android: camera_device: Rework CameraStream handling

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 then 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 camera streams 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 disallows 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: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

1 files changed, 11 insertions, 7 deletions

diff --git a/src/android/camera_device.h b/src/android/camera_device.h
index c0732fb8..376d001e 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