From adce95394ef508c5603f48f7e2b681aaf228db76 Mon Sep 17 00:00:00 2001
From: Andy Wickham <awickham@google.com>
Date: Thu, 18 May 2023 17:53:24 -0700
Subject: [PATCH] Enable returning to the previous app after Overview -> All
 Apps.

Back gesture from All Apps (history for state):
If previous state was background, use quick switch state to return
to the previous app.

Swipe down from All Apps:
Return to previous state (which will be Normal or Quick Switch).

This animates from All Apps overview scale/translation to full
screen of the previous task. In this case we are animating from
0.5x Overview scale and 0 translation (centered).

Video: https://drive.google.com/file/d/1cpQjtFemtJ4zu9aWu7IiUftWWVGFrbtM/view?usp=drive_link&resourcekey=0-1zuMEvYNsk81YBxv8o10hA

Note: This is mostly for the gesture/state handling but it would
be nice to polish this transition in the future.

Bug: 283336332
Test: Manual
Flag: ENABLE_ALL_APPS_FROM_OVERVIEW
Change-Id: Iec92df933ce6522f181d3d5ca889b6a6469f4cc6
---
 .../launcher3/uioverrides/QuickstepLauncher.java  |  2 +-
 .../uioverrides/states/AllAppsState.java          | 15 ++++++++++++++-
 .../PortraitStatesTouchController.java            |  5 ++++-
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/quickstep/src/com/android/launcher3/uioverrides/QuickstepLauncher.java b/quickstep/src/com/android/launcher3/uioverrides/QuickstepLauncher.java
index de46ba005d..8037a85ca0 100644
--- a/quickstep/src/com/android/launcher3/uioverrides/QuickstepLauncher.java
+++ b/quickstep/src/com/android/launcher3/uioverrides/QuickstepLauncher.java
@@ -525,7 +525,7 @@ public class QuickstepLauncher extends Launcher {
             }
             case QUICK_SWITCH_STATE_ORDINAL: {
                 RecentsView rv = getOverviewPanel();
-                TaskView tasktolaunch = rv.getTaskViewAt(0);
+                TaskView tasktolaunch = rv.getCurrentPageTaskView();
                 if (tasktolaunch != null) {
                     tasktolaunch.launchTask(success -> {
                         if (!success) {
diff --git a/quickstep/src/com/android/launcher3/uioverrides/states/AllAppsState.java b/quickstep/src/com/android/launcher3/uioverrides/states/AllAppsState.java
index a4db375046..f6a25ce761 100644
--- a/quickstep/src/com/android/launcher3/uioverrides/states/AllAppsState.java
+++ b/quickstep/src/com/android/launcher3/uioverrides/states/AllAppsState.java
@@ -23,6 +23,7 @@ import android.content.Context;
 import com.android.launcher3.Launcher;
 import com.android.launcher3.LauncherState;
 import com.android.launcher3.R;
+import com.android.launcher3.config.FeatureFlags;
 import com.android.launcher3.util.Themes;
 import com.android.launcher3.views.ActivityContext;
 
@@ -110,7 +111,19 @@ public class AllAppsState extends LauncherState {
 
     @Override
     public LauncherState getHistoryForState(LauncherState previousState) {
-        return previousState == OVERVIEW ? OVERVIEW : NORMAL;
+        return previousState == BACKGROUND_APP ? QUICK_SWITCH_FROM_HOME
+                : previousState == OVERVIEW ? OVERVIEW : NORMAL;
+    }
+
+    @Override
+    public float[] getOverviewScaleAndOffset(Launcher launcher) {
+        if (!FeatureFlags.ENABLE_ALL_APPS_FROM_OVERVIEW.get()) {
+            return super.getOverviewScaleAndOffset(launcher);
+        }
+        // This handles the case of returning to the previous app from Overview -> All Apps gesture.
+        // This is the start scale/offset of overview that will be used for that transition.
+        // TODO (b/283336332): Translate in Y direction (ideally with overview resistance).
+        return new float[] {0.5f /* scale */, NO_OFFSET};
     }
 
     @Override
diff --git a/quickstep/src/com/android/launcher3/uioverrides/touchcontrollers/PortraitStatesTouchController.java b/quickstep/src/com/android/launcher3/uioverrides/touchcontrollers/PortraitStatesTouchController.java
index bb74a3650a..454a1f5e91 100644
--- a/quickstep/src/com/android/launcher3/uioverrides/touchcontrollers/PortraitStatesTouchController.java
+++ b/quickstep/src/com/android/launcher3/uioverrides/touchcontrollers/PortraitStatesTouchController.java
@@ -29,6 +29,7 @@ import com.android.launcher3.DeviceProfile;
 import com.android.launcher3.Launcher;
 import com.android.launcher3.LauncherState;
 import com.android.launcher3.allapps.AllAppsTransitionController;
+import com.android.launcher3.config.FeatureFlags;
 import com.android.launcher3.states.StateAnimationConfig;
 import com.android.launcher3.touch.AbstractStateChangeTouchController;
 import com.android.launcher3.touch.AllAppsSwipeController;
@@ -92,7 +93,9 @@ public class PortraitStatesTouchController extends AbstractStateChangeTouchContr
     @Override
     protected LauncherState getTargetState(LauncherState fromState, boolean isDragTowardPositive) {
         if (fromState == ALL_APPS && !isDragTowardPositive) {
-            return NORMAL;
+            return FeatureFlags.ENABLE_ALL_APPS_FROM_OVERVIEW.get()
+                    ? mLauncher.getStateManager().getLastState()
+                    : NORMAL;
         } else if (fromState == OVERVIEW) {
             return isDragTowardPositive ? OVERVIEW : NORMAL;
         } else if (fromState == NORMAL && isDragTowardPositive) {