我正在尝试使用
RecyclerViewGridLayoutManagerItemDecorationpublic 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是它弄乱了最后一行网格中的元素高度。我猜测
GridLayoutManager这对于
LinearLayoutManagerGridLayoutManager如果您底部有
FABFAB只需添加填充并设置
android:clipToPadding="false"<RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="8dp"
android:clipToPadding="false" />
感谢这个精彩的答案！
我有类似的问题并回复了堆栈溢出中的另一个线程。为了帮助其他登陆此页面的人，我将在此处重新发布。
阅读所有其他回复后，我发现 recyclerview 布局 xml 中的更改按预期适用于我的回收器视图：
android:paddingBottom="127px"
android:clipToPadding="false"
android:scrollbarStyle="outsideOverlay"
完整的布局如下：
<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" />
这个问题的解决方案在于重写GridLayoutManager的SpanSizeLookup。
您必须在要膨胀 RecylerView 的 Activity 或 Fragment 中对 GridlayoutManager 进行更改。
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);
}
仅在最后一项的情况下应在回收器视图中使用装饰作为下边距
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 */;
}
}
}
您可以使用下面的代码来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。
@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;
看看可能的解决方案，我想写一些注释和正确的解决方案：
如果您对 RecyclerView 使用填充，它应该在大多数情况下都可以工作，但是一旦您开始使用自定义项目装饰（快速滚动器）或处理透明导航栏，您将看到各种问题。
您始终可以为 RecyclerView 适配器创建一个 ViewType，该适配器将作为其页脚，占据整个范围。这非常有效，但只是比其他解决方案需要更多的工作。
此处提供的 ItemDecoration 解决方案在大多数情况下都有效，但对于 GridLayoutManager 来说效果不佳，因为它有时会为最后一行上方的行添加间距（此处要求添加更好的解决方案）。
我在 android-x 上找到了一些代码，似乎可以解决这个问题，不过，在某种程度上与汽车相关：
底部偏移装饰
/**
* A {@link RecyclerView.ItemDecoration} that will add a bottom offset to the last item in the
* RecyclerView it is added to.
*
* @hide
*/
@RestrictTo(LIBRARY_GROUP_PREFIX)
public 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);
RecyclerView.Adapter adapter = parent.getAdapter();
if (adapter == null || adapter.getItemCount() == 0) {
return;
}
if (parent.getLayoutManager() instanceof GridLayoutManager) {
if (GridLayoutManagerUtils.isOnLastRow(view, parent)) {
outRect.bottom = mBottomOffset;
}
} else if (parent.getChildAdapterPosition(view) == adapter.getItemCount() - 1) {
// Only set the offset for the last item.
outRect.bottom = mBottomOffset;
} else {
outRect.bottom = 0;
}
}
/** Sets the value to use for the bottom offset. */
public void setBottomOffset(int bottomOffset) {
mBottomOffset = bottomOffset;
}
/** Returns the set bottom offset. If none has been set, then 0 will be returned. */
public int getBottomOffset() {
return mBottomOffset;
}
}
GridLayoutManagerUtils
/**
* Utility class that helps navigating in GridLayoutManager.
*
* <p>Assumes parameter {@code RecyclerView} uses {@link GridLayoutManager}.
*
* <p>Assumes the orientation of {@code GridLayoutManager} is vertical.
*
* @hide
*/
@RestrictTo(LIBRARY_GROUP_PREFIX)
public class GridLayoutManagerUtils {
private GridLayoutManagerUtils() {}
/**
* Returns the number of items in the first row of a RecyclerView that has a
* {@link GridLayoutManager} as its {@code LayoutManager}.
*
* @param recyclerView RecyclerView that uses GridLayoutManager as LayoutManager.
* @return number of items in the first row in {@code RecyclerView}.
*/
public static int getFirstRowItemCount(RecyclerView recyclerView) {
GridLayoutManager manager = (GridLayoutManager) recyclerView.getLayoutManager();
int itemCount = recyclerView.getAdapter().getItemCount();
int spanCount = manager.getSpanCount();
int spanSum = 0;
int numOfItems = 0;
while (numOfItems < itemCount && spanSum < spanCount) {
spanSum += manager.getSpanSizeLookup().getSpanSize(numOfItems);
numOfItems++;
}
return numOfItems;
}
/**
* Returns the span index of an item.
*/
public static int getSpanIndex(View item) {
GridLayoutManager.LayoutParams layoutParams =
((GridLayoutManager.LayoutParams) item.getLayoutParams());
return layoutParams.getSpanIndex();
}
/**
* Returns whether or not the given view is on the last row of a {@code RecyclerView} with a
* {@link GridLayoutManager}.
*
* @param view The view to inspect.
* @param parent {@link RecyclerView} that contains the given view.
* @return {@code true} if the given view is on the last row of the {@code RecyclerView}.
*/
public static boolean isOnLastRow(View view, RecyclerView parent) {
return getLastItemPositionOnSameRow(view, parent) == parent.getAdapter().getItemCount() - 1;
}
/**
* Returns the position of the last item that is on the same row as input {@code view}.
*
* @param view The view to inspect.
* @param parent {@link RecyclerView} that contains the given view.
