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
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
}
}
其他回答
class VerticalGridSpacingDecoration(private val spacing: Int) : RecyclerView.ItemDecoration() {
override fun getItemOffsets(
outRect: Rect,
view: View,
parent: RecyclerView,
state: State
) {
val layoutManager = parent.layoutManager as? GridLayoutManager
if (layoutManager == null || layoutManager.orientation != VERTICAL) {
return super.getItemOffsets(outRect, view, parent, state)
}
val spanCount = layoutManager.spanCount
val position = parent.getChildAdapterPosition(view)
val column = position % spanCount
with(outRect) {
left = if (column == 0) 0 else spacing / 2
right = if (column == spanCount.dec()) 0 else spacing / 2
top = if (position < spanCount) 0 else spacing
}
}
}
如果你想要物品周围的间距和物品大小相等,下面是一步一步的简单解决方案。
ItemOffsetDecoration
public class ItemOffsetDecoration extends RecyclerView.ItemDecoration {
private int mItemOffset;
public ItemOffsetDecoration(int itemOffset) {
mItemOffset = itemOffset;
}
public ItemOffsetDecoration(@NonNull Context context, @DimenRes int itemOffsetId) {
this(context.getResources().getDimensionPixelSize(itemOffsetId));
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
outRect.set(mItemOffset, mItemOffset, mItemOffset, mItemOffset);
}
}
实现
在源代码中,将ItemOffsetDecoration添加到RecyclerView中。 项偏移值应该是实际值的一半大小,作为项之间的空间。
mRecyclerView.setLayoutManager(new GridLayoutManager(context, NUM_COLUMNS);
ItemOffsetDecoration itemDecoration = new ItemOffsetDecoration(context, R.dimen.item_offset);
mRecyclerView.addItemDecoration(itemDecoration);
同样,设置项目偏移值为itsRecyclerView的填充,并指定android:clipToPadding=false。
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerview_grid"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipToPadding="false"
android:padding="@dimen/item_offset"/>
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!:)
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));
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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