Library question

[ilia_kr]

As far as I know there are two main GUI libraries availible: QT and GTK. KDE desktop environment is built using QT while Gnome and others are GTK based. Moreover, linux applications are either QT or GTK based.

 

I have a few questions:

 

- what are main diffrences between these two - philosophy, licence, usability etc.

- many independant software developers like Mozilla, Gaim, XMMS and its forks and others choose GTK. I know that there is plenty of QT pased programs but most of them are products of KDE group and not of independant developers (maybe I'm wrong). Why ?

- if i use a program based on on of the libraries on a DE that is based on another - will it increase RAM usage (by loading another library) ?

 

 

[moved from Software by spinynorman]

Edited February 23, 2007 by ilia_kr

[tyme]

- what are main diffrences between these two - philosophy, licence, usability etc.

As far as license, GTK+ is completely open source. Qt, on the other hand, is developed by Trolltech and allows one to purchase a commercial license thereby allowing you to develop private, non-open source code if you feel the need to. For a better understanding here is QT's licensing overview.

- many independant software developers like Mozilla, Gaim, XMMS and its forks and others choose GTK. I know that there is plenty of QT pased programs but most of them are products of KDE group and not of independant developers (maybe I'm wrong). Why ?

It has a lot to do with licensing. GTK has been open source, and GPL compatible, from the start. Qt was proprietery at first (which was largely the reason for the creation of GNOME) and later was put under a free license.

- if i use a program based on on of the libraries on a DE that is baset on another - will it increase RAM usage (by loading another library) ?

Yes - though the difference is often unnoticeable.

 

You can always try reading the GTK and Qt wikipedia articles to get a better understanding of them.

[pmpatrick]

tyme, I think you are wrong.

 

Gtk is licensed under the LGPL. With that license you are free to use the library for both non-GPL and GPL applications without paying any fee.

 

QT is licensed under the GPL, same as the linux kernel. If you use QT, the app must also be licensed under th GPL. However, if you want to make a proprietary app with QT, the owner is willing to give you a commercial QT license for a fee.

 

Open source developers with commercial aspirations for their software prefer Gtk and the LGPL for obvious reasons - it allows them to fork off a commercial version without having to pay any fee.

 

The main technical difference is QT is C++ based and Gtk is C based. A lot of open source developers are more comfortable in C than C++.

[tyme]

I think we said the same thing ;)

 

I simply pointed out that originally Qt was not under a open source, GPL-compatible license - that's a simple fact :P. All the information I provided came from the wikipedia article and Qt's own licensing page. Prior to Qt 1.45 it was under the FreeQt license, which was not considered open source nor compatible with the GPL.

[pmpatrick]

I guess I misinterpreted this:

 

As far as license, GTK+ is completely open source.

 

which seems to imply that GTK which is licensed under the LGPL is somehow truer to open source ideals than QT which is licensed under the GPL. However, since 1999, RSM has called for libraries to be licensed under the GPL instead of the LGPL:

 

http://www.gnu.org/licenses/why-not-lgpl.html

 

You also failed to point out that you can

 

develop private, non-open source code if you feel the need to

 

with GTK without paying any fee, leaving the implication that you could only develop proprietary apps with QT, not GTK.

 

I don't mean to nitpick, but there is a long history here of flamewars with kde supporters claiming that gnome supporters misrepresent the nature of kde licensing and gnomers claiming to be more open source friendly than kde/QT. As it currently stands, that is simply not the case. QT is currently licensed under the preferred GPL and encourages the production of GPL software by requiring a fee only from those wishing to use QT on non-GPL projects.

 

Given the contentious history on this subject, greater care and precision is needed in describing the licensing differences between QT and GTK. As with any controversial subject, wikipedia is not the best place to go for info.

[tyme]

absence isn't guilt ;)

 

i think ya just need to chill out and not take this stuff so seriously, man :P

[ilia_kr]

Are both DE compatible with each other 100% ?

I've noticed that KDE runs fuster on my pc than gnome, but i use mostly GTK apps, so what do you say?

[tyme]

Are both DE compatible with each other 100% ?

Hmm...I'm not sure what you mean by that question...

[ilia_kr]

Can I run apps written on GTK or for gnome in KDE without problems?

Will KDE apps work in Gnome so i coud not feel any difference?

[dexter11]

Sure you can they just run the needed KDE\GNOME processes so e.g. you want to run a KDE app under GNOME like k3b you still need to install kdebase even if you don't use KDE.