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
选择的答案几乎是完美的,但根据空间的不同,项目的宽度可能不相等。(对我来说,这很关键)。所以我最终用这个代码增加了一点空间,所以项目都是相同的宽度。
class GridSpacingItemDecoration(private val columnCount: Int, @Px preferredSpace: Int, private val includeEdge: Boolean): RecyclerView.ItemDecoration() {
/**
* In this algorithm space should divide by 3 without remnant or width of items can have a difference
* and we want them to be exactly the same
*/
private val space = if (preferredSpace % 3 == 0) preferredSpace else (preferredSpace + (3 - preferredSpace % 3))
override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State?) {
val position = parent.getChildAdapterPosition(view)
if (includeEdge) {
when {
position % columnCount == 0 -> {
outRect.left = space
outRect.right = space / 3
}
position % columnCount == columnCount - 1 -> {
outRect.right = space
outRect.left = space / 3
}
else -> {
outRect.left = space * 2 / 3
outRect.right = space * 2 / 3
}
}
if (position < columnCount) {
outRect.top = space
}
outRect.bottom = space
} else {
when {
position % columnCount == 0 -> outRect.right = space * 2 / 3
position % columnCount == columnCount - 1 -> outRect.left = space * 2 / 3
else -> {
outRect.left = space / 3
outRect.right = space / 3
}
}
if (position >= columnCount) {
outRect.top = space
}
}
}
}
其他回答
如果你使用Header和GridLayoutManager,使用以下代码在Kotlin中编写的网格间距:
inner class SpacesItemDecoration(itemSpace: Int) : RecyclerView.ItemDecoration() {
var space: Int = itemSpace
override fun getItemOffsets(outRect: Rect?, view: View?, parent: RecyclerView?, state: RecyclerView.State?) {
super.getItemOffsets(outRect, view, parent, state)
val position = parent!!.getChildAdapterPosition(view)
val viewType = parent.adapter.getItemViewType(position)
// Check to not to set any margin to header item
if (viewType == GridViewAdapter.TYPE_HEADER) {
outRect!!.top = 0
outRect.left = 0
outRect.right = 0
outRect.bottom = 0
} else {
outRect!!.left = space
outRect.right = space
outRect.bottom = space
if (parent.getChildLayoutPosition(view) == 0) {
outRect.top = space
} else {
outRect.top = 0
}
}
}
}
并将ItemDecoration传递给RecyclerView为:
gridView.addItemDecoration(SpacesItemDecoration(10))
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。
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
}
}
}
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;
}
}
}
}
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