[PATCH v1] py: Set `PYTHONPATH` in devenv

[Barnabás Pőcze]

If the python bindings are built, then set the `PYTHONPATH` environmental
variable in the meson devenv accordingly to make it easy to use.

  $ meson devenv -C build
  [libcamera] $ echo $PYTHONPATH
  /libcamera/build/src/py
  [libcamera] $ python
  Python 3.13.3 (main, Apr  9 2025, 07:44:25) [GCC 14.2.1 20250207] on linux
  Type "help", "copyright", "credits" or "license" for more information.
  >>> import libcamera
  >>> cm = libcamera.CameraManager.singleton()
  [...]
  [129:52:33.293860558] [4133380]  INFO Camera camera_manager.cpp:326 libcamera v0.5.0+169-7dbe74b5-dirty (2025-05-01)
  [...]

Signed-off-by: Barnabás Pőcze <barnabas.pocze at ideasonboard.com>
---
 src/py/libcamera/meson.build | 16 ----------------
 src/py/meson.build           | 12 ++++++++++++
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/src/py/libcamera/meson.build b/src/py/libcamera/meson.build
index 456ee7932..33ab65798 100644
--- a/src/py/libcamera/meson.build
+++ b/src/py/libcamera/meson.build
@@ -1,21 +1,5 @@
 # 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
-
-pybind11_dep = dependency('pybind11', required : get_option('pycamera'))
-
-if not pybind11_dep.found()
-    pycamera_enabled = false
-    subdir_done()
-endif
-
-pycamera_enabled = true
-
 pycamera_sources = files([
     'py_camera_manager.cpp',
     'py_color_space.cpp',
diff --git a/src/py/meson.build b/src/py/meson.build
index a4586b4ae..922806971 100644
--- a/src/py/meson.build
+++ b/src/py/meson.build
@@ -1,3 +1,15 @@
 # SPDX-License-Identifier: CC0-1.0
 
+py3_dep = dependency('python3', required : get_option('pycamera'))
+pybind11_dep = dependency('pybind11', required : get_option('pycamera'))
+
+pycamera_enabled = py3_dep.found() and pybind11_dep.found()
+if not pycamera_enabled
+    subdir_done()
+endif
+
 subdir('libcamera')
+
+pycamera_devenv = environment()
+pycamera_devenv.prepend('PYTHONPATH', meson.current_build_dir())
+meson.add_devenv(pycamera_devenv)
-- 
2.49.0