Qt SCXML 計算器 QML 範例

計算器 使用 Qt SCXML 去實現計算器範例 presented in the SCXML Specification.

The state machine is specified in the statemachine.scxml file and compiled into the CalculatorStateMachine class. The user interface is created using Qt Quick.

運行範例

要運行範例從 Qt Creator ，打開歡迎模式，然後選擇範例從範例。更多信息，拜訪構建和運行範例 .

編譯狀態機

We link against the Qt SCXML module by adding the following line to the .pro 文件：

QT += widgets scxml

接著，指定要編譯的狀態機：

STATECHARTS = ../calculator-common/statemachine.scxml

Qt SCXML 編譯器 qscxmlc , is run automatically to generate statemachine.h and statemachine.cpp , and to add them to the HEADERS and SOURCES variables for compilation.

實例化狀態機

We make the generated CalculatorStateMachine class available to QML by registering it as a QML type in the calculator-qml.cpp 文件：

#include "statemachine.h"
int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    qmlRegisterType<CalculatorStateMachine>("CalculatorStateMachine", 1, 0,
                                            "CalculatorStateMachine");
    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/calculator-qml.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;
    return app.exec();
}

To use the CalculatorStateMachine type in a QML file, we import it:

import CalculatorStateMachine 1.0

We instantiate a CalculatorStateMachine and listen to the updateDisplay event. When it occurs, we change the text on the calculator display:

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

When users press the calculator buttons, the buttons submit events to the state machine:

        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")
        }

文件：