From bed0d636fe9babf3d6e445ebc8fcb081d7741e3b Mon Sep 17 00:00:00 2001
From: Tony Wickham <twickham@google.com>
Date: Tue, 14 Jun 2022 15:51:09 -0700
Subject: [PATCH] Proper fix for gesture nav flicker using
 runOnPageScrollsInitialized()

I root caused the two areas causing the flicker:
A. If page scrolls aren't initialized when we get onActivityInit(), the first scroll even after linkRecentsViewScroll() will jump based on min scroll (due to Clear all button). Fix is to defer linking until page scrolls are initialized.
B. If page scrolls aren't initialized when the gesture starts, RecentsView can jump to the min scroll when calling showCurrentTask(), since that calls setCurrentPage(getRunningTaskIndex()) which might be out of bounds. Fix is to defer that setCurrentPage() until page scrolls are initialized.

Test: open a random app that hasn't been opened in a while, touch down
on nav handle and see if RecentsView scrolls partially or fully
offscreen; repeat 20 times to be sure
Fixes: 233112195

Change-Id: I000960775f8735920d97c87942065a430c9dce0c
---
 quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java | 2 +-
 quickstep/src/com/android/quickstep/views/RecentsView.java | 2 +-
 src/com/android/launcher3/PagedView.java                   | 4 +---
 3 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java b/quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java
index 713fa25383..c4cc5a4c61 100644
--- a/quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java
+++ b/quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java
@@ -446,7 +446,7 @@ public abstract class AbsSwipeUpHandler<T extends StatefulActivity<S>,
             });
 
         setupRecentsViewUi();
-        linkRecentsViewScroll();
+        mRecentsView.runOnPageScrollsInitialized(this::linkRecentsViewScroll);
         activity.runOnBindToTouchInteractionService(this::onLauncherBindToService);
 
         mActivity.registerActivityLifecycleCallbacks(mLifecycleCallbacks);
diff --git a/quickstep/src/com/android/quickstep/views/RecentsView.java b/quickstep/src/com/android/quickstep/views/RecentsView.java
index 12ddc38be4..891aff4ab7 100644
--- a/quickstep/src/com/android/quickstep/views/RecentsView.java
+++ b/quickstep/src/com/android/quickstep/views/RecentsView.java
@@ -2303,7 +2303,7 @@ public abstract class RecentsView<ACTIVITY_TYPE extends StatefulActivity<STATE_T
         boolean runningTaskTileHidden = mRunningTaskTileHidden;
         setCurrentTask(runningTaskViewId);
         mFocusedTaskViewId = runningTaskViewId;
-        setCurrentPage(getRunningTaskIndex());
+        runOnPageScrollsInitialized(() -> setCurrentPage(getRunningTaskIndex()));
         setRunningTaskViewShowScreenshot(false);
         setRunningTaskHidden(runningTaskTileHidden);
         // Update task size after setting current task.
diff --git a/src/com/android/launcher3/PagedView.java b/src/com/android/launcher3/PagedView.java
index cba0b7d709..73be5beb2c 100644
--- a/src/com/android/launcher3/PagedView.java
+++ b/src/com/android/launcher3/PagedView.java
@@ -1187,9 +1187,7 @@ public abstract class PagedView<T extends View & PageIndicator> extends ViewGrou
     }
 
     public int getScrollForPage(int index) {
-        // TODO(b/233112195): Use !pageScrollsInitialized() instead of mPageScrolls == null, once we
-        // root cause where we should be using runOnPageScrollsInitialized().
-        if (mPageScrolls == null || index >= mPageScrolls.length || index < 0) {
+        if (!pageScrollsInitialized() || index >= mPageScrolls.length || index < 0) {
             return 0;
         } else {
             return mPageScrolls[index];