獲取最大Horizo​​ntalScrollView滾動量

Question

我將浮動箭頭添加到我的HorizontalScrollView，這將讓用戶知道當前視圖外有更多項目。

我需要的是如何判斷視圖是否滾動到最大。你可能會認爲方法getMaxScrollAmount()會給你這個 - 它不，在我的代碼中，它給了我視圖的寬度。去計算爲什麼。這裏是我的代碼 - 優雅而簡單：從上面的調試

final ImageView leftArrow = (ImageView) toReturn.findViewById(R.id.leftArrow); 
    final ImageView rightArrow = (ImageView) toReturn.findViewById(R.id.rightArrow); 

    final HorizontalScrollView scrollView = (HorizontalScrollView) toReturn.findViewById(R.id.actionBarHoriztonalScroll); 


    final GestureDetector gd = new GestureDetector(new SimpleOnGestureListener() { 
     @Override 
     public boolean onScroll(MotionEvent e1, 
           MotionEvent e2, 
           float distanceX, 
           float distanceY) { 
      if(scrollView.getScrollX() == 0) { 
       leftArrow.setVisibility(View.GONE); 
      } else { 
       leftArrow.setVisibility(View.VISIBLE); 
      } 
      if(scrollView.getScrollX() == scrollView.getMaxScrollAmount() || 
       scrollView.getMaxScrollAmount() == 0) { 
       rightArrow.setVisibility(View.GONE); 
      } else { 
       rightArrow.setVisibility(View.VISIBLE); 
      } 

      Log.v(ClientDetailsFragment.class.getSimpleName(), "max: " + scrollView.getMaxScrollAmount() + 
                  "current: " + scrollView.getScrollX()); 
      return super.onScroll(e1, e2, distanceX, distanceY); 
     } 
    }); 

    scrollView.setOnTouchListener(new OnTouchListener() { 

     @Override 
     public boolean onTouch(View arg0, MotionEvent ev) { 
      gd.onTouchEvent(ev); 
      return false; 
     } 
    }); 

輸出：

10-03 14:36:16.343: VERBOSE/(20508): max: 240 current: 126 
10-03 14:36:16.363: VERBOSE/(20508): max: 240 current: 127 
10-03 14:36:16.386: VERBOSE/(20508): max: 240 current: 132 
10-03 14:36:16.398: VERBOSE/(20508): max: 240 current: 143 
10-03 14:36:16.417: VERBOSE/(20508): max: 240 current: 149 
10-03 14:36:16.433: VERBOSE/(20508): max: 240 current: 152 
10-03 14:36:16.449: VERBOSE/(20508): max: 240 current: 152 
10-03 14:36:16.468: VERBOSE/(20508): max: 240 current: 152 

（152是Max在這種情況下）

Answer 1

水平滾動型的孩子應該有正確的寬度。試試這個

Log.e("ScrollWidth",Integer.toString(horizontalScrollview.getChildAt(0).getMeasuredWidth()- 
     getWindowManager().getDefaultDisplay().getWidth())); 

這應該是最大滾動量。

將下面的代碼在你onCreate方法

ViewTreeObserver vto = scrollView.getViewTreeObserver(); 
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() { 
    @Override 
    public void onGlobalLayout() { 
     scrollView.getViewTreeObserver().removeGlobalOnLayoutListener(this); 
     Log.e("ScrollWidth",Integer.toString(horizontalScrollview.getChildAt(0) 
       .getMeasuredWidth()-getWindowManager().getDefaultDisplay().getWidth())); 

    } 
});