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
下面的代码将处理StaggeredGridLayoutManager、GridLayoutManager和LinearLayoutManager。
public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
private int halfSpace;
public SpacesItemDecoration(int space) {
this.halfSpace = space / 2;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
if (parent.getPaddingLeft() != halfSpace) {
parent.setPadding(halfSpace, halfSpace, halfSpace, halfSpace);
parent.setClipToPadding(false);
}
outRect.top = halfSpace;
outRect.bottom = halfSpace;
outRect.left = halfSpace;
outRect.right = halfSpace;
}
}
然后使用它
mRecyclerView.addItemDecoration(new SpacesItemDecoration(mMargin));
其他回答
这个问题的答案似乎比他们应该做的要复杂。以下是我的看法。
假设您希望网格项之间有1dp的间距。做以下几点:
为每个项目添加0.5dp的填充 给RecycleView添加-0.5dp的填充 就是这样!:)
当为儿童使用CardView时,项目之间的空格问题可以通过设置app:cardUseCompatPadding为true来解决。
为更大的边际扩大项目抬高。CardElevation是可选的(使用默认值)。
<androidx.cardview.widget.CardView
xmlns:app="http://schemas.android.com/apk/res-auto"
app:cardUseCompatPadding="true"
app:cardElevation="2dp">
下面是一个不需要“spanCount”(列数)的解决方案 我使用它是因为我使用GridAutofitLayoutManager(根据所需的单元格大小计算列数)
(注意,这将只工作在GridLayoutManager)
public class GridSpacesItemDecoration extends RecyclerView.ItemDecoration {
private final boolean includeEdge;
private int spacing;
public GridSpacesItemDecoration(int spacing, boolean includeEdge) {
this.spacing = spacing;
this.includeEdge = includeEdge;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
if (parent.getLayoutManager() instanceof GridLayoutManager) {
GridLayoutManager layoutManager = (GridLayoutManager)parent.getLayoutManager();
int spanCount = layoutManager.getSpanCount();
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
}
}
}
}
}
这是GridAutofitLayoutManager是谁感兴趣:
public class GridAutofitLayoutManager extends GridLayoutManager {
private int mColumnWidth;
private boolean mColumnWidthChanged = true;
public GridAutofitLayoutManager(Context context, int columnWidth)
{
/* Initially set spanCount to 1, will be changed automatically later. */
super(context, 1);
setColumnWidth(checkedColumnWidth(context, columnWidth));
}
public GridAutofitLayoutManager(Context context,int unit, int columnWidth)
{
/* Initially set spanCount to 1, will be changed automatically later. */
super(context, 1);
int pixColumnWidth = (int) TypedValue.applyDimension(unit, columnWidth, context.getResources().getDisplayMetrics());
setColumnWidth(checkedColumnWidth(context, pixColumnWidth));
}
public GridAutofitLayoutManager(Context context, int columnWidth, int orientation, boolean reverseLayout)
{
/* Initially set spanCount to 1, will be changed automatically later. */
super(context, 1, orientation, reverseLayout);
setColumnWidth(checkedColumnWidth(context, columnWidth));
}
private int checkedColumnWidth(Context context, int columnWidth)
{
if (columnWidth <= 0)
{
/* Set default columnWidth value (48dp here). It is better to move this constant
to static constant on top, but we need context to convert it to dp, so can't really
do so. */
columnWidth = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 48,
context.getResources().getDisplayMetrics());
}
return columnWidth;
}
public void setColumnWidth(int newColumnWidth)
{
if (newColumnWidth > 0 && newColumnWidth != mColumnWidth)
{
mColumnWidth = newColumnWidth;
mColumnWidthChanged = true;
}
}
@Override
public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state)
{
int width = getWidth();
int height = getHeight();
if (mColumnWidthChanged && mColumnWidth > 0 && width > 0 && height > 0)
{
int totalSpace;
if (getOrientation() == VERTICAL)
{
totalSpace = width - getPaddingRight() - getPaddingLeft();
}
else
{
totalSpace = height - getPaddingTop() - getPaddingBottom();
}
int spanCount = Math.max(1, totalSpace / mColumnWidth);
setSpanCount(spanCount);
mColumnWidthChanged = false;
}
super.onLayoutChildren(recycler, state);
}
}
最后:
mDevicePhotosView.setLayoutManager(new GridAutofitLayoutManager(getContext(), getResources().getDimensionPixelSize(R.dimen.item_size)));
mDevicePhotosView.addItemDecoration(new GridSpacesItemDecoration(Util.dpToPx(getContext(), 2),true));
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) {
StaggeredGridLayoutManager.LayoutParams params = (StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams();
int column = params.getSpanIndex();
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
}
}
}
}
与edwardaa的回答略有不同,不同之处在于列是如何确定的,因为在一些情况下,例如具有不同高度的项目,列不能简单地通过% spanCount确定
我根据edwardaa的回答做了一个Kotlin版本
class RecyclerItemDecoration(private val spanCount: Int, private val spacing: Int) : RecyclerView.ItemDecoration() {
override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
val spacing = Math.round(spacing * parent.context.resources.displayMetrics.density)
val position = parent.getChildAdapterPosition(view)
val column = position % spanCount
outRect.left = spacing - column * spacing / spanCount
outRect.right = (column + 1) * spacing / spanCount
outRect.top = if (position < spanCount) spacing else 0
outRect.bottom = spacing
}
}
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