RecyclerView smoothScroll位于中心位置.安卓

我正在为RecyclerView使用水平布局管理器.
我需要以下一种方式制作RecyclerView：当点击某个项目时 – 将smoothScrool放到该位置并将该项目放在RecyclerView的中心(如果可能的话,例如20中的10项).

所以,我对smoothScrollToPosition()没有问题,但是如何把项目放在RecyclerView的中心？

谢谢！

解决方法:

是的,这是可能的.

通过实现RecyclerView.SmoothScroller的方法onTargetFound(View,State,Action).

/**
 * Called when the target position is laid out. This is the last callback SmoothScroller
 * will receive and it should update the provided {@link Action} to define the scroll
 * details towards the target view.
 * @param targetView    The view element which render the target position.
 * @param state         Transient state of RecyclerView
 * @param action        Action instance that you should update to define final scroll action
 *                      towards the targetView
 */
abstract protected void onTargetFound(View targetView, State state, Action action);

特别是在LinearLayoutManager中使用LinearSmoothScroller：

public class CenterLayoutManager extends LinearLayoutManager {

    public CenterLayoutManager(Context context) {
        super(context);
    }

    public CenterLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
    }

    public CenterLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position) {
        RecyclerView.SmoothScroller smoothScroller = new CenterSmoothScroller(recyclerView.getContext());
        smoothScroller.setTargetPosition(position);
        startSmoothScroll(smoothScroller);
    }

    private static class CenterSmoothScroller extends LinearSmoothScroller {

        CenterSmoothScroller(Context context) {
            super(context);
        }

        @Override
        public int calculateDtToFit(int viewStart, int viewEnd, int boxStart, int boxEnd, int snapPreference) {
            return (boxStart + (boxEnd - boxStart) / 2) - (viewStart + (viewEnd - viewStart) / 2);
        }
    }
}

标签：android,android-recyclerview,linearlayoutmanager
来源： https://codeday.me/bug/20190930/1835102.html