在 RecyclerView 的末尾添加空格 [英] Add space to the end of the RecyclerView

问题描述

我有一个带有网格布局的回收视图.我想要的是当用户滚动到列表的末尾(看到我的坏模型)时，应该有一个空的高度为 50dp 的空间，与我的网格尺寸不同.

I have a recyclerview with a gridlayout. What I want is when the user scrolls to the end of the list (see my bad mockup), there should be an empty space with a height of 50dp, which isn't the same dimensions as my grid.

请注意，此空间仅在最后端可见，因为我不想更改布局.我可以使 recycerview 的边距底部为 50dp，但我不想这样做.

Note that this space is only visible at the very end end, as I do not want to change the layout. I could make it so that the recycerview has a margin bottom of 50dp, but I do not want to do that.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:fab="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity"
        android:scrollbars="vertical"
        />

</RelativeLayout>

推荐答案

这最好通过 项目装饰.

这是一个使用 LinearLayoutManager 的示例 - 您必须进行调整以适合您的网格布局.它所做的是检查每个项目以查看它是否是最后一个，如果是，则将偏移量添加到它的底部.对于 Grid 布局，难点在于确定您的项目位置是否在最后一行.

Here's an example that works with a LinearLayoutManager - you'll have to adjust to suit for your Grid layout. What it does is checks each item to see if it's the last one, and if it is it adds the offset to the bottom of it. For a Grid layout, the hard part is figuring out whether your item position is in the last row or not.

// After setting layout manager, adapter, etc...
float offsetPx = getResources().getDimension(R.dimen.bottom_offset_dp);
BottomOffsetDecoration bottomOffsetDecoration = new BottomOffsetDecoration((int) offsetPx);
mRecyclerView.addItemDecoration(bottomOffsetDecoration);

...

static class BottomOffsetDecoration extends RecyclerView.ItemDecoration {
    private int mBottomOffset;

    public BottomOffsetDecoration(int bottomOffset) {
        mBottomOffset = bottomOffset;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        int dataSize = state.getItemCount();
        int position = parent.getChildAdapterPosition(view);
        if (dataSize > 0 && position == dataSize - 1) {
            outRect.set(0, 0, 0, mBottomOffset);
        } else {
            outRect.set(0, 0, 0, 0);
        }

    }
}

对于 GridLayoutManager，在 getItemOffsets 方法中，您可以执行与此类似的操作以确定它是否是最后一行:

For a GridLayoutManager, inside the getItemOffsets method you could do something similar to this to figure out if it's the last row:

GridLayoutManager grid = (GridLayoutManager)parent.getLayoutManager();
if ((dataSize - position) <= grid.getSpanCount()) {
    outRect.set(0, 0, 0, mBottomOffset);
} else {
    outRect.set(0, 0, 0, 0);
}

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