first item center aligns in SnapHelper in RecyclerView

Question

I\'m using PagerSnapHelper in RecyclerView. the first item in RecyclerView in left position in the screen. I need the first item in center aligns.

LinearLayoutMa         


        

Answer 1

Here's a simpler version of the accepted answer, that is also more flexible since it doesn't refer to the screen width:

class BoundsOffsetDecoration : ItemDecoration() {
    override fun getItemOffsets(outRect: Rect,
                                view: View,
                                parent: RecyclerView,
                                state: RecyclerView.State) {
        super.getItemOffsets(outRect, view, parent, state)

        val itemPosition = parent.getChildAdapterPosition(view)

        // It is crucial to refer to layoutParams.width (view.width is 0 at this time)!
        val itemWidth = view.layoutParams.width
        val offset = (parent.width - itemWidth) / 2

        if (itemPosition == 0) {
            outRect.left = offset
        } else if (itemPosition == state.itemCount - 1) {
            outRect.right = offset
        }
    }
}

I've written a Medium post describing a step-by-step implementation of this kind of carousels using RecyclerView and SnapHelper, if you need more details.