Connecting signal and slot fails in Symbian emulator

[finngruwier]

Im am trying to make a very basic Qt application that will use C++ for the data model and QML for the GUI. To my surprise it is not easy to find a good tutorial for this, so it's very much "trial and error". This is the code I've got so far:

main.cpp:

#include <QtDeclarative>
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    QDeclarativeView view;
    view.setSource(QUrl::fromLocalFile("qml/myapp/main.qml"));
    view.show();
 
    QObject *root = view.rootObject();
 
    QObject::connect(root, SIGNAL(quit()), &app, SLOT(quit()));
 
    return app.exec();
}

#include <QtDeclarative>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QDeclarativeView view;
    view.setSource(QUrl::fromLocalFile("qml/myapp/main.qml"));
    view.show();

    QObject *root = view.rootObject();

    QObject::connect(root, SIGNAL(quit()), &app, SLOT(quit()));

    return app.exec();
}

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main.qml:

import QtQuick 1.0
 
Rectangle {
    width: 360
    height: 360
    Text {
        text: "Hello World"
        anchors.centerIn: parent
    }
    signal quit()
    MouseArea {
        anchors.fill: parent
        onClicked: {
            quit();
        }
    }
}

import QtQuick 1.0

Rectangle {
    width: 360
    height: 360
    Text {
        text: "Hello World"
        anchors.centerIn: parent
    }
    signal quit()
    MouseArea {
        anchors.fill: parent
        onClicked: {
            quit();
        }
    }
}

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What it does is very simple: it shows a rectangle with the text "Hello World", and when you click in the rectangle the program quits. I know that this is exactly the same as the default app that Qt Creator creates when you choose to make a new "Qt Quick Application", but my app does it another and (I think) generally more useful way as I don't just start a QML program that sort of lives its own life but actually establish a connection between the C++ layer and the QML layer (with the signal/slot connection).

Now to the problem. This runs without errors for the Desktop target. But if I choose the Qt Simulator as target it still runs, but I get this message in the console:

Object::connect: No such signal QDeclarativeRectangle::quit()

When I click the rectangle the app doesn't quit, and the console says:

Signal QDeclarativeEngine::quit() emitted, but no receivers connected to handle it.

Can someone please correct my code?

[Zlatomir]

***I didn't tried your code, but the problem is that there is no signal declared.

i don't know QML but i think you should declare the signal, see this documentation page and also search the documentation - you should find references about what you want (or at least i think what you want makes sense - the QML isn't there to replace C++, it's just for quick UI "bling-bling" and it should be easy to connect with a C++ layer)

LE: i saw the declared signal after i posted - it's strange that it won't work

[finngruwier]

I have investigated this problem a little more myself, and it turns out that it's not my code that's bad. The problem is that Qt Creator doesn't put a new copy of main.qml in the build directory when I build for the emulator. When I took an updated copy of main.qml and placed it in the build directory it worked. So I guess the problem is in the configuration of my project.

---

Added after 4 minutes:

"or at least i think what you want makes sense - the QML isn't there to replace C++, it's just for quick UI "bling-bling" and it should be easy to connect with a C++ layer"

- Exactly!