[libcamera-devel] [PATCH v2 10/12] android: camera_device: Rework CameraStream handling

[Jacopo Mondi]

The CameraDevice::streams_ vector of CameraStream instances is
currently mostly accessed by index. The current implementation
creates all the CameraStream during the first loop that inspects the
camera3_stream instances, and the update the index of the
StreamConfiguration associated with the CameraStream during a second
loop that inspects MJPEG streams. A third loop creates the JPEG encoder
associated with CameraStreams that produce MJPEG format.

As the index-based association is hard to follow and rather fragile,
rework the creation and handling of CameraStream:

1) Make the StreamConfiguration index a constructor parameter and a
   private struct member.  This disallow the creation of CameraStream
   without a StreamConfiguration index assigned.

2) Create CameraStream only after the associated StreamConfiguration
   has been identified. The first loop creates CameraStream for non-JPEG
   streams, the second for the JPEG ones after having identified the
   associated StreamConfiguration. Since we have just created the
   CameraStream, create the JPEG encoder at the same time instead of
   deferring it.

This change removes all accesses by index to the CameraDevice::streams_
vector.

No functional changes intended, but this change aims to make the code
easier to follow and more robust.

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/android/camera_device.cpp | 75 +++++++++++++++++++----------------
 src/android/camera_device.h   | 18 +++++----
 2 files changed, 51 insertions(+), 42 deletions(-)

diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
index 3630e87e8814..9bcd1d993c17 100644
--- a/src/android/camera_device.cpp
+++ b/src/android/camera_device.cpp
@@ -168,8 +168,8 @@ MappedCamera3Buffer::MappedCamera3Buffer(const buffer_handle_t camera3buffer,
 	}
 }
 
-CameraStream::CameraStream(PixelFormat f, Size s)
-	: index(-1), format(f), size(s), jpeg(nullptr)
+CameraStream::CameraStream(PixelFormat f, Size s, unsigned int i)
+	: format(f), size(s), jpeg(nullptr), index_(i)
 {
 }
 
@@ -1212,30 +1212,28 @@ int CameraDevice::configureStreams(camera3_stream_configuration_t *stream_list)
 		if (!format.isValid())
 			return -EINVAL;
 
-		streams_.emplace_back(format, size);
-		stream->priv = static_cast<void *>(&streams_[i]);
-
 		/* Defer handling of MJPEG streams until all others are known. */
 		if (stream->format == HAL_PIXEL_FORMAT_BLOB)
 			continue;
 
 		StreamConfiguration streamConfiguration;
-
 		streamConfiguration.size = size;
 		streamConfiguration.pixelFormat = format;
 
-		streams_[i].index = config_->addConfiguration(streamConfiguration);
+		unsigned int index = config_->addConfiguration(streamConfiguration);
+		CameraStream &cameraStream = streams_.emplace_back(format, size, index);
+		stream->priv = static_cast<void *>(&cameraStream);
 	}
 
 	/* Now handle MJPEG streams, adding a new stream if required. */
 	for (unsigned int i = 0; i < stream_list->num_streams; ++i) {
 		camera3_stream_t *stream = stream_list->streams[i];
-		bool match = false;
-
 		if (stream->format != HAL_PIXEL_FORMAT_BLOB)
 			continue;
 
-		/* Search for a compatible stream */
+		/* Search for a compatible stream in the non-JPEG ones. */
+		bool match = false;
+		unsigned int index;
 		for (unsigned int j = 0; j < config_->size(); j++) {
 			StreamConfiguration &cfg = config_->at(j);
 
@@ -1243,13 +1241,15 @@ int CameraDevice::configureStreams(camera3_stream_configuration_t *stream_list)
 			 * \todo The PixelFormat must also be compatible with
 			 * the encoder.
 			 */
-			if (cfg.size == streams_[i].size) {
-				LOG(HAL, Info) << "Stream " << i
-					       << " using libcamera stream " << j;
+			if (cfg.size.width != stream->width ||
+			    cfg.size.height != stream->height)
+				continue;
 
-				match = true;
-				streams_[i].index = j;
-			}
+			LOG(HAL, Info) << "Stream " << i
+				       << " using libcamera stream " << j;
+
+			index = j;
+			match = true;
 		}
 
