QHistoryState露

PyQt5.QtCore.QHistoryState: Inherits from QAbstractState.

Description露

The QHistoryState class provides a means of returning to a previously active substate.

A history state is a pseudo-state that represents the child state that the parent state was in the last time the parent state was exited. A transition with a history state as its target is in fact a transition to one or more other child states of the parent state. QHistoryState is part of The State Machine Framework.

Use the setDefaultState() function to set the state that should be entered if the parent state has never been entered. Example:

QStateMachine machine;

QState *s1 = new QState();
QState *s11 = new QState(s1);
QState *s12 = new QState(s1);

QHistoryState *s1h = new QHistoryState(s1);
s1h->setDefaultState(s11);

machine.addState(s1);

QState *s2 = new QState();
machine.addState(s2);

QPushButton *button = new QPushButton();
// Clicking the button will cause the state machine to enter the child state
// that s1 was in the last time s1 was exited, or the history state's default
// state if s1 has never been entered.
s1->addTransition(button, SIGNAL(clicked()), s1h);

If more than one default state has to be entered, or if the transition to the default state(s) has to be acted upon, the defaultTransition() should be set instead. Note that the eventTest() method of that transition will never be called: the selection and execution of the transition is done automatically when entering the history state.

By default a history state is shallow, meaning that it won鈥檛 remember nested states. This can be configured through the historyType() property.

Enums露

HistoryType

This enum specifies the type of history that a QHistoryState records.

Member	Value	Description
DeepHistory	1	Nested states are recorded. In this case a transition with the history state as its target will end up in the most deeply nested descendant state the parent was in the last time it was exited.
ShallowHistory	0	Only the immediate child states of the parent state are recorded. In this case a transition with the history state as its target will end up in the immediate child state that the parent was in the last time it was exited. This is the default.

Methods露

__init__(parent: QState = None): TODO

__init__(HistoryType, parent: QState = None): Constructs a new history state of the given type, with the given parent state.

defaultState() → QAbstractState: Returns this history state鈥檚 default state. The default state indicates the state to transition to if the parent state has never been entered before.

See also

setDefaultState().

defaultTransition() → QAbstractTransition: Returns this history state鈥檚 default transition. The default transition is taken when the history state has never been entered before. The target states of the default transition therefore make up the default state.

See also

setDefaultTransition().

event(QEvent) → bool: TODO

historyType() → HistoryType: Returns the type of history that this history state records.

See also

setHistoryType().

onEntry(QEvent): TODO

onExit(QEvent): TODO

setDefaultState(QAbstractState)

Sets this history state鈥檚 default state to be the given state. state must be a sibling of this history state.

Note that this function does not set state as the initial state of its parent.

Signals露

defaultStateChanged(): TODO

defaultTransitionChanged(): TODO

historyTypeChanged(): TODO