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
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;
}
}
}
其他回答
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"/>
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));
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
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));
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