*/
public static int getLastItemPositionOnSameRow(View view, RecyclerView parent) {
GridLayoutManager layoutManager = ((GridLayoutManager) parent.getLayoutManager());
GridLayoutManager.SpanSizeLookup spanSizeLookup = layoutManager.getSpanSizeLookup();
int spanCount = layoutManager.getSpanCount();
int lastItemPosition = parent.getAdapter().getItemCount() - 1;
int currentChildPosition = parent.getChildAdapterPosition(view);
int spanSum = getSpanIndex(view) + spanSizeLookup.getSpanSize(currentChildPosition);
// Iterate to the end of the row starting from the current child position.
while (currentChildPosition <= lastItemPosition && spanSum <= spanCount) {
spanSum += spanSizeLookup.getSpanSize(currentChildPosition + 1);
if (spanSum > spanCount) {
return currentChildPosition;
}
currentChildPosition++;
}
return lastItemPosition;
}
}
因此，我制作了一个 Kotlin 解决方案来解决所有问题（此处提供示例和库）：
//https://androidx.de/androidx/car/widget/itemdecorators/BottomOffsetDecoration.html
class BottomOffsetDecoration(private val mBottomOffset: Int, private val layoutManagerType: LayoutManagerType) : ItemDecoration() {
enum class LayoutManagerType {
GRID_LAYOUT_MANAGER, LINEAR_LAYOUT_MANAGER
}
override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
super.getItemOffsets(outRect, view, parent, state)
when (layoutManagerType) {
LayoutManagerType.LINEAR_LAYOUT_MANAGER -> {
val position = parent.getChildAdapterPosition(view)
outRect.bottom =
if (state.itemCount <= 0 || position != state.itemCount - 1)
0
else
mBottomOffset
}
LayoutManagerType.GRID_LAYOUT_MANAGER -> {
val adapter = parent.adapter
outRect.bottom =
if (adapter == null || adapter.itemCount == 0 || GridLayoutManagerUtils.isOnLastRow(view, parent))
0
else
mBottomOffset
}
}
}
}
//https://androidx.de/androidx/car/util/GridLayoutManagerUtils.html
/**
* Utility class that helps navigating in GridLayoutManager.
*
*
* Assumes parameter `RecyclerView` uses [GridLayoutManager].
*
*
* Assumes the orientation of `GridLayoutManager` is vertical.
*/
object GridLayoutManagerUtils {
/**
* Returns whether or not the given view is on the last row of a `RecyclerView` with a
* [GridLayoutManager].
*
* @param view The view to inspect.
* @param parent [RecyclerView] that contains the given view.
* @return `true` if the given view is on the last row of the `RecyclerView`.
*/
fun isOnLastRow(view: View, parent: RecyclerView): Boolean {
return getLastItemPositionOnSameRow(view, parent) == parent.adapter!!.itemCount - 1
}
/**
* Returns the position of the last item that is on the same row as input `view`.
*
* @param view The view to inspect.
* @param parent [RecyclerView] that contains the given view.
*/
private fun getLastItemPositionOnSameRow(view: View, parent: RecyclerView): Int {
val layoutManager = parent.layoutManager as GridLayoutManager
val spanSizeLookup = layoutManager.spanSizeLookup
val spanCount = layoutManager.spanCount
val lastItemPosition = parent.adapter!!.itemCount - 1
var currentChildPosition = parent.getChildAdapterPosition(view)
val itemSpanIndex = (view.layoutParams as GridLayoutManager.LayoutParams).spanIndex
var spanSum = itemSpanIndex + spanSizeLookup.getSpanSize(currentChildPosition)
// Iterate to the end of the row starting from the current child position.
while (currentChildPosition <= lastItemPosition && spanSum <= spanCount) {
spanSum += spanSizeLookup.getSpanSize(currentChildPosition + 1)
if (spanSum > spanCount)
return currentChildPosition
++currentChildPosition
}
return lastItemPosition
}
}
<androidx.recyclerview.widget.RecyclerView
...
android:clipToPadding="false"
android:paddingTop="16dp"
android:paddingBottom="16dp"
...
/>
android：clipToPadding =“假”
您可以做的就是向您的回收视图添加一个空页脚。您的内边距将是页脚的大小。
@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;
}
🍑 最简单的解决方案是：
recyclerView.setClipToPadding(false);
// Sets whether this ViewGroup will clip its children to
// its padding and resize (but not clip) any EdgeEffect
// to the padded region, if padding is present.
// By default(true), children are clipped to the padding
// of their parent ViewGroup.
// * So that's why we have to set this false !
recyclerView.setPadding(0,0,0,bottomSpaceInPX);
对于这样的事情，建议使用 ItemDecoration 来解决，因为它们就是为此而设计的。
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);
}
}
我复制了我原来答案的编辑内容here，它实际上是等间距的，但它是相同的概念。
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drawHorizontal()中
<View
android:layout_width="match_parent"
android:layout_height="@dimen/_10sdp"
android:id="@+id/space"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:background="@color/white"
android:visibility="gone"
/>
将其添加到您的自定义行中
在 onBindviewHolder 添加这个
if(position == getItemCount())
holder.space.visibilty = View.Visible
else
holder.space.visibilty = View.Gone
将这些属性添加到recyclerview中。它适用于我的情况
android:clipToPadding="false"
android:paddingBottom="80dp"