diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/statemachine.qdoc | 141 |
1 files changed, 16 insertions, 125 deletions
diff --git a/doc/src/statemachine.qdoc b/doc/src/statemachine.qdoc index c017827..d2b508d 100644 --- a/doc/src/statemachine.qdoc +++ b/doc/src/statemachine.qdoc @@ -85,36 +85,20 @@ The following snippet shows the code needed to create such a state machine. First, we create the state machine and states: - \code - QStateMachine machine; - QState *s1 = new QState(); - QState *s2 = new QState(); - QState *s3 = new QState(); - \endcode + \snippet doc/src/snippets/statemachine/main.cpp 0 Then, we create the transitions by using the QState::addTransition() function: - \code - s1->addTransition(button, SIGNAL(clicked()), s2); - s2->addTransition(button, SIGNAL(clicked()), s3); - s3->addTransition(button, SIGNAL(clicked()), s1); - \endcode + \snippet doc/src/snippets/statemachine/main.cpp 1 Next, we add the states to the machine and set the machine's initial state: - \code - machine.addState(s1); - machine.addState(s2); - machine.addState(s3); - machine.setInitialState(s1); - \endcode + \snippet doc/src/snippets/statemachine/main.cpp 2 Finally, we start the state machine: - \code - machine.start(); - \endcode + \snippet doc/src/snippets/statemachine/main.cpp 3 The state machine executes asynchronously, i.e. it becomes part of your application's event loop. @@ -127,11 +111,7 @@ entered. In the following snippet, the value that should be assigned to a QLabel's text property is specified for each state: - \code - s1->assignProperty(label, "text", "In state s1"); - s2->assignProperty(label, "text", "In state s2"); - s3->assignProperty(label, "text", "In state s3"); - \endcode + \snippet doc/src/snippets/statemachine/main.cpp 4 When any of the states is entered, the label's text will be changed accordingly. @@ -142,10 +122,7 @@ state \c s3 is entered, and the button's showMinimized() slot will be called when \c s3 is exited: - \code - QObject::connect(s3, SIGNAL(entered()), button, SLOT(showMaximized())); - QObject::connect(s3, SIGNAL(exited()), button, SLOT(showMinimized())); - \endcode + \snippet doc/src/snippets/statemachine/main.cpp 5 Custom states can reimplement QAbstractState::onEntry() and QAbstractState::onExit(). @@ -194,22 +171,9 @@ initial one (i.e. which child state the state machine should enter when the parent state is the target of a transition). - \code - QState *s1 = new QState(); - QState *s11 = new QState(s1); - QState *s12 = new QState(s1); - QState *s13 = new QState(s1); - s1->setInitialState(s11); - machine.addState(s1); - \endcode + \snippet doc/src/snippets/statemachine/main2.cpp 0 - \code - QFinalState *s2 = new QFinalState(); - s1->addTransition(quitButton, SIGNAL(clicked()), s2); - machine.addState(s2); - - QObject::connect(&machine, SIGNAL(finished()), QApplication::instance(), SLOT(quit())); - \endcode + \snippet doc/src/snippets/statemachine/main2.cpp 1 In this case we want the application to quit when the state machine is finished, so the machine's finished() signal is connected to the @@ -219,9 +183,7 @@ following code adds a transition that effectively causes the Quit button to be ignored when the state machine is in state \c s12. - \code - s12>addTransition(quitButton, SIGNAL(clicked()), s12); - \endcode + \snippet doc/src/snippets/statemachine/main2.cpp 2 A transition can have any state as its target, i.e. the target state does not have to be on the same level in the state hierarchy as the source state. @@ -259,21 +221,7 @@ simply display a message box when \c s3 is entered, then immediately return to the previous child state of \c s1 via the history state. - \code - QHistoryState *s1h = s1->addHistoryState(); - - QState *s3 = new QState(); - s3->assignProperty(label, "text", "In s3"); - QMessageBox mbox; - mbox.addButton(QMessageBox::Ok); - mbox.setText("Interrupted!"); - mbox.setIcon(QMessageBox::Information); - QObject::connect(s3, SIGNAL(entered()), &mbox, SLOT(exec())); - s3->addTransition(s1h); - machine.addState(s3); - - s1->addTransition(interruptButton, SIGNAL(clicked()), s3); - \endcode + \snippet doc/src/snippets/statemachine/main2.cpp 3 \section1 Using Parallel States to Avoid a Combinatorial Explosion of States @@ -305,12 +253,7 @@ To create a parallel state group, pass QState::ParallelStates to the QState constructor. - \code - QState *s1 = new QState(QState::ParallelStates); - // s11 and s12 will be entered in parallel - QState *s11 = new QState(s1); - QState *s12 = new QState(s1); - \endcode + \snippet doc/src/snippets/statemachine/main3.cpp 0 When a parallel state group is entered, all its child states will be simultaneously entered. Transitions within the individual child states @@ -334,9 +277,7 @@ finished(). We use a signal transition to cause this event to trigger a state change: - \code - s1->addTransition(s1, SIGNAL(finished()), s2); - \endcode + \snippet doc/src/snippets/statemachine/main3.cpp 1 Using final states in composite states is useful when you want to hide the internal details of a composite state; i.e. the only thing the outside world @@ -372,42 +313,12 @@ Here we define our own custom event type, \c StringEvent, for posting strings to the state machine: - \code - struct StringEvent : public QEvent - { - StringEvent(const QString &val) - : QEvent(QEvent::Type(QEvent::User+1)), - value(val) {} - - QString value; - }; - \endcode + \snippet doc/src/snippets/statemachine/main4.cpp 0 Next, we define a transition that only triggers when the event's string matches a particular string (a \e guarded transition): - \code - class StringTransition : public QAbstractTransition - { - public: - StringTransition(const QString &value) - : m_value(value) {} - - protected: - virtual bool eventTest(QEvent *e) const - { - if (e->type() != QEvent::Type(QEvent::User+1)) // StringEvent - return false; - StringEvent *se = static_cast<StringEvent*>(e); - return (m_value == se->value); - } - - virtual void onTransition(QEvent *) {} - - private: - QString m_value; - }; - \endcode + \snippet doc/src/snippets/statemachine/main4.cpp 1 In the eventTest() reimplementation, we first check if the event type is the desired one; if so, we cast the event to a StringEvent and perform the @@ -422,31 +333,11 @@ Here's what the implementation of the statechart looks like: - \code - QStateMachine machine; - QState *s1 = new QState(); - QState *s2 = new QState(); - QFinalState *done = new QFinalState(); - - StringTransition *t1 = new StringTransition("Hello"); - t1->setTargetState(s2); - s1->addTransition(t1); - StringTransition *t2 = new StringTransition("world"); - t2->setTargetState(done); - s2->addTransition(t2); - - machine.addState(s1); - machine.addState(s2); - machine.addState(done); - machine.setInitialState(s1); - \endcode + \snippet doc/src/snippets/statemachine/main4.cpp 2 Once the machine is started, we can post events to it. - \code - machine.postEvent(new StringEvent("Hello")); - machine.postEvent(new StringEvent("world")); - \endcode + \snippet doc/src/snippets/statemachine/main4.cpp 3 An event that is not handled by any relevant transition will be silently consumed by the state machine. It can be useful to group states and provide |