pass data between qt controls (slider) and C++ application

[anda_skoa]

I have one question though , when does the Qt Property System gets initialized ? right after the call of the class constructor ?

The property system doesn't need any initialization, it is based on invoking member functions which are callable as soon as an object instance has been created.

What if the property system do have to access some read-only value after some other classes initialization ? Is it possible to make the Qt property system to be inintialized in lazy manner ?

You can change a property's value at any time, all bindings on that property will get re-evaluated.

Now it seems that the Qt property system gets the initialization call before the opengl initialization at the back-end ? Any idea to get it working ?

As there is no "initializtion" of the property system, just make sure that the getter of the property returns the correct value once it is available.
Make sure you have emitted the property's change notifiier signal when you need QML to update the bindings for the new value.

Cheers,
_