Old comercial app and qt5 licensing

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costel78:
Hello!

I need help regarding qt licensing.
We distribute a system (hardware and software) PC, tablets etc. On PC OS is Linux and contain a 6 years old program made in Lazarus.
If somebody encounter a similar situation, please help me to know what to expect. This is a preparation phase, probably nothing will be done in the next 3 months.
The original development team is no longer available, the (external) firm responsabile was closed two years ago, but we will have the source code in 1-2 months.

Problem:
gtk+ 2 is end of life and not maintained anymore. gtk+3 is not ready in Lazarus. It might be necessary to switch to qt5 in the next 12-24 months when gtk2 will be removed from distros.
If we try to switch lcl to qt5 what licensing issues to expect ?
Based on what I read it is legal to distribute software commercially dynamically linked to unmodified LGPL QT5. Is that correct ?

We do not have any modified qt5 library, prefer to not distribute source code and can not afford ~10000€ (VAT included) Qt5 commercial license for 3 years.
Can we use qt5 licensed under LGPL dynamically linked ?
Do Lazarus static link anything regarding qt5, anything than qt5pas library ?

Right now, I can test only gtk+ version.

--- Code: Bash [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---ldd test_prg linux-vdso.so.1 (0x00007ffe841a6000) libgdk-x11-2.0.so.0 => /usr/lib64/libgdk-x11-2.0.so.0 (0x00007fb7b28e5000) libgtk-x11-2.0.so.0 => /usr/lib64/libgtk-x11-2.0.so.0 (0x00007fb7b248f000) libX11.so.6 => /usr/lib64/libX11.so.6 (0x00007fb7b232e000) libgdk_pixbuf-2.0.so.0 => /usr/lib64/libgdk_pixbuf-2.0.so.0 (0x00007fb7b22fd000) libgobject-2.0.so.0 => /usr/lib64/libgobject-2.0.so.0 (0x00007fb7b2295000) libglib-2.0.so.0 => /usr/lib64/libglib-2.0.so.0 (0x00007fb7b212c000) libgthread-2.0.so.0 => /usr/lib64/libgthread-2.0.so.0 (0x00007fb7b2125000) libgmodule-2.0.so.0 => /usr/lib64/libgmodule-2.0.so.0 (0x00007fb7b211f000) libpango-1.0.so.0 => /usr/lib64/libpango-1.0.so.0 (0x00007fb7b20bd000) libcairo.so.2 => /usr/lib64/libcairo.so.2 (0x00007fb7b1f40000) libatk-1.0.so.0 => /usr/lib64/libatk-1.0.so.0 (0x00007fb7b1f0b000) libXtst.so.6 => /usr/lib64/libXtst.so.6 (0x00007fb7b1f02000) libc.so.6 => /lib64/libc.so.6 (0x00007fb7b1d0d000) libpangocairo-1.0.so.0 => /usr/lib64/libpangocairo-1.0.so.0 (0x00007fb7b1cfc000) libharfbuzz.so.0 => /usr/lib64/libharfbuzz.so.0 (0x00007fb7b1c12000) libgio-2.0.so.0 => /usr/lib64/libgio-2.0.so.0 (0x00007fb7b19e0000) libfontconfig.so.1 => /usr/lib64/libfontconfig.so.1 (0x00007fb7b1988000) libfreetype.so.6 => /usr/lib64/libfreetype.so.6 (0x00007fb7b1891000) libXrender.so.1 => /usr/lib64/libXrender.so.1 (0x00007fb7b1882000) libXi.so.6 => /usr/lib64/libXi.so.6 (0x00007fb7b186c000) libXrandr.so.2 => /usr/lib64/libXrandr.so.2 (0x00007fb7b185c000) libXcursor.so.1 => /usr/lib64/libXcursor.so.1 (0x00007fb7b184d000) libXcomposite.so.1 => /usr/lib64/libXcomposite.so.1 (0x00007fb7b1848000) libXdamage.so.1 => /usr/lib64/libXdamage.so.1 (0x00007fb7b1843000) libXfixes.so.3 => /usr/lib64/libXfixes.so.3 (0x00007fb7b1838000) libXext.so.6 => /usr/lib64/libXext.so.6 (0x00007fb7b181f000) libm.so.6 => /lib64/libm.so.6 (0x00007fb7b174a000) libpangoft2-1.0.so.0 => /usr/lib64/libpangoft2-1.0.so.0 (0x00007fb7b172f000) libxcb.so.1 => /usr/lib64/libxcb.so.1 (0x00007fb7b1701000) libpng16.so.16 => /usr/lib64/libpng16.so.16 (0x00007fb7b16ae000) libffi.so.8 => /usr/lib64/libffi.so.8 (0x00007fb7b16a2000) libpcre.so.1 => /lib64/libpcre.so.1 (0x00007fb7b1625000) libfribidi.so.0 => /usr/lib64/libfribidi.so.0 (0x00007fb7b1606000) libpixman-1.so.0 => /usr/lib64/libpixman-1.so.0 (0x00007fb7b14c7000) libEGL.so.1 => /usr/lib64/libEGL.so.1 (0x00007fb7b14b4000) libxcb-shm.so.0 => /usr/lib64/libxcb-shm.so.0 (0x00007fb7b14ad000) libxcb-render.so.0 => /usr/lib64/libxcb-render.so.0 (0x00007fb7b149d000) libz.so.1 => /lib64/libz.so.1 (0x00007fb7b147e000) libGL.so.1 => /usr/lib64/libGL.so.1 (0x00007fb7b13f7000) /lib64/ld-linux-x86-64.so.2 (0x00007fb7b29b8000) libgraphite2.so.3 => /usr/lib64/libgraphite2.so.3 (0x00007fb7b13ce000) libmount.so.1 => /lib64/libmount.so.1 (0x00007fb7b1382000) libexpat.so.1 => /usr/lib64/libexpat.so.1 (0x00007fb7b134e000) libuuid.so.1 => /lib64/libuuid.so.1 (0x00007fb7b1344000) libbz2.so.1 => /lib64/libbz2.so.1 (0x00007fb7b132a000) libXau.so.6 => /usr/lib64/libXau.so.6 (0x00007fb7b1325000) libXdmcp.so.6 => /usr/lib64/libXdmcp.so.6 (0x00007fb7b131a000) libmvec.so.1 => /lib64/libmvec.so.1 (0x00007fb7b12ee000) libGLdispatch.so.0 => /usr/lib64/libGLdispatch.so.0 (0x00007fb7b1236000) libGLX.so.0 => /usr/lib64/libGLX.so.0 (0x00007fb7b1202000) libblkid.so.1 => /lib64/libblkid.so.1 (0x00007fb7b11c4000) libbsd.so.0 => /usr/lib64/libbsd.so.0 (0x00007fb7b11a5000) libmd.so.0 => /usr/lib64/libmd.so.0 (0x00007fb7b1194000) nm test_prg nm: test_prg: no symbols
When will have the source code, what else to test to be sure that we are compliant ?

Thank you!

zeljko:
Qt5 is LGPL, so yes you can use it for your commercial apps.

costel78:
Thank you for confirmation.

So, I should not worry about static linking in Lazarus ? Everything is dynamically linked ?

avra:
QT licensing has already been discussed:
https://forum.lazarus.freepascal.org/index.php/topic,55440.msg415530.html#msg415530
https://forum.lazarus.freepascal.org/index.php/topic,49100.0.html

costel78:
Thank you very much!
Everything is clear now.

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