Detect QGraphicsScene changes



  • Hi,
    I am currently developing a small graphic application. It consist on a QMainWindow with a QGraphicsScene as centralwidget !
    I want to implement a function that, when the application is closed, will check if the graphicsScene modifications (add/delete/move graphics items) are saved to an XML file. I know this function:

    @changed ( const QList<QRectF> & region )@

    I don't know how to use it ! It sometimes work and sometimes don't !
    any idea ?



  • This is not a function, it is a signal. Add a bool sceneChanged to your main window, connect the changed() signal to a slot that sets the sceneChanged to true, and when closing the application, check if the scene has changed, and if so - serialize it to disk in a format of your choice.

    I'd personally prefer JSON over XML - it is faster to parse and more space efficient. Also easier on the eyes in case you need to modify it manually.



  • yes it's a signal and i will use :
    @void sceneRectChanged ( const QRectF & rect )@

    instead :)

    Well another question how to use JSON with Qt ?


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