Best way to separate a humongous QTabWidget's functionality into separate classes?

tmladek

Hello!
I have a widget that started out as a QTabWidget with little functionality, so it didn't matter that the class managed it all - now it's responsibilities and capabilities have grown, and I've separated the code into different files which I #included into the main file - but that isn't a very good solution, as the IDEs (neither Qt Creator nor VS) aren't suited to deal with code split like that, and logically, it didn't simplify anything.

So, I'd like to split the functionality of each tab into its own class. My approach would be to first create .ui files and transfer all the appropriate widgets, then create a class subclassing QWidget and transfer all the code. Second, to include these new widgets into my former "main" QTabWidget, but I don't know how to do that in Qt Designer (going through the dance to make the widget a truly integrated and reusable one seems like a needlessly involved approach, as the widget is going to be included exactly once).

I'm open to any and all suggestions, what were your ways to solve this? Thanks!

m.sue

You do not need to make your custom widget "fully integrated" just to use it once or more often.

You can use your custom widget's base class, which may e.g. be just "QWidget", and then declare that it represents your custom widget. This you do by right-click on it and call the context-menu entry "Promoting widget..." like explained here (for Qt 4.8). Should work as before, though: http://doc.qt.io/qt-4.8/designer-using-custom-widgets.html

kshegunov

@tmladek
Do you really need to derive from QTabWidget or from QWidget for that matter? What I usually do is to initialize the generic classes "from outside", that is from a controller. Said controller I derive from QObject to be able to handle signals in it (which with c++11's lambdas isn't even needed) . Basically I do this:

#include ui_MyForm1.h"
#include ui_MyForm2.h"
#include ui_MyContainerForm.h"

class MyController : public QObject
{
    Q_OBJECT

public:
    MyController()
        : containerWidget(Q_NULLPTR) //< You should give a parent to the widget, this is a simplified example
    {
         MyContainerForm containerForm;
         containerForm.setupUi(&containerWidget); //< Initialize the widget with the container form

         MyForm1 form1;
         form1.setupUi(containerForm.form1Placeholder); //< form1Placeholder is a regular QWidget that comes from the designer

         MyForm2 form2;
         form2.setupUi(containerForm.form2Placeholder); //< form1Placeholder is a regular QWidget that comes from the designer

         // Do connects for whatever I need for form1, form2, containerForm
    }

    QWidget containerWidget;
}

No subclassing involved, except for the one from QObject. Just my 2 cents, I don't know if that really helps you.