From 96985e74261a0dacec66cb127821d7f2248f8438 Mon Sep 17 00:00:00 2001
From: Matthew Ng <ngmatthew@google.com>
Date: Tue, 8 May 2018 15:46:13 -0700
Subject: [PATCH] Fade back button in and out tied with the overview/shelf
 (1/2)

Back button changes opacity when moving the shelf during swipe up
between home screen and overview. The alpha changes depending on the
progress of the swipe up animation. When going from app to home and vice
versa, the fade animation does not tie with the swipe up progress. The
fade animation also masks the back button drawable when ime visibility
changes.

Change-Id: Idaf219923af58732715d0f0b59386dea7ab0d0ad
Fixes: 74581837
Fixes: 76900236
Test: swipe up from home screen to overview
---
 .../shared/recents/ISystemUiProxy.aidl        |  6 +++
 .../shared/system/NavigationBarCompat.java    |  8 +---
 .../systemui/OverviewProxyService.java        | 14 +++++++
 .../statusbar/phone/ButtonDispatcher.java     | 42 +++++++++++--------
 .../phone/NavigationBarFragment.java          |  7 ++++
 .../statusbar/phone/NavigationBarView.java    |  5 +--
 6 files changed, 53 insertions(+), 29 deletions(-)

diff --git a/packages/SystemUI/shared/src/com/android/systemui/shared/recents/ISystemUiProxy.aidl b/packages/SystemUI/shared/src/com/android/systemui/shared/recents/ISystemUiProxy.aidl
index 3ecf89cebc475..ebfadd881c19a 100644
--- a/packages/SystemUI/shared/src/com/android/systemui/shared/recents/ISystemUiProxy.aidl
+++ b/packages/SystemUI/shared/src/com/android/systemui/shared/recents/ISystemUiProxy.aidl
@@ -54,4 +54,10 @@ interface ISystemUiProxy {
      * Get the secondary split screen app's rectangle when not minimized.
      */
     Rect getNonMinimizedSplitScreenSecondaryBounds() = 7;
+
+    /**
+     * Control the {@param alpha} of the back button in the navigation bar and {@param animate} if
+     * needed from current value
+     */
+    void setBackButtonAlpha(float alpha, boolean animate) = 8;
 }
diff --git a/packages/SystemUI/shared/src/com/android/systemui/shared/system/NavigationBarCompat.java b/packages/SystemUI/shared/src/com/android/systemui/shared/system/NavigationBarCompat.java
index cc536a50bfc0f..96ec232a7cbb8 100644
--- a/packages/SystemUI/shared/src/com/android/systemui/shared/system/NavigationBarCompat.java
+++ b/packages/SystemUI/shared/src/com/android/systemui/shared/system/NavigationBarCompat.java
@@ -62,8 +62,7 @@ public class NavigationBarCompat {
     @Retention(RetentionPolicy.SOURCE)
     @IntDef({FLAG_DISABLE_SWIPE_UP,
             FLAG_DISABLE_QUICK_SCRUB,
-            FLAG_SHOW_OVERVIEW_BUTTON,
-            FLAG_HIDE_BACK_BUTTON
+            FLAG_SHOW_OVERVIEW_BUTTON
     })
     public @interface InteractionType {}
 
@@ -82,11 +81,6 @@ public class NavigationBarCompat {
      */
     public static final int FLAG_SHOW_OVERVIEW_BUTTON = 0x4;
 
-    /**
-     * Interaction type: show/hide the back button while this service is connected to launcher
-     */
-    public static final int FLAG_HIDE_BACK_BUTTON = 0x8;
-
     private static int convertDpToPixel(float dp){
         return (int) (dp * Resources.getSystem().getDisplayMetrics().density);
     }
diff --git a/packages/SystemUI/src/com/android/systemui/OverviewProxyService.java b/packages/SystemUI/src/com/android/systemui/OverviewProxyService.java
index 9307c224ef270..42bd66ae4a90d 100644
--- a/packages/SystemUI/src/com/android/systemui/OverviewProxyService.java
+++ b/packages/SystemUI/src/com/android/systemui/OverviewProxyService.java
@@ -161,6 +161,19 @@ public class OverviewProxyService implements CallbackController<OverviewProxyLis
                 Binder.restoreCallingIdentity(token);
             }
         }
+
+        public void setBackButtonAlpha(float alpha, boolean animate) {
+            long token = Binder.clearCallingIdentity();
+            try {
+                mHandler.post(() -> {
+                    for (int i = mConnectionCallbacks.size() - 1; i >= 0; --i) {
+                        mConnectionCallbacks.get(i).onBackButtonAlphaChanged(alpha, animate);
+                    }
+                });
+            } finally {
+                Binder.restoreCallingIdentity(token);
+            }
+        }
     };
 
     private final Runnable mDeferredConnectionCallback = () -> {
@@ -389,5 +402,6 @@ public class OverviewProxyService implements CallbackController<OverviewProxyLis
         default void onInteractionFlagsChanged(@InteractionType int flags) {}
         default void onOverviewShown(boolean fromHome) {}
         default void onQuickScrubStarted() {}
+        default void onBackButtonAlphaChanged(float alpha, boolean animate) {}
     }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/ButtonDispatcher.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/ButtonDispatcher.java
index fb94756c23198..3c0b22660c17b 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/ButtonDispatcher.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/ButtonDispatcher.java
@@ -14,13 +14,15 @@
 
 package com.android.systemui.statusbar.phone;
 
