SignalTransition QML Type

The SignalTransition type provides a transition based on a Qt signal. More...

Import Statement:	import QtQml.StateMachine 6.7
Inherits:	QSignalTransition

List of all members, including inherited members

Properties

guard : bool
signal : signal

Detailed Description

SignalTransition is part of Qt State Machine QML API.

Example Usage

import QtQuick
import QtQml.StateMachine as DSM

Rectangle {
    DSM.StateMachine {
        id: stateMachine
        initialState: state
        running: true
        DSM.State {
            id: state
            DSM.SignalTransition {
                targetState: finalState
                signal: button.clicked
                guard: guardButton.checked
            }
        }
        DSM.FinalState {
            id: finalState
        }
        onFinished: Qt.quit()
    }
    Row {
        spacing: 2
        Button {
            id: button
            text: "Finish state"
        }

        Button {
            id: guardButton
            checkable: true
            text: checked ? "Press to block the SignalTransition" : "Press to unblock the SignalTransition"
        }
    }
}

See also StateMachine, FinalState, and TimeoutTransition.

Property Documentation

guard : bool

Guard conditions affect the behavior of a state machine by enabling transitions only when they evaluate to true and disabling them when they evaluate to false.

When the signal associated with this signal transition is emitted the guard condition is evaluated. In the guard condition the arguments of the signal can be used as demonstrated in the example below.

import QtQuick
import QtQml.StateMachine as DSM

Rectangle {
    Button {
        anchors.fill: parent
        id: button
        DSM.StateMachine {
            DSM.State {
                DSM.SignalTransition {
                    targetState: finalState
                    signal: button.mysignal
                    // the guard condition uses the mystr string argument from mysignal
                    guard: mystr == "test"
                }
            }
            DSM.FinalState {
                id: finalState
            }
        }
        // define the signal the SignalTransition is connected with
        signal mysignal(mystr: string)
        // on clicking the button emit the signal with a single string argument
        onClicked: button.mysignal("test")
    }
}

See also signal.

signal : signal

The signal which is associated with this signal transition.

import QtQuick
import QtQml.StateMachine as DSM

Rectangle {
    Button {
        anchors.fill: parent
        id: button
        DSM.StateMachine {
            DSM.State {
                DSM.SignalTransition {
                    targetState: finalState
                    signal: button.clicked
                }
            }
            DSM.FinalState {
                id: finalState
            }
        }
    }
}

© 2024 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.