Android - 水平滾動左右使用RecyclerView

Question

我做了一個自定義佈局管理器來平滑滾動後點擊左鍵或右鍵。一切只在滾動時才起作用！對於，computeScrollVectorForPosition永遠不會被調用。是什麼賦予了？我試過設置mReverseLayout時，但沒有幫助。任何我沒有做的事/俯視？

public class SmoothScrollLayoutManager extends LinearLayoutManager { 

private static final float MILLISECONDS_PER_INCH = 50f; 
private Context context; 
public boolean shouldGoRight = false; 

public SmoothScrollLayoutManager(Context context, int orientation, boolean reverseLayout) { 
    super(context, orientation, reverseLayout); 
    this.context = context; 
} 

@Override 
public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position) { 
    LinearSmoothScroller smoothScroller = new LinearSmoothScroller(context) { 

     @Override 
     public PointF computeScrollVectorForPosition(int targetPosition) { 
      if (getChildCount() == 0) { 
       return null; 
      } 
      final int firstChildPos = getPosition(getChildAt(0)); 
      final int direction = targetPosition < firstChildPos != shouldGoRight ? -1 : 1; 
      return new PointF(direction, 0); 

     } 

     @Override 
     protected float calculateSpeedPerPixel(DisplayMetrics displayMetrics) { 
      return MILLISECONDS_PER_INCH/displayMetrics.densityDpi; 
     } 
    }; 

    smoothScroller.setTargetPosition(position); 
    startSmoothScroll(smoothScroller); 
} 

}

Answer 1

comupteScrollVectorForPosition只打電話找出來到其中的LinearSmoothScroller有滾動到最終找到該元素的方向。如果LinearSmoothScroller已經想知道元素在哪裏，它將不會調用這個函數。已經加載顯示的元素就是這種情況，就像右側的元素一樣。