Interconversion of Qt types

Swati777999

Hi All,

Just want to if it is possible to convert a variable of QVariant type to QWidget type.

sierdzio

If you hold a pointer to QWidget in your variant, then yes. Otherwise - no.

Swati777999

@sierdzio Can you give an example of it?

jsulm

@Swati777999 There are examples in the documentation (https://doc.qt.io/qt-6/qvariant.html and https://doc.qt.io/qt-6/qvariant.html#value), like:

QVariant variant;
...
QColor color = variant.value<QColor>();

JonB

@jsulm
QVariant is not a QWidget!? :)

Swati777999

@JonB

QVariant *l = new QVariant;
           QWidget *window = new QWidget;
           QHBoxLayout *lay = new QHBoxLayout(window);
            lay->addWidget(l,0,0);
            lay->addWidget(img,0,1);

What's wrong in the above lines , in terms of conversion?

sierdzio

addWidget() accepts a QWidget, not QVariant. These are 2 completely unrelated classes. If your l variant is holding a QWidget, then you can extract it like @jsulm mentioned:

l = QVariant::fromValue(window);
lay->addWidget(l.value<QWidget*>(),0,0);

JonB

@Swati777999

l points to an invalid variant.
addWidget(QWidget *) will not accept a QVariant *.