[libcamera-devel] [PATCH] meson: Use library() in order to let user chose the library type

[Christian Rauch]

Hi Laurent,

Am 28.11.22 um 06:29 schrieb Laurent Pinchart:
> Hi Christian,
>
> Thank you for the patch.
>
> On Mon, Nov 28, 2022 at 12:01:10AM +0100, Christian Rauch via libcamera-devel wrote:
>> Defining libraries via shared_library() prevents compiling libcamera as
>> static library. The meson project recommends using library() instead of
>> shared_library(), static_library() or both_libraries():
>> https://mesonbuild.com/Reference-manual_functions.html#library
>
> I'm curious, do you personally have use cases for libcamera as a static
> library ?

Yes. I want/have to distribute my application with a statically linked
libcamera in order to avoid dynamic linking issues with the libcamera
package distributed by Ubuntu.

>
>> Signed-off-by: Christian Rauch <Rauch.Christian at gmx.de>
>> ---
>>   src/android/meson.build        | 16 ++++++++--------
>>   src/gstreamer/meson.build      |  2 +-
>>   src/libcamera/base/meson.build | 18 +++++++++---------
>>   src/libcamera/meson.build      | 18 +++++++++---------
>>   src/v4l2/meson.build           | 12 ++++++------
>>   5 files changed, 33 insertions(+), 33 deletions(-)
>>
>> diff --git a/src/android/meson.build b/src/android/meson.build
>> index 1bba54de..51b365e3 100644
>> --- a/src/android/meson.build
>> +++ b/src/android/meson.build
>> @@ -67,11 +67,11 @@ android_camera_metadata = static_library('camera_metadata',
>>                                            c_args : '-Wno-shadow',
>>                                            include_directories : android_includes)
>>
>> -libcamera_hal = shared_library('libcamera-hal',
>> -                               android_hal_sources,
>> -                               name_prefix : '',
>> -                               link_with : android_camera_metadata,
>> -                               install : true,
>> -                               cpp_args : android_cpp_args,
>> -                               include_directories : android_includes,
>> -                               dependencies : android_deps)
>> +libcamera_hal = library('libcamera-hal',
>> +                        android_hal_sources,
>> +                        name_prefix : '',
>> +                        link_with : android_camera_metadata,
>> +                        install : true,
>> +                        cpp_args : android_cpp_args,
>> +                        include_directories : android_includes,
>> +                        dependencies : android_deps)
>
> I'm curious, how do you envision the HAL to be loaded by the Android
> camera service if it's a static library ? :-)

Isn't it possible to link the libraries statically on Android too?

>
>> diff --git a/src/gstreamer/meson.build b/src/gstreamer/meson.build
>> index eda246d7..b364837d 100644
>> --- a/src/gstreamer/meson.build
>> +++ b/src/gstreamer/meson.build
>> @@ -39,7 +39,7 @@ if cc.get_id() == 'clang' and glib_dep.version().version_compare('<2.63.0')
>>       libcamera_gst_cpp_args += ['-Wno-unused-function']
>>   endif
>>
>> -libcamera_gst = shared_library('gstlibcamera',
>> +libcamera_gst = library('gstlibcamera',
>
> Same here, and for the V4L2 compat library.

I might have overdone this. How is this library supposed to be used? Do
you preload it in order to emulate V4L2 APIs? Could this also be done
with a 'shared_module'?

>
>>       libcamera_gst_sources,
>>       cpp_args : libcamera_gst_cpp_args,
>>       dependencies : [libcamera_private, gstvideo_dep, gstallocator_dep],
>> diff --git a/src/libcamera/base/meson.build b/src/libcamera/base/meson.build
>> index 7a7fd7e4..91dc1e71 100644
>> --- a/src/libcamera/base/meson.build
>> +++ b/src/libcamera/base/meson.build
>> @@ -48,15 +48,15 @@ libcamera_base_deps = [
>>   # the use of headers which must not be exposed to the libcamera public api.
>>   libcamera_base_args = [ '-DLIBCAMERA_BASE_PRIVATE' ]
>>
>> -libcamera_base_lib = shared_library('libcamera-base',
>> -                                    [libcamera_base_sources, libcamera_base_headers],
>> -                                    version : libcamera_version,
>> -                                    soversion : libcamera_soversion,
>> -                                    name_prefix : '',
>> -                                    install : true,
>> -                                    cpp_args : libcamera_base_args,
>> -                                    include_directories : libcamera_includes,
>> -                                    dependencies : libcamera_base_deps)
>> +libcamera_base_lib = library('libcamera-base',
>> +                             [libcamera_base_sources, libcamera_base_headers],
>> +                             version : libcamera_version,
>> +                             soversion : libcamera_soversion,
>> +                             name_prefix : '',
>> +                             install : true,
>> +                             cpp_args : libcamera_base_args,
>> +                             include_directories : libcamera_includes,
>> +                             dependencies : libcamera_base_deps)
>>
>>   libcamera_base = declare_dependency(sources : [
>>                                           libcamera_base_headers,
>> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
>> index 0494e808..cd1bf4ed 100644
>> --- a/src/libcamera/meson.build
>> +++ b/src/libcamera/meson.build
>> @@ -163,15 +163,15 @@ libcamera_deps = [
>>   # runtime if the library is running from an installed location by checking
>>   # for the presence or abscence of the dynamic tag.
>>
>> -libcamera = shared_library('libcamera',
>> -                           libcamera_sources,
>> -                           version : libcamera_version,
>> -                           soversion : libcamera_soversion,
>> -                           name_prefix : '',
>> -                           install : true,
>> -                           include_directories : includes,
>> -                           build_rpath : '/',
>> -                           dependencies : libcamera_deps)
>> +libcamera = library('libcamera',
>> +                    libcamera_sources,
>> +                    version : libcamera_version,
>> +                    soversion : libcamera_soversion,
>> +                    name_prefix : '',
>> +                    install : true,
>> +                    include_directories : includes,
>> +                    build_rpath : '/',
>> +                    dependencies : libcamera_deps)
>
> Do libcameraBuildPath() and libcameraSourcePath() still work as expected
> when compiling libcamera as a static library ?

I haven't tested this yet. I only tested that I can build and link
libcamera statically. I added this option in order to test this and get
some feedback. The default behaviour will still build a shared library.

>
>>
>>   libcamera_public = declare_dependency(sources : [
>>                                             libcamera_ipa_headers,
>> diff --git a/src/v4l2/meson.build b/src/v4l2/meson.build
>> index f132103c..46dab168 100644
>> --- a/src/v4l2/meson.build
>> +++ b/src/v4l2/meson.build
>> @@ -27,12 +27,12 @@ v4l2_compat_cpp_args = [
>>       '-fvisibility=hidden',
>>   ]
>>
>> -v4l2_compat = shared_library('v4l2-compat',
>> -                             v4l2_compat_sources,
>> -                             name_prefix : '',
>> -                             install : true,
>> -                             dependencies : [libcamera_private, libdl],
>> -                             cpp_args : v4l2_compat_cpp_args)
>> +v4l2_compat = library('v4l2-compat',
>> +                      v4l2_compat_sources,
>> +                      name_prefix : '',
>> +                      install : true,
>> +                      dependencies : [libcamera_private, libdl],
>> +                      cpp_args : v4l2_compat_cpp_args)
>>
>>   # Provide a wrapper script to support easily loading applications with the V4L2
>>   # adaptation layer.
>