QDeclarativeView problem

huluyige

Hi everyone,

in main.cpp

@QDeclarativeView view;

view.rootContext()->setContextProperty("numFromCPP", QVariant("3"));
view.setSource(QUrl("/mainPage.qml"));
view.setResizeMode(QDeclarativeView::SizeRootObjectToView);
view.showFullScreen()@

the property value is from another thread (another signal will send the value).

The problem is: I want to set property when the value is available . But setContextProperty is not a slot, i can not connect it to the signal.

or, do you have some solutions? for example, is there any ways that i can update the loaded qml's property?

I am really confused with the problem. Thank you very much

andre

What you could do, is create a simple QObject class that works as a proxy for the property value. Create a property, and make the setter method a slot while you emit a signal when the value changes (see Q_PROPERTY). Connect the slot to the signal from the other thread, and then expose the QObject to your QML using a new QDeclarativeContext and it's setContextObject method.

huluyige

Hi,

Thank you very much.

i have tried your solution. what i can't understand is this sentence

"expose the QObject to your QML using a new QDeclarativeContext and it’s setContextObject method"

what i want to change in the mainPage.qml is just a property, not an QObject.

Here is the code, i dont know how to do it for the next step
@ Proxy proxy;
QObject::connect(&parserDirects,SIGNAL(allFinished (int)),&proxy,SLOT(setNumber(int)));

QDeclarativeView view;

view.rootContext()->setContextProperty("numFromCPP", QVariant("3"));
view.setSource(QUrl("/home/zhiheng/Projets/LequipeOVI-build-simulator/qml/LequipeOVI/mainPage.qml"));
view.setResizeMode(QDeclarativeView::SizeRootObjectToView);
view.showFullScreen();@

[quote author="Andre" date="1299243800"]What you could do, is create a simple QObject class that works as a proxy for the property value. Create a property, and make the setter method a slot while you emit a signal when the value changes (see Q_PROPERTY). Connect the slot to the signal from the other thread, and then expose the QObject to your QML using a new QDeclarativeContext and it's setContextObject method.[/quote]

andre

[quote author="huluyige" date="1299248555"]what i want to change in the mainPage.qml is just a property, not an QObject.
[/quote]

The point I was trying to make, is that you could make a QObject in order to expose your value to the QML. I understand that you currently don't have a QObject, but that is exactly your problem I think. A QObject can have a slot (you said you need one to connect to a signal in your value-providing thread), and it can be exposed to QML if you give it properties. Sounds like the bridge you need to me...

huluyige

Thank you very much.

Now, I totally understand your point.

By doing this, I have others problems (i am new to QT):

"A new QDeclarativeContext " why i have to use a NEW QDeclarativeContext.
the method "setContextObject" is to set another object to the Context ? if it is yes, how can i connect the new object to the former objet(apprarently, it's the object of mainPage.qml)

Thanks

[quote author="Andre" date="1299250351"][quote author="huluyige" date="1299248555"]what i want to change in the mainPage.qml is just a property, not an QObject.
[/quote]

The point I was trying to make, is that you could make a QObject in order to expose your value to the QML. I understand that you currently don't have a QObject, but that is exactly your problem I think. A QObject can have a slot (you said you need one to connect to a signal in your value-providing thread), and it can be exposed to QML if you give it properties. Sounds like the bridge you need to me...[/quote]