爲什麼在軟鍵盤處於打開狀態時，heightDiff == 50？

Question

這是我最頂層LL在我的XML

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/rootLayout" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:background="@color/blue_bg" 
    android:gravity="center_horizontal" 
    android:orientation="vertical" > 

然後我用這個代碼：

private void setKeyboardVisibilityListener() 
{ 
    final View root = findViewById(R.id.rootLayout); 

    root.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() { 

     @Override 
     public void onGlobalLayout() { 
      // TODO Auto-generated method stub 
      View continueButton = findViewById(R.id.continueButton); 
      int heightDiff = root.getRootView().getHeight() - root.getHeight(); 
       if (heightDiff > 100) { // more than 100 pixels is probably a keyboard 
        // keyboard is shown 
        mInputBox.setBackgroundResource(R.drawable.input_box_active); 
       } else { 
        // keyboard is not shown 
        mInputBox.setBackgroundResource(R.drawable.input_box_idle); 
       } 
      } 
     }); 
} 

，但我總是得到heightDiff == 50當軟鍵盤是，當它的出

Answer 1

我根據我的要求製作了這個Singleton幫手類，以便您可以輕鬆地將其移植到您的需求中：

public final class SoftInputUtils { 

    private transient SoftReference<View> mView; 
    private int mLastHeightDifference = 0; 

    public void startDetectingSoftInput(final View view) { 
     if (view.getViewTreeObserver().isAlive()) { 
      mView = new SoftReference<View>(view); 

      if (mView.get() != null) { 
       View v = mView.get(); 
       v.getViewTreeObserver().addOnGlobalLayoutListener(
         new OnGlobalLayoutListener() { 

          @Override 
          public void onGlobalLayout() { 
           checkPotentialSoftInputVisibility(); 
          } 
         }); 
      } 
     } 
    } 

    private void checkPotentialSoftInputVisibility() { 
     if (mView != null && mView.get() != null) { 
      View v = mView.get(); 

      Rect r = new Rect(); 
      v.getWindowVisibleDisplayFrame(r); 

      int screenHeight = v.getRootView().getHeight(); 
      int heightDifference = screenHeight - (r.bottom - r.top); 

      // Soft input potentially got visible, so we readjust view height 
      if (heightDifference > screenHeight/5 
        && heightDifference != mLastHeightDifference) { 
       ViewGroup.LayoutParams lp = (ViewGroup.LayoutParams) v 
         .getLayoutParams(); 
       lp.height = screenHeight - heightDifference; 
       v.requestLayout(); 

       mLastHeightDifference = heightDifference; 
      } else if (heightDifference != mLastHeightDifference) { 
       // And now most likely not visible so adjust height back 
       ViewGroup.LayoutParams lp = (ViewGroup.LayoutParams) v 
         .getLayoutParams(); 
       lp.height = ViewGroup.LayoutParams.MATCH_PARENT; 
       v.requestLayout(); 

       mLastHeightDifference = heightDifference; 
      } 
     } 
    } 
}