Qt5:QML:c++ 调用qml中的函数

落日映苍穹つ 2022-07-14 07:08 308阅读 0赞

### 简介 ###

c++可以直接调用QML中的函数，这个函数原型是

bool QMetaObject::invokeMethod(QObject *obj, const char *member, Qt::ConnectionType type, QGenericReturnArgument ret, QGenericArgument val0 = QGenericArgument( Q_NULLPTR ), QGenericArgument val1 = QGenericArgument(), QGenericArgument val2 = QGenericArgument(), QGenericArgument val3 = QGenericArgument(), QGenericArgument val4 = QGenericArgument(), QGenericArgument val5 = QGenericArgument(), QGenericArgument val6 = QGenericArgument(), QGenericArgument val7 = QGenericArgument(), QGenericArgument val8 = QGenericArgument(), QGenericArgument val9 = QGenericArgument())

### 警告 ###

Q\_RETURN\_ARG() 和 Q\_ARG() 参数必须是QVariant，否则会提示找不到调用函数

### 代码 ###

main.qml

import QtQuick 2.5
    import QtQuick.Controls 1.4
    
    ApplicationWindow { visible: true width: 640 height: 480 Loader { sourceComponent: idTextExtend height:200 width:200 }
    
        Component
        { id:idTextExtend Rectangle { objectName: "TextExtend" property string strText:"Hello" function setTextString(msg) { strText=msg }
    
                Text
                { id:idInnerText anchors.fill: parent text:strText verticalAlignment: Text.AlignVCenter horizontalAlignment: Text.AlignHCenter color:"red" }
    
            }
    
        }
    
    }

main.cpp

#include <QGuiApplication>
    #include <QQmlApplicationEngine>
    
    int main(int argc, char *argv[])
    {
        QGuiApplication app(argc, argv);
    
        QQmlApplicationEngine engine;
        engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    
        QObject* root = engine.rootObjects().first();
    
    
        QObject* pctrlobj = root->findChild<QObject*>("TextExtend");
        if (pctrlobj)
        {
    
            QVariant returnedValue;
            QVariant msg = "message sended from C++";
            QMetaObject::invokeMethod(pctrlobj, "setTextString", Q_RETURN_ARG(QVariant, returnedValue),Q_ARG(QVariant, msg));
    
    
        }
    
        return app.exec();
    }

### 参考 ###

> 【1】[http://doc.qt.io/qt-5/qtqml-cppintegration-interactqmlfromcpp.html\#invoking-qml-methods][http_doc.qt.io_qt-5_qtqml-cppintegration-interactqmlfromcpp.html_invoking-qml-methods]

### 源码地址 ###

下载地址 : [https://github.com/CodeBees/qtExample/tree/master/cplusplusCallQmlFucntion][https_github.com_CodeBees_qtExample_tree_master_cplusplusCallQmlFucntion]

[http_doc.qt.io_qt-5_qtqml-cppintegration-interactqmlfromcpp.html_invoking-qml-methods]: http://doc.qt.io/qt-5/qtqml-cppintegration-interactqmlfromcpp.html#invoking-qml-methods
[https_github.com_CodeBees_qtExample_tree_master_cplusplusCallQmlFucntion]: https://github.com/CodeBees/qtExample/tree/master/cplusplusCallQmlFucntion