java - 如何从RecyclerView的ItemDecoration类访问LayoutManager？

Question

我没找到任何相关的帖子...

我们有旧的RecyclerView.ItemDecoration代码(取自 Suleiman's Mansonry Github project ):

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;
    }
}

我想要一个根据当前 LayoutManager 设置 mSpace (偏移/边距)的条件在 RecyclerView .

例如:

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

Answer 1

所以...当我重新阅读这个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一个 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() 即可。

示例:

@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
}