Android使用gridlayoutmanager在recyclerview中的最后一个元素下方添加间距

84

我试图在增加最后一个元件行下面的间距RecyclerView有GridLayoutManager。ItemDecoration为此，我将custom用于底部填充，如下所示：

public class SpaceItemDecoration extends RecyclerView.ItemDecoration {
private int space;
private int bottomSpace = 0;

public SpaceItemDecoration(int space, int bottomSpace) {
    this.space = space;
    this.bottomSpace = bottomSpace;
}

public SpaceItemDecoration(int space) {
    this.space = space;
    this.bottomSpace = 0;
}

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

    int childCount = parent.getChildCount();
    final int itemPosition = parent.getChildAdapterPosition(view);
    final int itemCount = state.getItemCount();

    outRect.left = space;
    outRect.right = space;
    outRect.bottom = space;
    outRect.top = space;

    if (itemCount > 0 && itemPosition == itemCount - 1) {
        outRect.bottom = bottomSpace;
    }
}
}

但是这种方法的问题在于，它弄乱了最后一行网格中的元素高度。我猜想这GridLayoutManager会根据剩余间距更改元素的高度。实现此目的的正确方法是什么？

这将正常工作LinearLayoutManager。以防万一GridLayoutManager它有问题。

如果您的FAB底部是in，并且需要最后一行的项目在上方滚动FAB以使其可见，这非常有用。

android  android-recyclerview  gridlayoutmanager 
— J
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Answers:

11

该问题的解决方案在于重写GridLayoutManager的SpanSizeLookup。

您必须在要扩展RecylerView的Activity或Fragment中更改GridlayoutManager。

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //your code 
    recyclerView.addItemDecoration(new PhotoGridMarginDecoration(context));

    // SPAN_COUNT is the number of columns in the Grid View
    GridLayoutManager gridLayoutManager = new GridLayoutManager(context, SPAN_COUNT);

    // With the help of this method you can set span for every type of view
    gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
        @Override
        public int getSpanSize(int position) {
            if (list.get(position).getType() == TYPE_HEADER) {
                // Will consume the whole width
                return gridLayoutManager.getSpanCount();
            } else if (list.get(position).getType() == TYPE_CONTENT) {
                // will consume only one part of the SPAN_COUNT
                return 1;
            } else if(list.get(position).getType() == TYPE_FOOTER) {
                // Will consume the whole width
                // Will take care of spaces to be left,
                // if the number of views in a row is not equal to 4
                return gridLayoutManager.getSpanCount();
            }
            return gridLayoutManager.getSpanCount();
        }
    });
    recyclerView.setLayoutManager(gridLayoutManager);
}
— 德鲁·潘乔利（Dhruv Pancholi）
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436

只需添加一个填充并设置 android:clipToPadding="false"

<RecyclerView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="8dp"
    android:clipToPadding="false" />

感谢这个美妙的答案！

— 吠陀
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2
这为我做到了。当您需要在回收站中平均放置物品时，快速简便的解决方案。谢谢。
— Empty2k12
3
这正是我想要的！谢谢！
— Mariano Zorrilla
1
简便的解决方案。谢谢！
— Mikhail
1
这很棒，但是会弄乱衰落的边缘，例如android：requiresFadingEdge =“ vertical”或recyclerView.setVerticalFadingEdgeEnabled（true）;。
— Stephan Henningsen
6
这不会将回收站视图的滚动条扩展到最底部。编辑：防止此添加android:scrollbarStyle="outsideOverlay"
— 塞巴斯蒂安
8

仅在最后一项的情况下，才应使用“ Recycler View中的装饰”作为下边距

recyclerView.addItemDecoration(MemberItemDecoration())

public class MemberItemDecoration extends RecyclerView.ItemDecoration {

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        // only for the last one
        if (parent.getChildAdapterPosition(view) == parent.getAdapter().getItemCount() - 1) {
            outRect.bottom = 50/* set your margin here */;
        }
    }
}
— 迪内什·巴凡（Dinesh Bagvan）
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6

