SignalTransition QML Type

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"
        }
    }
}
					

另请参阅 StateMachine , FinalState ，和 TimeoutTransition .

特性文档编制

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")
    }
}
				

另请参阅 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
            }
        }
    }
}