LGLPL licensing for commercial application

[lurky]

Hello all.
I've read a lot of stuff about licensing issues when using QT libraries but I was not able to answer to the critical questions:

1. may I use QT libraries under LGPL to develop a commercial image elaboration application? (I will NOT modify the QT source code, I would subclass some widget)

2. in this case, is there a difference between building my application against the statical or dynamical version of the QT libraries?

3. if the answer to first question is 'yes', which are requirements about logos, copyright, credits to inform about the use of QT in my project?

Thanks a lot.

[yogeshgokul]

1. may I use QT libraries under LGPL to develop a commercial image elaboration application? (I will NOT modify the QT source code, I would subclass some widget)

Yes.

2. in this case, is there a difference between building my application against the statical or dynamical version of the QT libraries?

You have to build Qt libs dynamically.

[Lykurg]

Hello all.
I've read a lot of stuff about licensing issues when using QT libraries but I was not able to answer to the critical questions:

1. may I use QT libraries under LGPL to develop a commercial image elaboration application? (I will NOT modify the QT source code, I would subclass some widget)

yes.

2. in this case, is there a difference between building my application against the statical or dynamical version of the QT libraries?

With LGPL you must link dynamical.

3. if the answer to first question is 'yes', which are requirements about logos, copyright, credits to inform about the use of QT in my project?

Thanks a lot.

Put the text of the LGPL to your project and write a short sentence in your README that you use Qt under the LGPL.

[lurky]

Thank you all.

[rexi]

Just to make this clear, as it oftens seems to be the stumbling block when understanding and employing LGPL: the main requirement when using a LGPL library is that the user can replace said library with any other one that implements the same API. This alone totally rules out static linking.

On the other hand, you do not have to release your application's code when using a LGPL library, even when you change code of said library. Supposed you have to alter the library to fit your needs, you are only required to publish the modifications of that library. You can choose any license you want for your application's code itself.

Anyway, as this forum isn't driven by legal experts (and I am none, too, just a coder with a hang of gettings his licenses right), you probably should seek proper legal counsel in case you want to develop commercial applications.