[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;
 
+    /** Animation duration for fade-in and fade-out. */

[joedow, 2016/10/05 22:10:25]

I'd change this to 'Duration for fade-in and fade-out animations for the
ActionBar.'

[Yuwei, 2016/10/05 22:22:22]

Done.

+    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;
 
     /** Indicates whether a Soft Input UI (such as a keyboard) is visible. */
     private boolean mSoftInputVisible = false;
 
     /** Holds the scheduled task object which will be called to hide the ActionBar. */
     private Runnable mActionBarAutoHideTask;
 
     /** The Toolbar instance backing our SupportActionBar. */
     private Toolbar mToolbar;
 
     /** Tracks the current input mode (e.g. trackpad/touch). */
     private InputMode mInputMode = InputMode.UNKNOWN;
 
     /** Indicates whether the remote host supports touch injection. */
     private CapabilityManager.HostCapability mHostTouchCapability =
             CapabilityManager.HostCapability.UNKNOWN;
 
     private DesktopView mRemoteHostDesktop;
 
+    private Animation createAnimation(int animationId) {

[joedow, 2016/10/05 22:10:25]

rename to 'createToolbarVisibilityAnimation'?  It is pretty specific to the
ActionBar/Toolbar.

I'm not actually sure a helper method is cleaner than just creating the
animation inline with the call to use it.  If you decide to keep the method, I'd
move it below the public methods on the class.

[Yuwei, 2016/10/05 22:22:22]

Done.

+        Animation animation = AnimationUtils.loadAnimation(this, animationId);
+        animation.setDuration(ACTIONBAR_ANIMATION_DURATION_MS);
+        return animation;
+    }
+
     /** Called when the activity is first created. */
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.desktop);
 
         mClient = Client.getInstance();
         mInjector = new InputEventSender(mClient);
 
         Preconditions.notNull(mClient);
@@ skipping 302 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() {
+        mToolbar.startAnimation(createAnimation(android.R.anim.fade_in));
+
         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() {
+        mToolbar.startAnimation(createAnimation(android.R.anim.fade_out));
+
         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);
     }
 }