如何从RecyclerView的ItemDecoration类访问LayoutManager？

Question

我找不到任何关于它的帖子...

我们有旧的RecyclerView.ItemDecoration代码（摘自Suleiman的Mansonry Github项目 ）：

public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
    private final int mSpace;

    public SpacesItemDecoration(int space) {
        this.mSpace = space;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        outRect.left = mSpace;
        outRect.right = mSpace;
        outRect.bottom = mSpace;

        // Add top margin only for the first item to avoid double space between items
        if (parent.getChildAdapterPosition(view) == 0)
            outRect.top = mSpace;
    }
}

我想根据RecyclerView中的当前LayoutManager设置mSpace （偏移/边距）的条件。

例如：

if(/* LayoutManager is LinearLayoutManager*/){
   //Set larger margin
}else{
   //Set lower margin
}

Answer 1

所以...当我重新阅读该问题以检查是否缺少任何内容时，我意识到您实际上获得了RecyclerView引用（父级）作为getItemOffsets（）的参数。

因此，您只需从函数内部调用parent.getLayoutManager() 。

例：

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {

    if (parent.getLayoutManager() instanceof LinearLayoutManager){
        margin = 2;
    }else if (parent.getLayoutManager() instanceof StaggeredGridLayoutManager){
        margin = 1;
    }else{
        margin = 0;
    }

    //Do magic
}