confused about licenses ...

[jimmybaeten]

Hi,

I'm currently developing an appliction which I plan to realease under Linux, Windows and maybe eventually on Mac. I'm using the free Qt4.5 version and I also have a directory with some LGPL licensed png images. And I want to release my appliction under GPL.

As I understand it, the LGPL'd images are no problem, because I just have to put a license file in the same directory that says they were released under LGPL, right?

Do I include a GPL license file when I'm releasing the source or the linux binaries?

Windows seems like the most complicated. Am I permitted to simply include the necessary dll files (QtNetwork.dll for example) in my release? Do I have to include a copy of the LGPL or GPL license?

As you can see, I'm pretty confused by all this :p

[Lykurg]

As I understand it, the LGPL'd images are no problem, because I just have to put a license file in the same directory that says they were released under LGPL, right?
Yepp.

Do I include a GPL license file when I'm releasing the source or the linux binaries?
That's the common way. Normaly I also put a GPL explanation on top of each source file. But that's additionally. It is sufficient to mention in a readme, that all files are deployed under GPL and where one could find the text of the license.


Windows seems like the most complicated. Am I permitted to simply include the necessary dll files (QtNetwork.dll for example) in my release? Do I have to include a copy of the LGPL or GPL license?
Just write a readme and say you are using Qt (with an url where you can get the sources) under GPL.

That's it.

[ericV]

Hi,

Since I am also unclear about the Licenses, I figured that this thread is apropriate. (Didn't want to "polute" the forum with unecessary threads :) )

As far as i understood, I can write a comercial programm under the LGPL. But I am not quite sure what limitations I will have.

From what I read in the license documentation, I can release my programm under the LGPL comercialy as long as I do not make any changes to the QtLibraries.

Since I only want to subclass from these I think that the LGPL is sufficent.

Can anyone tell me if I understood the license?

Thanks

- Eric

[Lykurg]

From what I read in the license documentation, I can release my programm under the LGPL comercialy as long as I do not make any changes to the QtLibraries.

Since I only want to subclass from these I think that the LGPL is sufficent.
Fist of all, I am not a lawyer, but that is the common understanding of the license. Remember, you are not allowed to link your program statically under LGPL!

[nish]

you are correct...

EDIT: I am late again..

[ericV]

Fist of all, I am not a lawyer, but that is the common understanding of the license. Remember, you are not allowed to link your program statically under LGPL!

OK... this might be dumb .... but what exactly is a static Link?

Oh and thanks for the quick responses

[Lykurg]

Static linking an application means, that you don't have to ship the qt*dll with your app. They are included in the *.exe (to talk in "windows").

[ericV]

OH!
So that means i cant use the LGPL... since without those the Programm wont run....
Or am I wrong?

[Lykurg]

OH!
So that means i cant use the LGPL... since without those the Programm wont run....
Or am I wrong?

Of course you can, with dynamic linking (which is the default). Read Deploying an Application on Windows (http://doc.qtsoftware.com/4.5/deployment-windows.html).

[ericV]

Ok Thankyou very much for the Info...

[FS Lover]

with both GPL and LGPL you can make and release commercial software.
but if you mean from the commercial the proprietary (e.g. closed source, or with other restrictions), it makes a difference.
you can not write proprietary programs with GPL.
you can write proprietary programs with LGPL licensed software but LGPL parts should be separate parts under the original license (LGPL) from other parts of your software.
so I think you can even modify qt sources but you must put your work under LGPL too. it means that you must give all of the freedoms mentioned in the LGPL to your users; and in the first place, they need access to the source code.

in other words,
you can write your code, named 'A'
and use the functionality from some LGPL software, named 'B', in your 'A'
'A' can be proprietary; e.g. you don't give your source code or you set other restrictions on using your code/program that aren't mentioned in LGPL.
but 'B' is still a separate part under LGPL that the users can take their deserved freedoms about it.

I think the 'functionality' refers to using the required/standard interfaces to make use of the LGPL software, not inserting its source codes within your proprietary codes directly and certainly not inserting a modified version of the LGPL sources.
if you create a modified version of a LGPL software, you must release it under LGPL too.

see free software philosophy: http://www.gnu.org/philosophy/philosophy.html
and http://www.gnu.org/philosophy/open-source-misses-the-point.html
(I translated many of these articles to my native language).

while “Open Source” misses the point of Free Software, practically it is still almost the same and uses original and robust (copyleft-ed) free software licenses like GPL and LGPL very often.

in free software, free is as in freedom, not as in free beer.
commercial use and business aren't necessarily against the freedoms required by the free software.