Как центрировать горизонтальный андроид recycle ListView

Question

Я добавляю элементы в listview горизонтально, но если у меня есть один элемент, я хочу, чтобы он находился в центре по горизонтали.

Я пробовал много решений из переполнения стека, но все же помогал меньше.

1. Я попытался с помощью относительной раскладки (centerInParent, centerHorizontally)
2. гравитацию, layout_gravity недвижимости и т.д.

Пожалуйста, помогите.

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" android:layout_width="match_parent" 
    android:weightSum="10" 
    android:layout_height="match_parent"> 

    <LinearLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:id="@+id/noUser_layout" 
     android:orientation="vertical" 
     android:layout_weight="10" 
     android:visibility="gone" 
     android:gravity="center"> 

     <ImageView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:id="@+id/noMessageLogo" 
      android:src="@mipmap/eapp_icon"/> 

     <TextView android:text="@string/loading_Message" android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:layout_marginTop="15dp" 
      android:layout_marginLeft="25dp" 
      android:layout_marginRight="25dp" 
      android:id="@+id/noMessage" 
      android:gravity="center" 
      android:fontFamily="sans-serif" 
      android:textSize="16sp" 
      android:textStyle="bold" 
      android:textColor="@android:color/black" /> 
    </LinearLayout> 


    <LinearLayout 
     android:layout_width="match_parent" 
     android:layout_height="0dp" 
     android:id="@+id/parentLayout" 
     android:orientation="vertical" 
     android:layout_weight="3.8" 
     android:gravity="center|center_horizontal"> 

     <TextView android:text="Parent" android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_margin="10dp" 
      android:id="@+id/parentText" 
      android:gravity="center" 
      android:fontFamily="sans-serif" 
      android:textSize="16sp" 
      android:textStyle="bold" 
      android:textColor="@android:color/holo_blue_dark" /> 

      <android.support.v7.widget.RecyclerView 
       android:id="@+id/parentList" 
       android:layout_width="wrap_content" 
       android:layout_centerHorizontal="true" 
       android:layout_height="wrap_content" 
       /> 
    </LinearLayout> 

    <LinearLayout 
     android:layout_width="wrap_content" android:layout_height="0dp" 
     android:layout_gravity="center" 
     android:layout_weight="2.5" 
     android:paddingTop="10dp" 
     android:paddingBottom="10dp" 
     android:id="@+id/contactLayout" 
     android:layout_centerHorizontal="true" 
     android:orientation="vertical"> 

     <ImageView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_margin="8dp" 
      android:id="@+id/userImage" 
      android:layout_gravity="center" 
      android:src="@drawable/user_icon" /> 

     <TextView android:text="Contact Name" android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_marginLeft="5dp" 
      android:layout_marginRight="5dp" 
      android:id="@+id/name" 
      android:fontFamily="sans-serif" 
      android:textSize="15sp" 
      android:textStyle="bold" 
      android:layout_gravity="left" 
      android:textColor="@android:color/black"/> 
    </LinearLayout> 

    <LinearLayout 
     android:layout_width="match_parent" 
     android:layout_height="0dp" 
     android:id="@+id/childrenLayout" 
     android:layout_centerHorizontal="true" 
     android:layout_weight="3.8" 
     android:orientation="vertical" 
     android:gravity="center|center_horizontal"> 

     <TextView android:text="Child" android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:id="@+id/childText" 
      android:gravity="center" 
      android:layout_margin="10dp" 
      android:fontFamily="sans-serif" 
      android:textSize="16sp" 
      android:textStyle="bold" 
      android:textColor="@android:color/holo_blue_dark" /> 

     <android.support.v7.widget.RecyclerView 
      android:id="@+id/childList" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_gravity="center|center_horizontal" /> 

    </LinearLayout> 

</LinearLayout> 

Answer 1

Используйте этот макет менеджер на ваш RecyclerView

public class WrapContentLinearLayoutManager extends LinearLayoutManager { 

    public WrapContentLinearLayoutManager(Context context, int orientation, boolean reverseLayout) { 
     super(context, orientation, reverseLayout); 
    } 

    private int[] mMeasuredDimension = new int[2]; 

