SCXML 计算器

实现 SCXML 规范中的计算器示例的应用程序。

计算器使用Qt SCXML 实现 SCXML 规范中的计算器示例。

状态机在statemachine.scxml文件中指定，并编译到CalculatorStateMachine 类中。用户界面通过Qt Quick 创建。

运行示例

运行示例 Qt Creator，打开Welcome 模式，并从Examples 中选择示例。更多信息，请参阅Qt Creator: 教程：构建并运行。

实例化状态机

我们在calculator-qml.h文件中将生成的CalculatorStateMachine 类声明为 QML 类型，使其在 QML 中可用：

struct CalculatorStateMachineRegistration
{
    Q_GADGET
    QML_FOREIGN(CalculatorStateMachine)
    QML_NAMED_ELEMENT(CalculatorStateMachine)
    QML_ADDED_IN_VERSION(1, 0)
};

我们实例化 CalculatorStateMachine 并监听updateDisplay 事件。当事件发生时，我们会更改计算器显示屏上的文本：

    CalculatorStateMachine {
        id: statemachine
        running: true
        EventConnection {
            events: ["updateDisplay"]
            onOccurred: (event)=> resultText.text = event.data.display
        }
    }

当用户按下计算器按钮时，按钮会向状态机提交事件：

        Button {
            id: resultButton
            x: 3 * width
            y: parent.height / 5
            textHeight: y - 2
            fontHeight: 0.4
            width: parent.width / 4
            height: y * 4
            color: pressed ? "#e0b91c" : "#face20"
            text: "="
            onClicked: statemachine.submitEvent("EQUALS")
        }

示例项目 @ code.qt.io

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