PySide6.QtStateMachine.QState

class QState

The QState class provides a general-purpose state for QStateMachine . More…

Inheritance diagram of PySide6.QtStateMachine.QState

Inherited by: QStateMachine

Synopsis

Properties

Methods

Signals

Note

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Detailed Description

QState objects can have child states, and can have transitions to other states. QState is part of Qt State Machine Framework .

The addTransition() function adds a transition. The removeTransition() function removes a transition. The transitions() function returns the state’s outgoing transitions.

The assignProperty() function is used for defining property assignments that should be performed when a state is entered.

Top-level states must be passed a QStateMachine object as their parent state, or added to a state machine using addState() .

States with Child States

The childMode property determines how child states are treated. For non-parallel state groups, the setInitialState() function must be called to set the initial state. The child states are mutually exclusive states, and the state machine needs to know which child state to enter when the parent state is the target of a transition.

The state emits the finished() signal when a final child state ( QFinalState ) is entered.

The setErrorState() sets the state’s error state. The error state is the state that the state machine will transition to if an error is detected when attempting to enter the state (e.g. because no initial state has been set).

class ChildMode

This enum specifies how a state’s child states are treated.

Constant

Description

QState.ExclusiveStates

The child states are mutually exclusive and an initial state must be set by calling setInitialState() .

QState.ParallelStates

The child states are parallel. When the parent state is entered, all its child states are entered in parallel.
class RestorePolicy

This enum specifies the restore policy type. The restore policy takes effect when the machine enters a state which sets one or more properties. If the restore policy is set to RestoreProperties, the state machine will save the original value of the property before the new value is set.

Later, when the machine either enters a state which does not set a value for the given property, the property will automatically be restored to its initial value.

Only one initial value will be saved for any given property. If a value for a property has already been saved by the state machine, it will not be overwritten until the property has been successfully restored.

Constant

Description

QState.DontRestoreProperties

The state machine should not save the initial values of properties and restore them later.

QState.RestoreProperties

The state machine should save the initial values of properties and restore them later.

See also

globalRestorePolicy assignProperty()

Note

Properties can be used directly when from __feature__ import true_property is used or via accessor functions otherwise.

property childModeᅟ: QState.ChildMode

This property holds the child mode of this state.

The default value of this property is ExclusiveStates .

Access functions:
property errorStateᅟ: QAbstractState

This property holds the error state of this state.

Access functions:
property initialStateᅟ: QAbstractState

This property holds the initial state of this state (one of its child states).

Access functions:
__init__([parent=None])
Parameters:

parent – QState

Constructs a new state with the given parent state.

__init__(childMode[, parent=None])
Parameters:

Constructs a new state with the given childMode and the given parent state.

addTransition(target)
Parameters:

target – QAbstractState

Return type:

QAbstractTransition

Adds an unconditional transition from this state to the given target state, and returns then new transition object.

addTransition(transition)
Parameters:

transition – QAbstractTransition

Adds the given transition. The transition has this state as the source. This state takes ownership of the transition.

addTransition(signal, arg__2)
Parameters:
Return type:

QSignalTransition

addTransition(sender, signal, target)
Parameters:
Return type:

QSignalTransition

Adds a transition associated with the given signal of the given sender object, and returns the new QSignalTransition object. The transition has this state as the source, and the given target as the target state.

assignProperty(object, name, value)
Parameters:

  • object – QObject

  • name – str

  • value – object

Instructs this state to set the property with the given name of the given object to the given value when the state is entered.

childMode()
Return type:

ChildMode

Returns the child mode of this state.

See also

setChildMode()

Getter of property childModeᅟ .

childModeChanged()

This signal is emitted when the childMode property is changed.

See also

childMode

Notification signal of property childModeᅟ .

errorState()
Return type:

QAbstractState

Returns this state’s error state.

Getter of property errorStateᅟ .

errorStateChanged()

This signal is emitted when the errorState property is changed.

See also

errorState

Notification signal of property errorStateᅟ .

finished()

This signal is emitted when a final child state of this state is entered.

See also

QFinalState

initialState()
Return type:

QAbstractState

Returns this state’s initial state, or None if the state has no initial state.

Getter of property initialStateᅟ .

initialStateChanged()

This signal is emitted when the initialState property is changed.

See also

initialState

Notification signal of property initialStateᅟ .

propertiesAssigned()

This signal is emitted when all properties have been assigned their final value. If the state assigns a value to one or more properties for which an animation exists (either set on the transition or as a default animation on the state machine), then the signal will not be emitted until all such animations have finished playing.

If there are no relevant animations, or no property assignments defined for the state, then the signal will be emitted immediately before the state is entered.

See also assignProperty() and addAnimation()

removeTransition(transition)
Parameters:

transition – QAbstractTransition

Removes the given transition from this state. The state releases ownership of the transition.

See also

addTransition()

setChildMode(mode)
Parameters:

mode – ChildMode

Sets the child mode of this state.

See also

childMode()

Setter of property childModeᅟ .

setErrorState(state)
Parameters:

state – QAbstractState

Sets this state’s error state to be the given state. If the error state is not set, or if it is set to None, the state will inherit its parent’s error state recursively. If no error state is set for the state itself or any of its ancestors, an error will cause the machine to stop executing and an error will be printed to the console.

See also

errorState()

Setter of property errorStateᅟ .

setInitialState(state)
Parameters:

state – QAbstractState

Sets this state’s initial state to be the given state. state has to be a child of this state.

See also

initialState()

Setter of property initialStateᅟ .

transitions()
Return type:

.list of QAbstractTransition

Returns this state’s outgoing transitions (i.e. transitions where this state is the source state ), or an empty list if this state has no outgoing transitions.

See also

addTransition()