Remove consumeNextDraw and replace with SurfaceSyncer

Replace the usage of consumeNextDraw with the SurfaceSyncer since
it's safer and integrated with VRI in a cleaner way.

Test: Internet Dialog in Notification Shade
Bug: 200284684
Change-Id: Ia837086040329c5fd3b8bb5b0adb0fddb339f3f9

core/java/android/view/ViewRootImpl.java

@@ -228,7 +228,6 @@ import java.util.List;
 import java.util.Objects;
 import java.util.Queue;
 import java.util.concurrent.CountDownLatch;
-import java.util.function.Consumer;
 
 /**
  * The top of a view hierarchy, implementing the needed protocol between View
@@ -827,8 +826,6 @@ public final class ViewRootImpl implements ViewParent,
      */
     private long mRtLastAttemptedDrawFrameNum = 0;
 
-    private Consumer<SurfaceControl.Transaction> mBLASTDrawConsumer;
-
     private HashSet<ScrollCaptureCallback> mRootScrollCaptureCallbacks;
 
     private long mScrollCaptureRequestTimeout = SCROLL_CAPTURE_REQUEST_TIMEOUT_MILLIS;
@@ -3493,36 +3490,24 @@ public final class ViewRootImpl implements ViewParent,
     }
 
     private void createSyncIfNeeded() {
-        // Started a sync already.
+        // Started a sync already or there's nothing needing to sync
-        if (mLastSyncId != -1) {
+        if (mLastSyncId != -1 || !mReportNextDraw) {
             return;
         }
 
-        Consumer<Transaction> syncConsumer = null;
         final int seqId = mSyncSeqId;
-
-        if (mBLASTDrawConsumer != null) {
-            syncConsumer = mBLASTDrawConsumer;
-            mBLASTDrawConsumer = null;
-        } else if (mReportNextDraw) {
-            syncConsumer = transaction -> {
-                mSurfaceChangedTransaction.merge(transaction);
-                reportDrawFinished(seqId);
-            };
-        }
-
-        if (syncConsumer != null) {
-            final Consumer<Transaction> capturedSyncConsumer = syncConsumer;
         mLastSyncId = mSurfaceSyncer.setupSync(transaction -> {
             // Callback will be invoked on executor thread so post to main thread.
-                mHandler.postAtFrontOfQueue(() -> capturedSyncConsumer.accept(transaction));
+            mHandler.postAtFrontOfQueue(() -> {
+                mSurfaceChangedTransaction.merge(transaction);
+                reportDrawFinished(seqId);
+            });
         });
         if (DEBUG_BLAST) {
             Log.d(mTag, "Setup new sync id=" + mLastSyncId);
         }
         mSurfaceSyncer.addToSync(mLastSyncId, mSyncTarget);
     }
-    }
 
     private void notifyContentCatpureEvents() {
         Trace.traceBegin(Trace.TRACE_TAG_VIEW, "notifyContentCaptureEvents");
@@ -10775,37 +10760,6 @@ public final class ViewRootImpl implements ViewParent,
                 showControl, transformationApplied, callback);
     }
 
-    /**
-     * Redirect the next draw of this ViewRoot (from the UI thread perspective)
-     * to the passed in consumer. This can be used to create P2P synchronization
-     * between ViewRoot's however it comes with many caveats.
-     *
-     * 1. You MUST consume the transaction, by either applying it immediately or
-     *    merging it in to another transaction. The threading model doesn't
-     *    allow you to hold in the passed transaction.
-     * 2. If you merge it in to another transaction, this ViewRootImpl will be
-     *    paused until you finally apply that transaction and it receives
-     *    the callback from SF. If you lose track of the transaction you will
-     *    ANR the app.
-     * 3. Only one person can consume the transaction at a time, if you already
-     *    have a pending consumer for this frame, the function will return false
-     * 4. Someone else may have requested to consume the next frame, in which case
-     *    this function will return false and you will not receive a callback.
-     * 5. This function does not trigger drawing so even if it returns true you
-     *    may not receive a callback unless there is some other UI thread work
-     *    to trigger drawing. If it returns true, and a draw occurs, the callback
-     *    will be called (Though again watch out for the null transaction case!)
-     * 6. This function must be called on the UI thread. The consumer will likewise
-     *    be called on the UI thread.
-     */
-    public boolean consumeNextDraw(Consumer<SurfaceControl.Transaction> consume) {
-       if (mBLASTDrawConsumer != null) {
-           return false;
-       }
-       mBLASTDrawConsumer = consume;
-       return true;
-    }
-
     boolean wasRelayoutRequested() {
         return mRelayoutRequested;
     }

packages/SystemUI/animation/src/com/android/systemui/animation/ViewRootSync.kt

@@ -1,15 +1,15 @@
 package com.android.systemui.animation
 
 import android.app.ActivityManager
-import android.view.SurfaceControl
 import android.view.View
-import android.view.ViewRootImpl
+import android.window.SurfaceSyncer
 
 /** A util class to synchronize 2 view roots. */
 // TODO(b/200284684): Remove this class.
 object ViewRootSync {
     // TODO(b/217621394): Remove special handling for low-RAM devices after animation sync is fixed
     private val forceDisableSynchronization = ActivityManager.isLowRamDeviceStatic()
+    private var surfaceSyncer: SurfaceSyncer? = null
 
     /**
      * Synchronize the next draw between the view roots of [view] and [otherView], then run [then].
@@ -33,35 +33,11 @@ object ViewRootSync {
             return
         }
 
-        // Consume the next frames of both view roots to make sure the ghost view is drawn at
+        surfaceSyncer = SurfaceSyncer().apply {
-        // exactly the same time as when the touch surface is made invisible.
+            val syncId = setupSync(Runnable { then() })
-        var remainingTransactions = 0
+            addToSync(syncId, view)
-        val mergedTransactions = SurfaceControl.Transaction()
+            addToSync(syncId, otherView)
-
+            markSyncReady(syncId)
-        fun onTransaction(transaction: SurfaceControl.Transaction?) {
-            remainingTransactions--
-            transaction?.let { mergedTransactions.merge(it) }
-
-            if (remainingTransactions == 0) {
-                mergedTransactions.apply()
-                then()
-            }
-        }
-
-        fun consumeNextDraw(viewRootImpl: ViewRootImpl) {
-            if (viewRootImpl.consumeNextDraw(::onTransaction)) {
-                remainingTransactions++
-
-                // Make sure we trigger a traversal.
-                viewRootImpl.view.invalidate()
-            }
-        }
-
-        consumeNextDraw(view.viewRootImpl)
-        consumeNextDraw(otherView.viewRootImpl)
-
-        if (remainingTransactions == 0) {
-            then()
         }
     }