You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
428 lines
15 KiB
428 lines
15 KiB
/*!
|
|
|
|
\page faq.html
|
|
|
|
\title The Qt FAQ
|
|
|
|
See also the \link commonproblems.html Technical FAQ\endlink.
|
|
|
|
\tableofcontents
|
|
|
|
<hr>
|
|
\section1 General Questions
|
|
|
|
<hr width="30%">
|
|
\section2 What is Qt?
|
|
|
|
Qt is a multiplatform C++ GUI toolkit. It
|
|
provides application developers with all the functionality
|
|
needed to build applications with state-of-the-art graphical
|
|
user interfaces. Qt is fully object-oriented, easily
|
|
extensible, and allows true component programming.
|
|
|
|
Qt is supported on the following platforms:
|
|
|
|
\list
|
|
\i <b>MS/Windows</b> -- 95, 98, NT 4.0, ME, 2000, and XP
|
|
\i <b>Unix/X11</b> -- Linux, Sun Solaris, HP-UX, Compaq Tru64 UNIX,
|
|
IBM AIX, SGI IRIX and a wide range of others
|
|
\i <b>Macintosh</b> -- Mac OS X
|
|
\i <b>Embedded</b> -- Linux platforms with framebuffer support.
|
|
\endlist
|
|
|
|
It has become the emerging standard development
|
|
environment for IT professionals who want to:
|
|
|
|
\list
|
|
\i Write (and maintain) a single source-tree.
|
|
\i Port their applications to multiple platforms with a simple
|
|
recompilation.
|
|
\i Internationalize their applications.
|
|
\i Provide their applications with native look and feel.
|
|
\i Have their applications run at native speed.
|
|
\endlist
|
|
|
|
<hr width="30%">
|
|
\section2 What is Trolltech?
|
|
|
|
Trolltech is an international software company with
|
|
headquarters in Oslo, the capital of Norway, and with offices
|
|
in Brisbane, Australia, and Redwood City, California. Our
|
|
flagship product is Qt, the multi-platform C++ GUI toolkit.
|
|
|
|
Trolltech ASA was founded in 1994, although, the core team of designers
|
|
started Qt's development in 1992.
|
|
|
|
More details can be found at \link troll.html Trolltech\endlink.
|
|
|
|
<hr width="30%">
|
|
\section2 How can I evaluate Qt?
|
|
|
|
We offer 30 day evaluation versions of Qt on all our supported platforms.
|
|
Further details can be found here: \l http://www.trolltech.com/evaluate.html.
|
|
|
|
<hr width="30%">
|
|
\section2 What does Qt cost?
|
|
|
|
This depends on your number of developers, on how many
|
|
different platforms you target, and on the edition of Qt you
|
|
choose. Currently we offer two different editions (Enterprise
|
|
Edition and Professional Edition) on four different
|
|
platforms (Microsoft Window, Unix/X11, Macintosh and Linux/embedded).
|
|
|
|
We also offer discounts for academic and research institutions.
|
|
|
|
Details on pricing can be found here:
|
|
\l http://www.trolltech.com/pricing.html.
|
|
|
|
<hr width="30%">
|
|
\section2 How can I buy Qt?
|
|
|
|
To purchase, please visit the <a
|
|
href="https://webshop.trolltech.com/cgi-bin/index.cgi">Trolltech
|
|
webshop</a>. In the webshop, you can generate a Purchase Order, order
|
|
a Quote, or purchase directly using a credit card.
|
|
|
|
For further information and assistance, please contact Trolltech sales:
|
|
|
|
Email: \link mailto:sales@trolltech.com sales@trolltech.com\endlink
|
|
Phone, US office (for North America): <strong>(+1) 650-813-1676</strong>
|
|
Phone, Norway office (for others): <strong>+47 2160 4800</strong>
|
|
|
|
<hr width="30%">
|
|
\section2 What kind of technical support is available for Qt?
|
|
|
|
Trolltech offers email support to commercial licensees. The first year
|
|
of Trolltech's Support and Maintenance Service is included with the
|
|
purchase of Qt Professional and Qt Enterprise Edition licenses.
|
|
Licenses can be kept up-to-date and fully supported by buying
|
|
the Support and Maintenance Service for the licenses held in each
|
|
subsequent year.
|
|
|
|
For further information see here:
|
|
\l http://www.trolltech.com/support/.
|
|
|
|
<hr width="30%">
|
|
\section2 Who provides training for Qt?
