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
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。
其他回答
对于那些有问题的staggeredLayoutManager(如https://imgur.com/XVutH5u)
recyclerView的方法:
getChildAdapterPosition(view)
getChildLayoutPosition(view)
有时返回-1作为索引,所以我们可能会遇到设置itemDecor的麻烦。我的解决方案是覆盖已弃用的ItemDecoration的方法:
public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent)
而不是新手:
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state)
是这样的:
recyclerView.addItemDecoration(new RecyclerView.ItemDecoration() {
@Override
public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
TheAdapter.VH vh = (TheAdapter.VH) recyclerView.findViewHolderForAdapterPosition(itemPosition);
View itemView = vh.itemView; //itemView is the base view of viewHolder
//or instead of the 2 lines above maybe it's possible to use View itemView = layoutManager.findViewByPosition(itemPosition) ... NOT TESTED
StaggeredGridLayoutManager.LayoutParams itemLayoutParams = (StaggeredGridLayoutManager.LayoutParams) itemView.getLayoutParams();
int spanIndex = itemLayoutParams.getSpanIndex();
if (spanIndex == 0)
...
else
...
}
});
到目前为止似乎对我有用:)
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));
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);
如果你有一个在列表和网格之间切换的拨动开关,不要忘记在设置任何新的项目装饰之前调用recyclerView.removeItemDecoration(..)。如果不是这样,那么新的间隔计算将是不正确的。
就像这样:
recyclerView.removeItemDecoration(gridItemDecorator)
recyclerView.removeItemDecoration(listItemDecorator)
if (showAsList) {
recyclerView.layoutManager = LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)
recyclerView.addItemDecoration(listItemDecorator)
} else {
recyclerView.layoutManager = GridLayoutManager(this, spanCount)
recyclerView.addItemDecoration(gridItemDecorator)
}
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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