py: Generate control enums from yaml

Generate enums for controls from control_ids.yaml. The generator script
has some heuristics to generate nicer enum names. E.g. instead of having
"LensShadingMapMode.LensShadingMapModeOff" we get
"LensShadingMapMode.Off". This heuristics may need to be updated when
the yaml file is changed or new controls are added.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/py/libcamera/gen-py-control-enums.py

@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Generate Python bindings enums for controls from YAML
+
+import argparse
+import string
+import sys
+import yaml
+
+
+def find_common_prefix(strings):
+    prefix = strings[0]
+
+    for string in strings[1:]:
+        while string[:len(prefix)] != prefix and prefix:
+            prefix = prefix[:len(prefix) - 1]
+        if not prefix:
+            break
+
+    return prefix
+
+
+def generate_py(controls):
+    out = ''
+
+    for ctrl in controls:
+        name, ctrl = ctrl.popitem()
+
+        enum = ctrl.get('enum')
+        if not enum:
+            continue
+
+        if ctrl.get('draft'):
+            ns = 'libcamera::controls::draft::'
+        else:
+            ns = 'libcamera::controls::'
+
+        cpp_enum = name + 'Enum'
+
+        out += '\tpy::enum_<{}{}>(m, \"{}\")\n'.format(ns, cpp_enum, name)
+
+        if name == 'LensShadingMapMode':
+            prefix = 'LensShadingMapMode'
+        else:
+            prefix = find_common_prefix([e['name'] for e in enum])
+
+        for entry in enum:
+            cpp_enum = entry['name']
+            py_enum = entry['name'][len(prefix):]
+
+            out += '\t\t.value(\"{}\", {}{})\n'.format(py_enum, ns, cpp_enum)
+
+        out += '\t;\n'
+
+    return {'enums': out}
+
+
+def fill_template(template, data):
+    template = open(template, 'rb').read()
+    template = template.decode('utf-8')
+    template = string.Template(template)
+    return template.substitute(data)
+
+
+def main(argv):
+    # Parse command line arguments
+    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:])
+
+    data = open(args.input, 'rb').read()
+    controls = yaml.safe_load(data)['controls']
+
+    data = generate_py(controls)
+
+    data = fill_template(args.template, data)
+
+    if args.output:
+        output = open(args.output, 'wb')
+        output.write(data.encode('utf-8'))
+        output.close()
+    else:
+        sys.stdout.write(data)
+
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))

src/py/libcamera/meson.build

@@ -17,6 +17,18 @@ pycamera_sources = files([
     'pymain.cpp',
 ])
 
+gen_input_files = [
+    meson.project_source_root() / 'src' / 'libcamera' / 'control_ids.yaml',
+    'pyenums_generated.cpp.in',
+]
+
+generated_sources = custom_target('py_gen_controls',
+                                  input : gen_input_files,
+                                  output : ['pyenums_generated.cpp'],
+                                  command : ['gen-py-control-enums.py', '-o', '@OUTPUT@', '@INPUT@'])
+
+pycamera_sources += generated_sources
+
 pycamera_deps = [
     libcamera_public,
     py3_dep,

src/py/libcamera/pyenums_generated.cpp.in

@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
+ *
+ * Python bindings - Auto-generated enums
+ *
+ * This file is auto-generated. Do not edit.
+ */
+
+#include <libcamera/libcamera.h>
+
+#include <pybind11/smart_holder.h>
+
+namespace py = pybind11;
+
+using namespace libcamera;
+
+void init_pyenums_generated(py::module& m)
+{
+${enums}
+}

src/py/libcamera/pymain.cpp

@@ -137,10 +137,12 @@ static void handleRequestCompleted(Request *req)
 }
 
 void init_pyenums(py::module &m);
+void init_pyenums_generated(py::module &m);
 
 PYBIND11_MODULE(_libcamera, m)
 {
 	init_pyenums(m);
+	init_pyenums_generated(m);
 
 	/* Forward declarations */