Question

I’m trying to collect an often used subset of GUI-Elements together into one Subclass, which can be “included” into the real GUIs later without rewriting the given functionality (don’t ask why, I wanna learn it for later use). The Subclass should use it’s own *.ui-File and should be put into an QWidget resding in the real GUI. After this, it would be nice to access some methods of the Subclass from the real GUI — like the state of a button or so.

But how do I do this right?

In the moment, my Subclass works and is instantiated in main, but cannot be accessed from the real GUI because its only declared in main.

My Subclass Header-File:

class logger : public QWidget, private Ui::loggerWidget {
    Q_OBJECT

public:
    logger(QWidget *parent = 0);
    virtual ~logger();
    // some more stuff...
}

The corresponding constructor. I had to run setupUI with “parent” instead of “this”, but I’m not sure that this is correct — anyways, it works… otherwise, the subelements from the subclass are not shown in the main-window of the real GUI.

logger::logger(QWidget *parent) : QWidget(parent){
    setupUi(parent);
    //ctor
}

Inside the main.cpp the main-window is constructed, which uses it’s own *.ui-File (containing one widget “widget_loggerArea”) aswell. Doing so, I can not access methods of “logger” from within “loggerTest”:

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    loggerTest window;

    logger myLog(window.widget_loggerArea);

    window.show();

    return app.exec();
}

I can’t put the constructor of “logger” into the constructor of the main-window “loggerTest”, since it will be destroyed immidiately and never enters the event-loop.

I’m sure I’m missing some concept of object-oriented programming, or the way qt handles its stuff… I would be gratefull if someone could put my nose to this 😉

---

I was so stupid… using a pointer with new and delete does the job… this is so silly, I can’t believe it! I’m more used to VHDL recently, this weakens my C++-karma…

Answer 1

So, the answer is in the real GUI class. The Constructor:

testLogger::testLogger(QMainWindow *parent) : QMainWindow(parent){
    setupUi(this);

    myLog = new logger(widget_loggerArea);
}

In main.cpp:

QApplication app(argc, argv);
testLogger window;
window.show();

And in constructor of logger, setupUi works with “this”:

dfkiLogger::dfkiLogger(QWidget *parent) : QWidget(parent){
    setupUi(this);
}

Yes, thats it… Just for completebility, maybe someone needs a similar “push in the right direction”…

EDIT: In the header of the SubClass the scope of the ui-Elements has to be updated to “public”, too:

class logger : public QWidget, public Ui::loggerWidget {
    Q_OBJECT

    public:
        logger(QWidget *parent = 0);
        virtual ~logger();
}