Qml or c++ or both

niqt

I use qt since 1997 (version 0.6 can not remember), now I'm studying QML, but I still have not clear ideas about it. What is the ideal use? Graphics with QML and logic with C + +? QML only for simple mobile application? Use C ++ only for performance? It 'can hope to Pugin QML for browsers?

hhartz

It depends on your use-case. You could think of it as a presentation-layer for your App where the business logic is in C++ - or where high performance computation/graphics are written in C++. You can also use JavaScript for simple imperative code. QML can be used both for simple and complex applications - again it depends on your use-case. There is no QtDeclarative plugin for browser in Qt.

gregschlom

We use QML with C++ to make a desktop app that looks and behave like those web 2.0 apps. It's very powerful. All the logic is done in C++, and all the graphics in QML.

I think the ideal use for desktop apps is:

You want a beautiful interface
With lots of effects and animations
That looks the same on all platforms
And that doesn't use the native widgets.

So anything that should look like a web app or an iPhone / iPad app qualifies pretty well.

Look at Spotify, for example (http://spotify.com/). That's the kind of interface that is easier to achieve in QML than in pure C++.

archerabi

Its easier to get consistent looking UI for multiple screen sizes if you use layouts in C++ .

But for fixed screen sizes i guess QML is really wonderful.

mario

@gregschlom: Well, I think that some parts are harder to accomplish with QML, for example, treeviews/tableviews with headers. Can you do them in QML w/o to much hack (or is it possible at all)?

But when it comes to doing delegates for listviews nothing beats QML :)

Hmm, you could still have an hybrid QML/Widget app though with the best from both worlds.

DenisKormalev

We are using C++ and Qml together. Only Qml will not provide a lot of functionality for you, but together with C++ it will give a lot of power.

mario, I've treeview qml implementation with not a big hack, but it supports only trees with not too many children. If you can read russian you can read it in my blog (in my profile).

gregschlom

@archerabi: I don't have a lot of experience with layouts, but I would say the anchoring system in QML is powerful enough to make it easy to deal with different screen sizes.

@mario: haven't tried to make list views with headers, but we did re-implemented our own list view component as QML's default one wasn't suiting our needs. So the bottom line is that it's really easy to extend QML, and with a few (ok, maybe a hundred or so) lines of C++ code, you can get exactly what you want.

But yes, it's not for any project. It's more suited for projects with a strong focus on fluid user interface.

mario

Denis, Looks good! I don't know Russian but I understand code and the screenshot :)

Do you have the code downloadable somewhere (I guess it's free to use)? I'm to lazy to copy&paste it from the webpage :)

gregschlom, I agree, it's very easy to extend and I love the way how you do UIs with QML. But sometime it's hard to go from Widget-based UIs with a large portfolio of components (like comboboxes with completion) to nearly start from scratch. I think I have to change my mindset when building UIs with QML :)

DenisKormalev

mario, yeah, I've uploaded this example to our lug server and you can download it "here":http://dl.yarlug.org/devel/Qt/qmlTreeModel.tar.gz .