Add Python bindings

Add libcamera Python bindings. pybind11 is used to generate the C++ <->
Python layer.

We use pybind11 'smart_holder' version to avoid issues with private
destructors and shared_ptr. There is also an alternative solution here:

https://github.com/pybind/pybind11/pull/2067

Only a subset of libcamera classes are exposed. Implementing and testing
the wrapper classes is challenging, and as such only classes that I have
needed have been added so far.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@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>

1 files changed, 52 insertions, 0 deletions

diff --git a/src/py/libcamera/meson.build b/src/py/libcamera/meson.build
new file mode 100644
index 00000000..edf4a629
--- /dev/null
+++ b/src/py/libcamera/meson.build
@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: CC0-1.0
+
+py3_dep = dependency('python3', required : get_option('pycamera'))
+
+if not py3_dep.found()
+    pycamera_enabled = false
+    subdir_done()
+endif
+
+pycamera_enabled = true
+
+pybind11_proj = subproject('pybind11')
+pybind11_dep = pybind11_proj.get_variable('pybind11_dep')
+
+pycamera_sources = files([
+    'pyenums.cpp',
+    'pymain.cpp',
+])
+
+pycamera_deps = [
+    libcamera_public,
+    py3_dep,
+    pybind11_dep,
+]
+
+pycamera_args = [
+    '-fvisibility=hidden',
+    '-Wno-shadow',
+    '-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT',
+    '-DLIBCAMERA_BASE_PRIVATE',
+]
+
+destdir = get_option('libdir') / ('python' + py3_dep.version()) / 'site-packages' / 'libcamera'
+
+pycamera = shared_module('_libcamera',
+                         pycamera_sources,
+                         install : true,
+                         install_dir : destdir,
+                         name_prefix : '',
+                         dependencies : pycamera_deps,
+                         cpp_args : pycamera_args)
+
+run_command('ln', '-fsT', '../../../../src/py/libcamera/__init__.py',
+            meson.current_build_dir() / '__init__.py',
+            check: true)
+
+install_data(['__init__.py'], install_dir : destdir)
+
+# \todo Generate stubs when building. See https://peps.python.org/pep-0484/#stub-files
+# Note: Depends on pybind11-stubgen. To generate pylibcamera stubs:
+# $ PYTHONPATH=build/src/py pybind11-stubgen --no-setup-py -o build/src/py libcamera
+# $ mv build/src/py/libcamera-stubs/* build/src/py/libcamera/