SafeLinearLayoutManager.kt

package com.reactnativepagerview

import android.content.Context
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import androidx.viewpager2.widget.ViewPager2

/**
 * A LinearLayoutManager that catches the "Scrapped or attached views may not be recycled"
 * IllegalArgumentException thrown by RecyclerView during scroll-based recycling.
 *
 * This crash occurs when RecyclerView's internal removeAndRecycleViewAt calls removeViewAt
 * to detach a view, but the view's mParent remains non-null (e.g. due to the view being
 * held as a "disappearing view" by ViewGroup). The subsequent recycleViewHolderInternal
 * check throws because holder.itemView.getParent() != null.
 *
 * Since this only happens during teardown (back navigation while mid-scroll), catching
 * the exception and aborting the scroll is safe — the view is being destroyed anyway.
 */
class SafeLinearLayoutManager(
    context: Context,
    private val viewPager: ViewPager2
) : LinearLayoutManager(context) {

    override fun calculateExtraLayoutSpace(state: RecyclerView.State, extraLayoutSpace: IntArray) {
        val pageLimit = viewPager.offscreenPageLimit
        if (pageLimit == ViewPager2.OFFSCREEN_PAGE_LIMIT_DEFAULT) {
            super.calculateExtraLayoutSpace(state, extraLayoutSpace)
            extraLayoutSpace[0] = extraLayoutSpace[0].coerceAtLeast(getPageSize())
            extraLayoutSpace[1] = extraLayoutSpace[1].coerceAtLeast(getPageSize())
        } else {
            val offscreenSpace = getPageSize() * pageLimit
            extraLayoutSpace[0] = offscreenSpace
            extraLayoutSpace[1] = offscreenSpace
        }
    }

    private fun getPageSize(): Int {
        val rv = viewPager.getChildAt(0) as? RecyclerView ?: return 0
        return if (orientation == HORIZONTAL) {
            rv.width - rv.paddingLeft - rv.paddingRight
        } else {
            rv.height - rv.paddingTop - rv.paddingBottom
        }
    }

    override fun scrollHorizontallyBy(dx: Int, recycler: RecyclerView.Recycler, state: RecyclerView.State): Int {
        return try {
            super.scrollHorizontallyBy(dx, recycler, state)
        } catch (_: IllegalArgumentException) {
            0
        }
    }

    override fun scrollVerticallyBy(dy: Int, recycler: RecyclerView.Recycler, state: RecyclerView.State): Int {
        return try {
            super.scrollVerticallyBy(dy, recycler, state)
        } catch (_: IllegalArgumentException) {
            0
        }
    }

    override fun onLayoutChildren(recycler: RecyclerView.Recycler, state: RecyclerView.State) {
        try {
            super.onLayoutChildren(recycler, state)
        } catch (_: IllegalArgumentException) {
            // View is being torn down, layout will not be needed again
        }
    }
}