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
确保你在gradle模块中实现了这个:
implementation 'com.github.grzegorzojdana:SpacingItemDecoration:1.1.0'
创建这个简单的函数:
public static int dpToPx(Context c, int dp) {
Resources r = c.getResources();
return Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, r.getDisplayMetrics()));
}
最后实现如下所示的空格:
photosRecycler.addItemDecoration(new SpacingItemDecoration(2, dpToPx(this, 4), true));
其他回答
对于任何像我一样,想要最好的答案,但在kotlin,这里是:
class GridItemDecoration(
val spacing: Int,
private val spanCount: Int,
private val includeEdge: Boolean
) :
RecyclerView.ItemDecoration() {
/**
* 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
) {
val position = parent.getChildAdapterPosition(view) // item position
val 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
}
}
}
}
如果你想从dimensions .xml中获取数字,然后将其转换为原始像素,你可以使用getDimensionPixelOffset简单地做到这一点,就像这样:
recyclerView.addItemDecoration(
GridItemDecoration(
resources.getDimensionPixelOffset(R.dimen.h1),
3,
true
)
)
下面的代码将处理StaggeredGridLayoutManager、GridLayoutManager和LinearLayoutManager。
public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
private int halfSpace;
public SpacesItemDecoration(int space) {
this.halfSpace = space / 2;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
if (parent.getPaddingLeft() != halfSpace) {
parent.setPadding(halfSpace, halfSpace, halfSpace, halfSpace);
parent.setClipToPadding(false);
}
outRect.top = halfSpace;
outRect.bottom = halfSpace;
outRect.left = halfSpace;
outRect.right = halfSpace;
}
}
然后使用它
mRecyclerView.addItemDecoration(new SpacesItemDecoration(mMargin));
public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {
private int spanCount;
private int spacing;
private boolean includeEdge;
public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge) {
this.spanCount = spanCount;
this.spacing = spacing;
this.includeEdge = includeEdge;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
StaggeredGridLayoutManager.LayoutParams params = (StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams();
int column = params.getSpanIndex();
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
}
}
}
}
与edwardaa的回答略有不同,不同之处在于列是如何确定的,因为在一些情况下,例如具有不同高度的项目,列不能简单地通过% spanCount确定
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。
上面的回答已经阐明了设置边缘处理GridLayoutManager和LinearLayoutManager的方法。
但是对于StaggeredGridLayoutManager, Pirdad Sakhizada的回答是:“它可能不太适合StaggeredGridLayoutManager”。应该是关于IndexOfSpan的问题。
您可以通过以下方式获取:
private static class MyItemDecoration extends RecyclerView.ItemDecoration {
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
int index = ((StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams()).getSpanIndex();
}
}
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