[Interest] using a custom class as parameter of signal/slot, used in QML

Sylvain Pointeau sylvain.pointeau at gmail.com
Fri Mar 1 17:08:15 CET 2019

Hi Jason,

thank you for the link, I did have a look but they are doing the same, with
a comment "// parent-less QObject -> ownership transferred to the JS engine"

but what if there was no connection, or consumed by another object, then I
guess there will be a memory leak?

I don't feel comfortable sending pointer to objects through the signals,
the ownership for me is not clear.
I guess there is no real solution, except to avoid using objects in signals
if QML is a consumer?

it is really puzzling me...

Best regards,

On Fri, Mar 1, 2019 at 4:12 PM Jason H <jhihn at gmx.com> wrote:

> Check out qtmultimedia/examples/multimedia/video/qmlvideofilter_opencl fo
> the filter result types. I think that's what you want?
> I find it easier to code and work with to just rely on QVariant
> conversion. QVariantList and QVariantMap are transparently converted to JS
> Objects.
> *Sent:* Friday, March 01, 2019 at 6:43 AM
> *From:* "Sylvain Pointeau" <sylvain.pointeau at gmail.com>
> *To:* "Qt Project" <interest at qt-project.org>
> *Subject:* [Interest] using a custom class as parameter of signal/slot,
> used in QML
> Dear all,
> I understood how to use a struct / simple class as a parameter of a signal
> / slot, and it works well by value.
> However as soon as we have to declare the type for QML, it is not good
> anymore.
> It seems that it must be derived from QObject and passed by pointer.
> Do I understand well that the QML world does only accept pointers on
> QObject?
> However I don't understand, who owns the pointer of the custom class
> (derived from QObject) and who actually deletes it?
> (I tried a sharepointer but QML does not know how to handle it)
> Do you have any idea?
> Best regards,
> Sylvain
> _______________________________________________ Interest mailing list
> Interest at qt-project.org https://lists.qt-project.org/listinfo/interest
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