@raven-worx @mrjj @Wieland @Pablo-J-Rogina
Thank you guys !
It worked perfectly. I'm now able to read and write a XML file and load items to my drawing.

Thank you again
Happy coding !

Thanks guys for replies, generally my app isn't well designed because it's for education purpose. Anyway thank you very much.

Hi
Just a note first
Having
class SerialPort : public QObject
and then
QSerialPort *serialPort;
Where only diffence is capital S to the main class is just confusing.

anyway, why is the issue with
settings(new SettingsDialog()),

did you declare it as
void settings(SettingsDialog *mydialog)

Im not sure what you dont understand.

To use a pointer to a class in another class, you simply give the pointer to the other class and it can use it

class B {}; class A { B* mykeptBpointer; setB(B* myb) { mykeptBpointer = myb; } void DoB { mykeptBpointer->xxxx(); }; A mya; B* myb = new B; mya.setB(b);

oh, is
settings(new SettingsDialog())
rather
settings = new SettingsDialog();

@alex_malyu
The original post is some 2 months old. So I wrote a whole lot of a post in reply to the original question ... well didn't my ears burn, when I noticed the post time ... I felt like a complete idiot. :)

@reezeus said:

Is it a good practice to use QThreadPool even if I have only one thread?

I've never used QThreadPool but I can imagine that it eases scaling if you do so... The day you want to increase the number of threads, simply have a bigger pool. On the other hand if you know that one thread is what you need and will continue to need, QThread seems more reasonable IMHO.

@SGaist Thank you mate, that clears it up a lot!

EDIT: Is there a way for me to know when I should free something? Or will it just come by practice?

@Afterwork said:

I recreate them every time. Are there better way ?

If they change then there's no way around it but if they're the same every frame then it's a waste of time. Generate the list once, store it as a class member and just expose them by reference e.g.

//split that to .h and .cpp of course class GameWidget : public QWidget { Q_OBJECT public: GameWidget(QWidget* parent = nullptr) : QWidget(parent) { generateMyListOfObjects(); } const QVector<Object>& objects() const { return objects_; } private: void generateMyListOfObjects() { //fill the objects vector here } QVector<Object> objects_; };

And how i can connect the slot of differents objects to built-in timer of QWidget ?

You don't. As I said - reimplement the timerEvent method. It will be called every time the timer times out. You can call some methods directly in it or emit a custom signal if you'd like.

Yes that was it. You slot looks good.

For that second task you can use QSignalMapper)