 		/*
@@ -1272,7 +1272,26 @@ int CameraDevice::configureStreams(camera3_stream_configuration_t *stream_list)
 			LOG(HAL, Info) << "Adding " << streamConfiguration.toString()
 				       << " for MJPEG support";
 
-			streams_[i].index = config_->addConfiguration(streamConfiguration);
+			index = config_->addConfiguration(streamConfiguration);
+		}
+
+		StreamConfiguration &cfg = config_->at(index);
+		PixelFormat format = formats::MJPEG;
+		Size size = cfg.size;
+
+		CameraStream &cameraStream = streams_.emplace_back(format, size, index);
+		stream->priv = static_cast<void *>(&cameraStream);
+
+		/*
+		 * Construct a software encoder for MJPEG streams from the
+		 * chosen libcamera source stream.
+		 */
+		cameraStream.jpeg = new EncoderLibJpeg();
+		int ret = cameraStream.jpeg->configure(cfg);
+		if (ret) {
+			LOG(HAL, Error)
+				<< "Failed to configure encoder";
+			return ret;
 		}
 	}
 
@@ -1295,25 +1314,11 @@ int CameraDevice::configureStreams(camera3_stream_configuration_t *stream_list)
 
 	for (unsigned int i = 0; i < stream_list->num_streams; ++i) {
 		camera3_stream_t *stream = stream_list->streams[i];
-		CameraStream *cameraStream = &streams_[i];
-		StreamConfiguration &cfg = config_->at(cameraStream->index);
+		CameraStream *cameraStream = static_cast<CameraStream *>(stream->priv);
+		StreamConfiguration &cfg = config_->at(cameraStream->index());
 
 		/* Use the bufferCount confirmed by the validation process. */
 		stream->max_buffers = cfg.bufferCount;
-
-		/*
-		 * Construct a software encoder for MJPEG streams from the
-		 * chosen libcamera source stream.
-		 */
-		if (cameraStream->format == formats::MJPEG) {
-			cameraStream->jpeg = new EncoderLibJpeg();
-			int ret = cameraStream->jpeg->configure(cfg);
-			if (ret) {
-				LOG(HAL, Error)
-					<< "Failed to configure encoder";
-				return ret;
-			}
-		}
 	}
 
 	/*
@@ -1427,7 +1432,7 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
 		}
 		descriptor->frameBuffers.emplace_back(buffer);
 
-		StreamConfiguration *streamConfiguration = &config_->at(cameraStream->index);
+		StreamConfiguration *streamConfiguration = &config_->at(cameraStream->index());
 		Stream *stream = streamConfiguration->stream();
 
 		request->addBuffer(stream, buffer);
@@ -1482,7 +1487,7 @@ void CameraDevice::requestComplete(Request *request)
 			continue;
 		}
 
-		StreamConfiguration *streamConfiguration = &config_->at(cameraStream->index);
+		StreamConfiguration *streamConfiguration = &config_->at(cameraStream->index());
 		Stream *stream = streamConfiguration->stream();
 		FrameBuffer *buffer = request->findBuffer(stream);
 		if (!buffer) {
diff --git a/src/android/camera_device.h b/src/android/camera_device.h
index dc0ee664d443..f8f237203ce9 100644
--- a/src/android/camera_device.h
+++ b/src/android/camera_device.h
@@ -28,20 +28,24 @@
 class CameraMetadata;
 
 struct CameraStream {
-	CameraStream(libcamera::PixelFormat, libcamera::Size);
+public:
+	CameraStream(libcamera::PixelFormat, libcamera::Size, unsigned int i);
 	~CameraStream();
 
-	/*
-	 * The index of the libcamera StreamConfiguration as added during
-	 * configureStreams(). A single libcamera Stream may be used to deliver
-	 * one or more streams to the Android framework.
-	 */
-	unsigned int index;
+	unsigned int index() const { return index_; }
 
 	libcamera::PixelFormat format;
 	libcamera::Size size;
 
 	Encoder *jpeg;
+
+private:
+	/*
+	 * The index of the libcamera StreamConfiguration as added during
+	 * configureStreams(). A single libcamera Stream may be used to deliver
+	 * one or more streams to the Android framework.
+	 */
+	unsigned int index_;
 };
 
 class CameraDevice : protected libcamera::Loggable
-- 
2.28.0