }
-        setupCarousel(true)
+
+        if (isCarouselMode) {
+            setupCarousel(true)
+        } else {
+            setupCarousel(false)
+        }
    }

    fun notifyLaidOut(fallBackBottomInset: Int) {
@ -221,7 +261,10 @@ class CarouselRecyclerView @JvmOverloads constructor(
        if (gameAdapter.cardSize != newCardSize) {
            gameAdapter.setCardSize(newCardSize)
        }
-        setupCarousel(true)
+
+        if (isCarouselMode) {
+            setupCarousel(true)
+        }
    }

    fun cardSize(bottomInset: Int): Int {
@ -252,17 +295,6 @@ class CarouselRecyclerView @JvmOverloads constructor(
                internalFlingMultiplier
            ).coerceIn(1f, 5f)

-            gameAdapter .registerAdapterDataObserver(object : RecyclerView.AdapterDataObserver() {
-                override fun onChanged() {
-                    if (pendingScrollAfterReload) {
-                        doOnNextLayout {
-                            refreshView()
-                            pendingScrollAfterReload = false
-                        }
-                    }
-                }
-            })
-
            // Detach SnapHelper during setup
            pagerSnapHelper?.attachToRecyclerView(null)

@ -321,22 +353,27 @@ class CarouselRecyclerView @JvmOverloads constructor(

    override fun onScrollStateChanged(state: Int) {
        super.onScrollStateChanged(state)
-        if (state == RecyclerView.SCROLL_STATE_IDLE) {
+        if (state == RecyclerView.SCROLL_STATE_IDLE && isCarouselMode) {
            focusCenteredCard()
        }
    }

    override fun scrollToPosition(position: Int) {
+        if (isCarouselMode) {
+            (layoutManager as? LinearLayoutManager)?.scrollToPositionWithOffset(position, overlapPx)
+            doOnNextLayout {
+                refreshView()
+            }
+        } else {
        super.scrollToPosition(position)
-        (layoutManager as? LinearLayoutManager)?.scrollToPositionWithOffset(position, overlapPx)
-        doOnNextLayout {
-            refreshView()
        }
    }

    private var lastFocusSearchTime: Long = 0
    override fun focusSearch(focused: View, direction: Int): View? {
-        if (layoutManager !is LinearLayoutManager) return super.focusSearch(focused, direction)
+        if (!isCarouselMode) {
+            return super.focusSearch(focused, direction)
+        }
        val vh = findContainingViewHolder(focused) ?: return super.focusSearch(focused, direction)
        val itemCount = adapter?.itemCount ?: return super.focusSearch(focused, direction)
        val position = vh.bindingAdapterPosition
@ -371,6 +408,8 @@ class CarouselRecyclerView @JvmOverloads constructor(
                    focused
                }
            }
+            // Prevent focus from escaping to external UI elements when forced snapping was removed
+            View.FOCUS_DOWN -> focused
            else -> super.focusSearch(focused, direction)
        }
    }
@ -434,7 +473,7 @@ class CarouselRecyclerView @JvmOverloads constructor(

        // NEEDED: fixes center snapping, but introduces ghost movement
        override fun findSnapView(layoutManager: RecyclerView.LayoutManager): View? {
-            if (layoutManager !is LinearLayoutManager) return null
+            if (!isCarouselMode) return null
            return layoutManager.findViewByPosition(getClosestChildPosition())
        }

@ -443,12 +482,10 @@ class CarouselRecyclerView @JvmOverloads constructor(
            layoutManager: RecyclerView.LayoutManager,
            targetView: View
        ): IntArray? {
-            if (layoutManager !is LinearLayoutManager) {
-                return super.calculateDistanceToFinalSnap(
-                    layoutManager,
-                    targetView
-                )
+            if (!isCarouselMode) {
+                return super.calculateDistanceToFinalSnap(layoutManager, targetView)
            }
+
            val out = IntArray(2)
            out[0] = getChildDistanceToCenter(targetView).toInt()
            out[1] = 0
@ -461,8 +498,11 @@ class CarouselRecyclerView @JvmOverloads constructor(
            velocityX: Int,
            velocityY: Int
        ): Int {
-            if (layoutManager !is LinearLayoutManager) return RecyclerView.NO_POSITION
+            if (!isCarouselMode) return RecyclerView.NO_POSITION
+
            val closestPosition = this@CarouselRecyclerView.getClosestChildPosition()
+            if (closestPosition == RecyclerView.NO_POSITION) return RecyclerView.NO_POSITION
+
            val internalMaxFling = resources.getInteger(R.integer.carousel_max_fling_count)
            val maxFling = preferences.getInt(CAROUSEL_MAX_FLING_COUNT, internalMaxFling).coerceIn(
                1,