scrollToPositionWithOffset from LinearLayoutManager on RecyclerView not working

Question

I'm trying to make an horizontal list of sticky images with RecyclerView and I'd like to move them by pixels' offset with scrollToPositionWithOffset. I thought passing 0 as position and the pixels I want to move to right / left as offset.

But it doesn't work, the list remains untouched, unscrolled, it doesn't move. This is my implementation:

final LargeImageAdapter mLargeImageAdapter = new LargeImageAdapter(this);
linearLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
recyclerView.setLayoutManager(linearLayoutManager);
recyclerView.setAdapter(mLargeImageAdapter);

seekBar = (SeekBar)findViewById(R.id.seekBar);
seekBar.setMax(7000);
seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
    @Override
    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
        int scrollToDX = progress;

        ((LinearLayoutManager)recyclerView.getLayoutManager()).scrollToPositionWithOffset(0, scrollToDX);
        // tried invoking also linearLayoutManager instead getLayoutManager.
    }

    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {

    }

    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {

    }
});

what am I doing wrong?

Thank you very much.

Regards.

Rafael.

Answer 1

I had a similar issue. My problem was that my recyclerview wasn't of the same size of its parent layout. I solved it by setting the recycler view width and height to match_parent. I don't know why this happens in this case.

Answer 2

A late answer to your first question, and an addition to your answer:

Your method works better for your personal needs, because scrollToPositionWithOffset is not intended to do what you want.

As the doc says here:

[...]Resolved layout start depends on [...] getLayoutDirection(android.view.View) [...]

Which means it would offset the scroll target position in the layout direction, vertically in your case.

I don't understand what's the utility of the function scrollToPositionWithOffset.

it allows to not only scroll to a given item in the list, but also position it at a more "visible" or otherwise convenient place.

Answer 3

recently I encountered this problem too, I invoke scrollToPositionWithOffset when onScrolled() directly, but nothing change, with that I turn to scrollToPosition() even scrollBy() but not help, finally I attempt to delay that so it work, first time I delay 50ms, but two weeks later I found that's not enough, so I increase to 100ms with no approachs in my hands, of course it work, just feel a little unsettled.

val layoutManager = LinearLayoutManager(hostActivity, VERTICAL, false)
fileRv.layoutManager = layoutManager
fileRv.addOnScrollListener(object : RecyclerView.OnScrollListener() {
    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
        if (dx == 0 && dy == 0) {
            scrollToLastPosition()
        }
    }

    private fun scrollToLastPosition() {
        val lastScrollPosition = viewModel.consumeLastScrollPosition()
        if (lastScrollPosition > 0) {
            Handler().postDelayed({ layoutManager.scrollToPositionWithOffset(lastScrollPosition, 0) }, 100)
        }
    }
})

override fun onItemClick(position: Int) {
    layoutManager.findFirstVisibleItemPosition().let {
        if (it >= 0) viewModel.markLastScrollPosition(it)
    }
}

fun markLastScrollPosition(position: Int) {
    currentFolderListData.value?.lastOrNull()?.lastScrollPosition = position
}

fun consumeLastScrollPosition(): Int {
    currentFolderListData.value?.lastOrNull()?.run {
        return lastScrollPosition.apply { lastScrollPosition = -1 }
    }
    return 0
}

Answer 4

I find a solution. Coz I am the developer of DNA Launcher. When I use RecyclerView to display A-Z App List, I found that the function scrollToPositionWithOffset is not working. I track the problem for almost one day and I figured it out.

When the RecyclerView display again, just let the parent of RecyclerView do requestLayout.

It works for me.

And I know how to make the function scrollToPositionWithOffset not working. You just need to add a view on it and make it gone then.