如何從RecyclerView的ItemDecoration類訪問LayoutManager？

Question

我一直沒能找到任何關於它的帖子...

我們有良好的老RecyclerView.ItemDecoration碼（從Suleiman's Mansonry Github project拍攝）：

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; 
    } 
} 

我想有套mSpace條件（抵消/保證金），取決於RecyclerView中的當前LayoutManager。

例如：

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

Answer 1

所以...因爲我是重讀的問題，檢查是否有任何失蹤，我意識到，你實際上得到一個RecyclerView引用（父）作爲參數getItemOffsets()。

所以你可以從函數內部調用parent.getLayoutManager()。

實施例：

@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 
}