Snap Recyclerview item to Center when loaded

Question

I am using an infinite scroll for recyclerview with X items which repeats. Also i want am using PagerSnapHelper() to snap the scroll like viewpager.

So initially when the list is loaded the display is like -

As soon as i start scrolling on either side left or right the PageSnapHelper() come in work an snap it like viewpager with center alignment like this -

I want to show recyclerview as like 2nd image when initially loaded. Please tell what to do next to acheive that.

here is the code snipet -

linearLayoutManager = new LinearLayoutManager(mContext,   LinearLayoutManager.HORIZONTAL, false);
this.recyclerView.setLayoutManager(linearLayoutManager);
SnapHelper snapHelper = new PagerSnapHelper();
adapterCarousel = new AdapterCarousel(mContext, glideRequestManager);
adapterCarousel.setViewType(RECYCLER_VIEW_TYPE_NORMAL);
adapterCarousel.setCarousel(carousel);
this.recyclerView.setAdapter(adapterCarousel);
snapHelper.attachToRecyclerView(recyclerView);
linearLayoutManager.scrollToPosition(Integer.MAX_VALUE / 2);

Did you find answer to this question? – Andrey Jul 24 '18 at 06:47 — Andrey, Jul 24 '18 at 06:47

idunnololz · Answer 1 · 2018-02-14T02:28:07.680

I solved the issue by using LinearLayoutManager#scrollToPositionWithOffset(pos, offset). I just offset the scroll position by half of the padding between items. This worked for me as my items was the same width as the screen. In your case you need to do some math.

Let's say that your item's width is W, your RecyclerView had width rvW and the padding between items was padding then the amount you want to offset by is given by (rvW - W)/2 - padding/2 or (rvW - W - padding)/2.

Final code:

// post to give the recyclerview time to layout so it's width isn't 0
mRecyclerView.post(new Runnable() {
    void run() {
        int padding = getResources().getDimensionPixelSize(R.dimen.some_padding);
        int rvWidth = mRecyclerView.getWidth();
        int itemWidth = getResources().getDimensionPixelSize(R.dimen.itemWidth);
        int offset = (rvWidth - itemWidth - padding) / 2;
        mLinearLayoutManager.scrollToPositionWithOffset(pos, offset);
    }
});

Some optional improvements to the code:

Instead of posting to the RecyclerView, you can use View#measure() and View#getMeasuredWidth() or even the display's width if you are certain that the RecyclerView will always fit the screen's width.
If your RecyclerView's children are variable sized you can get the View via mLinearLayoutManager.findViewByPosition(mLinearLayoutManager.findFirstVisibleItemPosition()) and get it's width that way.

score 0 · Answer 2 · answered Mar 29 '17 at 11:07

0

for me using recyclerView.smoothScrollToPosition(x); instead of linearLayoutManager.scrollToPosition(x); did the trick

answered Mar 29 '17 at 11:07

Katharina

1,612
15
27

this did not work for me, as my list is infinite with max size `Integer.Max_Value` – Rahul Mar 29 '17 at 11:09

score 0 · Answer 3 · answered Mar 31 '17 at 09:28

0

   linearLayoutManager.scrollToPosition((Integer.MAX_VALUE / 2)-1);
   linearLayoutManager.smoothScrollToPosition(Integer.MAX_VALUE / 2);

If there is a better way, please tell me

answered Mar 31 '17 at 09:28

Mr_gao

1
1

When I do this there is a very noticable jerk animation when the activity/fragment first loads which is undesirable. – idunnololz Feb 14 '18 at 01:53

Snap Recyclerview item to Center when loaded

3 Answers3