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I'm about to publish a free software written with Qt 4.8 GUI, can I publish the stand-alone version with dlls such as QtCore? Do I have to publish my code also?
If possible, could you make some examples of using GPL license legally?
Thanks very much!
If you want to publish your software using GPL then you have to provide the source code no matter is it free or you charge money for it. In GPL "Free" doesn't mean cost free but freedom to change the code etc.
In your case if you don't wish to give away your source code, then you you should use LGPL license. Qt is available under LGPL license too. The only restriction it puts is that you cannot statically link with Qt libs. You ought to use dlls as you are using. And if you only use Qt dlls then you can even charge money for your application.
http://en.wikipedia.org/wiki/GNU_Lesser_General_Public_License#Differences_from_the_GPL
You can use LGPL library in your commercial, closed source, non-free/free application provided you link to the LGPL library dynamically (using .dlls, .so etc.).
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I'm looking at a Qt Extended application built circa 2006-2008 and upgrading to a newer Qt framework. What direction(s) are recommended to upgrade / rewrite this application to get on the latest supported version of some Qt framework?
I assume this is an embedded platform, and in this is case first of all you need to get Linux BSP with newer Qt version (you can look into Buildroot or Yocto or even a distribution like Debian, all of these have excellent support for Qt), and make sure that you have full HW supported for your platform. This is pretty much platform and product dependent, so i can't really be more specific.
After you got the OS up and running, you can start to port your application to port to Qt5. This can be pretty straightforward (see for example https://wiki.qt.io/Transition_from_Qt_4.x_to_Qt5), but can be rather complicated if a lot of Qt Extended related features were used. Again, this depends a lot on the application itself, so hard to give guidelines.
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We are developing an enrollment system through asp.net (c#), we are required to generate PDF reports and be deployed on a Web Host. We are going to use iTextSharp since it can be used for free but under Affero General Public License (AGPL). How can we deploy oursystem that is under Affero General Public License (AGPL) or more likely the free versions of iTextSharp ?
You need to distribute the complete source code of the project using iTextSharp using the same medium you use to distribute your software. For instance: in old days, software was distributed on a CD. In that case, the complete source code had to be distributed on the same CD(-set).
In your case, you are distributing the code on a Web Host (the main difference between the AGPL and the GPL is that putting code on a web site is also considered as distribution). This means that you should host the complete source code on the same site where you deploy your application.
Everybody visiting your site needs to have access to your complete source code. As many companies wish to avoid this, they purchase a commercial license.
There is also a persistent misconception where some project manager think "we did not modify iText, hence we do not have the obligation to share our code." That is wrong: linking to an AGPL library is generally considered being a modification of the library.
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I'm a Delphi developer I only used to develop application on Windows platform only.
From now on, I wish to develop a GUI based database applications which target Windows, Ubuntu, OSX.
I don't have much knowledge about cross platform solution, I know I little about Java, I know almost nothing about Python and Qt.
Anyway, I prefer to use Python as the programming language and use Qt for GUI, my question is I'm not quite sure about...
What development tool and version (prefer latest if possible) do I need to install on my development machine which is running Ubuntu 13.04?
What are major differences between PyQt, Qt Designer?
Did you read basic Qt documentation?
You should write platform independed code to make it portable ;). Do not use OS-specific features, use Qt classes. You need a compiler for each platform. You need a Qt for each platform.
Visit qt-project.org and get latest versions. (And a lot of other information about Qt)
PyQt - is port of Qt libraries to python. Qt Designer - is software (tool) for making .ui files. Others??
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I want to start a cross-platform project. I had my researches and now I am almost certain Qt is the right deal. There is a big obstacle here though: licensing.
I want to sell my project and I also don't want to give out any source related to my work or pay for a license. I checked and noticed Qt offers both commercial and open source solutions. I have heard too many conflicting sayings on Qt licensing which confused me a lot. Some say that even if I use LGPL version of Qt, I still need to submit my code. Is this true?
Can someone give me a simple explanation on Qt licenses and tell me if I can sell my application without any kind of restrictions at all or not? Would anyone tell me any other equivalents to Qt for cross-platform development without any restrictions?
Just dynamically link to Qt. If you dynamically link to LGPL libraries, there's nothing to worry about.
If you statically link to them, you can just distribute your object files (not your source code), and you'll be fine.
The idea of the LGPL is that the end user has to be able to replace the LGPL library with a version they want. Dynamically linking to the LGPL library lets you do that, as does statically linking and distributing your object files. So long as you do this, you can sell your closed source program all you want.
Of course, there's more to the LGPL than just this, but that's the relevant part.
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Suppose I have a commercial license for Qt (say, for 4.5.2 ), is it possible to reuse part of the QtCreator (say, version 2.0) source code to develop a completely proprietary software? I read the QtLicensing information, but it doesn't provide any information about QtCreator licensing.
QtCreator is licensed under the LGPL just like Qt - check the Gitorious QtCreator source tree for details, specifically LICENSE.LGPL, LGPL_EXCEPTION.TXT, and the README where the various third party libraries used by QtCreator are detailed.)
Thus you can reuse the QtCreator source code in the same conditions that apply to any other LGPL-licensed product - see my answer here for additional details.
As klez said, the best thing to do would be to ask Nokia. However, if your commercial license is for Qt 4.5.2, I seriously doubt you can apply the same license to QtCreator 2.0, because QtCreator 2.0 is based on Qt 4.7. You will want to stick to QtCreator 1.3 with Qt 4.5.
Using the LGPL, you can include unmodified code from Qt Creator in a proprietary application, but if you modify any of the Qt Creator code, you must make that code (just the modified code, not your entire application) available under the LGPL.