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can qt4 be considered stable in Linux(Fedora,ubuntu,CentOS..)?
I am planing using Qt4 library more heavily in my programs.
I'd like to be more sure that the future revisions of Qt
library for Linux will remain stable in Qt4 series.
So far as I know, Qt4 is released with LGPL. qt5 is owned by Nokia. qt6 is owned by Microsoft. Open source programs on Linux should better use Qt4.
@wij2 Where do you have this information from? Or are you joking?
Qt isn't owned by Nokia since many years already. There is no Qt6 yet, and when it is released it will for sure not be owned by Microsoft. Qt4 isn't supported anymore. So use Qt5.
So far as I know
Your information is wrong.
Many years ago, I bought a qt3 commercial version.
Later, Troll Tech released version 4, then sold to Nokia.
Then, Nokia modified it a bit for its favor and released version5. qt4 was then changed to use LGPL.
Not long after this, I somewhat had an impression that
Qt library was sold to Microsoft, which modfied it for
the similar reason and released version 6.
Then I googled to find this Qt Library 'official site'
I am totally confused now.
Simply put, is qt5 also LGPL licensed?
@wij2 Check https://www.qt.io/licensing/ and https://www.qt.io/download
And read https://en.wikipedia.org/wiki/Qt_(software) if you want to really know the history of Qt.
Actually it isn't hard to find the official Qt site: https://www.qt.io/developers/
Yes, Qt is available under GPL, LGPL and commercial license.
To add to @jsulm and short version:
Trolltech was acquired by Nokia
Digia acquired what was Trolltech from Nokia
Digia made a spinoff named The Qt Company with what was Trolltech
Microsoft bought the handset division of Nokia, they never touched Trolltech at any point in time.
@jsulm OK. Thanks for the information. I think I need first
understand more about qt5 before porting my programs and
@SGaist Thanks for clarifying the ownership, though I still
don't fully understand.
@wij2 You don't understand what?
Qt is an open source project, licensed under LGPL (partly GPL) and a commercial license. The commercial license is sold by The Qt Company, which is fully independent of Nokia and Microsoft.
Also, there is the Qt-KDE contract, which assures there will always be an open-source Qt version available.
@wij2 Whether you need a license depends on whether you can fulfil the LGPL license (or need better support from Qt Company). If you can you don't need a commercial license even for proprietary software using Qt.
@aha_1980 Good to hear that "there will always be an open-source Qt version available".
@jsulm About half of my programs are open-soure, another
half (compiled executables) are for sell. In both cases, no
modification of qt library is made.
So, I don't need commercial license for the LGPL licensed part
of qt library,right? How to deal with the GPL licensed part?
How to deal with the GPL licensed part?
If you use GPL licensed modules (i.e. QtCharts) in your program, you need to make it GPL too. Otherwise you need a commercial license.
@aha_1980 Thanks again. I think I get correct informations
now. Since this is my first time in this forum, how should I do
to make this questioning 'solved' from 'unsolved'?
@wij2 The should be a button "Topic Tools" below your first post, from there select "Mark as Solved"