Qt-interest Archive, July 2007
How to set a void* data in QVariant ?
Message 1 in thread
Hi Everyone,
I need to set my own object pointer to QVariant. My own object is not
a QT class/object. I use following code to set the data into QVariant :
MyOwnClass* pMyPointer=_GetMyObject();
QVariant myVar=QVariant(QVariant::UserType, pMyPointer);
I'm not sure if I do the right way.
Most important of all, I don't know how to get the pointer back from
the QVariant. I use
MyOwnClass* pGetBackPointer=myVar.value<MyOwnClass*>();
This will make failed in GCC.
So now I'm stuck here. Please help me out.
Thanks.
Regards,
Pagan
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Message 2 in thread
Of course we know void * is wrong ;) So there must be a qt way :)
For a given class XXXXX
Call the macro
Q_DECLARE_METATYPE( XXXXX * );
Note the macro is declared in <QVariant> and class XXXXX must be fully
defined at the macro call, I usually call it right after the class is
defined
Ie
Class XXXXX
{
....
};
Q_DECLARE_METATYPE( XXXXX * );
Then, when you want to create a QVariant of that type call
qVariantFromValue() with the variable to be made into a variant
ie
XXXXX * value = new value();
QVariant var = qVariantFromValue( value );
Then to get the value back call the value method on the variant
XXXXX * otherValue = var.value< XXXXX * >();
Good luck.
Scott
> -----Original Message-----
> From: Pagan Chou [mailto:pagan_chou@xxxxxxxxxxxxxx]
> Sent: Sunday, July 01, 2007 7:25 PM
> To: qt-interest@xxxxxxxxxxxxx
> Subject: How to set a void* data in QVariant ?
>
> Hi Everyone,
> I need to set my own object pointer to QVariant. My own object is not
> a QT class/object. I use following code to set the data into QVariant
:
>
> MyOwnClass* pMyPointer=_GetMyObject();
>
> QVariant myVar=QVariant(QVariant::UserType, pMyPointer);
>
> I'm not sure if I do the right way.
>
> Most important of all, I don't know how to get the pointer back from
> the QVariant. I use
>
> MyOwnClass* pGetBackPointer=myVar.value<MyOwnClass*>();
>
> This will make failed in GCC.
>
> So now I'm stuck here. Please help me out.
>
> Thanks.
>
> Regards,
> Pagan
>
>
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