ForwardingImageReaderListener.java
/*
* Copyright (C) 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.core;
import androidx.annotation.GuardedBy;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* An {@link ImageReaderProxy.OnImageAvailableListener} which forks and forwards newly available
* images to multiple {@link ImageReaderProxy} instances.
*/
final class ForwardingImageReaderListener implements ImageReaderProxy.OnImageAvailableListener {
@GuardedBy("this")
private final List<QueuedImageReaderProxy> mImageReaders;
/**
* Creates a new forwarding listener.
*
* @param imageReaders list of image readers which will receive a copy of every new image
* @return new {@link ForwardingImageReaderListener} instance
*/
ForwardingImageReaderListener(List<QueuedImageReaderProxy> imageReaders) {
// Make a copy of the incoming List to avoid ConcurrentAccessException.
mImageReaders = Collections.unmodifiableList(new ArrayList<>(imageReaders));
}
@Override
public synchronized void onImageAvailable(ImageReaderProxy imageReaderProxy) {
ImageProxy imageProxy = imageReaderProxy.acquireNextImage();
if (imageProxy == null) {
return;
}
ReferenceCountedImageProxy referenceCountedImageProxy =
new ReferenceCountedImageProxy(imageProxy);
for (QueuedImageReaderProxy queuedImageReaderProxy : mImageReaders) {
synchronized (queuedImageReaderProxy) {
if (!queuedImageReaderProxy.isClosed()) {
ImageProxy forkedImage = referenceCountedImageProxy.fork();
ForwardingImageProxy imageToEnqueue =
ImageProxyDownsampler.downsample(
forkedImage,
queuedImageReaderProxy.getWidth(),
queuedImageReaderProxy.getHeight(),
ImageProxyDownsampler.DownsamplingMethod.AVERAGING);
queuedImageReaderProxy.enqueueImage(imageToEnqueue);
}
}
}
referenceCountedImageProxy.close();
}
}