Creating QQuick Items from C++

1XU7

Hi!!

Can i make this:

QML:

Button {
    id: myButton
    x: 200
    y: 400
    width: 200
    height: 30
    text: "Push me"
}

...but from C++ ?

I mean, i'm not looking to create a QPushButton but a QQuick Button but from C++... somehow transcribe my QML document into C++ .. If so, can you show an example?

Thanks in advance....

jeremy_k

Are you trying to instantiate a QML-defined component from C++?
QQmlComponent, which can be passed a URL to a file, or a byte array containing the source via the setData function.

If the goal is to create the button purely from C++, there's the direct use of the scene graph APIs, or QQuickPaintedItem for an API similar to Qt widgets.

Transcribing suggests that this involves a working program.

If this is a performance concern, have you seen the QML profiler built into Creator? Or is this a source obfuscation situation? There is some compilation into a binary format or C++ that also helps decrease load time. I don't know the current state.

1XU7

@jeremy_k

hi, QSceneGraph is what i was looking for... i preffer c++ always..
according to what i was looking, Scene Graph is faster than PaintedItems..

thanks.

Asperamanca

@1XU7 Just means doing everything from scratch. There is no "inherit from QML Button" in C++
The learning curve is pretty steep, examples are rare.

Asperamanca

@Asperamanca Also, for UI handling from C++, you'll want to add your own event filter.

Pl45m4

@Asperamanca

Sounds like you tried it, but didn't like the outcome?

Asperamanca

@Pl45m4 SceneGraph has it's uses for custom components.
An event filter on the C++ side is useful because you can enforce common event handling rules across all components.
Building a scene dynamically from C++ using prefabricated QML-building blocks has it's use cases.

But I wouldn't start writing basic QML UI via C++.

Pl45m4

@Asperamanca

I'm just curious, because I've never heard of it and usually you would design the QuickItems in their QMLanguage on QtQuick side and then connect your C++ code to it