QML, QtQuick - modify text object from C++ code

[marcin100]

I have done a lot of research but I failed to find such simple example. I'm obviously searching wrong thing because I cannot imagine that modifying a GUI text from code behind is very complex.

I have read the "QtBindings page":http://qt-project.org/doc/qt-4.8/qtbinding.html and the example included on this page (shown below) but was unable to apply it to my embedded Qt project which uses QDeclarativeView to interface with LCD.
@ // main.cpp
QDeclarativeEngine engine;
QDeclarativeComponent component(&engine, "MyItem.qml");
QObject *object = component.create();

QVariant returnedValue;
QVariant msg = "Hello from C++";
QMetaObject::invokeMethod(object, "myQmlFunction",
Q_RETURN_ARG(QVariant, returnedValue),
Q_ARG(QVariant, msg));

qDebug() << "QML function returned:" << returnedValue.toString();
delete object;@

So here is a simplified version of my code. Could someone tell me if it is possible for the QML to detect a change value of the QString variable when a setText() is invoked. I am guessing that I need a connect statement which will bind my textChanged() signal with the QML. I also was not able to find such example.
How would I define a slot in QML and for what object? In which file should I place this connect statement? I am really looking for syntax here...

I am also aware of findChild way of locating objects in QML but apparently this is not a good way of doing such task in Qt per the same qt-project page I have mentioned above.

This code works, but the second setText("Change 2") does not update screen. The screen is only updated once when the setContextProperty line is executed.

@// main.cpp
#include <QApplication>
#include "qmlapplicationviewer.h"
#include "mydisplay.h"

Q_DECL_EXPORT int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QDeclarativeView view;
MyDisplay display;

// This setText updates QML
display.setText("Change 1");

view.setSource(QUrl::fromLocalFile("qml/qmlTest1/main.qml"));
view.rootContext()->setContextProperty("myDisplay", &display);

// This setText does not update QML
display.setText("Change 2");
// Debug console displayes "Change 2" string correctly.
qDebug() << display.getText();
view.show();

return app.exec();

}
@
@//mydisplay.h
#include <QObject>
#include <QtDeclarative>

#ifndef MYDISPLAY_H
#define MYDISPLAY_H

class MyDisplay : public QObject
{
Q_OBJECT
Q_PROPERTY(QString newText READ getText WRITE setText NOTIFY textChanged)

public:
MyDisplay();

MyDisplay(QString);

Q_INVOKABLE QString getText() const;

public slots:
void setText(QString text);

signals:
void textChanged(QString);

private:
QString newText;
};

#endif // MYDISPLAY_H@

@//mydisplay.cpp
#include "mydisplay.h"

MyDisplay::MyDisplay()
{
newText = "";
}

MyDisplay::MyDisplay(QString text)
{
newText = text;
}

QString MyDisplay::getText() const
{
return newText;
}

void MyDisplay::setText(QString text)
{
if (text != newText)
{
newText = text;
emit textChanged(text);
}
}@

@// main.qml
import QtQuick 1.1

Rectangle {
width: 800
height: 480
color: "#000000"

Text {
    id: myQmlTextObject
    anchors.horizontalCenter: parent.horizontalCenter
    anchors.verticalCenter: parent.verticalCenter
    color: "#b9b9b9"

    font.pixelSize: 30
    text: myDisplay.getText();
}

}@
Working code would be greatly appreciated.

[sierdzio]

@
// in QML
text: myDisplay.newText
@

You need to bind to the property, not it's getter method.

[marcin100]

Thank you!
I knew this will be something obvious.