Qt:QML:QML于C++交互之信号与槽(signal&slot )

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connect c++ SIGNAL with QML SLOT

### 简介 ###

QML 与 C++ 混合编程时,总结了一下qml和c++互相直接调用、及信号与槽连接 的几种情况，详细使用情况看示例代码  
所有的QML对象都派生自QObject，不管是可视对象还是集成在c++程序中的对象。一旦QML对象被创建，就可以集成到c++中，读写属性，调用其方法和接收其信号

### 连接qml中信号与函数 ###

Component.onCompleted:
        {
            //qml 信号连接 qml函数
            sendMessageSigal.connect(getMessage);
        }

### 连接 qml中函数与c++中信号 ###

Connections
            {
                //qml 连接 c++ 信号
                target:interaction
                onConnectcppsignal:
                {
                    label2.text=strMsg;
                }
    
            }

### qml中直接调用c++函数 ###

//on<Signal>
      onClicked:
                {
                    //qml 调用 c++函数
                    interaction.test();
                }

### 连接c++中函数与qml中信号 ###

//c++ 函数连接 qml信号
        QObject* quitButton = root->findChild<QObject*>("quitButton");
        if (quitButton)
        {
            QObject::connect(quitButton, SIGNAL(clicked()), &app, SLOT(quit()));
        }

### c++中直接调用qml中函数 ###

QObject* textLabel = root->findChild<QObject*>("objNameL4");
        if (textLabel)
        {
            //c++ 直接调用qml函数
            QMetaObject::invokeMethod(textLabel, "setL4text");
    
        }

### c++连接信号与槽函数 ###

//连接c++ 信号与槽
        //QObject::connect(this,SIGNAL(valueChanged(int)),this,SLOT(setValue(int))); //qt4 语法
        QObject::connect(this,&CInteraction::valueChanged,this,&CInteraction::setValue); //qt5 新语法

### c++ 连接信号与普通函数 ###

//信号连接普通函数
        QObject::connect(this,&CInteraction::valueChanged,outPutInfo);

### c++ 连接信号与lambda函数 ###

// QObject::connect(this,&CInteraction::valueChanged,[=](int value){  qDebug()<<"lambda called, value:"<<value<<"\n"; }); QObject::connect(this,&CInteraction::valueChanged,[=,this](){ qDebug()<<"lambda called, value:"<<this->value_<<"\n"; });

### 代码 ###

[代码地址][Link 1]

### 参考 ###

> [http://blog.csdn.net/booirror/article/details/26973611][http_blog.csdn.net_booirror_article_details_26973611]  
> [https://www.devbean.net/2012/04/signals-slots-in-qt5/][https_www.devbean.net_2012_04_signals-slots-in-qt5]  
> [http://doc.qt.io/qt-5/qtqml-syntax-signals.html][http_doc.qt.io_qt-5_qtqml-syntax-signals.html]  
> [http://doc.qt.io/qt-5/qtqml-cppintegration-interactqmlfromcpp.html\#accessing-loaded-qml-objects-by-object-name][http_doc.qt.io_qt-5_qtqml-cppintegration-interactqmlfromcpp.html_accessing-loaded-qml-objects-by-object-name]

[Link 1]: https://github.com/CodeBees/qtExample/tree/master/signalslot
[http_blog.csdn.net_booirror_article_details_26973611]: http://blog.csdn.net/booirror/article/details/26973611
[https_www.devbean.net_2012_04_signals-slots-in-qt5]: https://www.devbean.net/2012/04/signals-slots-in-qt5/
[http_doc.qt.io_qt-5_qtqml-syntax-signals.html]: http://doc.qt.io/qt-5/qtqml-syntax-signals.html
[http_doc.qt.io_qt-5_qtqml-cppintegration-interactqmlfromcpp.html_accessing-loaded-qml-objects-by-object-name]: http://doc.qt.io/qt-5/qtqml-cppintegration-interactqmlfromcpp.html#accessing-loaded-qml-objects-by-object-name