Using Declarative State Machine with Custom C++ QML types

[GRAlves]

Hi,

I'd like to create a custom QML type in C++ that can contain one or more state machines. My idea is to have the state machine declared on the qml file.

So far I have created the following type:

class TestQML : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString name READ getName WRITE setName NOTIFY nameChanged)
public:
    explicit TestQML(QObject *parent = 0);
    QString getName() const;
    void setName(const QString &name);
signals:
    void nameChanged();
    void Started();

public slots:
    void start();

private:
    QString m_name;
};

And the following qml file:

import testbench 1.0
import QtQml 2.0
import QtQml.StateMachine 1.0

Test {
    name: "Test 1"

    onTestStarted: {
        machine.running = true;
    }

    StateMachine {
        id:machine
        initialState: ini
        running: false
        State {
            id: ini
            SignalTransition {
                targetState: final
            }
        }
        FinalState {
            id: final
        }
        onFinished: base.finish("OK!")
    }

}

Where base is an object with a finish slot that have been exposed to the engine using

    m_engine = new QQmlEngine(this);
    m_engine->rootContext()->setContextProperty("base",this);

I execute the QML script by using:

        QQmlComponent component(m_engine, url);
        QObject *obj = component.create();
        TestQML *tst = qobject_cast<TestQML*>(obj);
        if (tst) {
            qDebug() << "Teste ID: "            << tst->getName();
            tst->startTest();
        }
        delete obj;

I am getting the following error:

QQmlComponent: Component is not ready

If I remove the state machine the program works as expected. I isolated the problem to the "import QtQml.StateMachine 1.0" statment - if I remove it the program runs.
I read all the documentation available on the Declarative State Machine framework but I couldn't find anything related to this particular problem. Does anyone have had similar problems importing the framework? Is there a particular Qt Module that I have to link against in order to have StateMachine working?

[GRAlves]

@GRAlves
I found that I was missing the qml-module-qtqml-statemachine module on my ubuntu installation. That fixed the crash with the import statement but I still can't get the Test obejct to accept a StateMachine as a part of it. Is there some modification I need to do on the C++ class for it to accept StateMachine children?

After some more debugging I arrived to the following qml:

Teste {
    id: teste1
    name: "Teste 1"

    onTestStarted: {
        maquina.running = true;
    }
    StateMachine {
            id:maquina
            initialState: inicio
            running: false
            State {
                id: inicio
                SignalTransition {
                    targetState: finalizou;
                }
            }
            FinalState {
                id: finalizou;
            }
            onFinished: base.finish("Tudo certo!")
        }
}

It is now failing with

QQmlComponent: Component is not ready
(file:///.../teste1.qml:15:5: Cannot assign to non-existent default property
        StateMachine {
        ^)

I am pretty sure I need to add something to the TestQML class in order to make it work but I couldn't find any documentation on how to nest a State Machine on a custom QML type.

[GRAlves]

I couldn't get it to work deriving from QObject. My workaround was to derive TestQML from QQuickItem instead of QObject.