2 files changed, 21 insertions, 4 deletions
diff --git a/core/java/android/view/ViewRootImpl.java b/core/java/android/view/ViewRootImpl.java
index 1e96a1c21ac3..7b89620a9a84 100644
--- a/core/java/android/view/ViewRootImpl.java
+++ b/core/java/android/view/ViewRootImpl.java
@@ -3014,6 +3014,10 @@ public final class ViewRootImpl implements ViewParent,
         if ((relayoutResult & WindowManagerGlobal.RELAYOUT_RES_FIRST_TIME) != 0) {
             reportNextDraw();
         }
+        if ((relayoutResult & WindowManagerGlobal.RELAYOUT_RES_BLAST_SYNC) != 0) {
+            reportNextDraw();
+            setUseBLASTSyncTransaction();
+        }
 
         boolean cancelDraw = mAttachInfo.mTreeObserver.dispatchOnPreDraw() || !isViewVisible;
 
@@ -3722,7 +3726,7 @@ public final class ViewRootImpl implements ViewParent,
             if (needFrameCompleteCallback) {
                 final Handler handler = mAttachInfo.mHandler;
                 mAttachInfo.mThreadedRenderer.setFrameCompleteCallback((long frameNr) -> {
-                        finishBLASTSync();
+                        finishBLASTSync(!reportNextDraw);
                         handler.postAtFrontOfQueue(() -> {
                             if (reportNextDraw) {
                                 // TODO: Use the frame number
@@ -3756,7 +3760,7 @@ public final class ViewRootImpl implements ViewParent,
             if (usingAsyncReport && !canUseAsync) {
                 mAttachInfo.mThreadedRenderer.setFrameCompleteCallback(null);
                 usingAsyncReport = false;
-                finishBLASTSync();
+                finishBLASTSync(true /* apply */);
             }
         } finally {
             mIsDrawing = false;
@@ -9572,10 +9576,15 @@ public final class ViewRootImpl implements ViewParent,
         mNextDrawUseBLASTSyncTransaction = true;
     }
 
-    private void finishBLASTSync() {
+    private void finishBLASTSync(boolean apply) {
         if (mNextReportConsumeBLAST) {
             mNextReportConsumeBLAST = false;
-            mRtBLASTSyncTransaction.apply();
+
+            if (apply) {
+                mRtBLASTSyncTransaction.apply();
+            } else {
+                mSurfaceChangedTransaction.merge(mRtBLASTSyncTransaction);
+            }
         }
     }
 
diff --git a/core/java/android/view/WindowManagerGlobal.java b/core/java/android/view/WindowManagerGlobal.java
index 410d9afe73da..ab968d798745 100644
--- a/core/java/android/view/WindowManagerGlobal.java
+++ b/core/java/android/view/WindowManagerGlobal.java
@@ -102,6 +102,14 @@ public final class WindowManagerGlobal {
     public static final int RELAYOUT_RES_CONSUME_ALWAYS_SYSTEM_BARS = 0x40;
 
     /**
+     * This flag indicates the client should not directly submit it's next frame,
+     * but instead should pass it in the postDrawTransaction of
+     * {@link WindowManagerService#finishDrawing}. This is used by the WM
+     * BLASTSyncEngine to synchronize rendering of multiple windows.
+     */
+    public static final int RELAYOUT_RES_BLAST_SYNC = 0x80;
+
+    /**
      * Flag for relayout: the client will be later giving
      * internal insets; as a result, the window will not impact other window
      * layouts until the insets are given.