Java 使用RecyclerView GridLayoutManager按Item装饰设置列间距时,项的宽度不同
我正在尝试使用Java 使用RecyclerView GridLayoutManager按Item装饰设置列间距时,项的宽度不同,java,android,android-recyclerview,gridlayoutmanager,Java,Android,Android Recyclerview,Gridlayoutmanager,我正在尝试使用RecyclerView和GridLayoutManager创建一个3列网格,我使用ItemDecoration创建列间距,现在的问题是第三列中的项目宽度小于第一列和第二列中的项目!请参见下面的屏幕截图 如果我不将自定义的项目装饰添加到回收视图,一切正常 这是我的密码: MainActivity.java: public class MainActivity extends AppCompatActivity { private RecyclerView mRecycl
RecyclerView
和GridLayoutManager
创建一个3列网格,我使用ItemDecoration
创建列间距,现在的问题是第三列中的项目宽度小于第一列和第二列中的项目!请参见下面的屏幕截图
如果我不将自定义的项目装饰
添加到回收视图
,一切正常
这是我的密码:
MainActivity.java:
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private MyAdapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
mAdapter = new MyAdapter();
mRecyclerView.setAdapter(mAdapter);
GridLayoutManager gridLayoutManager = new GridLayoutManager(this, 3);
mRecyclerView.setLayoutManager(gridLayoutManager);
int horizontalSpacing = 20;
int verticalSpacing = 10;
SpacingDecoration decoration = new SpacingDecoration(horizontalSpacing, verticalSpacing, true);
mRecyclerView.addItemDecoration(decoration);
}
private static class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private int[] mColors = new int[]{Color.RED, Color.BLUE, Color.MAGENTA};
private static class ItemHolder extends RecyclerView.ViewHolder {
public MyTextView title;
public ItemHolder(View itemView) {
super(itemView);
title = (MyTextView) itemView.findViewById(android.R.id.text1);
title.setTextColor(Color.WHITE);
}
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item, parent, false);
ItemHolder holder = new ItemHolder(itemView);
holder.itemView.setOnClickListener(itemClickListener);
return holder;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder rHolder, int position) {
ItemHolder holder = (ItemHolder) rHolder;
holder.title.setText(String.format("[%d]width:%d", position, holder.itemView.getWidth()));
holder.itemView.setBackgroundColor(mColors[position % mColors.length]);
holder.itemView.setTag(position);
holder.title.setTag(position);
}
@Override
public int getItemCount() {
return 50;
}
private View.OnClickListener itemClickListener = new View.OnClickListener() {
@Override
public void onClick(View v) {
int position = (int) v.getTag();
showText(v.getContext(), String.format("[%d]->width:%d", position, v.getWidth()));
}
};
}
public static class SpacingDecoration extends RecyclerView.ItemDecoration {
private int mHorizontalSpacing = 5;
private int mVerticalSpacing = 5;
private boolean isSetMargin = true;
public SpacingDecoration(int hSpacing, int vSpacing, boolean setMargin) {
isSetMargin = setMargin;
mHorizontalSpacing = hSpacing;
mVerticalSpacing = vSpacing;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
boolean isSetMarginLeftAndRight = this.isSetMargin;
int bottomOffset = mVerticalSpacing;
int leftOffset = 0;
int rightOffset = 0;
RecyclerView.LayoutParams lp = (RecyclerView.LayoutParams) view.getLayoutParams();
if (parent.getLayoutManager() instanceof GridLayoutManager) {
GridLayoutManager lm = (GridLayoutManager) parent.getLayoutManager();
GridLayoutManager.LayoutParams gridLp = (GridLayoutManager.LayoutParams) lp;
if (gridLp.getSpanSize() == lm.getSpanCount()) {
// Current item is occupied the whole row
// We just need to care about margin left and right now
if (isSetMarginLeftAndRight) {
leftOffset = mHorizontalSpacing;
rightOffset = mHorizontalSpacing;
}
} else {
// Current item isn't occupied the whole row
if (gridLp.getSpanIndex() > 0) {
// Set space between items in one row
leftOffset = mHorizontalSpacing;
} else if (gridLp.getSpanIndex() == 0 && isSetMarginLeftAndRight) {
// Set left margin of a row
leftOffset = mHorizontalSpacing;
}
if (gridLp.getSpanIndex() == lm.getSpanCount() - gridLp.getSpanSize() && isSetMarginLeftAndRight) {
// Set right margin of a row
rightOffset = mHorizontalSpacing;
}
}
}
outRect.set(leftOffset, 0, rightOffset, bottomOffset);
}
}
private static Toast sToast;
public static void showText(Context context, String text) {
