[libcamera-devel] [RFC PATCH 0/8] Configuration files and parsing

[Kieran Bingham]

A preliminary posting of a series which allows me to parse controls on a
CameraSensor from a json file which overrides the location and rotation
properties.

For example, creating a camera_sensor.json file within the libcamera
sysconf paths, with the following content can manually set the
properties:

pi at mercury:~/libcamera $ cat /usr/local/etc/libcamera/camera_sensor.json 
{
  "/base/soc/i2c0mux/i2c at 1/imx219 at 10": {
	"properties": {
		"Rotation" : 270,
		"Location" : 0
	}
  }
}


This implementation exposes the nlohmann json library to libcamera
internals rather than wrapping it and re-encoding a generic any-type
into another type.

The series starts out by cleaning up our meson files to easily obtain
and parse the system paths from our config.h and cleans up the IPA meson
to re-use those new variables.

The Configuration class instance itself is really only about finding and
parsing the configuration files, and how the data is parsed is up to the
internal code that needs to use the files.


Kieran Bingham (8):
  meson: Simplify pkg_mod.generate
  src: meson: Re-order subdir layout
  src: meson: Simplify v4l2 enablement
  src: meson: Define system paths
  src: ipa: meson: Re-use existing system paths
  libcamera: Add configuration interface
  test: Add configuration parser tests
  libcamera: camera_sensor: Parse configuration properties

 README.rst                                 |   2 +-
 include/libcamera/internal/camera_sensor.h |   1 +
 include/libcamera/internal/configuration.h |  37 ++++++++
 meson.build                                |   3 +-
 src/ipa/meson.build                        |  16 ++--
 src/libcamera/camera_sensor.cpp            |  50 ++++++++++
 src/libcamera/configuration.cpp            |  91 ++++++++++++++++++
 src/libcamera/meson.build                  |   1 +
 src/meson.build                            |  23 ++++-
 src/v4l2/meson.build                       |   4 +
 test/configuration.cpp                     | 105 +++++++++++++++++++++
 test/data/test_configuration.json          |  15 +++
 test/data/unparsable.json                  |   7 ++
 test/meson.build                           |   1 +
 14 files changed, 339 insertions(+), 17 deletions(-)
 create mode 100644 include/libcamera/internal/configuration.h
 create mode 100644 src/libcamera/configuration.cpp
 create mode 100644 test/configuration.cpp
 create mode 100644 test/data/test_configuration.json
 create mode 100644 test/data/unparsable.json

-- 
2.25.1