SurfaceTexture: change onFrameAvailable behavior
This change alters the conditions under which the onFrameAvailable
callback gets called by the C++ SurfaceTexture class. The new behavior
is to call the callback whenever a frame gets queued that will be
visible to the buffer consumer. This means that buffers queued in
synchronous mode always trigger the callback, as those buffers will
remain pending until they are consumed. Buffers queued in asynchronous
mode will only trigger the callback if there was not previously an
unconsumed buffer pending.
The new behavior means that a consumer should perform a draw operation
exactly once for every onFrameAvailable call that it recieves. This
change also modifies SurfaceFlinger and the SurfaceTexture JNI to
support of the new behavior.
Change-Id: I8b2c6e00961d3d58b11c6af50b555b6e4c5f5b40
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 2bab6a8..35e29a6 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -101,9 +101,8 @@
}
void Layer::onFrameQueued() {
- if (android_atomic_or(1, &mQueuedFrames) == 0) {
- mFlinger->signalEvent();
- }
+ android_atomic_inc(&mQueuedFrames);
+ mFlinger->signalEvent();
}
// called with SurfaceFlinger::mStateLock as soon as the layer is entered
@@ -406,20 +405,18 @@
void Layer::lockPageFlip(bool& recomputeVisibleRegions)
{
- if (android_atomic_and(0, &mQueuedFrames)) {
+ if (mQueuedFrames > 0) {
+ // signal another event if we have more frames pending
+ if (android_atomic_dec(&mQueuedFrames) > 1) {
+ mFlinger->signalEvent();
+ }
+
if (mSurfaceTexture->updateTexImage() < NO_ERROR) {
// something happened!
recomputeVisibleRegions = true;
return;
}
- // signal another event if we have more frames waiting
- if (mSurfaceTexture->getQueuedCount()) {
- if (android_atomic_or(1, &mQueuedFrames) == 0) {
- mFlinger->signalEvent();
- }
- }
-
mActiveBuffer = mSurfaceTexture->getCurrentBuffer();
mSurfaceTexture->getTransformMatrix(mTextureMatrix);