From 17312c3566837cfdd30e813bd16a557ed21b28f8 Mon Sep 17 00:00:00 2001
From: Tony Wickham <twickham@google.com>
Date: Thu, 21 May 2020 00:55:54 -0500
Subject: [PATCH] Keep recents attached to app window on continued switching

- LAST_TASK now has recentsAttachedToAppWindow = true, to match
  NEW_TASK. Though this does mean there's a small chance of
  seeing recents translating in if you swipe up and back down,
  this is preferable to seeing recents translate away if you
  swipe right and back left in two consecutive gestures.
- Until passing the touch slop for a new gesture, keep recents
  attached to the app window. This avoids cases where you
  could have recents view translate away mid-gesture, such as
  in the following case: swipe from A to B, swipe from B back
  to A, touch down during the transition back to A. Before this
  change, you would see recents translate away; with this
  change, recents instead stays in place until we get another
  signal indicating it should detach, such as swiping to home.

Bug: 157153404
Change-Id: I63a3a8b988af1aac5177f101b0b75e73e56b1ceb
---
 .../OtherActivityInputConsumer.java            | 18 +++++++++++++++---
 .../com/android/quickstep/GestureState.java    |  2 +-
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/quickstep/recents_ui_overrides/src/com/android/quickstep/inputconsumers/OtherActivityInputConsumer.java b/quickstep/recents_ui_overrides/src/com/android/quickstep/inputconsumers/OtherActivityInputConsumer.java
index ab9ec21623..8b08ea76fe 100644
--- a/quickstep/recents_ui_overrides/src/com/android/quickstep/inputconsumers/OtherActivityInputConsumer.java
+++ b/quickstep/recents_ui_overrides/src/com/android/quickstep/inputconsumers/OtherActivityInputConsumer.java
@@ -112,6 +112,9 @@ public class OtherActivityInputConsumer extends ContextWrapper implements InputC
     private boolean mPassedWindowMoveSlop;
     // Slop used to determine when we say that the gesture has started.
     private boolean mPassedPilferInputSlop;
+    // Same as mPassedPilferInputSlop, except when continuing a gesture mPassedPilferInputSlop is
+    // initially true while this one is false.
+    private boolean mPassedSlopOnThisGesture;
 
     // Might be displacement in X or Y, depending on the direction we are swiping from the nav bar.
     private float mStartDisplacement;
@@ -244,6 +247,7 @@ public class OtherActivityInputConsumer extends ContextWrapper implements InputC
                 mLastPos.set(ev.getX(pointerIndex), ev.getY(pointerIndex));
                 float displacement = getDisplacement(ev);
                 float displacementX = mLastPos.x - mDownPos.x;
+                float displacementY = mLastPos.y - mDownPos.y;
 
                 if (!mPassedWindowMoveSlop) {
                     if (!mIsDeferredDownTarget) {
@@ -258,11 +262,18 @@ public class OtherActivityInputConsumer extends ContextWrapper implements InputC
 
                 float horizontalDist = Math.abs(displacementX);
                 float upDist = -displacement;
-                boolean isLikelyToStartNewTask = horizontalDist > upDist;
+                boolean passedSlop = squaredHypot(displacementX, displacementY)
+                        >= mSquaredTouchSlop;
+                if (!mPassedSlopOnThisGesture && passedSlop) {
+                    mPassedSlopOnThisGesture = true;
+                }
+                // Until passing slop, we don't know what direction we're going, so assume we might
+                // be quick switching to avoid translating recents away when continuing the gesture.
+                boolean isLikelyToStartNewTask = !mPassedSlopOnThisGesture
+                        || horizontalDist > upDist;
 
                 if (!mPassedPilferInputSlop) {
-                    float displacementY = mLastPos.y - mDownPos.y;
-                    if (squaredHypot(displacementX, displacementY) >= mSquaredTouchSlop) {
+                    if (passedSlop) {
                         if (mDisableHorizontalSwipe
                                 && Math.abs(displacementX) > Math.abs(displacementY)) {
                             // Horizontal gesture is not allowed in this region
@@ -339,6 +350,7 @@ public class OtherActivityInputConsumer extends ContextWrapper implements InputC
             mActiveCallbacks = mTaskAnimationManager.continueRecentsAnimation(mGestureState);
             mActiveCallbacks.addListener(mInteractionHandler);
             mTaskAnimationManager.notifyRecentsAnimationState(mInteractionHandler);
+            mInteractionHandler.setIsLikelyToStartNewTask(true);
             notifyGestureStarted();
         } else {
             intent.putExtra(INTENT_EXTRA_LOG_TRACE_ID, mGestureState.getGestureId());
diff --git a/quickstep/src/com/android/quickstep/GestureState.java b/quickstep/src/com/android/quickstep/GestureState.java
index 016ffea2d7..166a74f285 100644
--- a/quickstep/src/com/android/quickstep/GestureState.java
+++ b/quickstep/src/com/android/quickstep/GestureState.java
@@ -47,7 +47,7 @@ public class GestureState implements RecentsAnimationCallbacks.RecentsAnimationL
 
         NEW_TASK(false, ContainerType.APP, true),
 
-        LAST_TASK(false, ContainerType.APP, false);
+        LAST_TASK(false, ContainerType.APP, true);
 
         GestureEndTarget(boolean isLauncher, int containerType,
                 boolean recentsAttachedToAppWindow) {