Start my RecyclerView Horizontal Carousel from the center item

Question

I\'m creating a carousel Horizontal RecyclerView with Zoom on focused item that is starting from the first item of the RecyclerView.

Code for custom CenterZ

Answer 1

The solution is to change the timing of when LinearSnapHelper is attached to the RecyclerView. The following is a reworked onSetRecyclerView() that will snap the central item of the RecyclerView to the center of the screen. Notice that the LinearSnapHelper is not attached until the RecyclerView is laid out and scrolled appropriately. You do not need to do any scrolling in onLayoutChildren().

private void onSetRecyclerView() {
    recyclerView = findViewById(R.id.recyclerView);
    CenterZoomLayoutManager layoutManager =
        new CenterZoomLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
    recyclerView.setLayoutManager(layoutManager);
    recyclerView.setAdapter(adapter);
    // Scroll to the position we want to snap to
    layoutManager.scrollToPosition(storeList.size() / 2);
    // Wait until the RecyclerView is laid out.
    recyclerView.post(new Runnable() {
        @Override
        public void run() {
            // Shift the view to snap  near the center of the screen.
            // This does not have to be precise.
            int dx = (recyclerView.getWidth() - recyclerView.getChildAt(0).getWidth()) / 2;
            recyclerView.scrollBy(-dx, 0);
            // Assign the LinearSnapHelper that will initially snap the near-center view.
            LinearSnapHelper snapHelper = new LinearSnapHelper();
            snapHelper.attachToRecyclerView(recyclerView);
        }
    });
}

This is how the initial screen of my test app is displayed. There are 201 "stores."