From 225ea651900832384381b6e1022226f7531d0929 Mon Sep 17 00:00:00 2001
From: Robert Carr <racarr@google.com>
Date: Thu, 11 Mar 2021 21:10:03 -0800
Subject: [PATCH] WindowManager: Handle main window size change transaction
 with BLAST.

Rather than push and defer the pending transaction we can use the
new applyWithNextDraw primitive to make sure the transaction applies
with the app redraw. We need to be a little careful. Since
mainWindowSizeTransaction is consumed during layout, we need
to move the check for pending draw handlers to the end of relayout.

Test: Existing tests pass
Bug: 168505645
Change-Id: Iae7906ee6def94ee3adc71b5f5ba022157379c73
---
 .../server/wm/WindowStateAnimator.java        | 22 ++++++++-----------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/services/core/java/com/android/server/wm/WindowStateAnimator.java b/services/core/java/com/android/server/wm/WindowStateAnimator.java
index 3ef7ccd6bfabf..ca38bb90f19cd 100644
--- a/services/core/java/com/android/server/wm/WindowStateAnimator.java
+++ b/services/core/java/com/android/server/wm/WindowStateAnimator.java
@@ -538,21 +538,17 @@ class WindowStateAnimator {
                 // The sync transaction will contain the buffer so the bounds change transaction
                 // will only be applied with the buffer.
                 t.merge(task.getMainWindowSizeChangeTransaction());
+                task.setMainWindowSizeChangeTransaction(null);
             } else {
-                // Use pending transaction here instead of the transaction passed in because we
-                // want to ensure the defer transaction is applied on the main transaction and
-                // not on the sync  transaction. This is because the sync transaction could
-                // contain the buffer and we'd defer the transaction that contains the buffer
-                // we're deferring on.
-                SurfaceControl.Transaction pendingTransaction = mWin.getPendingTransaction();
-                pendingTransaction.deferTransactionUntil(
-                        task.getMainWindowSizeChangeTask().getSurfaceControl(),
-                        mWin.getClientViewRootSurface(), mWin.getFrameNumber());
-                pendingTransaction.deferTransactionUntil(mSurfaceController.mSurfaceControl,
-                        mWin.getClientViewRootSurface(), mWin.getFrameNumber());
-                pendingTransaction.merge(task.getMainWindowSizeChangeTransaction());
+                mWin.applyWithNextDraw(finishedFrame -> {
+                      final SurfaceControl.Transaction sizeChangedTransaction =
+                          task.getMainWindowSizeChangeTransaction();
+                      if (sizeChangedTransaction != null) {
+                          finishedFrame.merge(sizeChangedTransaction);
+                          task.setMainWindowSizeChangeTransaction(null);
+                      }
+                });
             }
-            task.setMainWindowSizeChangeTransaction(null);
         }
     }