[Remoting Android] Fading transition animation for desktop actionbar

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

Index: remoting/android/java/src/org/chromium/chromoting/Desktop.java
diff --git a/remoting/android/java/src/org/chromium/chromoting/Desktop.java b/remoting/android/java/src/org/chromium/chromoting/Desktop.java
index c115749677ffb9dab8db7ecd28567fc8e5b79200..e340f51af4f9b49eacd5dc460e41674f49c989fb 100644
--- a/remoting/android/java/src/org/chromium/chromoting/Desktop.java
+++ b/remoting/android/java/src/org/chromium/chromoting/Desktop.java
@@ -18,6 +18,8 @@ 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;
@@ -49,6 +51,9 @@ public class Desktop
     /** 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<>();
 
@@ -78,6 +83,12 @@ public class Desktop
 
     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) {
@@ -400,6 +411,8 @@ public class Desktop
 
     /** Shows the action bar without changing SystemUiVisibility. */
     private void showActionBar() {
+        mToolbar.startAnimation(createAnimation(android.R.anim.fade_in));
+
         getSupportActionBar().show();
         startActionBarAutoHideTimer();
     }
@@ -437,6 +450,8 @@ public class Desktop
 
     /** Hides the action bar without changing SystemUiVisibility. */
     private void hideActionBar() {
+        mToolbar.startAnimation(createAnimation(android.R.anim.fade_out));
+
         getSupportActionBar().hide();
         stopActionBarAutoHideTimer();
     }