QtQml.SignalTransition

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

Properties

• guard : bool
• signal : signal

Detailed Description

SignalTransition is part of The Declarative State Machine Framework.

Example Usage

import QtQuick 2.0
import QtQml.StateMachine 1.0 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 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 2.0
import QtQml.StateMachine 1.0 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(string mystr)
// on clicking the button emit the signal with a single string argument
onClicked: button.mysignal("test")
}
}

See also signal.

The signal which is associated with this signal transition.

import QtQuick 2.0
import QtQml.StateMachine 1.0 as DSM
Rectangle {
Button {
anchors.fill: parent
id: button
DSM.StateMachine {
DSM.State {
DSM.SignalTransition {
targetState: finalState
signal: button.clicked
}
}
DSM.FinalState {
id: finalState
}
}
}
}