Sample for RecyclerView smooth scroll animation speed and offset.

CustomSpeedLinearLayoutManager

class CustomSpeedLinearLayoutManager(
        context: Context,
        private val offsetProvider: (position: Int) -> Int
    ) : LinearLayoutManager(context) {

        override fun smoothScrollToPosition(recyclerView: RecyclerView, state: RecyclerView.State, position: Int) {
            val viewHolder = recyclerView.findViewHolderForAdapterPosition(position)?.itemView
            val itemHeight = viewHolder?.height ?: 0
            
            // just sample value, speed up if viewholder's height is long enough.
            val speedRatio = when {
                itemHeight <= 1000 -> 1.0f
                itemHeight <= 2000 -> 2.0f
                else -> 3.0f
            }

            val smoothScroller = object : LinearSmoothScroller(recyclerView.context) {
                override fun calculateSpeedPerPixel(displayMetrics: DisplayMetrics): Float {
                    return super.calculateSpeedPerPixel(displayMetrics) / speedRatio
                }

                override fun calculateDyToMakeVisible(view: View?, snapPreference: Int): Int {
                    return super.calculateDyToMakeVisible(view, snapPreference) - offsetProvider(position)
                }
            }
            smoothScroller.targetPosition = position
            startSmoothScroll(smoothScroller)
        }

    }