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
为了使https://stackoverflow.com/a/29905000/1649371(上面)解决方案工作，我必须修改以下方法(以及所有后续调用)
@SuppressWarnings("all")
protected int getItemSpanSize(RecyclerView parent, View view, int childIndex) {
RecyclerView.LayoutManager mgr = parent.getLayoutManager();
if (mgr instanceof GridLayoutManager) {
return ((GridLayoutManager) mgr).getSpanSizeLookup().getSpanSize(childIndex);
} else if (mgr instanceof StaggeredGridLayoutManager) {
return ((StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams()).isFullSpan() ? spanCount : 1;
} else if (mgr instanceof LinearLayoutManager) {
return 1;
}
return -1;
}
@SuppressWarnings("all")
protected int getItemSpanIndex(RecyclerView parent, View view, int childIndex) {
RecyclerView.LayoutManager mgr = parent.getLayoutManager();
if (mgr instanceof GridLayoutManager) {
return ((GridLayoutManager) mgr).getSpanSizeLookup().getSpanIndex(childIndex, spanCount);
} else if (mgr instanceof StaggeredGridLayoutManager) {
return ((StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams()).getSpanIndex();
} else if (mgr instanceof LinearLayoutManager) {
return 0;
}
return -1;
}
其他回答
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
}
}
这也适用于RecyclerView with header。
public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {
private int spanCount;
private int spacing;
private boolean includeEdge;
private int headerNum;
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 (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;
}
}
}
}
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));
对于这个问题，有一个非常简单而灵活的解决方案，它只使用适用于每个LayoutManager的XML。
假设你想要一个相等的X间距(例如8dp)。
在另一个布局中包装CardView项 给外层布局填充X/2 (4dp) 使外层布局背景透明
...
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="200dp"
android:layout_height="200dp"
android:background="@android:color/transparent"
android:padding="4dip">
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v7.widget.CardView>
</LinearLayout>
给你的RecyclerView填充X/2 (4dp)
...
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="4dp" />
就是这样。你有完美的X (8dp)间距。
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));
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