Using QtCharts in a MIT software
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Hi guys!
I am creating a software that uses QML and QtCharts. All the software I am creating is licensed as MIT. However, it uses QtCharts, which is licensed under GPL (and not LGPL).
Question: I know both licenses are compatible. However, what kind of cautions should I have when it is completed? I think that I can post my MIT source-code on Internet as MIT, right?
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IMHO I would be pretty ticked off to find out software I thought I licensed under MIT was indeed built on top of GPL license software, UNLESS it clearly stated this and the GPL software was optional. I would still most likely cause to steer clear of the library though. MIT embedded in GPL I can see, but GPL embedded in MIT is asking for trouble.
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It turns out that there is not problem at all!
The argument is pretty simple: just look at FFmpeg.
What will happen is: my entire source-code is MIT. If I, or anyone else, create a binary build of my source-code, which will use QtCharts (GPL), then this binary software is under GPL 3 and the redistribution requires to send the source-code.
On the other hand, someone can take my MIT source, remove all dependency to QtCharts, and build a MIT License binary. Precisely what I need.
More information here: https://opensource.stackexchange.com/questions/1640/if-im-using-a-gpl-3-library-in-my-project-can-i-license-my-project-under-mit-l?rq=1
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Doing something like FFmpeg, I add the following LICENSE.md:
# License All the source code files of <my software name> are under the MIT "Expat" License. Read the file `COPYING.MIT` for details. However, the graphical user interface (GUI) uses the QtChart component of Qt to plot the simulation graphics. This component is under the GNU General Public License version 3 (GPLv3). Read the file `COPYING.GPLv3` for details. Thus, all binary versions built from this source code as is, which will be linked against QtChart, will be under the GPLv3.
