Add basic home to recents anim for fallback recents

For users/OEMs who ship with a different default launcher, we should
provide at least a basic animation from home to recents. This creates a
simple cross-fade animation if coming from a separate home activity.

Bug: 132449252
Test: Have different default launcher, go to home, go to recents
Change-Id: I5ac7b0eedbcdf1e020c31d9cf120887a4bb3826a

go/quickstep/src/com/android/quickstep/AppToOverviewAnimationProvider.java

@@ -17,6 +17,7 @@ package com.android.quickstep;
 
 import static com.android.launcher3.anim.Interpolators.FAST_OUT_SLOW_IN;
 import static com.android.quickstep.views.IconRecentsView.REMOTE_APP_TO_OVERVIEW_DURATION;
+import static com.android.systemui.shared.system.RemoteAnimationTargetCompat.ACTIVITY_TYPE_HOME;
 import static com.android.systemui.shared.system.RemoteAnimationTargetCompat.MODE_CLOSING;
 import static com.android.systemui.shared.system.RemoteAnimationTargetCompat.MODE_OPENING;
 
@@ -134,7 +135,11 @@ final class AppToOverviewAnimationProvider<T extends BaseDraggingActivity> imple
             return anim;
         }
 
-        mRecentsView.playRemoteAppToRecentsAnimation(anim, closingAppTarget, recentsTarget);
+        if (closingAppTarget.activityType == ACTIVITY_TYPE_HOME) {
+            mRecentsView.playRemoteHomeToRecentsAnimation(anim, closingAppTarget, recentsTarget);
+        } else {
+            mRecentsView.playRemoteAppToRecentsAnimation(anim, closingAppTarget, recentsTarget);
+        }
 
         return anim;
     }

go/quickstep/src/com/android/quickstep/views/IconRecentsView.java

@@ -641,6 +641,53 @@ public final class IconRecentsView extends FrameLayout implements Insettable {
         mStartedEnterAnimation = true;
     }
 
+    /**
+     * Play remote app to recents animation when the app is the home activity. We use a simple
+     * cross-fade here. Note this is only used if the home activity is a separate app than the
+     * recents activity.
+     *
+     * @param anim animator set
+     * @param homeTarget the home surface thats closing
+     * @param recentsTarget the surface containing recents
+     */
+    public void playRemoteHomeToRecentsAnimation(@NonNull AnimatorSet anim,
+            @NonNull RemoteAnimationTargetCompat homeTarget,
+            @NonNull RemoteAnimationTargetCompat recentsTarget) {
+        SyncRtSurfaceTransactionApplierCompat surfaceApplier =
+                new SyncRtSurfaceTransactionApplierCompat(this);
+
+        SurfaceParams[] params = new SurfaceParams[2];
+        int boostedMode = MODE_CLOSING;
+
+        ValueAnimator remoteHomeAnim = ValueAnimator.ofFloat(0, 1);
+        remoteHomeAnim.setDuration(REMOTE_APP_TO_OVERVIEW_DURATION);
+
+        remoteHomeAnim.addUpdateListener(valueAnimator -> {
+            float val = (float) valueAnimator.getAnimatedValue();
+            float alpha;
+            RemoteAnimationTargetCompat visibleTarget;
+            RemoteAnimationTargetCompat invisibleTarget;
+            if (val < .5f) {
+                visibleTarget = homeTarget;
+                invisibleTarget = recentsTarget;
+                alpha = 1 - (val * 2);
+            } else {
+                visibleTarget = recentsTarget;
+                invisibleTarget = homeTarget;
+                alpha = (val - .5f) * 2;
+            }
+            params[0] = new SurfaceParams(visibleTarget.leash, alpha, null /* matrix */,
+                    null /* windowCrop */, getLayer(visibleTarget, boostedMode),
+                    0 /* cornerRadius */);
+            params[1] = new SurfaceParams(invisibleTarget.leash, 0.0f, null /* matrix */,
+                    null /* windowCrop */, getLayer(invisibleTarget, boostedMode),
+                    0 /* cornerRadius */);
+            surfaceApplier.scheduleApply(params);
+        });
+        anim.play(remoteHomeAnim);
+        animateFadeInLayoutAnimation();
+    }
+
     /**
      * Play remote animation from app to recents. This should scale the currently closing app down
      * to the recents thumbnail.