Creating QML elements at runtime

kuschky

Hello, I have some already existing QObject based classes representing some data I want display as graphic in QML.

For that I change my class defintion so that my classes now derived from QDeclarativeItem and providing a implementation for the paint method and make them accessible by qmlRegisterType.
@
class Car : public QDeclarativeItem
{
Q_OBJECT

Q_PROPERTY(int wheels READ wheels WRITE setWheels NOTIFY wheelsChanged)

....

}
@
I'm now able to embed these objects into QML:
@
Rectangle {
car {
id: car1
wheels: 1
}

car {
id: car2
wheels: 1
}
}
@
That's fine and works.

But is there a way to create those kinds of objects on the C++ side and add them on a dynamic way at runtime to a QML context or to replace an already existing QML element with them? What want to do is to add another Car Object / Element with id car3 or replace an existing Car element with a one created in C++?

Thanks & best regards Michael

dmcr

If the context that you associated to your QML contains an object car

@ Q_PROPERTY(Car car READ getCarte WRITE setCar NOTIFY carChanged)@

then when you update the object, the QML will be noticed
with the event carChanged

If you want many of them then you can use QDeclarativeListeProperty.

drixs

if i have QML declarations lets say Book.qml and Paper.qml, and i have set Book.qml as QDeclarativeView source.

how i can create and store some "paper" as child of "Book" on the C++ side at runtime?
thanks in advance :D

diro

Two solutions for add object to QML context:

QDeclarativeContext::setContextProperty()
"http://doc.qt.nokia.com/stable/qdeclarativecontext.html":http://doc.qt.nokia.com/stable/qdeclarativecontext.html
QDeclarativePropertyMap class
"http://doc.qt.nokia.com/4.7-snapshot/qdeclarativepropertymap.html":http://doc.qt.nokia.com/4.7-snapshot/qdeclarativepropertymap.html

The method 1 is good for few objects, and method 2 is good for object array.

For your case, if you want to the car(s) display in the Rectangle dynamically, I think "DataModel":http://doc.qt.nokia.com/latest/qdeclarativemodels.html#exposing-c-data-models-to-qml + "ListView":http://doc.qt.nokia.com/4.7-snapshot/qml-listview.html element would be the best solution.