将C++对象注册成QML控件并提供可被调用的函数

0x00 使用QML编写界面

import QtQuick 2.14
import QtQuick.Window 2.14
import QtQuick.Controls 1.4
import QtQuick.Controls 2.12 as Controls
import QtQuick.Controls.Styles 1.4
import QtQuick.Controls.Material 2.12
//import com.HLD 1.0

Window {
    visible: true;
    minimumHeight: 480;
    maximumHeight: 480;
    minimumWidth: 640;
    maximumWidth: 640;
    title: qsTr("HLD.TableView")
    color: Qt.rgba(127, 255, 170, 1.0)

    Row{
        anchors.centerIn: parent;
        spacing: 10;

        TextField {
            id: inputField;
            width: 300;
            placeholderText: "Enter text";

            style: TextFieldStyle {
                background: Rectangle {
                    color: "#ffffff"
                    border.color: "#40E0D0"
                    radius: 4
                }
            }
        }

        Button{
            id: btn;

            text: "发送";
            style: ButtonStyle {
                background: Rectangle {
                    color: "#2196f3"
                    radius: 4;
                }

                label: Text {
                    text: btn.text
                    color: "#ffffff"
                    font.pixelSize: 16
                }
            }

            onClicked: {
                if(inputField.text.length > 0)
                {
                    console.log(inputField.text);
                    UdpCli.sendMsg(inputField.text);
                }
            }
        }
    }
}

0x01 使用C++定义一个类，并用Q_INVOKABLE宏修饰一个发送UDP消息的成员函数。

#ifndef UDPCLI_H
#define UDPCLI_H

#include 
#include 
#include 

class UdpCli : public QObject
{
    Q_OBJECT
public:
    explicit UdpCli(QObject *parent = nullptr);

    Q_INVOKABLE void sendMsg(QString msg);

signals:

private:
    QUdpSocket* udpSocket;
};

#endif // UDPCLI_H

//----------------------------

#include "udpcli.h"
#include 

UdpCli::UdpCli(QObject *parent) : QObject(parent)
{
    udpSocket = new QUdpSocket(this);
    udpSocket->bind(QHostAddress::LocalHost, 9898);
}

void UdpCli::sendMsg(QString msg)
{
    udpSocket->writeDatagram(msg.toStdString().c_str(),msg.size(),
                             QHostAddress("127.0.01"), 19898);

}

将C++对象注册成QML控件

#include 
#include 
#include 
#include 
#include 
#include "udpcli.h"

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);
    QQuickStyle::setStyle("Material");

    UdpCli m_udpCli;

    /**
     * @brief qmlRegisterSingletonInstance
     * @param Url名
     * @param 主版本
     * @param 次版本
     * @param Qml中控件名
     * @param C++对象
     */
    // qmlRegisterSingletonInstance("com.HLD", 1, 0, "UdpCli", &m_udpCli);

    QQmlApplicationEngine engine;
    const QUrl url(QStringLiteral("qrc:/main.qml"));
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                     &app, [url](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);

    auto context = engine.rootContext();
    context->setContextProperty("UdpCli", &m_udpCli);

    engine.load(url);

    return app.exec();
}

• 效果演示