如何使用GridLayoutManager与RecyclerView设置列间距? 在我的布局中设置空白/填充没有效果。
当前回答
感谢edwardaa的回答https://stackoverflow.com/a/30701422/2227031
另一点需要注意的是:
如果total spacing和total itemWidth不等于屏幕宽度，您还需要调整itemWidth，例如，在适配器onBindViewHolder方法
Utils.init(_mActivity);
int width = 0;
if (includeEdge) {
width = ScreenUtils.getScreenWidth() - spacing * (spanCount + 1);
} else {
width = ScreenUtils.getScreenWidth() - spacing * (spanCount - 1);
}
int itemWidth = width / spanCount;
ConstraintLayout.LayoutParams layoutParams = (ConstraintLayout.LayoutParams) holder.imageViewAvatar.getLayoutParams();
// suppose the width and height are the same
layoutParams.width = itemWidth;
layoutParams.height = itemWidth;
holder.imageViewAvatar.setLayoutParams(layoutParams);
其他回答
选择的答案几乎是完美的，但根据空间的不同，项目的宽度可能不相等。(对我来说，这很关键)。所以我最终用这个代码增加了一点空间，所以项目都是相同的宽度。
class GridSpacingItemDecoration(private val columnCount: Int, @Px preferredSpace: Int, private val includeEdge: Boolean): RecyclerView.ItemDecoration() {
/**
* In this algorithm space should divide by 3 without remnant or width of items can have a difference
* and we want them to be exactly the same
*/
private val space = if (preferredSpace % 3 == 0) preferredSpace else (preferredSpace + (3 - preferredSpace % 3))
override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State?) {
val position = parent.getChildAdapterPosition(view)
if (includeEdge) {
when {
position % columnCount == 0 -> {
outRect.left = space
outRect.right = space / 3
}
position % columnCount == columnCount - 1 -> {
outRect.right = space
outRect.left = space / 3
}
else -> {
outRect.left = space * 2 / 3
outRect.right = space * 2 / 3
}
}
if (position < columnCount) {
outRect.top = space
}
outRect.bottom = space
} else {
when {
position % columnCount == 0 -> outRect.right = space * 2 / 3
position % columnCount == columnCount - 1 -> outRect.left = space * 2 / 3
else -> {
outRect.left = space / 3
outRect.right = space / 3
}
}
if (position >= columnCount) {
outRect.top = space
}
}
}
}
我最后用GridLayoutManager和HeaderView为我的RecyclerView做了这样的事情。
在下面的代码中，我在每个项目之间设置了4dp空间(每个项目周围都是2dp，整个RecyclerView周围是2dp填充)。
在layout.xml:
<android.support.v7.widget.RecyclerView
android:id="@+id/recycleview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="2dp" />
在你的片段/活动中:
GridLayoutManager manager = new GridLayoutManager(getContext(), 3);
recyclerView.setLayoutManager(manager);
int spacingInPixels = Utils.dpToPx(2);
recyclerView.addItemDecoration(new SpacesItemDecoration(spacingInPixels));
创建SpaceItemDecoration.java:
public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
private int mSpacing;
public SpacesItemDecoration(int spacing) {
mSpacing = spacing;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView recyclerView, RecyclerView.State state) {
outRect.left = mSpacing;
outRect.top = mSpacing;
outRect.right = mSpacing;
outRect.bottom = mSpacing;
}
}
在Utils.java:
public static int dpToPx(final float dp) {
return Math.round(dp * (Resources.getSystem().getDisplayMetrics().xdpi / DisplayMetrics.DENSITY_DEFAULT));
}
Yqritc的回答非常适合我。我用的是Kotlin，这里有一个等价物。
class ItemOffsetDecoration : RecyclerView.ItemDecoration {
// amount to add to padding
private val _itemOffset: Int
constructor(itemOffset: Int) {
_itemOffset = itemOffset
}
constructor(@NonNull context: Context, @DimenRes itemOffsetId: Int){
_itemOffset = context.resources.getDimensionPixelSize(itemOffsetId)
}
/**
* Applies padding to all sides of the [Rect], which is the container for the view
*/
override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView,state: RecyclerView.State) {
super.getItemOffsets(outRect, view, parent, state)
outRect.set(_itemOffset, _itemOffset, _itemOffset, _itemOffset)
}
}
其他一切都是一样的。
试试这个。它会照顾到周围的等距。适用于列表，网格和StaggeredGrid。
编辑
更新后的代码应该可以处理大多数带有跨度、方向等的角落情况。 注意，如果在GridLayoutManager中使用setSpanSizeLookup()，出于性能考虑，建议设置setSpanIndexCacheEnabled()。
