Fade back button in and out tied with the overview/shelf (2/3)

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: I51e42930640ba711e81880b385bb722d7ee8ad33
Fixes: 74581837
Fixes: 76900236
Test: swipe up from home screen to overview

2 files changed, 21 insertions, 0 deletions

diff --git a/src/com/android/launcher3/allapps/AllAppsTransitionController.java b/src/com/android/launcher3/allapps/AllAppsTransitionController.java
index 2c3e3ee7b..b5c821ac2 100644
--- a/src/com/android/launcher3/allapps/AllAppsTransitionController.java
+++ b/src/com/android/launcher3/allapps/AllAppsTransitionController.java
@@ -25,9 +25,11 @@ import com.android.launcher3.LauncherState;
 import com.android.launcher3.LauncherStateManager.AnimationConfig;
 import com.android.launcher3.LauncherStateManager.StateHandler;
 import com.android.launcher3.R;
+import com.android.launcher3.Utilities;
 import com.android.launcher3.anim.AnimationSuccessListener;
 import com.android.launcher3.anim.AnimatorSetBuilder;
 import com.android.launcher3.anim.PropertySetter;
+import com.android.launcher3.uioverrides.UiFactory;
 import com.android.launcher3.util.Themes;
 import com.android.launcher3.views.ScrimView;
 
@@ -182,6 +184,13 @@ public class AllAppsTransitionController implements StateHandler, OnDeviceProfil
         anim.setDuration(config.duration);
         anim.setInterpolator(builder.getInterpolator(ANIM_VERTICAL_PROGRESS, interpolator));
         anim.addListener(getProgressAnimatorListener());
+        if (toState.hideBackButton) {
+            anim.addUpdateListener(animation -> {
+                final float alpha = (float) animation.getAnimatedValue();
+                UiFactory.setBackButtonAlpha(mLauncher, 1 - Utilities.boundToRange(alpha, 0, 1),
+                        false /* animate */);
+            });
+        }
 
         builder.play(anim);
 
diff --git a/src/com/android/launcher3/touch/AbstractStateChangeTouchController.java b/src/com/android/launcher3/touch/AbstractStateChangeTouchController.java
index e29250a5e..8ffa62813 100644
--- a/src/com/android/launcher3/touch/AbstractStateChangeTouchController.java
+++ b/src/com/android/launcher3/touch/AbstractStateChangeTouchController.java
@@ -42,6 +42,7 @@ import com.android.launcher3.Utilities;
 import com.android.launcher3.anim.AnimationSuccessListener;
 import com.android.launcher3.anim.AnimatorPlaybackController;
 import com.android.launcher3.anim.AnimatorSetBuilder;
+import com.android.launcher3.uioverrides.UiFactory;
 import com.android.launcher3.userevent.nano.LauncherLogProto.Action.Direction;
 import com.android.launcher3.userevent.nano.LauncherLogProto.Action.Touch;
 import com.android.launcher3.userevent.nano.LauncherLogProto.ContainerType;
@@ -221,6 +222,8 @@ public abstract class AbstractStateChangeTouchController
             cancelAtomicComponentsController();
         }
         mProgressMultiplier = initCurrentAnimation(animComponents);
+        mCurrentAnimation.getAnimationPlayer().addUpdateListener(animation ->
+                setBackButtonAlphaWithProgress((float) animation.getAnimatedValue()));
         mCurrentAnimation.dispatchOnStart();
         return true;
     }
@@ -279,6 +282,7 @@ public abstract class AbstractStateChangeTouchController
             mAtomicComponentsController.setPlayFraction(fraction - mAtomicComponentsStartProgress);
         }
         maybeUpdateAtomicAnim(mFromState, mToState, fraction);
+        setBackButtonAlphaWithProgress(fraction);
     }
 
     /**
@@ -471,6 +475,14 @@ public abstract class AbstractStateChangeTouchController
         }
     }
 
+    private void setBackButtonAlphaWithProgress(float progress) {
+        if (mFromState.hideBackButton ^ mToState.hideBackButton) {
+            progress = Utilities.boundToRange(progress, 0, 1);
+            final float alpha = mToState.hideBackButton ? 1 - progress : progress;
+            UiFactory.setBackButtonAlpha(mLauncher, alpha, false /* animate */);
+        }
+    }
+
     private void logReachedState(int logAction) {
         // Transition complete. log the action
         mLauncher.getUserEventDispatcher().logStateChangeAction(logAction,