Qml使用cpp文件的信号槽

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一、C++文件Demo

Q_INVOKABLE是一个Qt元对象系统中的宏，用于将C++函数暴露给QML引擎。具体来说，它使得在QML代码中可以直接调用C++类中被标记为Q_INVOKABLE的成员函数。

public:SerialPort();// 返回可用串口Q_INVOKABLE QStringList availablePorts();// 打开串口Q_INVOKABLE bool open(QString portName, QString buadRate, QString dataBits, QString stopBits,QString parity, QString flowControl);// 关闭串口Q_INVOKABLE void close();// 直接调用接口Q_INVOKABLE void say();signals://返回串口打开信息Q_INVOKABLE void openMsg(bool open, QString error);//接口，用于多线程Q_INVOKABLE void sendMsg(QString msg);public slots://void sendMsgSlot(QString msg);private:QThread* m_thread;QSerialPort* m_port;QMutex m_mutex;

m_port = new QSerialPort();
connect(this, &SerialPort::sendMsg, this, &SerialPort::sendMsgSlot);tts = new QTextToSpeech(this);m_thread = new QThread;
m_thread->setObjectName("串口线程");
this->moveToThread(m_thread);
connect(m_thread, &QThread::finished, this, &QThread::deleteLater);
connect(m_thread, &QThread::finished, this, &SerialPort::deleteLater);
m_thread->start();

QStringList SerialPort::availablePorts()
{QStringList list;foreach(auto info, QSerialPortInfo::availablePorts()) list.append(info.portName());list<<"COM11"<<"COM22";return list;
}

bool SerialPort::open(QString portName, QString buadRate, QString dataBits, QString stopBits,QString parity, QString flowControl)
{bool ok = false;QString errstr = "m_port异常";{QMutexLocker locker(&m_mutex);if(!m_port){emit openMsg(false, errstr);locker.unlock();return false;}m_port->setPortName(portName);m_port->setBaudRate(buadRate.toInt());m_port->setDataBits((QSerialPort::DataBits)dataBits.toInt());m_port->setStopBits((QSerialPort::StopBits)stopBits.toInt());m_port->setParity((QSerialPort::Parity)parity.toInt());m_port->setFlowControl((QSerialPort::FlowControl)flowControl.toInt());ok = m_port->open(QIODevice::ReadWrite);errstr = m_port->errorString();}emit openMsg(ok, errstr);return ok;
}

void SerialPort::close()
{QMutexLocker locker(&m_mutex);if(m_port && m_port->isOpen()) m_port->close();
}

void SerialPort::say()
{qDebug()<<"SerialPort CurrrntThread = "<< QThread::currentThread();qDebug()<<"---------------------------------------------------------";QString text = "2,8,k,1,0";tts->say(text);
}

void SerialPort::sendMsgSlot(QString msg)
{qDebug()<<"SerialPort CurrrntThread = "<< QThread::currentThread();qDebug()<<msg;qDebug()<<"---------------------------------------------------------";
}

二、使用步骤

1. 初始化C++文件和QML文件，并建立信号槽

qml中的槽函数也是定义成signal, 所以connect时，槽函数也是SIGNAL()

serial = new SerialPort;
//serial 类向 QML 对象的上下文公开数据
ui->quickWidget_2->rootContext()->setContextProperty("serial", serial);
//根据窗口大小调整QML大小
ui->quickWidget_2->setResizeMode(QQuickWidget::SizeRootObjectToView);
// 
ui->quickWidget_2->setSource(QUrl("qrc:/Form02.qml"));
//
QObject* obj = ui->quickWidget_2->rootObject();
// 调用qml中信号或者槽函数，调用成功返回true，否则false
// 根节点，被调用信号或槽，连接方式，被调用信号或槽的参数1， 被调用信号或槽的参数2(最多10个参数)
if(QMetaObject::invokeMethod(obj, "slotOpenSerial", Qt::DirectConnection, Q_ARG(bool, true), Q_ARG(QString, "")))connect(serial, SIGNAL(openMsg(bool,QString)), obj, SIGNAL(slotOpenSerial(bool,QString)));

2.在qml中调用

QGroupButton 自定义的按钮组

Item {id: itemLayout.fillWidth: trueLayout.preferredHeight: 36property alias checkedButton: btngroup.checkedButtonproperty int btnIndexChanged: 0onBtnIndexChangedChanged: {if(btnIndexChanged == 0) {checkedButton = ok}else {checkedButton = cancle}}ButtonGroup {id: btngroupexclusive: truebuttons: row.childrenonCheckedButtonChanged:{console.log("button text: ", checkedButton.text)btnIndexChanged = checkedButton == ok ? 0 : 1;}}Rectangle{id: rectanchors.fill: parentRowLayout {id: rowanchors.fill: rectspacing: 6QButton{id: ok; text: "OK"}QButton{id: cancle; text: "Cancle"}}}
}

signal slotOpenSerial(bool isOpen, string error)onSlotOpenSerial: {//console.log(isOpen, error)if(!isOpen){group.btnIndexChanged = 1}
}

qrc:/Form02.qml

//自定义的按钮组
QGroupButton{id: groupLayout.columnSpan: 2Layout.fillWidth: trueonCheckedButtonChanged:{if(checkedButton.text == "OK"){open =  serial.open(portName.currentText, cboxBuad.currentText, dataBits.currentText,stopBits.currentText, parity.currentText, flowControl.currentText);console.log("serial return: ", open)}else{serial.close()}}
}

下面代码仅看这段：
QButton{
text: "1";
onClicked: {
//直接调用接口
serial.say();
//通过信号调用
serial.sendMsg("TTTT");
}
}

Rectangle {Layout.columnSpan: 2Layout.fillWidth: trueLayout.fillHeight: truecolor: "#156448"Flow {anchors.fill: parentanchors.margins: 9spacing: 6QButton{text: "1";onClicked: {serial.say();serial.sendMsg("TTTT");}}QButton{text: "2"}QButton{text: "3"}QButton{text: "4"}QButton{text: "5"}QButton{text: "6"}QButton{text: "7"}QButton{text: "8"}QButton{text: "9"}QButton{text: "10"}QButton{text: "11"}QButton{text: "12"}QButton{text: "13"}QButton{text: "14"}QButton{text: "15"}QButton{text: "16"}QButton{text: "17"}QButton{text: "18"}QButton{text: "19"}Rectangle {width:60height: 26color: "green"property alias text: in1.textonTextChanged: console.log(text)TextInput {id: in1anchors.fill: parenttext: "input"color: "red"KeyNavigation.tab: in2selectByMouse: true}}Rectangle {width:60height: 26color: "green"TextInput {id: in2anchors.fill: parenttext: "input"color: "red"KeyNavigation.tab: in1KeyNavigation.up: in1}}Loader {sourceComponent: testComponent}}
}

结果如图：
//---------------------------------------------------------
MainWindow CurrentThread = QThread(0x24ce850) //主线程
//---------------------------------------------------------
qml: button text: OK // 点击OK按钮打印
qml: button text: Cancle // 打开串口失败，取消OK按钮，默认Cancle按钮被点击打印
qml: serial return: false // serial.open(…)返回值打印
SerialPort CurrrntThread = QThread(0x24ce850) // serial.say() 函数运行的线程
//---------------------------------------------------------
SerialPort CurrrntThread = QThread(0xfcc9f0, name = “串口线程”) // serial.sendMsg(“TTTT”)运行的线程
“TTTT” // 槽函数打印
//---------------------------------------------------------

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