how can I use c ++ not qt QUICK / QML?

[Nathan Miguel]

I'm doing a little test, and was wondering how can I pass this string to the "text" in qml

QML

import QtQuick 2.9
import QtQuick.Window 2.2
import com.company.cpuname 1.0

Text {
            id: element
            x: 41
            y: 71
            width: 175
            height: 39
            text: cpuname.getcpu()
            style: Text.Sunken
            verticalAlignment: Text.AlignVCenter
            horizontalAlignment: Text.AlignHCenter
            fontSizeMode: Text.FixedSize
            font.pixelSize: 14
        }

Main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "cpuname.h"

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

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    qmlRegisterType<cpuname>("com.company.cpuname",1,0,"CpuName");
    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);
    engine.load(url);

    return app.exec();
}

cpuname.h/cpuname.cpp

#ifndef CPUNAME_H
#define CPUNAME_H

#include <QObject>

Q_PROPERTY ( QString theChange READ getTheChange NOTIFY changeOfStatus )

class cpuname : public QObject
{
    Q_OBJECT
public:
    explicit cpuname(QObject *parent = nullptr);
    Q_INVOKABLE void getcpu(QString namecpu);

signals:


public slots:

private:
    QString namecpu;
};

#endif // CPUNAME_H

-------------------------------------------

#include "cpuname.h"
#include <QProcess>
#include <QSysInfo>
#include <QDebug>

cpuname::cpuname(QObject *parent) : QObject(parent)
{

}

void cpuname::getcpu(QString namecpu)
{
    namecpu = QSysInfo::kernelType();
}

[sierdzio]

Is there any question here that you wanted to ask?

In the code you pasted, you have registered cpuname as a QML type but you never create the object anywhere. So to make that work you need to:

Text {
  CpuName { id: cpuname }
  text: cpuname.getcpu()
}

Or, a simpler solution is to add cpuname object as context property to your engine:

auto myCpu = cpuname();
engine.rootContext()->setContextProperty("cpuname", &cpuname);

[Nathan Miguel]

@sierdzio said in how can I use c ++ not qt QUICK / QML?:

Is there any question here that you wanted to ask?

Reformulating my question, I want to know how I can use c ++ in qt qml, because I saw several documents and videos and none worked at random, I'm trying to pass the kernel(Windows OR Linux) from the pc to the qml as a test, but it is not working .

I added as you said in "main.cpp" but I get this result on the output

Main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include "cpuname.h"

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

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    qmlRegisterType<cpuname>("com.company.cpuname",1,0,"CpuName");
    cpuname CpuName;
    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);
    engine.load(url);
    engine.rootContext()->setContextProperty("cpuname", &CpuName);

    return app.exec();
}

OUTPUT

15:26:35: Starting E:\Git\Denoiser-Script\QML_C++\build-Denoiser-Desktop_Qt_5_12_3_MinGW_64_bit2-Debug\debug\Denoiser.exe ...
QML debugging is enabled. Only use this in a safe environment.
qrc:/main.qml:33: Error: Insufficient arguments

[sierdzio]

@sierdzio said in how can I use c ++ not qt QUICK / QML?:

Or,

I've said OR. Do not implement both these solutions at once, because cpuname identifiers will clash...

Anyway, getting to your error. Your c++ code expects a string argument cpuname::getcpu(QString namecpu) but you are not providing any in QML text: cpuname.getcpu().

Which brings me to another bug:

Your getcpu method does not return anything! So QML will never get any data from it!

Your method should look more like:

QString cpuname::getcpu() const
{
    return QSysInfo::kernelType();
}

Lastly, the root context should be set before the QML code is loaded.

engine.rootContext()->setContextProperty("cpuname", &CpuName);
engine.load(url);

[Nathan Miguel]

@sierdzio said in how can I use c ++ not qt QUICK / QML?:

engine.rootContext()->setContextProperty("cpuname", &CpuName);

its works tnks