[libcamera-devel] [simple-cam PATCH 0/4] simple-cam: Update to latest API usage

[Kieran Bingham]

Hi Laurent,

On 24/09/2020 12:44, Laurent Pinchart wrote:
> Hi Kieran,
> 
> On Thu, Sep 24, 2020 at 09:52:11AM +0100, Kieran Bingham wrote:
>> On 24/09/2020 04:14, Laurent Pinchart wrote:
>>> On Wed, Sep 23, 2020 at 05:44:08PM +0100, Kieran Bingham wrote:
>>>> The simple-cam app needs to be updated with a few API updates to work on
>>>> the latest libcamera builds.
>>>>
>>>> This is based on the code at https://github.com/kbingham/simple-cam
>>>> though I hope to move this to a more official location soon.
>>>
>>> For the whole series,
>>>
>>> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>>>
>>> It would be interesting to test-compile simple-cam when libcamera gains
>>> new commits. It can probably wait until libcamera itself gets CI though
>>> :-)
>>
>> This is something I've been working on.
>>
>> There are two options, an easy way and a hard way (to do this without
>> installing the library on each build).
>>
>> The hard way (which is of course what was recommended in #meson) is to
>> provide a meson wrap for libcamera, so that it can be a subproject to
>> simple-cam. This means if libcamera is not found as a dependency it will
>> clone libcamera, build it - and automatically link against it statically.
>>
>> It doesn't work - due to faults in our set up of the build system and
>> incorrect usage of things like meson.build_root() and meson.source_root().
> 
> Patches are welcome :-)

Sure - they're already on my todo list from yesterday ;-)


>> My conversation led to one of the meson devs deciding to mark those as
>> deprecated :
>>  (See https://github.com/mesonbuild/meson/pull/7772)
>>
>> Anyway, the easy and quick way - is that meson creates a pkg-config
>> '-uninstalled' location at $BUILD/meson-uninstalled ... and it's really
>> easy to build an app against an uninstalled library by pointing
>> PKG_CONFIG_DIR=$BUILD/meson-uninstalled

Ahem, s/PKG_CONFIG_DIR/PKG_CONFIG_PATH/

>>
>> So that's a really quick and effective way of also compiling the
>> 'external' simple-cam against a 'just built' libcamera.
> 
> From a build server point of view, I thought the builder could get the
> latest libcamera master branch, build it, and install it. Why would we
> need an "uninstalled" location ?

Hrm, my original answer here was 'because you need to be root to
install' ... but that's not correct. You can install to a non-root owned
location (and then make sure the library is on the PKG_CONFIG_PATH...)

So that's also an option ... and also validates the install procedures.



> 
>> I'm adding that to my daily builder, (the one that also does a
>> coverity-scan build, and a full matrix build of all compilers on my
>> laptop) - so I'll know as soon as there is breakage.
>>
>> And indeed, sometime we'll move this to a more fully handled CI system too.
>>
>> Anyway, thanks for the review, I'll push these patches to my repo.
>>
>>>> Kieran Bingham (4):
>>>>   simple-cam: Use the new BufferMap interface
>>>>   simple-cam: Use a const stream
>>>>   meson: Remove incorrect default
>>>>   meson: Update to C++17
>>>>
>>>>  meson.build    | 3 +--
>>>>  simple-cam.cpp | 4 ++--
>>>>  2 files changed, 3 insertions(+), 4 deletions(-)
> 

-- 
Regards
--
Kieran