|
|
|
|
A number of companies provide Qt training, in Asia, Europe and the US.
|
|
Trolltech has agreements with a number of official training
|
|
partners, who offer Trolltech approved courses. In addition
|
|
there are a number of independently developed courses run by third
|
|
parties. You can find more information about the partners and the
|
|
courses here: \l http://www.trolltech.com/training/.
|
|
|
|
<hr width="30%">
|
|
\section2 Who provides consultancy for Qt?
|
|
|
|
A number of companies provide consultancy services for Qt and
|
|
Qtopia. You can find a partial list here:
|
|
\l http://www.trolltech.com/company/servicepartners.html.
|
|
|
|
<hr width="30%">
|
|
\section2 Are there any books about Qt programming?
|
|
|
|
Yes, there are quite a few books on Qt, most of them
|
|
available from amazon.com. You can find a partial list at
|
|
\l http://www.trolltech.com/developer/books.html.
|
|
|
|
The official Qt book is
|
|
<a href="http://www.amazon.com/exec/obidos/ASIN/0131240722/trolltech/">C++ GUI Programming with Qt 3</a>.
|
|
|
|
<hr width="30%">
|
|
\section2 What is the Open Source Edition?
|
|
|
|
The Qt Open Source Edition is our non-commercial versions of
|
|
Qt. You can use this edition to create and run free
|
|
software, i.e. software that is licensed under the GNU GPL or
|
|
a similarly recognized open source license.
|
|
|
|
Qt Open Source edition is available for Unix/X11, Macintosh and
|
|
Linux/embedded.
|
|
|
|
<hr width="30%">
|
|
\section2 What is the idea behind having a free version of Qt?
|
|
|
|
With the Open Source Edition, Trolltech has found a way to support
|
|
the free software concept. Part of our commitment is to enable
|
|
those who contribute to the free software pool to do so
|
|
without paying license fees.
|
|
|
|
<hr width="30%">
|
|
\section2 Is there a low-cost version of Qt for writing shareware?
|
|
|
|
No, but Qt's commercial licenses permit you to write and sell
|
|
shareware written with Qt.
|
|
|
|
|
|
<hr>
|
|
\section1 Questions about Qt's Users
|
|
|
|
<hr width="30%">
|
|
\section2 How many developers use Qt?
|
|
|
|
We don't know! We can count our many thousands of commercial
|
|
licensees, but the number of free software developers
|
|
using Qt can only be guessed based on download figures, book
|
|
sales, the number of open source Qt applications available on
|
|
the web, Universities teaching with Qt, and other factors. A
|
|
conservative estimate would put the figure at around 100,000 to
|
|
150,000 developers world-wide.
|
|
|
|
<hr width="30%">
|
|
\section2 Which major corporations use Qt?
|
|
|
|
See our list of reference customers at
|
|
\l http://www.trolltech.com/company/customers.html. Note that many
|
|
commercial customers do not disclose their use of Qt because they see
|
|
Qt as a competitive advantage.
|
|
|
|
<hr width="30%">
|
|
\section2 Are there any well-known applications that use Qt?
|
|
|
|
There are many, e.g. Adobe Photoshop Album from Abobe
|
|
Corporation and the KDE desktop. A partial list can be found at
|
|
\l http://www.trolltech.com/products/qt/apps-using-qt.html
|
|
|
|
|
|
<hr>
|
|
\section1 Questions about Developing Applications with Qt
|
|
|
|
<hr width="30%">
|
|
\section2 Is there a mailing list for Qt?
|
|
|
|
Trolltech operates several mailing lists for Qt users including
|
|
\c qt-announce, \c qt-interest and \c snapshot-users.
|
|
|
|
See \link http://lists.trolltech.com Mailing lists\endlink.
|
|
|
|
<hr width="30%">
|
|
\section2 Is Qt's documentation available online?
|
|
|
|
Yes, at \l http://doc.trolltech.com.
|
|
|
|
<hr width="30%">
|
|
\section2 Is there a technical newsletter for Qt?
|
|
|
|
Yes, \link http://doc.trolltech.com/qq/index.html Qt
|
|
Quarterly\endlink. It is a paper-based newsletter exclusively
|
|
available to Qt licensees.
|
|
|
|
As a courtesy and convenience to all our users, a selection of
|
|
articles is also published online about one month after publication.
|
|
|
|
|
|
<hr width="30%">
|
|
\section2 I think I have found a bug in Qt. Where can I report it?
