How to register and access C++ class methods in QML

Sushma_MP

Hi ,
Am trying to register my cpp class into QML by using qmlRegisterType and wanted to access methods present in cpp file in my main.qml .
As per my code i have two methods test() and demo() i am able to acces only test method in main.qml but not able to access demo() method.

can we use Q_INVOKABLE for more than one methods...????

handlecppclass.cpp


        
        #include "handlecppclass.h"
        
        HandleCppClass::HandleCppClass(QObject *parent) : QObject(parent)
        {
        
        }
        
        void HandleCppClass::test()
        {
            qDebug()<<"inside test slot"<<endl;
        }
        
        void HandleCppClass::demo()
        {
            qDebug()<<"inside demo slot"<<endl;
        }

handlecppclass.h


        
        #ifndef HANDLECPPCLASS_H
        #define HANDLECPPCLASS_H
        
        #include <QObject>
        #include <QDebug>
        
        class HandleCppClass : public QObject
        {
            Q_OBJECT
        public:
            explicit HandleCppClass(QObject *parent = 0);
        
        
        signals:
        
        public slots:
            Q_INVOKABLE void test();
            Q_INVOKABLE void demo();
        
        };
        
        #endif // HANDLECPPCLASS_H

main.cpp

 
        
        #include <QGuiApplication>
        #include <QQmlApplicationEngine>
        
        #include <handlecppclass.h>
        
        int main(int argc, char *argv[])
        {
            QGuiApplication app(argc, argv);
            qmlRegisterType<HandleCppClass>("com.cppclass",1,0,"HandleCppClass");
        
            QQmlApplicationEngine engine;
            engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
        
            return app.exec();
        }

main.qml

 
        
        import QtQuick 2.7
        import QtQuick.Window 2.2
        import com.cppclass 1.0
        
        Window {
            visible: true
            width: 640
            height: 480
            title: qsTr("Hello World")
        
            HandleCppClass{
                id : classhandle
            }
        
            MouseArea{
                id: mouse
                anchors.fill: parent
                onClicked: {
                    classhandle.test()
        
                }
            }
        }

raven-worx

@Sushma_MP said in How to register and acess cpp class methods in QML:

As per my code i have two methods test() and demo() i am able to acces only test method in main.qml but not able to access demo() method.

what is the exact error you receive?

Also you do not need to make slots invokable. Since they already are implicitly invokable.

Sushma_MP

there is no errors the thing is i am not able to access all methods which are present in my cpp class only test() is appearing in main.qml class

raven-worx

@Sushma_MP

when it doesn't work, there is definitely an error/notice. Check the console.
what do you mean with "appearing"? Do you mean QtCreator doesn't offer it in the auto-completion popup?

Sushma_MP

@raven-worx
when it doesn't work, there is definitely an error/notice. Check the console.

when we try to add new method try to access it in main.qml...like u said it is not appearing in auto-popup

raven-worx

@Sushma_MP
i don't know exactly when QtCreator updates it's completion model.
But closing and reopening the project should trigger it.

Sushma_MP

@raven-worx
how is it possible then...everytime we can't close and reopen Qt creator rite...is it a bug...??

sneubert

In Qt Creator did you try to call [Tools]->[QML/JS]->Reset Code Model, after you compiled your cpp class?

raven-worx

@Sushma_MP said in How to register and acess cpp class methods in QML:

how is it possible then...everytime we can't close and reopen Qt creator rite...is it a bug...??

i wasn't talking about restarting the whole QtCreator process, but only close and reopen the project.
The problem is, when is the right time to update the code-completion model?

Sushma_MP

Hi ,

Actually i am facing another problem :
I created cpp class and registered in main.cpp and imported in main.qml
when i try to access that class in maim.qml i am getting as a invalid property .
my code is as fallow```
import QtQuick 2.4
import QtQuick.Controls 1.3
import QtQuick.Window 2.2
import QtQuick.Dialogs 1.2
import QtQuick 2.5
import QtGraphicalEffects 1.0
import com.songclass 1.0

ApplicationWindow {
flags: Qt.FramelessWindowHint

title: qsTr("Infotainment")
width: (Screen.width/2)+200
height: (Screen.height/2)
visible: true
modality: Qt.WindowModal

selectsong{

here i get as invalid property with a red underlined for selectsong
}

MenuScreen{
    id:menusrcn
    visible: false
}
Settings{
    id:settingScreen
    visible: false
}
MusicVedio{
    id:vedioScreen
    visible: false
}
MediaPlay{
    id:musicScreen
    visible: false
}
Radio{
    id:radioScreen
    visible: false
}

Rectangle{
    id:main_rect
    width: parent.width
    height: parent.height
    color: "#e9ebf8"
    Image {
        id: back_img
        source: "qrc:/HomeScreen.png"
        anchors.centerIn: parent
    }

    Rectangle
    {
        id: welcome_rect
        width: 250
        height: 40
        anchors.top: parent.top
        anchors.topMargin: 100
        anchors.horizontalCenter: parent.horizontalCenter
        color: "transparent"
        Text {
            id: welcome_text
            text: qsTr("L&T Car Infotainment")
            color:"#fefcfd"
            font.pixelSize: 36
            font.family: "Courier"
            font.bold: true
            font.italic: true
            anchors.centerIn: parent
            style: Text.Sunken
            styleColor: "#000000"
        }
    }

    Rectangle{
        id: next_page_rect
        width: parent.width/6
        height: parent.height/12
        color:"Transparent"
        anchors.right: parent.right
        anchors.bottom: parent.bottom
        anchors.rightMargin: 15
        anchors.bottomMargin: 8
        Image {
            id: next_image
            source: "qrc:/Fwd_arrow.png"
            width: parent.width
            height: parent.height
            smooth: true
            fillMode: Image.PreserveAspectFit
            antialiasing: true
            MouseArea{
                id: next_page_rect_mousearea
                anchors.fill: parent
                onClicked: {
                    menusrcn.visible= true
                    main_rect.visible= false
                }
            }
        }
    }
}

}

raven-worx

@Sushma_MP
selectsong is not a valid property of ApplicationWindow type.
QML types must start with an Uppercase-Letter to distinguish them from properties as you can see in your error.

Sushma_MP

ohh but selectsong is my cpp class name

Sushma_MP

thank you soo much i got the solution by taking it as uppercase letter as you said...

raven-worx

@Sushma_MP said in How to register and acess cpp class methods in QML:

ohh but selectsong is my cpp class name

you can also leave the class name, but register it with a upper case name should also work.