注意，似乎与StaggeredGrid，似乎有一个错误的索引的孩子变得古怪和难以跟踪，所以下面的代码可能不会很好地与StaggeredGridLayoutManager。
public class ListSpacingDecoration extends RecyclerView.ItemDecoration {
private static final int VERTICAL = OrientationHelper.VERTICAL;
private int orientation = -1;
private int spanCount = -1;
private int spacing;
private int halfSpacing;
public ListSpacingDecoration(Context context, @DimenRes int spacingDimen) {
spacing = context.getResources().getDimensionPixelSize(spacingDimen);
halfSpacing = spacing / 2;
}
public ListSpacingDecoration(int spacingPx) {
spacing = spacingPx;
halfSpacing = spacing / 2;
}
@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) {
outRect.top = halfSpacing;
outRect.bottom = halfSpacing;
outRect.left = halfSpacing;
outRect.right = halfSpacing;
if (isTopEdge(parent, childCount, childIndex, itemSpanSize, spanIndex)) {
outRect.top = spacing;
}
if (isLeftEdge(parent, childCount, childIndex, itemSpanSize, spanIndex)) {
outRect.left = spacing;
}
if (isRightEdge(parent, childCount, childIndex, itemSpanSize, spanIndex)) {
outRect.right = spacing;
}
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 isLeftEdge(RecyclerView parent, int childCount, int childIndex, int itemSpanSize, int spanIndex) {
if (orientation == VERTICAL) {
return spanIndex == 0;
} else {
return (childIndex == 0) || isFirstItemEdgeValid((childIndex < spanCount), parent, childIndex);
}
}
protected boolean isRightEdge(RecyclerView parent, int childCount, int childIndex, int itemSpanSize, int spanIndex) {
if (orientation == VERTICAL) {
return (spanIndex + itemSpanSize) == spanCount;
} else {
return isLastItemEdgeValid((childIndex >= childCount - spanCount), parent, childCount, childIndex, spanIndex);
}
}
protected boolean isTopEdge(RecyclerView parent, int childCount, int childIndex, int itemSpanSize, int spanIndex) {
if (orientation == VERTICAL) {
return (childIndex == 0) || isFirstItemEdgeValid((childIndex < spanCount), parent, childIndex);
} else {
return spanIndex == 0;
}
}
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 isFirstItemEdgeValid(boolean isOneOfFirstItems, RecyclerView parent, int childIndex) {
int totalSpanArea = 0;
if (isOneOfFirstItems) {
for (int i = childIndex; i >= 0; i--) {
totalSpanArea = totalSpanArea + getItemSpanSize(parent, i);
}
}
return isOneOfFirstItems && totalSpanArea <= 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);
}
}
希望能有所帮助。
复制@edwardaa提供的代码，我使它完美地支持RTL:
public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {
private int spanCount;
private int spacing;
private boolean includeEdge;
private int headerNum;
private boolean isRtl = TextUtilsCompat.getLayoutDirectionFromLocale(Locale.getDefault()) == ViewCompat.LAYOUT_DIRECTION_RTL;
public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge, int headerNum) {
this.spanCount = spanCount;
this.spacing = spacing;
this.includeEdge = includeEdge;
this.headerNum = headerNum;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
int position = parent.getChildAdapterPosition(view) - headerNum; // item position
if (position >= 0) {
int column = position % spanCount; // item column
if(isRtl) {
column = spanCount - 1 - column;
}
if (includeEdge) {
outRect.left = spacing - column * spacing / spanCount; // spacing - column * ((1f / spanCount) * spacing)
outRect.right = (column + 1) * spacing / spanCount; // (column + 1) * ((1f / spanCount) * spacing)
if (position < spanCount) { // top edge
outRect.top = spacing;
}
outRect.bottom = spacing; // item bottom
} else {
outRect.left = column * spacing / spanCount; // column * ((1f / spanCount) * spacing)
outRect.right = spacing - (column + 1) * spacing / spanCount; // spacing - (column + 1) * ((1f / spanCount) * spacing)
if (position >= spanCount) {
outRect.top = spacing; // item top
}
}
} else {
outRect.left = 0;
outRect.right = 0;
outRect.top = 0;
outRect.bottom = 0;
}
}
}
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