RExItemDecoration.java 文件源码

@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
    final RecyclerView.LayoutManager manager = parent.getLayoutManager();
    if (manager instanceof StaggeredGridLayoutManager) {
        return;
    }

    //线性布局
    final LinearLayoutManager layoutManager = (LinearLayoutManager) manager;
    final int firstItem = layoutManager.findFirstVisibleItemPosition();
    for (int i = 0; i < layoutManager.getChildCount(); i++) {
        final int viewAdapterPosition = firstItem + i;
        final View view = layoutManager.findViewByPosition(viewAdapterPosition);
        if (view != null) {
            mItemDecorationCallback.draw(c, mTextPaint, view,
                    mItemDecorationCallback.getItemOffsets(layoutManager, viewAdapterPosition),
                    layoutManager.getItemCount(), viewAdapterPosition);
        }
    }
}