From dd6be4764a337628651f6384fcb18c4e43c7722a Mon Sep 17 00:00:00 2001
From: Evan Rosky <erosky@google.com>
Date: Tue, 22 Jun 2021 14:13:27 -0700
Subject: [PATCH] Keep wallpaper as a special-case in transitions

Wallpaper unfortunately needs to be handled specially by
transition players because of it's arrangement in the hierarchy
(being in a separate root displayareay) and because it has
specific ordering mechanics during animations.

Now that DisplayAreas are "organized", they interfere with
wallpaper's handling as a special-case in a transition. To prevent
this, explicitly prevent any of wallpaper's ancestor displayareas
from being part of the transition.

Bug: 187461719
Test: launch a landscape app from portrait launcher. Observe
      wallpaper not disappearing.
Change-Id: Id9e86f14d380b5ed8050b303edf5f1b48875ff20
---
 .../com/android/server/wm/Transition.java     | 16 ++++----
 .../android/server/wm/TransitionTests.java    | 38 +++++++++++++++++++
 2 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/services/core/java/com/android/server/wm/Transition.java b/services/core/java/com/android/server/wm/Transition.java
index 8e18da14d3b31..c8ae776c1d140 100644
--- a/services/core/java/com/android/server/wm/Transition.java
+++ b/services/core/java/com/android/server/wm/Transition.java
@@ -777,6 +777,8 @@ class Transition extends Binder implements BLASTSyncEngine.TransactionReadyListe
             if (reportIfNotTop(wc)) {
                 tmpList.add(wc);
             }
+            // Wallpaper must be the top (regardless of how nested it is in DisplayAreas).
+            boolean skipIntermediateReports = isWallpaper(wc);
             for (WindowContainer p = wc.getParent(); p != null; p = p.getParent()) {
                 if (!p.isAttached() || !changes.get(p).hasChanged(p)) {
                     // Again, we're skipping no-ops
@@ -785,7 +787,9 @@ class Transition extends Binder implements BLASTSyncEngine.TransactionReadyListe
                 if (participants.contains(p)) {
                     topParent = p;
                     break;
-                } else if (reportIfNotTop(p)) {
+                } else if (isWallpaper(p)) {
+                    skipIntermediateReports = true;
+                } else if (reportIfNotTop(p) && !skipIntermediateReports) {
                     tmpList.add(p);
                 }
             }
@@ -871,17 +875,11 @@ class Transition extends Binder implements BLASTSyncEngine.TransactionReadyListe
         }
 
         // Find the top-most shared ancestor of app targets
-        WindowContainer ancestor = null;
-        for (int i = appTargets.size() - 1; i >= 0; --i) {
-            final WindowContainer wc = appTargets.valueAt(i);
-            ancestor = wc;
-            break;
-        }
-        if (ancestor == null) {
+        if (appTargets.isEmpty()) {
             out.setRootLeash(new SurfaceControl(), 0, 0);
             return out;
         }
-        ancestor = ancestor.getParent();
+        WindowContainer ancestor = appTargets.valueAt(appTargets.size() - 1).getParent();
 
         // Go up ancestor parent chain until all targets are descendants.
         ancestorLoop:
diff --git a/services/tests/wmtests/src/com/android/server/wm/TransitionTests.java b/services/tests/wmtests/src/com/android/server/wm/TransitionTests.java
index 2dfb3a1a84bc1..45e5f8e55f8ae 100644
--- a/services/tests/wmtests/src/com/android/server/wm/TransitionTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/TransitionTests.java
@@ -338,6 +338,44 @@ public class TransitionTests extends WindowTestsBase {
                 tasks[showWallpaperTask].mRemoteToken.toWindowContainerToken()).getFlags());
     }
 
+    @Test
+    public void testTargets_noIntermediatesToWallpaper() {
+        final Transition transition = createTestTransition(TRANSIT_OLD_TASK_OPEN);
+
+        final WallpaperWindowToken wallpaperWindowToken = new WallpaperWindowToken(mWm,
+                mock(IBinder.class), true, mDisplayContent, true /* ownerCanManageAppTokens */);
+        // Make DA organized so we can check that they don't get included.
+        WindowContainer parent = wallpaperWindowToken.getParent();
+        while (parent != null && parent != mDisplayContent) {
+            if (parent.asDisplayArea() != null) {
+                parent.asDisplayArea().setOrganizer(
+                        mock(android.window.IDisplayAreaOrganizer.class), true /* skipAppear */);
+            }
+            parent = parent.getParent();
+        }
+        final WindowState wallpaperWindow = createWindow(null, TYPE_WALLPAPER, wallpaperWindowToken,
+                "wallpaperWindow");
+        wallpaperWindowToken.setVisibleRequested(false);
+        transition.collect(wallpaperWindowToken);
+        wallpaperWindowToken.setVisibleRequested(true);
+        wallpaperWindow.mHasSurface = true;
+        doReturn(true).when(mDisplayContent).isAttached();
+        transition.collect(mDisplayContent);
+        mDisplayContent.getWindowConfiguration().setRotation(
+                (mDisplayContent.getWindowConfiguration().getRotation() + 1) % 4);
+
+        ArraySet<WindowContainer> targets = Transition.calculateTargets(
+                transition.mParticipants, transition.mChanges);
+        TransitionInfo info = Transition.calculateTransitionInfo(
+                0, 0, targets, transition.mChanges);
+        // The wallpaper is not organized, so it won't have a token; however, it will be marked
+        // as IS_WALLPAPER
+        assertEquals(FLAG_IS_WALLPAPER, info.getChanges().get(0).getFlags());
+        // Make sure no intermediate display areas were pulled in between wallpaper and display.
+        assertEquals(mDisplayContent.mRemoteToken.toWindowContainerToken(),
+                info.getChanges().get(0).getParent());
+    }
+
     @Test
     public void testIndependent() {
         final Transition transition = createTestTransition(TRANSIT_OPEN);