[libcamera-devel] [PATCH v3 17/18] py: generate pixel formats list

[Tomi Valkeinen]

On 18/05/2022 16:54, Laurent Pinchart wrote:
> Hi Tomi,
> 
> Thank you for the patch.
> 
> On Wed, May 18, 2022 at 04:13:28PM +0300, Tomi Valkeinen wrote:
>> Generate a list of pixel formats under "libcamera.formats".
>>
>> I'm not super happy about this solution, as the user can change the
>> formats (libcamera.formats.XRGB8888 = None) and, for some reason,
> 
> I won't make it a blocker for this patch, but is there a way this could
> be fixed ?

I don't know. I don't think it's a big issue. Usually you can overwrite 
all kinds of things in Python, so this is no different.

I think another way would be to implement this in pure python (generated 
.py file). Perhaps a Python enum would work here.

Whatever we figure out in the future, I believe the style the user uses 
will stay the same (libcamera.format.XRGB8888).

>> pybind11-stubgen doesn't produce stubs for this.
>>
>> However, other than the two issues above, it works, and I haven't
>> figured out a better way.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
>> ---
>>   src/py/libcamera/gen-py-formats.py           | 56 ++++++++++++++++++++
>>   src/py/libcamera/meson.build                 | 12 +++++
>>   src/py/libcamera/py_formats_generated.cpp.in | 21 ++++++++
>>   src/py/libcamera/py_main.cpp                 |  3 ++
>>   4 files changed, 92 insertions(+)
>>   create mode 100755 src/py/libcamera/gen-py-formats.py
>>   create mode 100644 src/py/libcamera/py_formats_generated.cpp.in
>>
>> diff --git a/src/py/libcamera/gen-py-formats.py b/src/py/libcamera/gen-py-formats.py
>> new file mode 100755
>> index 00000000..72565a25
>> --- /dev/null
>> +++ b/src/py/libcamera/gen-py-formats.py
>> @@ -0,0 +1,56 @@
>> +#!/usr/bin/env python3
>> +# SPDX-License-Identifier: GPL-2.0-or-later
>> +#
>> +# Generate Python format definitions from YAML
>> +
>> +import argparse
>> +import string
>> +import sys
>> +import yaml
>> +
>> +
>> +def generate(formats):
>> +    fmts = []
>> +
>> +    for format in formats:
>> +        name, format = format.popitem()
>> +        fmts.append(f'formats.attr("{name}") = &libcamera::formats::{name};')
>> +
>> +    return {'formats': '\n'.join(fmts)}
>> +
>> +
>> +def fill_template(template, data):
>> +    with open(template, encoding='utf-8') as f:
>> +        template = f.read()
>> +
>> +    template = string.Template(template)
>> +    return template.substitute(data)
>> +
>> +
>> +def main(argv):
>> +    parser = argparse.ArgumentParser()
>> +    parser.add_argument('-o', dest='output', metavar='file', type=str,
>> +                        help='Output file name. Defaults to standard output if not specified.')
>> +    parser.add_argument('input', type=str,
>> +                        help='Input file name.')
>> +    parser.add_argument('template', type=str,
>> +                        help='Template file name.')
>> +    args = parser.parse_args(argv[1:])
>> +
>> +    with open(args.input, encoding='utf-8') as f:
>> +        formats = yaml.safe_load(f)['formats']
>> +
>> +    data = generate(formats)
>> +    data = fill_template(args.template, data)
>> +
>> +    if args.output:
>> +        with open(args.output, 'w', encoding='utf-8') as f:
>> +            f.write(data)
>> +    else:
>> +        sys.stdout.write(data)
>> +
>> +    return 0
>> +
>> +
>> +if __name__ == '__main__':
>> +    sys.exit(main(sys.argv))
>> diff --git a/src/py/libcamera/meson.build b/src/py/libcamera/meson.build
>> index a3388c63..0a7b65f3 100644
>> --- a/src/py/libcamera/meson.build
>> +++ b/src/py/libcamera/meson.build
>> @@ -30,6 +30,18 @@ pycamera_sources += custom_target('py_gen_controls',
>>                                     output : ['py_control_enums_generated.cpp'],
>>                                     command : [gen_py_control_enums, '-o', '@OUTPUT@', '@INPUT@'])
>>   
>> +gen_py_formats_input_files = files([
>> +    '../../libcamera/formats.yaml',
>> +    'py_formats_generated.cpp.in',
>> +])
>> +
>> +gen_py_formats = files('gen-py-formats.py')
>> +
>> +pycamera_sources += custom_target('py_gen_formats',
>> +                                  input : gen_py_formats_input_files,
>> +                                  output : ['py_formats_generated.cpp'],
>> +                                  command : [gen_py_formats, '-o', '@OUTPUT@', '@INPUT@'])
>> +
>>   pycamera_deps = [
>>       libcamera_public,
>>       py3_dep,
>> diff --git a/src/py/libcamera/py_formats_generated.cpp.in b/src/py/libcamera/py_formats_generated.cpp.in
>> new file mode 100644
>> index 00000000..1100c024
>> --- /dev/null
>> +++ b/src/py/libcamera/py_formats_generated.cpp.in
>> @@ -0,0 +1,21 @@
>> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
>> +/*
>> + * Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
>> + *
>> + * Python bindings - Auto-generated formats
>> + *
>> + * This file is auto-generated. Do not edit.
>> + */
>> +
>> +#include <libcamera/formats.h>
>> +
>> +#include <pybind11/smart_holder.h>
>> +
>> +namespace py = pybind11;
>> +
>> +void init_py_formats_generated(py::module& m)
>> +{
>> +auto formats = m.def_submodule("formats");
>> +
>> +${formats}
> 
> Could you indent this ? It's nicer to keep generated files readable.

Sure.

  Tomi