+import static com.android.systemui.Interpolators.ALPHA_IN;
+import static com.android.systemui.Interpolators.ALPHA_OUT;
+
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.ValueAnimator;
 import android.view.View;
 
 import android.view.View.AccessibilityDelegate;
-import com.android.systemui.Interpolators;
 import com.android.systemui.plugins.statusbar.phone.NavBarButtonProvider.ButtonInterface;
 import com.android.systemui.statusbar.policy.KeyButtonDrawable;
 
@@ -150,10 +152,27 @@ public class ButtonDispatcher {
     }
 
     public void setAlpha(float alpha) {
-        mAlpha = alpha;
-        final int N = mViews.size();
-        for (int i = 0; i < N; i++) {
-            mViews.get(i).setAlpha(alpha);
+        setAlpha(alpha, false /* animate */);
+    }
+
+    public void setAlpha(float alpha, boolean animate) {
+        if (animate) {
+            if (mFadeAnimator != null) {
+                mFadeAnimator.cancel();
+            }
+            mFadeAnimator = ValueAnimator.ofFloat(getAlpha(), alpha);
+            mFadeAnimator.setDuration(getAlpha() < alpha? FADE_DURATION_IN : FADE_DURATION_OUT);
+            mFadeAnimator.setInterpolator(getAlpha() < alpha ? ALPHA_IN : ALPHA_OUT);
+            mFadeAnimator.addListener(mFadeListener);
+            mFadeAnimator.addUpdateListener(mAlphaListener);
+            mFadeAnimator.start();
+            setVisibility(View.VISIBLE);
+        } else {
+            mAlpha = alpha;
+            final int N = mViews.size();
+            for (int i = 0; i < N; i++) {
+                mViews.get(i).setAlpha(alpha);
+            }
         }
     }
 
@@ -233,19 +252,6 @@ public class ButtonDispatcher {
         }
     }
 
-    public void animateFade(boolean in) {
-        if (mFadeAnimator != null) {
-            mFadeAnimator.cancel();
-        }
-        mFadeAnimator = ValueAnimator.ofFloat(getAlpha(), in ? 1 : 0);
-        mFadeAnimator.setDuration(in? FADE_DURATION_IN : FADE_DURATION_OUT);
-        mFadeAnimator.setInterpolator(in ? Interpolators.ALPHA_IN : Interpolators.ALPHA_OUT);
-        mFadeAnimator.addListener(mFadeListener);
-        mFadeAnimator.addUpdateListener(mAlphaListener);
-        mFadeAnimator.start();
-        setVisibility(View.VISIBLE);
-    }
-
     public ArrayList<View> getViews() {
         return mViews;
     }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarFragment.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarFragment.java
index 2ddae74868594..2a37845fb4fb2 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarFragment.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarFragment.java
@@ -186,6 +186,13 @@ public class NavigationBarFragment extends Fragment implements Callbacks {
             mNavigationBarView.updateStates();
             updateScreenPinningGestures();
         }
+
+        @Override
+        public void onBackButtonAlphaChanged(float alpha, boolean animate) {
+            final ButtonDispatcher backButton = mNavigationBarView.getBackButton();
+            backButton.setVisibility(alpha > 0 ? View.VISIBLE : View.INVISIBLE);
+            backButton.setAlpha(alpha, animate);
+        }
     };
 
     // ----- Fragment Lifecycle Callbacks -----
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
index 98f9f1abd301b..64fed7a39b8eb 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
@@ -85,7 +85,6 @@ import java.io.PrintWriter;
 import java.util.function.Consumer;
 
 import static com.android.systemui.shared.system.NavigationBarCompat.FLAG_DISABLE_QUICK_SCRUB;
-import static com.android.systemui.shared.system.NavigationBarCompat.FLAG_HIDE_BACK_BUTTON;
 import static com.android.systemui.shared.system.NavigationBarCompat.FLAG_SHOW_OVERVIEW_BUTTON;
 import static com.android.systemui.shared.system.NavigationBarCompat.HIT_TARGET_OVERVIEW;
 import static com.android.systemui.shared.system.NavigationBarCompat.HIT_TARGET_ROTATION;
@@ -655,8 +654,6 @@ public class NavigationBarView extends FrameLayout implements PluginListener<Nav
             disableRecent |= (flags & FLAG_SHOW_OVERVIEW_BUTTON) == 0;
             if (pinningActive) {
                 disableBack = disableHome = false;
-            } else {
-                disableBack |= (flags & FLAG_HIDE_BACK_BUTTON) != 0;
             }
         } else if (pinningActive) {
             disableBack = disableRecent = false;
@@ -863,7 +860,7 @@ public class NavigationBarView extends FrameLayout implements PluginListener<Nav
     public boolean isRotateButtonVisible() { return mShowRotateButton; }
 
     public void setMenuContainerVisibility(boolean visible) {
-        getMenuContainer().animateFade(visible);
+        getMenuContainer().setAlpha(visible ? 1 : 0, true /* animate */);
     }
 
     @Override