C++ to QML signal issue

Hoyt

I am having issues accessing an intValueChanged signal. I apologize in advance for this newbie question.

The class that defines the intValueChanged signal follows:

class IntValue : public QObject
{
    Q_OBJECT
    Q_PROPERTY(qint16 intValue READ intValue WRITE setIntValue NOTIFY intValueChanged)

public:
    void setIntValue(const qint16 &a)
    {
        if (a != v)
        {
            v = a;
            emit intValueChanged();
        }
    }

    qint16 intValue() const
    {
        return v;
    }

signals:
    void intValueChanged();

private:
    qint16 v;
};

My main.cpp file contains the following:

IntValue rotationAngle;
engine.rootContext()->setContextProperty("rotationAngle", &rotationAngle);

In my QML file, I can set read and set rotationAngle.intValue. For example, I can read rotationAngle.intValue as shown below:

angle: rotationAngle.intValue;

How would I access the intValueChanged signal?

Thank you in advance.

Hoyt

p3c0

@Hoyt
You can use Connections and keep the target as rotationAngle. Now since you have signal named intValueChanged Qt automatically provides a signal handler named onIntValueChanged. Use this handler in your Connections.
More info:
http://doc.qt.io/qt-5/qtqml-syntax-signals.html#receiving-signals-with-signal-handlers

shav

Hi,

I think you can use something like this:

Component.onCompleted: {
    if(rotationAngle !== null && rotationAngle !== undefined) {
        rotationAngle.intValueChanged.connect(function (/* parameters from signal if needed */) {
            //Dome code here
        });
    }
}

Hope this help.

Hoyt

@p3c0

Thank you very much. Connections, configured as you stated, worked perfectly.

If I wanted to receive the same signal with a C++ object, would I also use Connections? If so, would you mind explaining how to configure Connections?

Thanks again.

Hoyt

p3c0

@Hoyt You already have that signal in your IntValue class. So in case you are trying to access this signal from other C++ class you have the instantiated object here:

IntValue rotationAngle;
engine.rootContext()->setContextProperty("rotationAngle", &rotationAngle);

Use this object and connect to its SIGNAL intValueChanged.