Native Development

[gdev001]

Hello,

I am trying to run an example from this page(https://developer.blackberry.com/cascades/documentation/dev/integrating_cpp_qml/index.html) about "Using C++ classes in QML". I have the following

code as stated on that page:

CombineCppAndQml::CombineCppAndQml(bb::cascades::Application *app)
: QObject(app)
{

    QmlDocument *qml = QmlDocument::create("asset:///main.qml").parent(this);

	AbstractPane *root = qml->createRootObject<AbstractPane>();

    qmlRegisterType<QTimer>("my.library", 1, 0, "QTimer"); 

    app->setScene(root);
}

 and this I have in the QML file:

// Default empty project template
import bb.cascades 1.0
import my.library 1.0 


Page {
    Label {
        id: timerTestLabel
        text: "Hello world"
              
        attachedObjects: [
            QTimer {
                id: timer
                interval: 1000
                onTimeout :{
                    timerTestLabel.text = "Timer triggered"      
                }
            }
        ]
    }
          
    onCreationCompleted: {
        timer.start();
    }
}

 but I get a blank screen when I try to run the application. Can someone spot what is wrong here? Maybe I have called:

qmlRegisterType<QTimer>("my.library", 1, 0, "QTimer") 

at a wrong place?? Thanks.

[oliver_kranz]

That's the example.

Page {
    property alias labelText: label.text
    Container {
        Label {
            id: label
            text: "Label"
        }

        Button {
             objectName: "button"
             text: "Button"
        }
    }
}

 At a first glance I see that the container is missing.

[gdev001]

No no, thats the *first* example, I am referring to the example under section "Using C++ classes in QML", which is a bit below.

[oliver_kranz]

Ok, right. But the example works for me. I see the text "Hello world". And after a moment I see "Timer triggered".

[gdev001]

HM.... that's really strange. Is your code similar to what I pasted above??? ps. Maybe the problem is in SDK version that I use? Or the simulator version? Any help appreciated.

[oliver_kranz]

If it does not run then there should be some error message in the console of Momentics. Or in the compiler output during compilation should be an error message.

[gdev001]

No the problem is that it runs and compiles, I get a blank screen as I mentioned on this page: http://supportforums.blackberry.com/t5/Native-Development/Blank-screen/td-p/2129171
thanks.

[oliver_kranz]

What about removing all the QTimer code and just showing the Label. At least this should work.

Furthermore, you can debug the application. Set a break point and execute your code step by step to see where the error is.

[gdev001]

One problem I think is with the following line: If I remove this line: import my.library 1.0
from the QML file I manage to display *just* a Label. However, once I add that import line I get the blank screen I mentioned. Can I ask you where in your code do you add the: " qmlRegisterType<QTimer>("my.library", 1, 0, "QTimer");" line? Maybe that is causing the issues? thanks.

[dishooom · Accepted solution]

Hi

Can u please move  qmlRegisterType<QTimer>("my.library", 1, 0, "QTimer"); to the very first line of the constructor

CombineCppAndQml::CombineCppAndQml(bb::cascades::Application *app)
: QObject(app)
{
	 qmlRegisterType<QTimer>("my.library", 1, 0, "QTimer");
    QmlDocument *qml = QmlDocument::create("asset:///main.qml").parent(this);

	AbstractPane *root = qml->createRootObject<AbstractPane>();



    app->setScene(root);
}

 _ Dishooom

Hope this helps