SurfaceTextureReleaseBlockingListener.java
/*
* Copyright 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.camera.view;
import android.graphics.SurfaceTexture;
import android.view.TextureView;
import androidx.annotation.NonNull;
import androidx.camera.core.impl.utils.executor.CameraXExecutors;
import androidx.camera.core.impl.utils.futures.Futures;
import androidx.concurrent.futures.CallbackToFutureAdapter;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
/**
* An implementation of {@link android.view.TextureView.SurfaceTextureListener} that prevents the
* {@link TextureView} from releasing the {@link SurfaceTexture} until it is ready to be released.
*
* <p>When using this listener,
* {@link #setSurfaceTextureSafely(SurfaceTexture, ListenableFuture)} should be used to set the
* SurfaceTexture instead of calling {@link TextureView#setSurfaceTexture(SurfaceTexture)} in
* order to prevent the SurfaceTexture from being released prematurely. If a SurfaceTexture is
* set via setSurfaceTexture() then it will be released immediately when TextureView no longer
* needs it, instead of waiting to release.
*/
final class SurfaceTextureReleaseBlockingListener implements TextureView.SurfaceTextureListener {
private ConcurrentHashMap<SurfaceTexture, CallbackToFutureAdapter.Completer<Void>>
mSurfaceTextureCompleterConcurrentHashMap = new ConcurrentHashMap<>();
private final TextureView mTextureView;
SurfaceTextureReleaseBlockingListener(TextureView textureView) {
mTextureView = textureView;
mTextureView.setSurfaceTextureListener(this);
}
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
CallbackToFutureAdapter.Completer<Void> completer =
mSurfaceTextureCompleterConcurrentHashMap.get(surface);
// Some SurfaceTextures might not have been registered via getSurfaceDestroyedFuture
if (completer == null) {
return true;
}
completer.set(null);
mSurfaceTextureCompleterConcurrentHashMap.remove(surface);
return false;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture surface) {
}
/**
* Sets the {@link SurfaceTexture} on the {@link TextureView} passed by
* {@link
* SurfaceTextureReleaseBlockingListener#SurfaceTextureReleaseBlockingListener(TextureView)}.
*
* <p>The SurfaceTexture will not be immediately released when the TextureView is finished
* with it. Instead, it will be released when both the TextureView is finished with it and
* the surfaceReleasedBlockingFuture completes.
*
* @param surfaceReleaseBlockingFuture When this future completes, regardless of success or
* failure, the SurfaceTexture can be released by the
* TextureView.
*
* @throws IllegalArgumentException if the same SurfaceTexture is set multiple times.
*/
void setSurfaceTextureSafely(@NonNull SurfaceTexture surfaceTexture,
@NonNull ListenableFuture<Void> surfaceReleaseBlockingFuture) {
if (mSurfaceTextureCompleterConcurrentHashMap.containsKey(surfaceTexture)) {
throw new IllegalArgumentException("SurfaceTexture already registered for destroy "
+ "future");
}
ListenableFuture<Void> releasedByTextureViewFuture = CallbackToFutureAdapter.getFuture(
completer -> {
mSurfaceTextureCompleterConcurrentHashMap.put(surfaceTexture, completer);
return "SurfaceTextureDestroyCompleter";
});
// Setup the futures for releasing
List<ListenableFuture<Void>> futureList = Arrays.asList(surfaceReleaseBlockingFuture,
releasedByTextureViewFuture);
// Future should only complete once both safeToRelease completes and
// onSurfaceTextureDestroyed called from TextureView so it should always release the
// Surface and SurfaceTexture
ListenableFuture<List<Void>> future = Futures.successfulAsList(futureList);
// TODO(b/144878737) On API 28 and below exhibits null dereference crash in native code,
// during unit tests. May need a way to check for validity.
future.addListener(surfaceTexture::release, CameraXExecutors.directExecutor());
mTextureView.setSurfaceTexture(surfaceTexture);
}
}