在 RecyclerView 中的项目之间均匀分配空间

Question

我试图在RecyclerView 的项目之间放置相等的空间。为此，我使用下面的SpanningLinearLayoutManager。它的作用是，它会在RecyclerView 中的项目之间自动分配空间，但它会使RecyclerView 不可滚动。所有项目都将在父项的宽度内。这适用于 5 或​​ 6 个项目。但是如果列表有大约 10 个元素，那么所有元素都会非常接近。我想平均分配项目之间的空间并使recyclerview 可滚动方式。

我在父母RecyclerView 中有一个孩子RecyclerView。我想在孩子RecyclerView的项目之间平均分配空间@

这是我的代码：

import android.content.Context;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.view.ViewGroup;

public class SpanningLinearLayoutManager extends LinearLayoutManager {

public SpanningLinearLayoutManager(Context context) {
    super(context);
}

public SpanningLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
    super(context, orientation, reverseLayout);
}

public SpanningLinearLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
    super(context, attrs, defStyleAttr, defStyleRes);
}

@Override
public RecyclerView.LayoutParams generateDefaultLayoutParams() {
    return spanLayoutSize(super.generateDefaultLayoutParams());
}

@Override
public RecyclerView.LayoutParams generateLayoutParams(Context c, AttributeSet attrs) {
    return spanLayoutSize(super.generateLayoutParams(c, attrs));
}

@Override
public RecyclerView.LayoutParams generateLayoutParams(ViewGroup.LayoutParams lp) {
    return spanLayoutSize(super.generateLayoutParams(lp));
}

@Override
public boolean checkLayoutParams(RecyclerView.LayoutParams lp) {
    return super.checkLayoutParams(lp);
}

private RecyclerView.LayoutParams spanLayoutSize(RecyclerView.LayoutParams layoutParams){
    if(getOrientation() == HORIZONTAL){
        layoutParams.width = (int) Math.round(getHorizontalSpace() / (double) getItemCount());
    }
    else if(getOrientation() == VERTICAL){
        layoutParams.height = (int) Math.round(getVerticalSpace() /  (double) getItemCount());
    }
    return layoutParams;
}

@Override
public boolean canScrollVertically() {
    return false;
}
@Override
public boolean canScrollHorizontally() {
    return false;
}

private int getHorizontalSpace() {
    return getWidth() - getPaddingRight() - getPaddingLeft();
}

private int getVerticalSpace() {
    return getHeight() - getPaddingBottom() - getPaddingTop();
}
}

Answer 1

声明这两个变量flagDecoration和mItemDecoration：

private var flagDecoration = false

private var mItemDecoration: RecyclerView.ItemDecoration = object : RecyclerView.ItemDecoration() {
        override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
            super.getItemOffsets(outRect, view, parent, state)
            outRect.left = 20 //use the value as per your need
            outRect.right = 20
            outRect.top = 20
            outRect.bottom = 20
            flagDecoration = true
        }
    }

在您的recyclerView 中添加使用它。

if (!flagDecoration) {
   recyclerView.addItemDecoration(mItemDecoration)
}

Answer 2

您不需要自定义 LayoutManager 即可实现此目的。您可以使用 LinearLayoutManager 获得所需的结果。

为每个子项添加间距所需的只是一个 ItemDecorator。

https://developer.android.com/reference/android/support/v7/widget/RecyclerView.ItemDecoration?hl=en

@Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
                               RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        outRect.top = spacing;
    }

..

recyclerView.layoutManager = LinearLayoutManager(..)
recyclerView.addItemDecoration(MyItemDecorator())