qtlgplv3
2022-09-01 10:47阅读：
公司使用Qt到底要不要付费？
https://blog.csdn.net/chenchao_shenzhen/article/details/112059961?spm=1001.2014.3001.5501
Qt License分析、开源版与商业版的区别
https://www.cnblogs.com/linuxAndMcu/p/16359738.html
Adding LGPL v3 to Qt
August 20, 2014 by Lars Knoll | Comments
20 years ago, Trolltech, the company that created Qt, was founded.
One of its founding principles was to release Qt as free software
to the open source community. In the early versions, this was
limited to Unix/Linux and the X11 windowing system. Over the years,
more and more platforms were included into the open source version
of Qt.
At the same time, the licenses under which Qt was available
evolved. The Qt 1.x source code was still released under a rather
restrictive license. With Qt 2, we moved over to the QPL. Some
years later, with Qt 4.0, Qt started to embrace the GPL v2, to
remove som
e license conflicts between GPL-based applications and the
QPL.
Trolltech was involved in talks with the Free Software Foundation
(FSF) when the GPL v3 was created, and we added this license as an
optional license for Qt after it was published by the FSF. Finally,
in 2009 Nokia added LGPL v2.1 as a licensing option to Qt.
The spirit of all GNU licenses is about a strong copyleft, giving
users rather strong access and rights to the source code of
application and libraries. It was always meant to protect the
users’ freedom to modify the application and underlying libraries
and run the modified application.
In many people's opinion there is, however, a loophole in the LGPL
2.1, where it doesn’t clearly talk about running the applications
using a modified version of the library. Even though it violates
the spirit and intentions of the LGPL, this loophole has been
extensively used by companies that create locked-down devices. If
devices use LGPL v2.1 software, the user may not be able to install
modified versions of the library on the device and use it together
with the other software that is installed on it.
We also consider locked-down consumer devices using the LGPL’ed
version of Qt to be harmful for the Qt ecosystem. The device is not
open to third party developers and thus doesn’t contribute in
extending the size of the Qt ecosystem and the range of devices
that can be targeted by software developers using Qt. In addition
to not contributing to the ecosystem, it doesn’t fund the further
development of Qt.
For these reasons we believe that LGPL v2.1 is not protecting the
users’ freedom as it was intended by the Free Software Foundation.
To account for this, the FSF created version 3 of the LGPL, a
license we feel is legally formalizing the intentions of the
earlier version.
Changes in the Qt 5.4 Release with LGPLv3
Because of this, we are now adding LGPL v3 as a licensing option to
Qt 5.4 in addition to LGPL v2.1. All modules that are part of Qt
5.3 are currently released under LGPL v2.1, GPL v3 and the
commercial license. Starting with Qt 5.4, they will be released
under LGPL v2.1, LGPL v3 and the commercial license.
However, there will be a set of new add-ons that will be only
released under LGPL v3 (plus GPL v2 or later) or commercial
license. These add-ons are listed below. We have discussed with the
KDE Free Qt Foundation and have their support to make this change
in Qt 5.4. We are also in talks with the KDE Free Qt Foundation
about further strengthening the agreement.
New add-ons released under LGPL v3
In Qt 5.4, the new Qt WebEngine module will be released under LGPL
v3 in the open source version and under a LGPLv2.1/commercial
combination for Qt Enterprise customers.
Adding LGPLv3 will also allow us to release a few other add-ons
that Digia before intended to make available solely under the
enterprise license. In Qt 5.4, we will add a technology preview for
two brand new modules to Qt under the LGPL v3.
The first module, called Qt Canvas3D, will give us full WebGL
support inside Qt Quick. It is fully functional, but still marked
as a preview because the support for JavaScript typed arrays is
still implemented in a slow and not 100% compliant way.
The second module is a lightweight WebView module that will also be
released as a technology preview. It supports embedding the native
Web engines of the underlying operating system into Qt, and is
currently supported on Android.
There is a final add-on that will get released under LGPL v3. This
module will give native look and feel to the Qt Quick Controls on
Android. This module can’t be released under LGPL v2.1, as it has
to use code that is licensed under Apache 2.0, a license that is
incompatible with LGPL v2.1, but compatible with LGPL v3.
How does this change affect you as a Qt user?
One of the first questions you might have is, of course, how this
affects you as a user of Qt.
This first thing to notice is that if you are using Qt under a
commercial license, nothing changes at all.
Also, if you are using Qt under GPL v3, you are unaffected, since
LGPLv3 can always be converted to GPLv3.
All modules that existed in Qt 5.3 will still be available under
LGPL v2.1. So if you are using Qt under the GPL v2 or LGPL v2.1,
nothing changes as long as you don’t use any of the new modules
that are only available under LGPL v3. If you start using those,
your source code will fall under the conditions given by the LGPL
v3 (or GPL v2).
These changes will be effective in Qt 5.4 Alpha. I believe that
adding LGPL v3 as a licensing option will help both Qt and the open
source ecosystem. It is a lot clearer about the intent of the LGPL
license and its use in Free Software.
Please find more information about open source licenses at
http://www.gnu.org/licenses/.
If you are not sure what license you should be using in your
project, please consult a legal expert.
Digia has opened an email address for specific questions about
using Lgplv3 in your project. Please contact us via
Qtlicensing@digia.com.
https://www.qt.io/blog/2014/08/20/adding-lgpl-v3-to-qt
Integrated development environment Qt5.9.9\5.9.9\msvc2015_64
