adding QWidget to Quick based application

[mzimmers]

Hi all -

I'm implementing a desktop app using QML. I finally ran across something available in a QWidget that doesn't seem to have a QML wrapper.

I've done web searches, but haven't found anything on adding/using a QWidget class to QML code. I know that in years past, this was pretty much a non-starter, but I'm wondering whether there's anything in 6 that makes this easier.

Thanks for any information...

[Axel Spoerl]

@mzimmers
You may want to check the documentation of QQuickItemfor that purpose.

[mzimmers]

@Axel-Spoerl this looks like it's what I need. I've created a class:

class DatePicker : public QQuickItem
{
    Q_OBJECT
    QML_ELEMENT
    QCalendarWidget calendar;
    ...

and registered it:

    qmlRegisterType<DatePicker>("DatePicker", 1, 0, "DatePicker");

and I attempt to use it:

Window {
    visible: true
    DatePicker {
        anchors.fill: parent
    }

But nothing shows up. What am I missing?

EDIT:

I also gave it a size:

DatePicker::DatePicker()
{
    QSizeF size(300, 300);
    setSize(size);
}

Also, I needed to use QApplication instead of QGuiApplication, because the latter gave me a runtime error:

QWidget: Cannot create a QWidget without QApplication

I'd greatly prefer to use QGuiApplication; is this possible?

Thanks...

[Christian Ehrlicher]

@mzimmers said in adding QWidget to Quick based application:

I'd greatly prefer to use QGuiApplication; is this possible?

Since you already found out that a QWidget needs a QApplication - no.

[mzimmers]

@Christian-Ehrlicher OK, that's fine. I've modified my program to use QApplication, and in my QQuickItem c'tor, I've added a call to calendar.show().

Now, the calendar appears, but in a separate window. I suppose this is expected, as I create it without a parent, which according to the docs, a nullptr parent causes the c'tor to create a (new) window.

Given that I'm defining my Window in my Main.qml file, I'm not sure how to give the calendar the appropriate parent. Is there away to do this, or must I define my main window using a QQuickItem as well?

Thanks...

[JoeCFD]

@mzimmers
from @kkoehne here: https://forum.qt.io/topic/92859/how-to-embed-qwidget-into-qml/2
It is only supported it the other way round: Embedding a Qt Quick scene in QWidgets, either through QQuickView, QQuickWidget, or QWidget::createWindowContainer().

Ask @kkoehne about it. The post is old.

[SGaist]

Hi,

KDAB has created the DeclarativeWidgets project to integrate widgets in QtQuick applications.

[mzimmers]

@SGaist @JoeCFD thanks for the information.

That KDAB project is huge, and it doesn't appear to have been updated recently (which might be OK).

If this truly is such a major effort, I suppose I'm better off just implementing my own date picker QML component. I have to say that I'm a bit surprised that Qt doesn't have one.

[JonB]

@mzimmers said in adding QWidget to Quick based application:

implementing my own date picker QML component. I have to say that I'm a bit surprised that Qt doesn't have one

Remember I know nothing about QML. Or whether "QtQuick" matters. But why aren't:

• https://doc.qt.io/qt-5/qml-qtquick-controls-calendar.html
• https://felgo.com/doc/felgo-datepicker/
• https://stackoverflow.com/questions/74930721/how-to-build-a-scrollable-date-picker-in-qml

etc. "QML date pickers"? Hmm, maybe "QML component" isn't any good for "QtQuick" ....

[mzimmers]

@JonB thanks for the update - the last time I looked, Qt 6 didn't have the QML calendar (at least it wasn't documented in the normal location). Now, it appears that it does. I can probably use that and the MonthGrid, and a few other things to make my own (essentially what the SO article you referenced does). The felgo example doesn't look right for me -- I need a real calendar.

I'll start playing with the tools I'm given...thanks again.

[Bob64]

@JonB your first bullet point is the closest to anything officially supported by Qt. However it is in Quick Controls 1 which got deprecated towards the end of Qt 5 and was removed entirely from Qt 6. In Qt 5 we were encouraged to move to Quick Controls 2 but it lacked a lot of basic functionality. It never offered even provided a tree view in Qt 5 for example - that only appeared relatively recently in Qt 6.

Edit: For some reason mzimmers' reply wasn't visible when I wrote this. It looks like Qt 6 does have a QML calendar after all - possibly a recent addition.

[mzimmers]

@Bob64 said in adding QWidget to Quick based application:

It looks like Qt 6 does have a QML calendar after all - possibly a recent addition.

Yeah - I think originally it was part of the labs stuff, then it went away, then (recently) it reappeared as part of "mainstream" Qt.

[baburaoz558]

Perhaps a preview toggle would be useful as to prevent clutter while choosing layout while still having the option to see the result before confirming. I would recommend using icons instead of words for the preview toggle and confirmation button as the idea's theme is about order and aesthetics.