内容

• 特性
• 详细描述
• 用法范例

HistoryState QML Type

HistoryState type provides a means of returning to a previously active substate. 更多...

• 所有成员列表，包括继承成员

特性

• defaultState : QAbstractState
• historyType : enumeration

详细描述

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 of the other child states of the parent state. HistoryState is part of 声明状态机框架 .

使用 defaultState property to set the state that should be entered if the parent state has never been entered.

用法范例

import QtQuick 2.0
import QtQml.StateMachine 1.0 as DSM
Rectangle {
    Button {
        anchors.fill: parent
        id: button
        text: "Press me"
        DSM.StateMachine {
            id: stateMachine
            initialState: parentState
            running: true
            DSM.State {
                id: parentState
                initialState: child2
                onEntered: console.log("parentState entered")
                onExited: console.log("parentState exited")
                DSM.State {
                    id: child1
                    onEntered: console.log("child1 entered")
                    onExited: console.log("child1 exited")
                }
                DSM.State {
                    id: child2
                    onEntered: console.log("child2 entered")
                    onExited: console.log("child2 exited")
                }
                DSM.HistoryState {
                    id: historyState
                    defaultState: child1
                }
                DSM.SignalTransition {
                    targetState: historyState
                    // Clicking the button will cause the state machine to enter the child state
                    // that parentState was in the last time parentState was exited, or the history state's default
                    // state if parentState has never been entered.
                    signal: button.clicked
                }
            }
        }
    }
}