我有类似的问题，并回答了堆栈溢出中的另一个线程。为了帮助落入此页面的其他人，我将在此处重新发布。
阅读所有其他答复后，我发现recyclerview布局xml中的更改按预期可用于我的recycler视图： 

        android:paddingBottom="127px"
        android:clipToPadding="false"
        android:scrollbarStyle="outsideOverlay"

完整的布局如下所示： 

<android.support.v7.widget.RecyclerView
        android:id="@+id/library_list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="160px"
        android:layout_marginEnd="160px"
        tools:listitem="@layout/library_list_item" />

有关之前和之后的效果，请参见androidblog.us上的链接： 在Android Recylerview的末尾添加空间
让我知道它如何为您工作。

大卫

— us_david
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3

您可以使用下面的代码检测网格视图中的第一行和最后一行，并相应地设置顶部和底部偏移量。

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state) {
    LayoutParams params = (LayoutParams) view.getLayoutParams();
    int pos = params.getViewLayoutPosition();
    int spanCount = mGridLayoutManager.getSpanCount();

    boolean isFirstRow = pos < spanCount;
    boolean isLastRow = state.getItemCount() - 1 - pos < spanCount;

    if (isFirstRow) {
      outRect.top = top offset value here
    }

    if (isLastRow) {
      outRect.bottom = bottom offset value here
    }
}

// you also need to keep reference to GridLayoutManager to know the span count
private final GridLayoutManager mGridLayoutManager;
— 谢尔盖·沙法伦卡（Sergej Shafarenka）
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2

您可以做的是在您的recyclerview中添加一个空白页脚。您的填充将是页脚的大小。

@Override
public Holder onCreateViewHolder( ViewGroup parent, int viewType) {
    if (viewType == FOOTER) {
        return new FooterHolder();
    }
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item, parent, false);
    return new Holder(view);
}

@Override
public void onBindViewHolder(final Holder holder, final int position) {
    //if footer
    if (position == items.getSize() - 1) {
    //do nothing
        return;
    }
    //do regular object bindding

}

@Override
public int getItemViewType(int position) {
    return (position == items.getSize() - 1) ? FOOTER : ITEM_VIEW_TYPE_ITEM;
}

@Override
public int getItemCount() {
    //add one for the footer
    return items.size() + 1;
}
— 尼古拉斯
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这是一个不错的选择。但是，我的问题是我已经在使用自定义的ItemDecoration，它可以根据recyclerview中的项目位置工作，并决定在哪里放置什么间距和分隔线等。现在，如果我将此间距添加为其他元素，我的ItemDecoration会将其作为元素计数也将分隔符添加到间距。所以我在想是否有人尝试使用自定义ItemDecoration来解决问题。
— pratsJ 2015年
如果您的方法在LinearLayoutManager或GridLayoutManager（如果网格的底部行已满）的情况下也能很好地工作。否则，空间将进入空元素空间中的网格，而不是整个网格的底部。
— pratsJ 2015年
0

对于此类事情，建议使用ItemDecoration进行解决，因为它们是为此目的而设计的。 

public class ListSpacingDecoration extends RecyclerView.ItemDecoration {

  private static final int VERTICAL = OrientationHelper.VERTICAL;

  private int orientation = -1;
  private int spanCount = -1;
  private int spacing;


  public ListSpacingDecoration(Context context, @DimenRes int spacingDimen) {

    spacing = context.getResources().getDimensionPixelSize(spacingDimen);
  }

  public ListSpacingDecoration(int spacingPx) {

    spacing = spacingPx;
  }

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

    super.getItemOffsets(outRect, view, parent, state);

    if (orientation == -1) {
        orientation = getOrientation(parent);
    }

    if (spanCount == -1) {
        spanCount = getTotalSpan(parent);
    }

    int childCount = parent.getLayoutManager().getItemCount();
    int childIndex = parent.getChildAdapterPosition(view);

    int itemSpanSize = getItemSpanSize(parent, childIndex);
    int spanIndex = getItemSpanIndex(parent, childIndex);

