From 5885b074dc1595f430eaff46cad595bed4b6aa0f Mon Sep 17 00:00:00 2001
From: Alex Chau <alexchau@google.com>
Date: Fri, 5 Nov 2021 19:22:38 +0000
Subject: [PATCH] Fix a case that task jump when dismissing

- Fixed an edge case that RecentsView was not snapped to last tasks, but become snapped to last tasks after dismiss, as last pages' scroll is the position where ClearAllButton is barely invisible, instead of aligned to mLastComputedTaskSize.
- Fixed a case that misclassifed as split select

Fix: 202941373
Test: manual
Change-Id: Ib50dda471189da4325cd8ed57d600cc64907c978
---
 .../quickstep/BaseActivityInterface.java      |  1 -
 .../android/quickstep/views/RecentsView.java  | 39 ++++++++++++++++---
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/quickstep/src/com/android/quickstep/BaseActivityInterface.java b/quickstep/src/com/android/quickstep/BaseActivityInterface.java
index 834bc55787..f9b749ee14 100644
--- a/quickstep/src/com/android/quickstep/BaseActivityInterface.java
+++ b/quickstep/src/com/android/quickstep/BaseActivityInterface.java
@@ -306,7 +306,6 @@ public abstract class BaseActivityInterface<STATE_TYPE extends BaseState<STATE_T
      * Calculates the overview grid size for the provided device configuration.
      */
     public final void calculateGridSize(Context context, DeviceProfile dp, Rect outRect) {
-        Resources res = context.getResources();
         Rect insets = dp.getInsets();
         int topMargin = dp.overviewTaskThumbnailTopMarginPx;
         int bottomMargin = getOverviewActionsHeight(context, dp);
diff --git a/quickstep/src/com/android/quickstep/views/RecentsView.java b/quickstep/src/com/android/quickstep/views/RecentsView.java
index c721e501a5..a5534e7f42 100644
--- a/quickstep/src/com/android/quickstep/views/RecentsView.java
+++ b/quickstep/src/com/android/quickstep/views/RecentsView.java
@@ -2768,6 +2768,9 @@ public abstract class RecentsView<ACTIVITY_TYPE extends StatefulActivity<STATE_T
         boolean isSplitPlaceholderFirstInGrid = isSplitPlaceholderFirstInGrid();
         boolean isSplitPlaceholderLastInGrid = isSplitPlaceholderLastInGrid();
         TaskView lastGridTaskView = showAsGrid ? getLastGridTaskView() : null;
+        int currentPageScroll = getScrollForPage(mCurrentPage);
+        int lastGridTaskScroll = getScrollForPage(indexOfChild(lastGridTaskView));
+        boolean currentPageSnapsToEndOfGrid = currentPageScroll == lastGridTaskScroll;
         if (lastGridTaskView != null && lastGridTaskView.isVisibleToUser()) {
             // After dismissal, animate translation of the remaining tasks to fill any gap left
             // between the end of the grid and the clear all button. Only animate if the clear
@@ -2811,8 +2814,7 @@ public abstract class RecentsView<ACTIVITY_TYPE extends StatefulActivity<STATE_T
                     // Shift all the tasks to make space for split placeholder.
                     longGridRowWidthDiff += mIsRtl ? mSplitPlaceholderSize : -mSplitPlaceholderSize;
                 }
-            } else if (isLandscapeSplit && getScrollForPage(mCurrentPage)
-                    == getScrollForPage(indexOfChild(lastGridTaskView))) {
+            } else if (isLandscapeSplit && currentPageSnapsToEndOfGrid) {
                 // Use last task as reference point for scroll diff and snapping calculation as it's
                 // the only invariant point in landscape split screen.
                 snapToLastTask = true;
@@ -3183,14 +3185,39 @@ public abstract class RecentsView<ACTIVITY_TYPE extends StatefulActivity<STATE_T
                                 }
                             }
 
+                            TaskView newLastGridTaskView = getLastGridTaskView();
                             if (finalSnapToLastTask) {
                                 // If snapping to last task, find the last task after dismissal.
-                                pageToSnapTo = indexOfChild(getLastGridTaskView());
+                                pageToSnapTo = indexOfChild(newLastGridTaskView);
                             } else if (taskViewIdToSnapTo != -1) {
                                 // If snapping to another page due to indices rearranging, find
                                 // the new index after dismissal & rearrange using the task view id.
                                 pageToSnapTo = indexOfChild(
                                         getTaskViewFromTaskViewId(taskViewIdToSnapTo));
+                                int taskViewToSnapToScroll = getScrollForPage(pageToSnapTo);
+                                int lastGridTaskScroll = getScrollForPage(
+                                        indexOfChild(newLastGridTaskView));
+                                if (!currentPageSnapsToEndOfGrid
+                                        && taskViewToSnapToScroll == lastGridTaskScroll) {
+                                    // If it wasn't snapped to one of the last pages, but is now
+                                    // snapped to last pages, we'll need to compensate for the
+                                    // difference as last pages' scroll is the position where
+                                    // ClearAllButton is barely invisible, instead of aligned to
+                                    // mLastComputedTaskSize.
+                                    int normalTaskEnd = mIsRtl
+                                            ? mLastComputedTaskSize.right
+                                            : mLastComputedTaskSize.left;
+                                    int lastTaskStart = mIsRtl
+                                            ? mLastComputedGridSize.left
+                                            : mLastComputedGridSize.right;
+                                    // As snapped task is not the last task, it can only be the
+                                    // second last task.
+                                    int distanceToSnappedTaskEnd =
+                                            (mPageSpacing + mLastComputedGridTaskSize.width()) * 2;
+                                    int snappedTaskEnd = lastTaskStart + (mIsRtl
+                                            ? distanceToSnappedTaskEnd : -distanceToSnappedTaskEnd);
+                                    mCurrentPageScrollDiff += snappedTaskEnd - normalTaskEnd;
+                                }
                             }
                         }
                         setCurrentPage(pageToSnapTo);
@@ -3817,7 +3844,8 @@ public abstract class RecentsView<ACTIVITY_TYPE extends StatefulActivity<STATE_T
      * if RecentsView is in portrait or RecentsView isn't shown as grid.
      */
     private boolean isSplitPlaceholderFirstInGrid() {
-        if (!mActivity.getDeviceProfile().isLandscape || !showAsGrid()) {
+        if (!mActivity.getDeviceProfile().isLandscape || !showAsGrid()
+                || !isSplitSelectionActive()) {
             return false;
         }
         @StagePosition int position = mSplitSelectStateController.getActiveSplitStagePosition();
@@ -3831,7 +3859,8 @@ public abstract class RecentsView<ACTIVITY_TYPE extends StatefulActivity<STATE_T
      * RecentsView is in portrait or RecentsView isn't shown as grid.
      */
     private boolean isSplitPlaceholderLastInGrid() {
-        if (!mActivity.getDeviceProfile().isLandscape || !showAsGrid()) {
+        if (!mActivity.getDeviceProfile().isLandscape || !showAsGrid()
+                || !isSplitSelectionActive()) {
             return false;
         }
         @StagePosition int position = mSplitSelectStateController.getActiveSplitStagePosition();