From 9c5b677cef5568cb5c5db3e8b639e44caf78e9b1 Mon Sep 17 00:00:00 2001
From: Riddle Hsu <riddlehsu@google.com>
Date: Thu, 16 Jun 2022 22:36:14 +0800
Subject: [PATCH] Request starting window first when moving task with shell
 transition

Both binder calls (add-starting-window, request-transition) from core
to shell will post to wmshell.main thread. And because starting window
controller will post to its wmshell.splashscreen thread, if starting
window is scheduled earlier, these 2 operations can run in parallel.

This aligns the same order as startActivity.

Bug: 235323163
Test: adb shell setprop persist.wm.debug.shell_transit 1; reboot
      Launch app from recents.
Change-Id: Ibcefb4c446217f8a3bdc2e20bfbfce8029d6981b
---
 .../server/wm/ActivityTaskManagerService.java |  8 --------
 .../server/wm/ActivityTaskSupervisor.java     | 19 +++++++++++++++----
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
index 7bc551b2aacc6..b76582fcf3b95 100644
--- a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
+++ b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
@@ -2179,14 +2179,6 @@ public class ActivityTaskManagerService extends IActivityTaskManager.Stub {
                     : null;
             mTaskSupervisor.findTaskToMoveToFront(task, flags, realOptions, "moveTaskToFront",
                     false /* forceNonResizable */);
-
-            final ActivityRecord topActivity = task.getTopNonFinishingActivity();
-            if (topActivity != null) {
-
-                // We are reshowing a task, use a starting window to hide the initial draw delay
-                // so the transition can start earlier.
-                topActivity.showStartingWindow(true /* taskSwitch */);
-            }
         } finally {
             Binder.restoreCallingIdentity(origId);
         }
diff --git a/services/core/java/com/android/server/wm/ActivityTaskSupervisor.java b/services/core/java/com/android/server/wm/ActivityTaskSupervisor.java
index 863faa190692c..84740683f6aa1 100644
--- a/services/core/java/com/android/server/wm/ActivityTaskSupervisor.java
+++ b/services/core/java/com/android/server/wm/ActivityTaskSupervisor.java
@@ -1434,10 +1434,10 @@ public class ActivityTaskSupervisor implements RecentTasks.Callbacks {
                 mUserLeaving = true;
             }
 
-            task.mTransitionController.requestTransitionIfNeeded(TRANSIT_TO_FRONT,
-                    0 /* flags */, task, task /* readyGroupRef */,
-                    options != null ? options.getRemoteTransition() : null,
-                    null /* displayChange */);
+            final Transition newTransition = task.mTransitionController.isShellTransitionsEnabled()
+                    ? task.mTransitionController.isCollecting() ? null
+                    : task.mTransitionController.createTransition(TRANSIT_TO_FRONT) : null;
+            task.mTransitionController.collect(task);
             reason = reason + " findTaskToMoveToFront";
             boolean reparented = false;
             if (task.isResizeable() && canUseActivityOptionsLaunchBounds(options)) {
@@ -1480,6 +1480,17 @@ public class ActivityTaskSupervisor implements RecentTasks.Callbacks {
             handleNonResizableTaskIfNeeded(task, WINDOWING_MODE_UNDEFINED,
                     mRootWindowContainer.getDefaultTaskDisplayArea(), currentRootTask,
                     forceNonResizeable);
+            if (r != null) {
+                // Use a starting window to reduce the transition latency for reshowing the task.
+                // Note that with shell transition, this should be executed before requesting
+                // transition to avoid delaying the starting window.
+                r.showStartingWindow(true /* taskSwitch */);
+            }
+            if (newTransition != null) {
+                task.mTransitionController.requestStartTransition(newTransition, task,
+                        options != null ? options.getRemoteTransition() : null,
+                        null /* displayChange */);
+            }
         } finally {
             mUserLeaving = false;
         }