Choose of Qt Licence



  • Qt is an open source platforme … i am obliged to develop or to share my final work on an open soucre licence ?

    thanks


  • Moderators

    No. There are 3 choices. You could use Google, as this was discussed hundreds of times. But here we go:

    Qt Commercial license - you pay Digia, get support in return, help Qt being developed, and are free to choose any license you like

    GPL - you have to publish all the source code (not necessarily to everybody, but at least your customers)

    LGPL - you are not forced to publish the source code of your application. The only requirements are to publish the changes to Qt you have done (say, if you patch stock QString in your project), make sure users can swap the libraries (basically it boils down to dynamic linking of Qt libraries), and make sure you distribute the license for Qt with your project + mention usage of Qt in some kind of readme, about box etc.

    All 3 choices allow you to sell your application - GNU licenses are not about money.



  • Thanks for your help :-)

    [quote author="sierdzio" date="1363166433"]No. There are 3 choices. You could use Google, as this was discussed hundreds of times. But here we go: # Qt Commercial license - you pay Digia, get support in return, help Qt being developed, and are free to choose any license you like # GPL - you have to publish all the source code (not necessarily to everybody, but at least your customers) # LGPL - you are not forced to publish the source code of your application. The only requirements are to publish the changes to Qt you have done (say, if you patch stock QString in your project), make sure users can swap the libraries (basically it boils down to dynamic linking of Qt libraries), and make sure you distribute the license for Qt with your project + mention usage of Qt in some kind of readme, about box etc. All 3 choices allow you to sell your application - GNU licenses are not about money.[/quote]



  • I have one doubt,
    Suppose I used QCustomPlot,which comes under GPL licence and LGPL version of Qt to develop a GUI Application,then do i have to publish my GUI Application source code?


  • Moderators

    [quote author="nike.niec" date="1400411303"]I have one doubt,
    Suppose I used QCustomPlot,which comes under GPL licence and LGPL version of Qt to develop a GUI Application,then do i have to publish my GUI Application source code?[/quote]

    I don't know, but I suspect the whole package becomes GPLed in such scenario. However, if QCustomPlot uses GPLv2, then your app does not need to be GPLed (as far as I know).



  • If i am using LGPL version of Qt to develop a GUI Application,
    then do my customer need to install Qt libraries?
    Can i statically compiled my GUI Application to include Qt Libraries under LGPL version of Qt?



  • As sierdzio already said: In this case you have to ship the Qt dlls (easier than having the customer install Qt just to use your program), so the libraries are interchangable by the user. This prohibits static linking (of Qt, at least).


  • Moderators

    [quote author="thEClaw" date="1400433318"]As sierdzio already said: In this case you have to ship the Qt dlls (easier than having the customer install Qt just to use your program), so the libraries are interchangable by the user. This prohibits static linking (of Qt, at least).[/quote]

    Correct.

    Theoretically, one could get around that by providing linkable object files to adventurous customers... but that is not easy ;)

    On Android, Qt provides an automated service for managing Qt libs: Ministro. You should check that out.


Log in to reply
 

Looks like your connection to Qt Forum was lost, please wait while we try to reconnect.