[Remoting Android] Fading transition animation for desktop actionbar

remoting/android/java/src/org/chromium/chromoting/Desktop.java

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chromoting;
 
 import android.annotation.SuppressLint;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
 import android.support.v7.app.ActionBar.OnMenuVisibilityListener;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.Toolbar;
 import android.view.KeyEvent;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.View.OnLayoutChangeListener;
 import android.view.View.OnTouchListener;
+import android.view.animation.Animation;
+import android.view.animation.AnimationUtils;
 import android.view.inputmethod.InputMethodManager;
 
 import org.chromium.chromoting.help.HelpContext;
 import org.chromium.chromoting.help.HelpSingleton;
 import org.chromium.chromoting.jni.Client;
 
 import java.util.List;
 
 /**
  * A simple screen that does nothing except display a DesktopView and notify it of rotations.
@@ skipping 11 matching lines @@
             return this != UNKNOWN;
         }
     }
 
     /** Preference used to track the last input mode selected by the user. */
     private static final String PREFERENCE_INPUT_MODE = "input_mode";
 
     /** The amount of time to wait to hide the ActionBar after user input is seen. */
     private static final int ACTIONBAR_AUTO_HIDE_DELAY_MS = 3000;
 
+    /** Duration for fade-in and fade-out animations for the ActionBar. */
+    private static final int ACTIONBAR_ANIMATION_DURATION_MS = 250;
+
     private final Event.Raisable<SystemUiVisibilityChangedEventParameter>
             mOnSystemUiVisibilityChanged = new Event.Raisable<>();
 
     private final Event.Raisable<InputModeChangedEventParameter> mOnInputModeChanged =
             new Event.Raisable<>();
 
     private Client mClient;
     private InputEventSender mInjector;
 
     private ActivityLifecycleListener mActivityLifecycleListener;
@@ skipping 331 matching lines @@
 
         // The OS will not call onSystemUiVisibilityChange() if the soft keyboard is visible which
         // means our ActionBar will not be shown if this function is called in that scenario.
         if (mSoftInputVisible) {
             showActionBar();
         }
     }
 
     /** Shows the action bar without changing SystemUiVisibility. */
     private void showActionBar() {
+        Animation animation = AnimationUtils.loadAnimation(this, android.R.anim.fade_in);
+        animation.setDuration(ACTIONBAR_ANIMATION_DURATION_MS);
+        mToolbar.startAnimation(animation);
+
         getSupportActionBar().show();
         startActionBarAutoHideTimer();
     }
 
     @SuppressLint("InlinedApi")
     public void hideSystemUi() {
         // If a soft input device is present, then hide the ActionBar but do not hide the rest of
         // system UI.  A second call will be made once the soft input device is hidden.
         if (mSoftInputVisible) {
             hideActionBar();
@@ skipping 17 matching lines @@
             flags |= View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
             flags |= View.SYSTEM_UI_FLAG_IMMERSIVE;
         }
         flags |= getLayoutFlags();
 
         getWindow().getDecorView().setSystemUiVisibility(flags);
     }
 
     /** Hides the action bar without changing SystemUiVisibility. */
     private void hideActionBar() {
+        Animation animation = AnimationUtils.loadAnimation(this, android.R.anim.fade_out);
+        animation.setDuration(ACTIONBAR_ANIMATION_DURATION_MS);
+        mToolbar.startAnimation(animation);
+
         getSupportActionBar().hide();
         stopActionBarAutoHideTimer();
     }
 
     /** Called whenever an action bar button is pressed. */
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         int id = item.getItemId();
 
         mActivityLifecycleListener.onActivityOptionsItemSelected(this, item);
@@ skipping 90 matching lines @@
     @Override
     public boolean dispatchKeyEvent(KeyEvent event) {
         if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
             mClient.destroy();
             return super.dispatchKeyEvent(event);
         }
 
         return mInjector.sendKeyEvent(event);
     }
 }