    @Override 
    public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, 
          int widthSpec, int heightSpec) { 
     final int widthMode = View.MeasureSpec.getMode(widthSpec); 
     final int heightMode = View.MeasureSpec.getMode(heightSpec); 
     final int widthSize = View.MeasureSpec.getSize(widthSpec); 
     final int heightSize = View.MeasureSpec.getSize(heightSpec); 
     int width = 0; 
     int height = 0; 
     for (int i = 0; i < getItemCount(); i++) { 
      measureScrapChild(recycler, i, 
        View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED), 
        View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED), 
        mMeasuredDimension); 

      if (getOrientation() == HORIZONTAL) { 
       width = width + mMeasuredDimension[0]; 
       if (i == 0) { 
        height = mMeasuredDimension[1]; 
       } 
      } else { 
       height = height + mMeasuredDimension[1]; 
       if (i == 0) { 
        width = mMeasuredDimension[0]; 
       } 
      } 
     } 
     switch (widthMode) { 
      case View.MeasureSpec.EXACTLY: 
       width = widthSize; 
      case View.MeasureSpec.AT_MOST: 
      case View.MeasureSpec.UNSPECIFIED: 
     } 

     switch (heightMode) { 
      case View.MeasureSpec.EXACTLY: 
       height = heightSize; 
      case View.MeasureSpec.AT_MOST: 
      case View.MeasureSpec.UNSPECIFIED: 
     } 

     setMeasuredDimension(width, height); 
    } 

    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec, 
            int heightSpec, int[] measuredDimension) { 
     View view = recycler.getViewForPosition(position); 
     if (view != null) { 
      RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams(); 
      int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec, 
        getPaddingLeft() + getPaddingRight(), p.width); 
      int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec, 
        getPaddingTop() + getPaddingBottom(), p.height); 
      view.measure(childWidthSpec, childHeightSpec); 
      measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin; 
      measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin; 
      recycler.recycleView(view); 
     } 
    } 
} 

Answer 2

Этот простой example решить мою проблему :)

, сокращенный код здесь:

public class SpinnerWheelActivity extends Activity { 

private static final int NUM_ITEMS = 3; 
private static final String BUNDLE_LIST_PIXELS = "allPixels"; 

private float itemWidth; 
private float padding; 
private float firstItemWidth; 
private float allPixels; 
private int mLastPosition; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_spinner_wheel); 
    Display display = getWindowManager().getDefaultDisplay(); 
    Point size = new Point(); 
    display.getSize(size); 
    itemWidth = getResources().getDimension(R.dimen.item_width); 
    padding = (size.x - itemWidth)/2; 
    firstItemWidth = getResources().getDimension(R.dimen.padding_item_width); 

    allPixels = 0; 

    final RecyclerView items = (RecyclerView) findViewById(R.id.item_list); 

    LinearLayoutManager shopItemslayoutManager = new LinearLayoutManager(getApplicationContext()); 
    shopItemslayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL); 
    items.setLayoutManager(shopItemslayoutManager); 

    // to center item 
    items.setOnScrollListener(new RecyclerView.OnScrollListener() { 
     @Override 
     public void onScrollStateChanged(RecyclerView recyclerView, int newState) { 
      super.onScrollStateChanged(recyclerView, newState); 
      synchronized (this) { 
       if (newState == RecyclerView.SCROLL_STATE_IDLE) { 
        calculatePositionAndScroll(recyclerView); 
       } 
      } 
     } 

     @Override 
     public void onScrolled(RecyclerView recyclerView, int dx, int dy) { 
      super.onScrolled(recyclerView, dx, dy); 
      allPixels += dx; 
     } 
    }); 

    ExtraItemsAdapter adapter = new ExtraItemsAdapter(NUM_ITEMS); 
    items.setAdapter(adapter); 

    if (NUM_ITEMS > 0) // init position 
     scrollListToPosition(items, 0); 

} 

@Override 
protected void onResume() { 
    super.onResume(); 
    //final RecyclerView items = (RecyclerView) findViewById(R.id.item_list); 
    //ViewTreeObserver vto = items.getViewTreeObserver(); 
    //vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() { 
    // @Override 
    // public void onGlobalLayout() { 
    //  items.getViewTreeObserver().removeOnGlobalLayoutListener(this); 
    //  calculatePositionAndScroll(items); 
    // } 
    //}); 
} 

private void calculatePositionAndScroll(RecyclerView recyclerView) { 
    int expectedPosition = Math.round((allPixels + padding - firstItemWidth)/itemWidth); 
    // Special cases for the padding items 
    if (expectedPosition == -1) { 
     expectedPosition = 0; 
    } else if (expectedPosition >= recyclerView.getAdapter().getItemCount() - 2) { 
     expectedPosition--; 
    } 
    scrollListToPosition(recyclerView, expectedPosition); 
} 

private void scrollListToPosition(RecyclerView recyclerView, int expectedPosition) { 
    float targetScrollPos = expectedPosition * itemWidth + firstItemWidth - padding; 
    float missingPx = targetScrollPos - allPixels; 
    if (missingPx != 0) { 
     recyclerView.smoothScrollBy((int) missingPx, 0); 
    } 
} 

@Override 
protected void onRestoreInstanceState(@NonNull Bundle savedInstanceState) { 
    super.onRestoreInstanceState(savedInstanceState); 
    allPixels = savedInstanceState.getFloat(BUNDLE_LIST_PIXELS); 
} 

