Prevent RecyclerView to scroll by hand

Here's a solution for horizontal scrolling that allows you to turn off scrolling, but still enable it via calling smoothScrollToPosition. It also lets the user interact with child views within the recycler view.

I found that the other solutions which enabled scrolling temporarily to be able to call smoothScrollToPosition had the side effect of letting the user interrupt scrolling, even when disabling touch events or adding another view on top of the recyclerview.

The key is to getting smoothScrollToPosition to work is to override LinearSmoothScroller.calculateDxToMakeVisible and remove the check to canScrollHorizontally()

class NoScrollHorizontalLayoutManager(context: Context) : LinearLayoutManager(context, RecyclerView.HORIZONTAL, false) {

    override fun canScrollHorizontally(): Boolean {
        return false
    }

    override fun smoothScrollToPosition(recyclerView: RecyclerView, state: RecyclerView.State?, position: Int) {
        val linearSmoothScroller = ForceHorizontalLinearSmoothScroller(recyclerView.context)
        linearSmoothScroller.targetPosition = position
        startSmoothScroll(linearSmoothScroller)
    }
}



class ForceHorizontalLinearSmoothScroller(context: Context) : LinearSmoothScroller(context) {

    override fun calculateDxToMakeVisible(view: android.view.View, snapPreference: Int): Int {
        val layoutManager = layoutManager
        if (layoutManager == null) {
            return 0
        }
        val params = view.layoutParams as RecyclerView.LayoutParams
        val left = layoutManager.getDecoratedLeft(view) - params.leftMargin
        val right = layoutManager.getDecoratedRight(view) + params.rightMargin
        val start = layoutManager.paddingLeft
        val end = layoutManager.width - layoutManager.paddingRight
        return calculateDtToFit(left, right, start, end, snapPreference)
    }
}

EDIT: I found that the user could still stop scrolling when tapping on the recycle view while the scroll was in progress. The fix was to override the RecycleView.onInterceptTouchEvent and prevent events when the smooth scroll was in progress or when the scroll state was set to SCROLL_STATE_SETTLING. (Using RecycleView.addOnItemTouchListener for this wont work because the RecycleView stops scrolling then the listener returns true in RecyleView.onInterceptTouchEvent.)

class NoScrollRecyclerView : RecyclerView {
    constructor(context: Context) : super(context)

    constructor(context: Context, attrs: AttributeSet) : super(context, attrs)

    constructor(context: Context, attrs: AttributeSet, defStyle: Int) : super(context, attrs, defStyle)

    override fun onInterceptTouchEvent(e : MotionEvent) : Boolean {
        if (layoutManager?.isSmoothScrolling() == true || scrollState == SCROLL_STATE_SETTLING) {
            return true
        }
        return super.onInterceptTouchEvent(e)
    }

    @SuppressLint("ClickableViewAccessibility")
    override fun onTouchEvent(e :MotionEvent) : Boolean {
        if (layoutManager?.isSmoothScrolling() == true || scrollState == SCROLL_STATE_SETTLING) {
            return true
        }
        return super.onTouchEvent(e)
    }
}