if (sToast != null) {
sToast.cancel();
}
sToast = Toast.makeText(context, text, Toast.LENGTH_LONG);
sToast.show();
}
}
如果有人能解释这个问题,我将不胜感激。我自己找到了问题的原因。
项目装饰
中的偏移量被视为项目尺寸(宽度和高度)的一部分
让我们看看上面问题中的示例代码和屏幕截图。屏幕截图的宽度是480像素,这里有3列,每个项目的宽度是480/3=160像素。在SpacingDecoration
中,我在第一列和第二列上添加了一个左偏移量(20像素),因此第一列和第二列项目的内容宽度为160-20=140,然后我在第三列项目上添加了左偏移量和右偏移量,因此第三列项目的内容宽度为160-20-20=120
现在我们要使每个项目的内容(彩色矩形)具有相同的宽度,我们必须计算每个列项目除以一行的总间距的多少,但我不擅长编写详细的分析,因此我在这里编写了一个粗略的计算过程,您可以传递它并跳到结论
spacing = 20
columnCount = 3
rowWidth = 480
itemWidth = rowWidth / columnCount
itemOccupiedSpacing = (spacing * (columnCount + 1)) / columnCount = spacing + spacing * (1/columnCount)
itemContentWidth = itemWidth - itemOccupiedSpacing
firstItemLeftOffset = spacing = spacing * (3/columnCount)
firstItemRightOffset = itemOccupiedSpacing - spacing = spacing * (1/columnCount)
secondItemLeftOffset = spacing - firstRightOffset = spacing * (2/columnCount)
secondItemRightOffset = itemOccupiedSpacing - secondLeftOffset = spacing * (2/columnCount)
thirdItemLeftOffset = itemOccupiedSpacing - secondLeftOffset = spacing * (1/columnCount)
thirdItemRightOffset = spacing = spacing * (3/columnCount)
我们可以得出结论:
itemLeftOffset = spacing * ((columnCount - colunmnIndex) / columnCount)
itemRightOffset = spacing * ((colunmnIndex + 1) / columnCount)
colunmnIndex大于0且小于columnCount
这是我自定义的
项目装饰
间距,它与线性布局管理器
、网格布局管理器
和交错网格布局管理器
配合得很好,所有项目的宽度都相同。您可以在代码中直接使用它
public class SpacingDecoration extends ItemDecoration {
private int mHorizontalSpacing = 0;
private int mVerticalSpacing = 0;
private boolean mIncludeEdge = false;
public SpacingDecoration(int hSpacing, int vSpacing, boolean includeEdge) {
mHorizontalSpacing = hSpacing;
mVerticalSpacing = vSpacing;
mIncludeEdge = includeEdge;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
// Only handle the vertical situation
int position = parent.getChildAdapterPosition(view);
if (parent.getLayoutManager() instanceof GridLayoutManager) {
GridLayoutManager layoutManager = (GridLayoutManager) parent.getLayoutManager();
int spanCount = layoutManager.getSpanCount();
int column = position % spanCount;
getGridItemOffsets(outRect, position, column, spanCount);
} else if (parent.getLayoutManager() instanceof StaggeredGridLayoutManager) {
StaggeredGridLayoutManager layoutManager = (StaggeredGridLayoutManager) parent.getLayoutManager();
int spanCount = layoutManager.getSpanCount();
StaggeredGridLayoutManager.LayoutParams lp = (StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams();
int column = lp.getSpanIndex();
getGridItemOffsets(outRect, position, column, spanCount);
} else if (parent.getLayoutManager() instanceof LinearLayoutManager) {
outRect.left = mHorizontalSpacing;
outRect.right = mHorizontalSpacing;
if (mIncludeEdge) {
if (position == 0) {
outRect.top = mVerticalSpacing;
}
outRect.bottom = mVerticalSpacing;
} else {
if (position > 0) {
outRect.top = mVerticalSpacing;
}
}
}
}
private void getGridItemOffsets(Rect outRect, int position, int column, int spanCount) {
if (mIncludeEdge) {
outRect.left = mHorizontalSpacing * (spanCount - column) / spanCount;
outRect.right = mHorizontalSpacing * (column + 1) / spanCount;
if (position < spanCount) {
outRect.top = mVerticalSpacing;
}
outRect.bottom = mVerticalSpacing;
} else {
outRect.left = mHorizontalSpacing * column / spanCount;
outRect.right = mHorizontalSpacing * (spanCount - 1 - column) / spanCount;
if (position >= spanCount) {
outRect.top = mVerticalSpacing;
}
}
}
}
public类间距分隔扩展ItemDecoration{
私有int mHorizontalSpacing=0;
私有int mVerticalSpacing=0;
私有布尔值mincludedge=false;
公共间距分隔(int hSpacing、int vSpacing、布尔includeEdge){
mHorizontalSpacing=hSpacing;
mVerticalSpacing=vSpacing;
MINCLUDEDGE=包含边缘;
}
@凌驾
public void getItemOffsets(Rect outRect、View View、RecyclerView父级、RecyclerView.State){
super.getItemOffset(outRect、view、parent、state);
//只处理垂直的情况
int position=parent.getChildAdapterPosition(视图);
if(GridLayoutManager的parent.getLayoutManager()实例){
GridLayoutManager布局管理器=(GridLayoutManager)父级。getLayoutManager();