    /* INVALID SPAN */
    if (spanCount < 1) return;

    setSpacings(outRect, parent, childCount, childIndex, itemSpanSize, spanIndex);
  }

  protected void setSpacings(Rect outRect, RecyclerView parent, int childCount, int childIndex, int itemSpanSize, int spanIndex) {

    if (isBottomEdge(parent, childCount, childIndex, itemSpanSize, spanIndex)) {
        outRect.bottom = spacing;
    }
  }

  @SuppressWarnings("all")
  protected int getTotalSpan(RecyclerView parent) {

    RecyclerView.LayoutManager mgr = parent.getLayoutManager();
    if (mgr instanceof GridLayoutManager) {
        return ((GridLayoutManager) mgr).getSpanCount();
    } else if (mgr instanceof StaggeredGridLayoutManager) {
        return ((StaggeredGridLayoutManager) mgr).getSpanCount();
    } else if (mgr instanceof LinearLayoutManager) {
        return 1;
    }

    return -1;
  }

  @SuppressWarnings("all")
  protected int getItemSpanSize(RecyclerView parent, int childIndex) {

    RecyclerView.LayoutManager mgr = parent.getLayoutManager();
    if (mgr instanceof GridLayoutManager) {
        return ((GridLayoutManager) mgr).getSpanSizeLookup().getSpanSize(childIndex);
    } else if (mgr instanceof StaggeredGridLayoutManager) {
        return 1;
    } else if (mgr instanceof LinearLayoutManager) {
        return 1;
    }

    return -1;
  }

  @SuppressWarnings("all")
  protected int getItemSpanIndex(RecyclerView parent, int childIndex) {

    RecyclerView.LayoutManager mgr = parent.getLayoutManager();
    if (mgr instanceof GridLayoutManager) {
        return ((GridLayoutManager) mgr).getSpanSizeLookup().getSpanIndex(childIndex, spanCount);
    } else if (mgr instanceof StaggeredGridLayoutManager) {
        return childIndex % spanCount;
    } else if (mgr instanceof LinearLayoutManager) {
        return 0;
    }

    return -1;
  }

  @SuppressWarnings("all")
  protected int getOrientation(RecyclerView parent) {

    RecyclerView.LayoutManager mgr = parent.getLayoutManager();
    if (mgr instanceof LinearLayoutManager) {
        return ((LinearLayoutManager) mgr).getOrientation();
    } else if (mgr instanceof GridLayoutManager) {
        return ((GridLayoutManager) mgr).getOrientation();
    } else if (mgr instanceof StaggeredGridLayoutManager) {
        return ((StaggeredGridLayoutManager) mgr).getOrientation();
    }

    return VERTICAL;
  }

  protected boolean isBottomEdge(RecyclerView parent, int childCount, int childIndex, int itemSpanSize, int spanIndex) {

    if (orientation == VERTICAL) {

        return isLastItemEdgeValid((childIndex >= childCount - spanCount), parent, childCount, childIndex, spanIndex);

    } else {

        return (spanIndex + itemSpanSize) == spanCount;
    }
  }

  protected boolean isLastItemEdgeValid(boolean isOneOfLastItems, RecyclerView parent, int childCount, int childIndex, int spanIndex) {

    int totalSpanRemaining = 0;
    if (isOneOfLastItems) {
        for (int i = childIndex; i < childCount; i++) {
            totalSpanRemaining = totalSpanRemaining + getItemSpanSize(parent, i);
        }
    }

    return isOneOfLastItems && (totalSpanRemaining <= spanCount - spanIndex);
  }
}

我在这里复制了原始答案中的编辑内容，实际上是等间距的，但这是相同的概念。

— Pirdad Sakhizada
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0

您可以从源代码中以DividerItemDecoration.java为例，并替换

for (int i = 0; i < childCount; i++)

与

for (int i = 0; i < childCount - 1; i++)

在drawVertical（）和drawHorizo​​ntal（）中

— 卡米尔
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