- Qt 5.5
- Qt Widgets
- Two-way Button Example
- Qt 5.5.1 Reference Documentation

# Two-way Button Example

    int main(int argc, char **argv)
    {
        QApplication app(argc, argv);
        QPushButton button;
        QStateMachine machine;

The application's main() function begins by constructing the application object, a button and a state machine.

        QState *off = new QState();
        off->assignProperty(&button, "text", "Off");
        off->setObjectName("off");

        QState *on = new QState();
        on->setObjectName("on");
        on->assignProperty(&button, "text", "On");

The state machine has two states; `on` and `off`. When either state is entered, the text of the button will be set accordingly.

        off->addTransition(&button, SIGNAL(clicked()), on);
        on->addTransition(&button, SIGNAL(clicked()), off);

When the state machine is in the `off` state and the button is clicked, it will transition to the `on` state; when the state machine is in the `on` state and the button is clicked, it will transition to the `off` state.

        machine.addState(off);
        machine.addState(on);

The states are added to the state machine; they become top-level (sibling) states.

        machine.setInitialState(off);
        machine.start();

The initial state is `off`; this is the state the state machine will immediately transition to once the state machine is started.

        button.resize(100, 50);
        button.show();
        return app.exec();
    }

Finally, the button is resized and made visible, and the application event loop is entered.

Files:

- statemachine/twowaybutton/main.cpp
- statemachine/twowaybutton/twowaybutton.pro