|
|
|
|
Bugs should be reported to \link mailto:qt-bugs@trolltech.com
|
|
qt-bugs@trolltech.com\endlink. But \e please read (the very short)
|
|
\link bughowto.html How to Report a Bug\endlink page \e first.
|
|
|
|
|
|
<hr>
|
|
\section1 Questions about Professional Licensing
|
|
|
|
<hr width="30%">
|
|
\section2 We have purchased a license, but the developer is leaving the company
|
|
project. Can we transfer the license to another developer?
|
|
|
|
Yes. Qt licences are for the individual use of named developers. If
|
|
the developer associated with a licence leaves the organization, or
|
|
moves on to another project that does not require a Qt license,
|
|
another developer can take over the licence. You can change the name
|
|
of the developer using a licence at any time, but after a change you
|
|
must wait at least six (6) months before changing again.
|
|
|
|
|
|
<hr width="30%">
|
|
\section2 Can I purchase floating licenses for Qt?
|
|
|
|
No, we do not offer floating licenses.
|
|
|
|
The reason is this: Floating licenses are based on the concept
|
|
of defining a maximum number of concurrent users. For example,
|
|
for a word processor, this means the maximum number of
|
|
instances of that application that can be running at any
|
|
time. However, for a library product like Qt, there is no main
|
|
application that is always running when the product is being
|
|
used. Hence, it is not possible to count the number of
|
|
concurrent users, and therefore floating licenses do not
|
|
make sense.
|
|
|
|
|
|
\omit
|
|
#if 0 // ##### Just an idea, no clue if this is policy today
|
|
While we want to develop our software for multiple platforms, some
|
|
of our developers will only need to work on a single platform. Can
|
|
we purchase single packs for those?
|
|
|
|
No, you can only purchase single packs as long as you target
|
|
one platform only.
|
|
#endif
|
|
\endomit
|
|
|
|
<hr width="30%">
|
|
\section2 Can we use the Open Source Edition while developing our non-free
|
|
application and then purchase commercial licenses when we start to
|
|
sell it?
|
|
|
|
No: our commercial license agreements only apply to software
|
|
that was developed with Qt under the agreement. They do not
|
|
apply to code that was developed with the Qt Open Source Edition
|
|
prior to the agreement. Any software developed with Qt
|
|
without a commercial license agreement must be released as
|
|
free/open source software.
|
|
|
|
<hr>
|
|
\section1 Questions about Open Source Software Licensing
|
|
|
|
<hr width="30%">
|
|
\section2 I just want to run KDE and other Qt-based software on my
|
|
machine. Can I do that with the Open Source Edition?
|
|
|
|
Yes. You may use the Qt Open Source Edition for running applications,
|
|
both at home and at work, without restrictions.
|
|
|
|
<hr width="30%">
|
|
\section2 I want to put Qt, and applications that use it, on a CD-ROM or on
|
|
a web site. Can I do that with the Open Source Edition?
|
|
|
|
Yes. You may copy and redistribute the Qt Open Source Edition, both
|
|
at home and at work, without restrictions.
|
|
|
|
<hr width="30%">
|
|
\section2 Can I make software with the Qt Open Source Edition and release it under
|
|
the GNU GPL, BSD, or Artistic license?
|
|
|
|
Yes. The GNU GPL, GPL-compatible licenses, or any other
|
|
approved open source license will do. The FSF.org and
|
|
OpenSource.org web sites list approved software licenses.
|
|
|
|
<hr width="30%">
|
|
\section2 I don't want to give away my source code. What do I do?
|
|
|
|
You need to buy a commercial Qt license.
|
|
|
|
<hr width="30%">
|
|
\section2 Is software based on the Qt Open Source Edition really free? Does it
|
|
carry any Trolltech-specific license restrictions?
|
|
|
|
Yes, it really is free. This is because the Qt Open Source Edition
|
|
uses the GNU GPL, which forbids the imposition of any license
|
|
restrictions on software based on the Open Source Edition that would
|
|
make it non-free. And no, there are no Trolltech-specific
|
|
license restrictions on software produced using the Open Source
|
|
Edition.
|
|
|
|
<hr width="30%">
|
|
\section2 What if Trolltech stops releasing Open Source Editions of Qt?
