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
下面的代码工作得很好，每个列都有相同的宽度:
public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {
private int spanCount;
private int spacing;
private boolean includeEdge;
public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge) {
this.spanCount = spanCount;
this.spacing = spacing;
this.includeEdge = includeEdge;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
int position = parent.getChildAdapterPosition(view); // item position
int column = position % spanCount; // item 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
}
}
}
}
使用
1. 没有优势
int spanCount = 3; // 3 columns
int spacing = 50; // 50px
boolean includeEdge = false;
recyclerView.addItemDecoration(new GridSpacingItemDecoration(spanCount, spacing, includeEdge));
2. 与边缘
int spanCount = 3; // 3 columns
int spacing = 50; // 50px
boolean includeEdge = true;
recyclerView.addItemDecoration(new GridSpacingItemDecoration(spanCount, spacing, includeEdge));
其他回答
这是我对SpacesItemDecoration的修改，它可以在顶部，底部，左边和右边同样采取numofcolumns和空间。
public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
private int space;
private int mNumCol;
public SpacesItemDecoration(int space, int numCol) {
this.space = space;
this.mNumCol=numCol;
}
@Override
public void getItemOffsets(Rect outRect, View view,
RecyclerView parent, RecyclerView.State state) {
//outRect.right = space;
outRect.bottom = space;
//outRect.left = space;
//Log.d("ttt", "item position" + parent.getChildLayoutPosition(view));
int position=parent.getChildLayoutPosition(view);
if(mNumCol<=2) {
if (position == 0) {
outRect.left = space;
outRect.right = space / 2;
} else {
if ((position % mNumCol) != 0) {
outRect.left = space / 2;
outRect.right = space;
} else {
outRect.left = space;
outRect.right = space / 2;
}
}
}else{
if (position == 0) {
outRect.left = space;
outRect.right = space / 2;
} else {
if ((position % mNumCol) == 0) {
outRect.left = space;
outRect.right = space/2;
} else if((position % mNumCol) == (mNumCol-1)){
outRect.left = space/2;
outRect.right = space;
}else{
outRect.left=space/2;
outRect.right=space/2;
}
}
}
if(position<mNumCol){
outRect.top=space;
}else{
outRect.top=0;
}
// Add top margin only for the first item to avoid double space between items
/*
if (parent.getChildLayoutPosition(view) == 0 ) {
} else {
outRect.top = 0;
}*/
}
}
并在逻辑上使用下面的代码。
recyclerView.addItemDecoration(new SpacesItemDecoration(spacingInPixels, numCol));
这是我在Kotlin中编写的更灵活的版本，您可以在dp中设置参数。
class ItemDividerGrid(private val numberOfColumns: Int, private val rowSpacingDP: Float = 0f, private val columnSpacingDP: Float = 0f, private val edgeSpacingVerticalDP: Float = 0f, private val edgeSpacingHorizontalDP: Float = 0f) : ItemDecoration() {
override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
val position = parent.getChildAdapterPosition(view)
val numberOfRows = (parent.adapter?.itemCount?:-1)/numberOfColumns
val column = position % numberOfColumns
val row = position / numberOfColumns
val context = view.context
///horizontal
when(column){
0 -> {
outRect.left = convertDpToPixel(edgeSpacingVerticalDP,context)
outRect.right = convertDpToPixel(columnSpacingDP/2, context)
}
numberOfColumns-1 -> {
outRect.left = convertDpToPixel(columnSpacingDP/2, context)
outRect.right = convertDpToPixel(edgeSpacingVerticalDP, context)
}
else -> {
outRect.left = convertDpToPixel(columnSpacingDP/2, context)
outRect.right = convertDpToPixel(columnSpacingDP/2, context)
}
}
//vertical
when(row){
0 -> {
outRect.top = convertDpToPixel(edgeSpacingHorizontalDP,context)
outRect.bottom = convertDpToPixel(rowSpacingDP/2, context)
}
numberOfRows -> {
outRect.top = convertDpToPixel(rowSpacingDP/2, context)
outRect.bottom = convertDpToPixel(edgeSpacingHorizontalDP, context)
}
else -> {
outRect.top = convertDpToPixel(rowSpacingDP/2, context)
outRect.bottom = convertDpToPixel(rowSpacingDP/2, context)
}
}
}
fun convertDpToPixel(dp: Float, context: Context?): Int {
return if (context != null) {
val resources = context.resources
val metrics = resources.displayMetrics
(dp * (metrics.densityDpi.toFloat() / DisplayMetrics.DENSITY_DEFAULT)).roundToInt()
} else {
val metrics = Resources.getSystem().displayMetrics
(dp * (metrics.densityDpi.toFloat() / DisplayMetrics.DENSITY_DEFAULT)).roundToInt()
}
}
}
如果你想要物品周围的间距和物品大小相等，下面是一步一步的简单解决方案。
ItemOffsetDecoration
public class ItemOffsetDecoration extends RecyclerView.ItemDecoration {
private int mItemOffset;
public ItemOffsetDecoration(int itemOffset) {
mItemOffset = itemOffset;
}
public ItemOffsetDecoration(@NonNull Context context, @DimenRes int itemOffsetId) {
this(context.getResources().getDimensionPixelSize(itemOffsetId));
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
outRect.set(mItemOffset, mItemOffset, mItemOffset, mItemOffset);
}
}
实现
在源代码中，将ItemOffsetDecoration添加到RecyclerView中。 项偏移值应该是实际值的一半大小，作为项之间的空间。
mRecyclerView.setLayoutManager(new GridLayoutManager(context, NUM_COLUMNS);
ItemOffsetDecoration itemDecoration = new ItemOffsetDecoration(context, R.dimen.item_offset);
mRecyclerView.addItemDecoration(itemDecoration);
同样，设置项目偏移值为itsRecyclerView的填充，并指定android:clipToPadding=false。
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerview_grid"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipToPadding="false"
android:padding="@dimen/item_offset"/>
RecyclerViews支持ItemDecoration的概念:围绕每个元素的特殊偏移和绘图。从这个答案中可以看出，你可以使用
public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
private int space;
public SpacesItemDecoration(int space) {
this.space = space;
}
@Override
public void getItemOffsets(Rect outRect, View view,
RecyclerView parent, RecyclerView.State state) {
outRect.left = space;
outRect.right = space;
outRect.bottom = space;
// Add top margin only for the first item to avoid double space between items
if (parent.getChildLayoutPosition(view) == 0) {
outRect.top = space;
} else {
outRect.top = 0;
}
}
}
然后通过
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.my_recycler_view);
int spacingInPixels = getResources().getDimensionPixelSize(R.dimen.spacing);
mRecyclerView.addItemDecoration(new SpacesItemDecoration(spacingInPixels));
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。
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