Any example to use libcamera for Qt5 desktop application?

rollyng

@SGaist said in Any example to use libcamera for Qt5 desktop application?:

widgets module

Hi SGaist, Thank you and I add the widgets and include path to the libcamera.pro file. I can see the missing header files are now found. But I have the private header error, and I have no idea how to resolve these. Please take a look. Thank you!

I believe it only necessary to build the "qcam" example in Qt Creator for my purpose, so I copy "qcam" and did some modification to the qcam.pro file. But it seems unable to resolve the declaration in its own folder? as it failed to find DNGWriter which is declared in the dng_writer.h?

SGaist

You need to read the meson file to see what additional defines and paths/options they use.

Just in case, even if your Qt Creator does not support meson, nothing stops you from using from the command line to build the projet.

rollyng

@SGaist May I ask what are these requirements in the meson file? It is strange to me that Qt Creator complains that DNGWriter is not declared despite the dng_writer.h file is already in the same directory as shown above. Besides, how should I modify the qcam.pro as the following meson file? Thank you.

# SPDX-License-Identifier: CC0-1.0

qt5 = import('qt5')
qt5_dep = dependency('qt5',
                     method : 'pkg-config',
                     modules : ['Core', 'Gui', 'Widgets'],
                     required : get_option('qcam'),
                     version : '>=5.4')

if not qt5_dep.found()
    qcam_enabled = false
    subdir_done()
endif

qcam_enabled = true

qcam_sources = files([
    '../cam/image.cpp',
    '../cam/options.cpp',
    '../cam/stream_options.cpp',
    'format_converter.cpp',
    'main.cpp',
    'main_window.cpp',
    'message_handler.cpp',
    'viewfinder_qt.cpp',
])

qcam_moc_headers = files([
    'main_window.h',
    'viewfinder_qt.h',
])

qcam_resources = files([
    'assets/feathericons/feathericons.qrc',
])

qcam_deps = [
    libatomic,
    libcamera_public,
    qt5_dep,
]

qt5_cpp_args = ['-DQT_NO_KEYWORDS']

tiff_dep = dependency('libtiff-4', required : false)
if tiff_dep.found()
    qt5_cpp_args += ['-DHAVE_TIFF']
    qcam_deps += [tiff_dep]
    qcam_sources += files([
        'dng_writer.cpp',
    ])
endif

if cxx.has_header_symbol('QOpenGLWidget', 'QOpenGLWidget',
                         dependencies : qt5_dep, args : '-fPIC')
    qcam_sources += files([
        'viewfinder_gl.cpp',
    ])
    qcam_moc_headers += files([
        'viewfinder_gl.h',
    ])
    qcam_resources += files([
        'assets/shader/shaders.qrc'
    ])
endif

# gcc 9 introduced a deprecated-copy warning that is triggered by Qt until
# Qt 5.13. clang 10 introduced the same warning, but detects more issues
# that are not fixed in Qt yet. Disable the warning manually in both cases.
if ((cc.get_id() == 'gcc' and cc.version().version_compare('>=9.0') and
     qt5_dep.version().version_compare('<5.13')) or
    (cc.get_id() == 'clang' and cc.version().version_compare('>=10.0')))
    qt5_cpp_args += ['-Wno-deprecated-copy']
endif

resources = qt5.preprocess(moc_headers: qcam_moc_headers,
                           qresources : qcam_resources,
                           dependencies: qt5_dep)

qcam  = executable('qcam', qcam_sources, resources,
                   install : true,
                   dependencies : qcam_deps,
                   cpp_args : qt5_cpp_args)

rollyng

@SGaist Hi, I have finally successful to compile qcam as my first Qt GUI code. What I did is removing the dng_writer.h and dng_writer.cpp from the project. Plz have a look, thank you!

SGaist

Have a look for why you had to disable the dng_writer part ?

rollyng

@SGaist said in Any example to use libcamera for Qt5 desktop application?:

Have a look for why you had to disable the dng_writer part ?

Qt Creator seems unable to pickup dng_writer.h although it is included in the project.

This is due to a special definition in the dng_writer.h and I am including the file here for your quick look.

/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2020, Raspberry Pi (Trading) Ltd.
 *
 * dng_writer.h - DNG writer
 */

#pragma once

#ifdef HAVE_TIFF /* what is this for? */
#define HAVE_DNG

#undef signals
#undef slots
#undef emit
#undef foreach

#include <libcamera/camera.h>
#include <libcamera/controls.h>
#include <libcamera/framebuffer.h>
#include <libcamera/stream.h>

class DNGWriter
{
public:
    static int write(const char *filename, const libcamera::Camera *camera,
                     const libcamera::StreamConfiguration &config,
                     const libcamera::ControlList &metadata,
                     const libcamera::FrameBuffer *buffer,
                     const void *data);
};

#endif /* HAVE_TIFF, this is going to break the definition for DNGWriter above*/

This is very strange to me whether to include the HAVE_TIFF option or not?
Thanks,
rolly

SGaist

It's a define that you can add to the DEFINES variable. The meson project defines it if memory serves well.

rollyng

@SGaist Thank you and I have decided not to include the dng_writer function as it is not my concern. Best, rolly

AlexKN

@rollyng Dear rollyng! Could you share a working qt project that you have successfully compiled and launched?

p1ng

@AlexKN here is the qt project. i did it myself.

https://github.com/henrihallik/myqam