|
|
|
|
We have absolutely no intention of doing that. Together with
|
|
the K Desktop Environment project, we have set up the KDE Free
|
|
Qt Foundation (see
|
|
\l http://www.kde.org/whatiskde/kdefreeqtfoundation.php) to
|
|
legally guarantee the availability of Qt for free software
|
|
development now and forever - even if circumstances beyound
|
|
our control prevent us from producing new free editions.
|
|
|
|
<hr width="30%">
|
|
\section2 Using the Open Source Edition, can I make non-free software for internal
|
|
use in my company/organization?
|
|
|
|
No. Software developed with the Open Source Edition is always free
|
|
software, i.e. it can only be distributed under a free
|
|
software license. In particular, all the source code for all
|
|
the modules your software is based on, regardless of whether
|
|
they have been written by you or by others, must be free
|
|
software. This is part of our commitment to the free software
|
|
community, and enables those who contribute to the free
|
|
software pool to do so without paying license fees.
|
|
|
|
Although it is possible to write free software for internal
|
|
use, it is difficult to ensure that such software is used and
|
|
distributed legally. For example, if your free software
|
|
requires any modules that impose conditions on you that
|
|
contradict the conditions of the GNU GPL, including, but not
|
|
limited to, software patents, commercial license agreements,
|
|
copyrighted interface definitions or any sort of
|
|
non-disclosure agreement, then you cannot distribute it at
|
|
all; hence it cannot be given to consultants, employees for
|
|
their personal computers, subsidiaries, other divisions, or
|
|
even to new owners.
|
|
|
|
Consequently we recommend using commercial licenses for all
|
|
internal software development.
|
|
|
|
|
|
<hr width="30%">
|
|
\section2 Is Qt Open Source Edition really free software in the GNU meaning of the
|
|
word?
|
|
|
|
Yes - it is free software both as in "no cost" and as in
|
|
"free speech". Even more, it is actually available under the
|
|
terms of the GNU GPL. This means you can link GPL'ed software
|
|
to it, and you can take code from Qt and put it into other
|
|
GPL'ed software.
|
|
|
|
<hr width="30%">
|
|
\section2 If the Open Source Edition is GNU GPL, aren't there license conflicts
|
|
with incompatible open source licenses? How come people can even
|
|
run commercial software like the Opera web browser with it?
|
|
|
|
If the Open Source Edition was licensed purely under the GNU GPL,
|
|
there would be problems. However, as long as Qt-based
|
|
software is either open source or was developed under a
|
|
commercial license agreement with Trolltech, we grant
|
|
permission to compile, link and run those programs with the
|
|
Open Source Edition. This is written down in our second free software
|
|
license, the QPL.
|
|
|
|
<hr width="30%">
|
|
\section2 Doesn't such an en extra license in addition to the GNU GPL
|
|
violate the terms of the GPL or at least make the whole package
|
|
GPL-incompatible?
|
|
|
|
No, because those extra license terms give you rights in
|
|
addition to those of the GNU GPL, including the right to
|
|
remove those extra terms.
|
|
|
|
<hr width="30%">
|
|
\section2 Why is Qt Open Source Edition not distributed under the GNU Lesser
|
|
General Public License (LGPL)?
|
|
|
|
The LGPL is designed to "permit developers of non-free
|
|
programs to use free libraries" (quote from the LGPL). In
|
|
other words, if Qt Open Source Edition were LGPL'd, companies would
|
|
not have to purchase our commercial editions in order to make
|
|
commercial/proprietary software, they could just use the Open Source
|
|
Edition, free of charge. That would mean Trolltech would not
|
|
get the revenue necessary for improving and extending Qt.
|
|
|
|
Note also that the Free Software Foundation discourages the
|
|
use of the LGPL.
|
|
|
|
|
|
<hr>
|
|
\section1 Questions about other programming languages
|
|
|
|
<hr width="30%">
|
|
\section2 Are there bindings to languages other than C++?
|
|
|
|
Yes there are, e.g. bindings to Perl (PerlQt) and Python
|
|
(PyQt). These bindings were written by the open source
|
|
community and are not supported by Trolltech.
|
|
|
|
<hr width="30%">
|
|
\section2 Can I develop commercial applications with PerlQt or PyQt or other
|
|
Qt wrappers?
|
|
|
|
Yes, if you have purchased a commercial license. The licensing
|
|
conditions are the same whether you use the Qt API directly in
|
|
C++, or you use it through some API wrapper in another
|
|
programming language. All developers that write code
|
|
containing calls to the Qt API (directly or through a wrapper)
|
|
need Qt licenses.
|
|
|
|
*/
|