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
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));
其他回答
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));
Yqritc的回答非常适合我。我用的是Kotlin，这里有一个等价物。
class ItemOffsetDecoration : RecyclerView.ItemDecoration {
// amount to add to padding
private val _itemOffset: Int
constructor(itemOffset: Int) {
_itemOffset = itemOffset
}
constructor(@NonNull context: Context, @DimenRes itemOffsetId: Int){
_itemOffset = context.resources.getDimensionPixelSize(itemOffsetId)
}
/**
* Applies padding to all sides of the [Rect], which is the container for the view
*/
override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView,state: RecyclerView.State) {
super.getItemOffsets(outRect, view, parent, state)
outRect.set(_itemOffset, _itemOffset, _itemOffset, _itemOffset)
}
}
其他一切都是一样的。
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;
}
}
}
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()
}
}
}
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