How do you use Q_INVOKABLE to access c++ functions in QML?

Question

I am looking for the most simple and straightforward example.

For my part;

.h

public:
KTerminalDisplay(QQuickItem *parent = 0);
~KTerminalDisplay();
Q_INVOKABLE void setFontStyle(QString & s);  

.cpp

void KTerminalDisplay::setFontStyle(QString & s){
m_fontStyle = QString(s);
}

This works fine thus far. No issues. The question is; how do I use this function in a QML file?

Answer 1

To make the KTerminalDisplay instance accessible from QML, you must register it in your main.cpp. Since you're expecting parent to be a QQuickItem, your question is not so simple. After looking at the terminal app, I can propose the following trick:

QQuickItem *item = view.rootObject();
KTerminalDisplay * display = (KTerminalDisplay *) item;
view.engine()->rootContext()->setContextProperty("kdisplay", display);

Once registered, you can call setFontStyle from QML:

kdisplay.setFontStyle("foo")

Note: See Embedding C++ Objects into QML with Context Properties as you can mark your method as a slot.

Source: http://developer.nokia.com/community/wiki/Calling_Qt_class_methods_from_QML