[Interest] Creating Qt Quick controls from C++

Benjamin TERRIER b.terrier at gmail.com
Tue Jul 19 11:10:26 CEST 2016

If your app is for desktop only, I suggest you go with Widget instead
of Qt Quick.

Sure Qt Quick has many advantages but for desktop only software it still lacks
major features, for instance Qt Quick Controls 2 does not handle mouse hovering
(e.g Buttons will not highlight when the cursor is over) and Qt Quick Controls 1
does not handle keyboard focus properly (e.g you cannot press 'space' to toggle
a check box, https://bugreports.qt.io/browse/QTBUG-47658 ).

Also as you already spotted the public C++ API fro Qt Quick and the
Scene Graph is very
limited*. So you will need to generate QML from your C++ code and then
run it through the QML
engine to create your GUI, if you choos to go this way.

* you can't even create a C++ "QuickButton" class derived from
QQuickItem with Qt public API
as you have nothing to easily draw text on the SceneGraph



2016-07-07 23:52 GMT+02:00 Rob Allan <rob_allan at trimble.com>:
> I'm part of a team that is looking at migrating an existing Windows C++ app
> to Qt. The first decision is whether to use Widgets or Qt Quick. Since Qt
> Quick is newer, shinier, faster, etc, that seems like the obvious choice.
> However, for reasons that I won't go into here, the vast majority of forms
> in our app are built dynamically in code. This kind of approach seems easy
> enough with Widgets, but looks like it could be difficult, or even
> infeasible, with Qt Quick. That's because the preferred way of creating Qt
> Quick layouts is using QML, and while there is an object model backing that,
> my impression is that this object model is not designed to support
> heavy-duty creation and manipulation of layout elements. For example, while
> QQuickItem is documented, none of its derived classes are, and I believe
> their interfaces may be private - so the only way to manipulate items is
> using a generic "setProperty" syntax. And while there are a few articles
> around that talk about accessing the Qt Quick model from C++, such as this
> one
> [http://stackoverflow.com/questions/31890372/add-objects-to-qml-layout-from-c],
> they tend to use snippets of QML to get the job done in a rather hacky way,
> and make various comments about the perils and pitfalls of trying to
> manipulate the model from code.
> I can't help comparing this with two other popular layout frameworks:
> WPF/XAML, and Android/AXML. In both of these worlds, the markup language and
> the "code-behind" class hierarchy of UI elements are absolutely equivalent
> 1st class citizens. Anything you can do in XAML, you can also do in the C#
> code-behind, whether it be creating controls, changing their properties,
> altering layouts, etc. Likewise in Android/AXML, I can (if I choose) create
> FrameLayouts, RelativeLayouts, TextViews, etc in code, and arrange them and
> manipulate them any way I like, as an alternative to creating an AXML
> designer layout.
> It seems very unfortunate that Qt Quick doesn't take this approach, and that
> the "code-behind" experience is so limited.
> Am I missing something here? Assuming I'm not, are there any plans to make
> the Qt Quick class model more "open", with full documentation and public
> interfaces for all relevant properties and methods?
> Thanks,
> Rob
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