Archived:How to create a 2-state button using the Qt State Machine Framework

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Qt Quick should be used for all UI development on mobile devices. The approach described in this article (using C++ for the Qt app UI) is deprecated.

This example shows how to use the Qt State Machine Framework to implement a simple state machine that toggles the current state when a button is clicked.

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Created: chintandave_er (21 Nov 2010)

Last edited: hamishwillee (11 Oct 2012)

Implementation

1. construct a button and a state machine

   QPushButton button;
   QStateMachine machine;

2. Create two states: on and off. assign Property and ObjectName of the each state

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

3. 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.

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

4. add states to the state machine

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

5. set the Initial State

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

6. show the button

    button.resize(100, 50);
    button.show();

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• Archived:Using QStateMachine and QState