QML c++ signal & slots - c++

Question

I've got following code:
main.cpp
QDeclarativeView *qmlView = new QDeclarativeView();
qmlView->setSource(QUrl("qrc:/nav.qml"));
ui->nav->addWidget(qmlView);
Blockschaltbild bild;
QObject *value = qmlView->rootObject();
QObject::connect(value, SIGNAL(testSig()), &bild, SLOT(BlockSlot()));
The signals and slots connect correctly. (QObject::connect returns "true")
qml file:
Rectangle {
id: rectangle1
....
signal testSig()
MouseArea{
id: mousearea
anchors.fill: parent
onEntered: parent.color = onHoverColor
onExited: parent.color = parent.buttonColor
onClicked: {
rectangle1.testSig()
console.log("Button clicked")
}
}
}
This is where the slot is located:
Blockschaltbild.h
class Blockschaltbild: public QObject
{
Q_OBJECT
public slots:
void BlockSlot(){
cout << "Slot is working" << endl;
}
public:
....
}
If I click on the mouse area, the console shows "Button clicked" but not "Slot is working".
I use Qt 4.8.4 with QtQuick 1.1. Where is my mistake?

Answer 1

If you simply require to work with your Blockschaltbild object in QML, you can also decide against a loose coupling with signal and slots and simply pass your object as a context parameter, to make it available in QML.
QDeclarativeView *qmlView = new QDeclarativeView();
qmlView->setSource(QUrl("qrc:/nav.qml"));
ui->nav->addWidget(qmlView);
Blockschaltbild* bild;
QObject *value = qmlView->engine().rootContext()->setContextProperty("bild", bild);
You can then call the BlockSlot() slot of your object from QML with:
Rectangle {
id: rectangle1
....
MouseArea{
id: mousearea
anchors.fill: parent
onEntered: parent.color = onHoverColor
onExited: parent.color = parent.buttonColor
onClicked: {
bild.BlockSlot() // call BlockSlot of "bild" context property
console.log("Button clicked")
}
}
}
It is also possible to use qmlRegisterType, which allows you to create instances of your Blockschaltbild class with QML. See here for more information.