@Override 
protected void onSaveInstanceState(@NonNull Bundle outState) { 
    super.onSaveInstanceState(outState); 
    outState.putFloat(BUNDLE_LIST_PIXELS, allPixels); 
} 

/*---------- Adapters ----------*/ 

public class ExtraItemsAdapter extends RecyclerView.Adapter<ViewHolder> { 
    private static final int VIEW_TYPE_PADDING = 1; 
    private static final int VIEW_TYPE_ITEM = 2; 

    private final int mNumItems; 

    public ExtraItemsAdapter(int numItems) { 
     mNumItems = numItems; 
    } 

    @Override 
    public int getItemCount() { 
     return mNumItems + 2; // We have to add 2 paddings 
    } 

    @Override 
    public int getItemViewType(int position) { 
     if (position == 0 || position == getItemCount() - 1) { 
      return VIEW_TYPE_PADDING; 
     } 
     return VIEW_TYPE_ITEM; 
    } 

    @Override 
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
     // create a new view 
     if (viewType == VIEW_TYPE_ITEM) { 
      View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item, parent, false); 
      return new ViewHolder(v); 
     } else { 
      View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_padding, parent, false); 
      return new ViewHolder(v); 
     } 
    } 

    @Override 
    public void onBindViewHolder(ViewHolder holder, final int position) { 
     if (getItemViewType(position) == VIEW_TYPE_ITEM) { 
      // We bind the item to the view 
      holder.text.setText(String.valueOf(position)); 
     } 
    } 
} 

/*---------- ViewHolders ----------*/ 

public class ViewHolder extends RecyclerView.ViewHolder { 

    TextView text; 

    public ViewHolder(View itemView) { 
     super(itemView); 
     text = (TextView) itemView.findViewById(R.id.item_text); 
    } 
} 
} 

Answer 3

Я использовал окно менеджер, чтобы получить общую ширину экрана и использовать для установки режима просмотра.

В следующем Layout Manager для горизонтального вида рецикла т.е. LinearLayoutManager

public class WrapHeightLinearLayoutManager extends LinearLayoutManager { 

    Context mContext; 

    public WrapHeightLinearLayoutManager(Context context, int orientation, boolean reverseLayout) { 
     super(context, orientation, reverseLayout); 
     mContext = context; 
    } 

    private int[] mMeasuredDimension = new int[2]; 

    @Override 
    public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, 
          int widthSpec, int heightSpec) { 
     final int widthMode = View.MeasureSpec.getMode(widthSpec); 
     final int heightMode = View.MeasureSpec.getMode(heightSpec); 
     final int widthSize = View.MeasureSpec.getSize(widthSpec); 
     final int heightSize = View.MeasureSpec.getSize(heightSpec); 
     int width = 0; 
     int height = 0; 
     for (int i = 0; i < getItemCount(); i++) { 
      measureScrapChild(recycler, i, 
        View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED), 
        View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED), 
        mMeasuredDimension); 

      if (getOrientation() == HORIZONTAL) { 
       //width = width + mMeasuredDimension[0]; 
       if (i == 0) { 

        WindowManager wm = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE); 
        Display display = wm.getDefaultDisplay(); 
        Point size = new Point(); 
        display.getSize(size); 
        int widthWin = size.x; 
        int heightWin = size.y; 

        width = widthWin; 

        height = mMeasuredDimension[1]; 
       } 
      } else { 
       height = height + mMeasuredDimension[1]; 
       if (i == 0) { 
        width = mMeasuredDimension[0]; 
       } 
      } 
     } 
     switch (widthMode) { 
      case View.MeasureSpec.EXACTLY: 
       width = widthSize; 
      case View.MeasureSpec.AT_MOST: 
      case View.MeasureSpec.UNSPECIFIED: 
     } 

     switch (heightMode) { 
      case View.MeasureSpec.EXACTLY: 
       height = heightSize; 
      case View.MeasureSpec.AT_MOST: 
      case View.MeasureSpec.UNSPECIFIED: 
     } 

     Logger.getInstanceLogger().printVerbose("WrapHeightLinearLayoutManager","width ==>"+width+" height==>"+height); 

     setMeasuredDimension(width, height); 
    } 

    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec, 
            int heightSpec, int[] measuredDimension) { 
     View view = recycler.getViewForPosition(position); 
     if (view != null) { 
      RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams(); 
      int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec, 
        getPaddingLeft() + getPaddingRight(), p.width); 
      int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec, 
        getPaddingTop() + getPaddingBottom(), p.height); 
      view.measure(childWidthSpec, childHeightSpec); 
      measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin; 
      measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin; 
      recycler.recycleView(view); 
     } 
    } 

}