int spanCount=layoutManager.getSpanCount();
int列=位置%spanCount;
GetGridItemOffset(outRect、position、column、spanCount);
}else if(StaggedGridLayoutManager的父级.getLayoutManager()实例){
StaggedGridLayoutManager布局管理器=(StaggedGridLayoutManager)父级。getLayoutManager();
int spanCount=layoutManager.getSpanCount();
StaggedGridLayoutManager.LayoutParams lp=(StaggedGridLayoutManager.LayoutParams)视图。getLayoutParams();
int column=lp.getSpanIndex();
GetGridItemOffset(outRect、position、column、spanCount);
}else if(LinearLayoutManager的父级.getLayoutManager()实例){
outRect.left=mHorizontalSpacing;
outRect.right=mHorizontalSpacing;
if(mincludedge){
如果(位置==0){
outRect.top=垂直间距;
}
outRect.bottom=垂直间距;
}否则{
如果(位置>0){
outRect.top=垂直间距;
}
}
}
}
私有void getGridItemOffset(Rect-outRect、int-position、int-column、int-spanCount){
if(mincludedge){
outRect.left=mHorizontalSpacing*(spanCount-列)/spanCount;
outRect.right=mHorizontalSpacing*(列+1)/spanCount;
如果(位置=spanCount){
outRect.top=垂直间距;
}
}
}
}
根据@AvatarQing的回答,我写了一个更加健壮的项目装饰:
您可以在项目之间设置相同的垂直或水平间距,此外还可以为不同类型的项目设置不同的间距
在您的公式中,右边距中的
+1
实际上不是+1
,它应该是单元格的+span大小
。(您可以使用spanSizeLookup或在单元格的LayoutParams中检索跨度大小)感谢分享@Bos!现在,您的类的关键部分已经包含在库中并得到了改进,以处理更高级的功能。
spacing = 20
columnCount = 3
rowWidth = 480
itemWidth = rowWidth / columnCount
itemOccupiedSpacing = (spacing * (columnCount + 1)) / columnCount = spacing + spacing * (1/columnCount)
itemContentWidth = itemWidth - itemOccupiedSpacing
firstItemLeftOffset = spacing = spacing * (3/columnCount)
firstItemRightOffset = itemOccupiedSpacing - spacing = spacing * (1/columnCount)
secondItemLeftOffset = spacing - firstRightOffset = spacing * (2/columnCount)
secondItemRightOffset = itemOccupiedSpacing - secondLeftOffset = spacing * (2/columnCount)
thirdItemLeftOffset = itemOccupiedSpacing - secondLeftOffset = spacing * (1/columnCount)
thirdItemRightOffset = spacing = spacing * (3/columnCount)
itemLeftOffset = spacing * ((columnCount - colunmnIndex) / columnCount)
itemRightOffset = spacing * ((colunmnIndex + 1) / columnCount)
public class SpacingDecoration extends ItemDecoration {
private int mHorizontalSpacing = 0;
private int mVerticalSpacing = 0;
private boolean mIncludeEdge = false;
public SpacingDecoration(int hSpacing, int vSpacing, boolean includeEdge) {
mHorizontalSpacing = hSpacing;
mVerticalSpacing = vSpacing;
mIncludeEdge = includeEdge;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
// Only handle the vertical situation
int position = parent.getChildAdapterPosition(view);
if (parent.getLayoutManager() instanceof GridLayoutManager) {
GridLayoutManager layoutManager = (GridLayoutManager) parent.getLayoutManager();
int spanCount = layoutManager.getSpanCount();
int column = position % spanCount;
getGridItemOffsets(outRect, position, column, spanCount);
} else if (parent.getLayoutManager() instanceof StaggeredGridLayoutManager) {
StaggeredGridLayoutManager layoutManager = (StaggeredGridLayoutManager) parent.getLayoutManager();
int spanCount = layoutManager.getSpanCount();
StaggeredGridLayoutManager.LayoutParams lp = (StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams();
int column = lp.getSpanIndex();
getGridItemOffsets(outRect, position, column, spanCount);
} else if (parent.getLayoutManager() instanceof LinearLayoutManager) {
outRect.left = mHorizontalSpacing;
outRect.right = mHorizontalSpacing;
if (mIncludeEdge) {
if (position == 0) {
outRect.top = mVerticalSpacing;
}
outRect.bottom = mVerticalSpacing;
} else {
if (position > 0) {
outRect.top = mVerticalSpacing;
}
}
}
}
private void getGridItemOffsets(Rect outRect, int position, int column, int spanCount) {
if (mIncludeEdge) {
outRect.left = mHorizontalSpacing * (spanCount - column) / spanCount;
outRect.right = mHorizontalSpacing * (column + 1) / spanCount;
if (position < spanCount) {
outRect.top = mVerticalSpacing;
}
outRect.bottom = mVerticalSpacing;
} else {
outRect.left = mHorizontalSpacing * column / spanCount;
outRect.right = mHorizontalSpacing * (spanCount - 1 - column) / spanCount;
if (position >= spanCount) {
outRect.top = mVerticalSpacing;
}
}
}
}