最后我找到了解决方案reprocessableCaptureSession工作。
我使用 Flux 架构，所以当你看到时不要感到困惑Dispatcher.dispatch(action)，只需将其视为回调即可。所以，这是我的代码：
首先会话是如何创建的：
//Configure preview surface
Size previewSize = previewState.previewSize;
previewState.previewTexture.setDefaultBufferSize(previewSize.getWidth(), previewSize.getHeight());
ArrayList<Surface> targets = new ArrayList<>();
for (SessionOutputTarget outputTarget : state.outputTargets) {
Surface surface = outputTarget.getSurface();
if (surface != null) targets.add(surface);
}
targets.add(previewState.previewSurface);
CameraCharacteristics cameraCharacteristics = cameraStore.state().availableCameras.get(cameraStore.state().selectedCamera);
Size size = CameraCharacteristicsUtil.getYuvOutputSizes(cameraCharacteristics).get(0);
InputConfiguration inputConfiguration = new InputConfiguration(size.getWidth(),
size.getHeight(), ImageFormat.YUV_420_888);
CameraCaptureSession.StateCallback sessionStateCallback = new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession session) {
if (sessionId != currentSessionId) {
Timber.e("Session opened for an old open request, skipping. Current %d, Request %d", currentSessionId, sessionId);
//performClose(session);
return;
}
try {
session.getInputSurface();
//This call is irrelevant,
//however session might have closed and this will throw an IllegalStateException.
//This happens if another camera app (or this one in another PID) takes control
//of the camera while its opening
} catch (IllegalStateException e) {
Timber.e("Another process took control of the camera while creating the session, aborting!");
}
Dispatcher.dispatchOnUi(new SessionOpenedAction(session));
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession session) {
if (sessionId != currentSessionId) {
Timber.e("Configure failed for an old open request, skipping. Current %d, request %d", currentSessionId, sessionId);
return;
}
Timber.e("Failed to configure the session");
Dispatcher.dispatchOnUi(new SessionFailedAction(session, new IllegalStateException("onConfigureFailed")));
}
};
if (state.outputMode == OutputMode.PHOTO) {
cameraState.cameraDevice.createReprocessableCaptureSession(inputConfiguration, targets, sessionStateCallback, handlers.bg());
} else if (state.outputMode == OutputMode.VIDEO) {
cameraState.cameraDevice.createCaptureSession(targets, sessionStateCallback, handlers.bg());
}
} catch (IllegalStateException | IllegalArgumentException e) {
Timber.e(e, "Something went wrong trying to start the session");
} catch (CameraAccessException e) {
//Camera will throw CameraAccessException if another we try to open / close the
//session very fast.
Timber.e("Failed to access camera, it was closed");
}
照片会话使用 4 个表面创建（预览、YUV（输入）、JPEG 和 RAW）。之后，我配置我的 imageWriter：
Dispatcher.subscribe(Dispatcher.VERY_HIGH_PRIORITY, SessionOpenedAction.class)
.filter(a -> isInPhotoMode())
.subscribe(action -> {
PhotoState newState = new PhotoState(state());
newState.zslImageWriter = ImageWriter.newInstance(action.session.getInputSurface(), MAX_REPROCESS_IMAGES);
setState(newState);
});
好的，现在我们已经创建了 ImageWriter 和会话。不，我们通过重复请求开始流式传输：
CaptureRequest.Builder captureRequestBuilder =
cameraStore.state().cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_ZERO_SHUTTER_LAG);
captureRequestBuilder.addTarget(previewStore.state().previewSurface);
captureRequestBuilder.addTarget(photoStore.state().yuvImageReader.getSurface());
state.session.setRepeatingRequest(captureRequestBuilder.build(), state.zslCaptureCallback, handlers.bg());
为了不添加大量代码，只需说 zslCaptureCallback 是一个自定义回调，它保存在LinkedBlockingQueue<TotalCaptureRequest>最后 X 个 TotalCaptureRequests。另外，我对 yuvImageReader（输入一个）执行相同的操作，将最后 X 个图像保存在队列中。
最后这是我的“拍照”方法：
try {
//Retrieve the last image stored by the zslImageReader
Image image = zslImageReaderListener.getImage();
//Retrieve the last totalCaptureResult from the zslCaptureCallback and create a reprocessableCaptureRequest with it
TotalCaptureResult captureResult = sessionStore.state().zslCaptureCallback.getCaptureResult(image.getTimestamp());
CaptureRequest.Builder captureRequest = cameraStore.state().cameraDevice.createReprocessCaptureRequest(captureResult);
//Add the desired target and values to the captureRequest
captureRequest.addTarget(state().jpegImageReader.getSurface());
//Queued back to ImageWriter for future consumption.
state.zslImageWriter.queueInputImage(image);
//Drain all the unused and queued CapturedResult from the CaptureCallback
sessionStore.state().zslCaptureCallback.drain();
//Capture the desired frame
CaptureRequest futureCaptureResult = captureRequest.build();
sessionStore.state().session.capture(futureCaptureResult, new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {
Dispatcher.dispatchOnUi(new PhotoStatusChangedAction(PhotoState.Status.SUCCESS));
}
@Override
public void onCaptureFailed(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull CaptureFailure failure) {
super.onCaptureFailed(session, request, failure);
Exception captureFailedException = new RuntimeException(
String.format("Capture failed: Reason %s in frame %d, was image captured? -> %s",
failure.getReason(),
failure.getFrameNumber(),
failure.wasImageCaptured()));
Timber.e(captureFailedException, "Cannot take mediaType, capture failed!");
Dispatcher.dispatchOnUi(new PhotoStatusChangedAction(PhotoState.Status.ERROR, captureFailedException));
}
}, this.handlers.bg());
//Capture did not blow up, we are taking the photo now.
newState.status = PhotoState.Status.TAKING;
} catch (CameraAccessException | InterruptedException| IllegalStateException | IllegalArgumentException | SecurityException e) {
Timber.e(e, "Cannot take picture, capture error!");
newState.status = PhotoState.Status.ERROR;
}
