detects keyboard show and hide on android software keyboard

AndroidKeyboardDetector.java

import android.util.TypedValue;
import android.view.View;
import android.view.ViewTreeObserver;

public class KeyboardDetector implements ViewTreeObserver.OnGlobalLayoutListener, ViewTreeObserver.OnPreDrawListener {

   private static final int DP_KEYBOARD_THRESHOLD = 60;
   private int keyboardThreshold;

   private int currentHeight;
   private View view;
   private boolean isKeyboardShown = false;
   private KeyboardListener listener;

   public void attachToView(View view, KeyboardListener listener) {
      this.listener = listener;
      if (listener == null) return;

      keyboardThreshold = (int) TypedValue.applyDimension(
         TypedValue.COMPLEX_UNIT_DIP, DP_KEYBOARD_THRESHOLD, view.getResources().getDisplayMetrics());

      this.view = view;
      currentHeight = view.getHeight();
      view.getViewTreeObserver().addOnGlobalLayoutListener(this);

      if (currentHeight <= 0) {
         view.getViewTreeObserver().addOnPreDrawListener(this);
      }

   }

   public void detachFromView() {
      if (view != null) {
         view.getViewTreeObserver().removeGlobalOnLayoutListener(this);
         view.getViewTreeObserver().removeOnPreDrawListener(this);
         view = null;
      }
      listener = null;
   }

   @Override
   public void onGlobalLayout() {
      int newHeight = view.getHeight();
      if (currentHeight > 0) {
         int diff = newHeight - currentHeight;
         if (diff < -keyboardThreshold) {
            Log.d(this, "onGlobalLayout. keyboard is show. height diff = " + -diff);
            // keyboard is show
            isKeyboardShown = true;
            if (listener != null)
               listener.onKeyboardShow(-diff);

         } else if (diff > keyboardThreshold) {
            Log.d(this, "onGlobalLayout.keyboard is hide.  height diff = " + diff);
            // keyboard is hide
            isKeyboardShown = false;
            if (listener != null)
               listener.onKeyboardHide(diff);
         } else {
            Log.v(this, "onGlobalLayout. height diff = " + diff);
         }
      }
      currentHeight = newHeight;
   }

   public boolean isKeyboardShown() {
      return isKeyboardShown;
   }

   @Override
   public boolean onPreDraw() {
      currentHeight = view.getHeight();
      view.getViewTreeObserver().removeOnPreDrawListener(this);
      return true;
   }

   public interface KeyboardListener {
      public void onKeyboardShow(int height);

      public void onKeyboardHide(int height);
   }
}