@Christian-Ehrlicher Thanks! That saves a lot of trouble for me :)

@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)