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Intel Dev: GTK's Biggest Problem, and What Qt Does Better
Freshly Exhumed writes "Phoronix has an article about how Dirk Hohndel of Intel's Open-Source Technology Center has stirred the hornet's nest with a talk at Australia's Linux.Conf.Au (MP4 file) about what he views as the biggest problem with the GTK: he finds dealing with upstream GTK/GNOME developers to be tough, with frequent abuse and flame-wars, with accusations from the developers that "you're doing it wrong." Conversely, he found the Qt development community to be quite the opposite: willing to engage and help, with plenty of application developer documentation and fewer communication problems than with their GTK counterparts."
There hasn't been a good GTK / Qt flamewar around here for ages!
Now that Qt is free, shouldn't we be migrating away from GTK?
pissing you off, mainly.
The only reason to use it now is if for some reason you want to avoid C++ and develop in pure C.
That was because the FSF was spreading FUD about Trolltech. Trolltech was free software friendly and was never going to make Qt non-free.
Licenses matter, especially for businesses. You have to know that this piece of software you want to build things around, to rely on, isn't going to be taken from you. And, you shouldn't have to be a "judge of character" for a business in order to have that security. FUD is a heavy characterization that seems to devalue the perspective of those who do feel they need to operate under license security.
Do you even know what "existing toolkits" looked like at the time? They were solid crap. I'm no fan of GTK, but man, reuse of platform-provided functionality in a multi-platform toolkit is usually something you do at the beginning and then quickly backpedal on. There is a very good technical reason why Qt comes with its own raster rendering code, its own event loop, its own containers and atomics, and a host of other things: the platform stuff, if present, is broken in its own way on each platform Qt runs on. Or, if it's not broken, the standards the platform libraries follow simply leave too much to undefined- or implementation-defined behavior to, you know, actually use in practice. For C++ standard library that may be a bit of a less of a problem with modern compilers, but remember that even Qt 4 has to compile on some very broken compilers and very quirky platforms.
A successful API design takes a mixture of software design and pedagogy.
I would argue exactly the other way around: Qt is stand-alone and GTK is not. If you want to write any app you need more than the UI. You actually want the application to *do* something but render a couple of widgets.
With GTK you end up hunting down a host of glib/gnome based libraries, all with slightly different peculiarities and all of them coming with little useful documentation. How is that stand-alone? With Qt you get everything in one convenient package (and are still free to leave out the parts you do not need in your binary packages).
Qt is a C++ library: Any C++ compiler can compile it on a wide range of platforms. How would that be possible if Qt was written in a weird dialect?
Of course the object model leaks into the language bindings. How could it not be? The same is true for "object-oriented" libraries written in C.
Yes, even with Qt you can not get perfect cross-platform applications. You will need to some platform-specific code in any non-trivial application. That is perfectly possible in Qt... and it still gets you at least 90% of the way! That was the other reason for switching that Dirk gave in his presentation: That GTK does *not* run properly on windows nor on Mac. He claimed that some core GTK people are actually opposing the toolkit working on those platforms and that independent teams are trying to maintain the cross-platform parts as good as they can against a hostile core team.
Subsurface was cross-platform with GTK and it looked like shit on *all* platforms incl. Linux. The Qt port looks way better -- they could finally get the UI they wanted but could not manage to implement in GTK -- and works equally well on all three target platforms. Check the demo right in the middle of the video: Dirk shows of the new UI and contrasts it with the old one in pretty gory details. So, yes, Qt is not perfect, but it is pretty good nontheless:-)
Regards, Tobias
The license issues were bad enough at one point that the KDE developers themselves started developing their own OSS version of Qt called Harmony. After Trolltech made the license more open Harmony folded.
"weird dialect of C++98" - WTF? What is this dialect you speak of? Do you need to pass --weird to G++ to get it to compile? Of course not! It's using the same C++ every other C++ app in the world is using. Both C++98 and C++11 are supported. It doesn't REQUIRE you to use C++11, but that is a benefit not a drawback.
"it has its own object model" - Of course it does, that's because C++ does not have one of its own. QObject is there to provide for the introspection that C++ lacks. Once you have that introspection you can start communicating with other objects. I fail to understand why this is a disadvantage in your eyes.
"networking stack" - Of course. Why should it not? It is an cross-platform application framework.
"container library" - When Qt began the STL was fragmented, not standardized, and poorly supported. Yet containers are useful. Qt kept them around because they turned out to be better than the STL containers. They're a balance between raw performance and the "bloat" of pure templatized containers. Externally they end up being 100% compatible with the STL.
"threading library" - It was only extremely recent that C++ got its own threading, and it's just very low level threading. Qt threading provides a nice usable wrapper around threads (which are native C++ threads underneath if built with C++11), and the ability to easily communicate between threads with signals/slots.
"graphics primitive library" - Why not? Seriously, why not? Isnt't that the whole point of a GUI toolkit? Underneath it draws widgets using the native controls, if available, or uses its own if not. That's why the widgets look like native controls on Windows and Mac, because they ARE native controls! On X11 it will draw its own. It doesn't use Cairo, why should it use Cairo, who made Cairo king that we all have to bow down before it?
Don't blame me, I didn't vote for either of them!
instead of reusing an existing toolkit
GIMP version 0.54 (January 1996) "It had a dependency on Motif for its GUI toolkit, which made efficient distribution to a lot of users impossible."
A New Toolkit - The 0.60 Series:
Peter got really fed up with Motif. So he decided to write his own. He called them gtk and gdk, for the Gimp Tool Kit, and the Gimp Drawing Kit. Peter tells us now that they never intended for it to become a general purpose toolkit - they just wanted something to use with GIMP, and it "seemed like a good idea at the time". GIMP History