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
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()
}
}
}
其他回答
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));
只有一个简单的解决方案，您可以记住并在任何需要的地方实施。没有bug，没有疯狂的计算。在卡片/物品布局中放置空白，并在RecyclerView中放置相同大小的填充:
item_layout.xml
<CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:margin="10dp">
activity_layout.xml
<RecyclerView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"/>
更新:
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()
}
}
}
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
}
}
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));
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