commit 7ee4f464bf6e70007a17df078e905898efc5a80e
author Vishnu Nair <vishnun@google.com> Wed Apr 19 09:54:09 2023 -0700
committer Vishnu Nair <vishnun@google.com> Wed Apr 19 09:54:09 2023 -0700
tree 638c6ff65aacd44af7d5c094de2dcfb4fd466933
parent 9402f4fa5166f95c4cc5f8164f0930261ff58dd0

[sf] Release the currently presented buffer when setBuffer is called
with null

Fixes a regression introduced in T which ignores a setBuffer call
with a null buffer. The expected behavior should be to release the
currently presented buffer from surfaceflinger. The subsequent frame
will not present this layer so the region behind the layer will be
composited instead.

Bug: 241271897
Test: presubmit
Change-Id: Ie06025c59c58cc75a267b783729996a3cbceef45

libs/gui/SurfaceComposerClient.cpp

diff --git a/libs/gui/SurfaceComposerClient.cpp b/libs/gui/SurfaceComposerClient.cpp
index 7700aa4..eb5cc4f 100644
--- a/libs/gui/SurfaceComposerClient.cpp
+++ b/libs/gui/SurfaceComposerClient.cpp
@@ -898,7 +898,7 @@
 }
 
 void SurfaceComposerClient::Transaction::releaseBufferIfOverwriting(const layer_state_t& state) {
-    if (!(state.what & layer_state_t::eBufferChanged)) {
+    if (!(state.what & layer_state_t::eBufferChanged) || !state.bufferData->hasBuffer()) {
         return;
     }
 
@@ -1642,28 +1642,25 @@
 
     releaseBufferIfOverwriting(*s);
 
-    if (buffer == nullptr) {
-        s->what &= ~layer_state_t::eBufferChanged;
-        s->bufferData = nullptr;
-        return *this;
-    }
-
     std::shared_ptr<BufferData> bufferData = std::make_shared<BufferData>();
     bufferData->buffer = buffer;
-    uint64_t frameNumber = sc->resolveFrameNumber(optFrameNumber);
-    bufferData->frameNumber = frameNumber;
-    bufferData->producerId = producerId;
-    bufferData->flags |= BufferData::BufferDataChange::frameNumberChanged;
-    if (fence) {
-        bufferData->acquireFence = *fence;
-        bufferData->flags |= BufferData::BufferDataChange::fenceChanged;
+    if (buffer) {
+        uint64_t frameNumber = sc->resolveFrameNumber(optFrameNumber);
+        bufferData->frameNumber = frameNumber;
+        bufferData->producerId = producerId;
+        bufferData->flags |= BufferData::BufferDataChange::frameNumberChanged;
+        if (fence) {
+            bufferData->acquireFence = *fence;
+            bufferData->flags |= BufferData::BufferDataChange::fenceChanged;
+        }
+        bufferData->releaseBufferEndpoint =
+                IInterface::asBinder(TransactionCompletedListener::getIInstance());
+        setReleaseBufferCallback(bufferData.get(), callback);
     }
-    bufferData->releaseBufferEndpoint =
-            IInterface::asBinder(TransactionCompletedListener::getIInstance());
+
     if (mIsAutoTimestamp) {
         mDesiredPresentTime = systemTime();
     }
-    setReleaseBufferCallback(bufferData.get(), callback);
     s->what |= layer_state_t::eBufferChanged;
     s->bufferData = std::move(bufferData);
     registerSurfaceControlForCallback(sc);
@@ -1684,6 +1681,25 @@
     return *this;
 }
 
+SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::unsetBuffer(
+        const sp<SurfaceControl>& sc) {
+    layer_state_t* s = getLayerState(sc);
+    if (!s) {
+        mStatus = BAD_INDEX;
+        return *this;
+    }
+
+    if (!(s->what & layer_state_t::eBufferChanged)) {
+        return *this;
+    }
+
+    releaseBufferIfOverwriting(*s);
+
+    s->what &= ~layer_state_t::eBufferChanged;
+    s->bufferData = nullptr;
+    return *this;
+}
+
 void SurfaceComposerClient::Transaction::setReleaseBufferCallback(BufferData* bufferData,
                                                                   ReleaseBufferCallback callback) {
     if (!callback) {