How to use classes in Qt / QML

hejkki

How can i use "kakkanna" in qml?
i cannot seem to get it working even after reading the docs since they seem to look a lot different.
I see nowhere anything like this what i'm trying to do...

when i click on the button, it will give me "qrc:///main.qml:32: ReferenceError: kusihousu is not defined"

i tried several methods like this in main.cpp:
@
engine.rootContext()->setContextProperty("kusihousu", kakkanna);
@

here is my code:

main.cpp:
@#include <QApplication>
#include <QQmlApplicationEngine>
#include <QObject>
#include "kakkanna.h"

int main(int argc, char argv[])
{
Kakkanna kannakka = new Kakkanna();

QApplication app(argc, argv);

QQmlApplicationEngine engine;


engine.load(QUrl(QStringLiteral("qrc:///main.qml")));


return app.exec();

}
@

kakkanna.h:
@
#ifndef KAKKANNA_H
#define KAKKANNA_H

#include <QObject>

class Kakkanna : public QObject
{
Q_OBJECT
public:
explicit Kakkanna(QObject *parent = 0);
int value() const {return m_value;}

signals:
void valueChanged(int newValue);

public slots:
void setValue(int value);
void increment();
void decrement();

private:
int m_value;
};

#endif // KAKKANNA_H
@

kakkanna.cpp:
@
#include "kakkanna.h"

Kakkanna::Kakkanna(QObject *parent) :
QObject(parent)
{
m_value = 0;
}

void Kakkanna::setValue(int newValue)
{
if (newValue != m_value)
{
m_value = newValue;
emit valueChanged(newValue);

}

void Kakkanna::increment()
{
setValue(value()+1);
}

void Kakkanna::decrement()
{
setValue(value()-1);
}
@

main.qml:
@
import QtQuick 2.2
import QtQuick.Controls 1.1

ApplicationWindow {
visible: true
width: 640
height: 480
title: qsTr("Hello World")

menuBar: MenuBar {
    Menu {
        title: qsTr("File")
        MenuItem {
            text: qsTr("Exit")
            onTriggered: Qt.quit();
        }
    }
}

Text {
    text: qsTr("Hello World")
    anchors.verticalCenterOffset: 1
    anchors.horizontalCenterOffset: 0
    anchors.centerIn: parent
}

Button {
    id: button1
    x: 185
    y: 116
    text: qsTr("Button")
    onClicked: kusihousu.increment();
}

}
@

shav

Hi,

You need add to your kakkanna.h line with this code:
@
QML_DECLARE_TYPE(Kakkanna)
@

Than add the line to you main.cpp file before load the main QML file next code:
@
mlRegisterType<Kakkanna>("com.kakkanna", 1, 0, "Kakkanna");
@

In main QML file you need add line on the top of file:
@
import com.kakkanna 1.0
@

And now you can create and use your class in QML file:
@
Kakkanna {
id: someIdHere
}
@

Also you can read about QML plugins "here":http://qt-project.org/doc/qt-5/qtqml-modules-cppplugins.html.

Iktwo

You can also do

@
engine.rootContext()->setContextProperty("kusihousu", kakkanna);
@

as you were doing, just do it before loading your qml
@
engine.load(QUrl(QStringLiteral("qrc:///main.qml")));
@

Then from qml you can access the Q_PROPERTYs, Q_INVOKABLE methods or public slots with kusihousu.NAME

hejkki

this site isn't working, i just posted a reply and i never saw it online. ok trying another time:

None of this is working.
@
engine.rootContext()->setContextProperty("kusihousu", kakkanna);
@

This will give me:
error: invalid use of incomplete type 'class QQmlContext'

@
QML_DECLARE_TYPE(Kakkanna)
@

This will give me:
error: expected constructor, destructor, or type conversion before '(' token

@
mlRegisterType<Kakkanna>("com.kakkanna", 1, 0, "Kakkanna");
@

This will give me:
error: 'mlRegisterType' was not declared in this scope

i figured out this could be:

@
mlRegisterType<Kakkanna>("com.kakkanna", 1, 0, "Kakkanna");
@

This will give me:
error: 'qmlRegisterType' was not declared in this scope

Iktwo

Just include QQmlContext