[Qt-qml] Using C++ classes in signals on the QML side

[aaron.kennedy at nokia.com]

Hi,

On 27/03/10 7:48 AM, "ext Ademar de Souza Reis Jr."
<ademar.reis at openbossa.org> wrote:

> Hi there.
> 
> Is there a way to use an exported C++ class as a parameter in a
> signal sent to QML?
> 
> Following the code from examples/declarative/extending/signal/, this is what I
> wan to do:
> 
> ["Boy" is a C++ class exported to QML]
> 
> birthdayparty.h:
>  signals:
>       void partyStarted(const QTime &time);
> +    void newGuestString(const QString &str); // works
> +    void newGuestBoy(const Boy &guest); // doesn't
> 
> example.qml:
>  BirthdayParty {
>      onPartyStarted: console.log("This party started rockin' at " + time);
> +    onNewGuestBoy: console.log("There's a new guest (boy): " + guest.name);
> // doesn't work
> +    onNewGuestString: console.log("There's a new guest (string): " + str); //
> works
> 
> (simplified diff, you get the idea)
> 
> This is the output when the three signals are emitted from the C++ code:
> 
> """
> This party started rockin' at 18:16:16
> QMetaProperty::read: Unable to handle unregistered datatype 'Person' for
> property 'QDeclarativeBoundSignalParameters::guest'
> file::example.qml:7: TypeError: Result of expression 'guest' [undefined] is
> not an object.
> There's a new guest (string): foobar
> """
> 
> So as you can see using QTime and QString works, but using Boy doesn't. Any
> ideas?

Assuming Boy is a C++ class exposed to QML as you say, emitting it as a
pointer parameter should work.  For example

signals:
    void newGuestBoy(const Boy *guest)

Cheers,

Aaron