Subclassing QLabel to be used in QtDesigner

[yoyega]

Hi all,
I am designing a dialog for which I need a label that changes some of its properties (color, text, etc...) according to some events. So I am subclassing QLabel in a class called VerdLabel to code the paintEvent function properly. The problem is that when I try to integrate this new class in QtCreator by promoting it from QLabel to VerdLabel the following error appears when compiling the code:

Ui_pruebas01Class::setupUi(QDialog*)’:
ui_pruebas01.h:105: error: no matching function for call to ‘VerdLabel::VerdLabel(QDialog*&)’

Ui_pruebas01Class::setupUi(QDialog*)’:
ui_pruebas01.h:105: error: no matching function for call to ‘VerdLabel::VerdLabel(QDialog*&)’

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I am trying to use the following test code for the constructor:

VerdLabel::VerdLabel()
{
    this->setText( "verdura" );
}

VerdLabel::VerdLabel()
{
    this->setText( "verdura" );
}

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It looks like the 'Ui_pruebas01Class::setupUi(QDialog*)' is looking for a VerdLabel(QDialog*&) for the VerdLabel class but the constructor is defined as VerdLabel(), so I changed the code to:

VerdLabel::VerdLabel(QDialog *parent)
        :QDialog(parent)
{
    Q_D(QLabel);
    d->init();
    this->setText( "verdura" );
}

VerdLabel::VerdLabel(QDialog *parent)
        :QDialog(parent)
{
    Q_D(QLabel);
    d->init();
    this->setText( "verdura" );
}

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but in this case, the following error appears:

verdlabel.cpp: In constructor ‘VerdLabel::VerdLabel(QDialog*)’:
verdlabel.cpp:4: error: the type ‘QDialog’ is not a direct base of ‘VerdLabel’

verdlabel.cpp: In constructor ‘VerdLabel::VerdLabel(QDialog*)’:
verdlabel.cpp:4: error: the type ‘QDialog’ is not a direct base of ‘VerdLabel’

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So I don't know how to solve this, so if anybody can help me I would really appreciate it.

Thanks,
yoyega

[Coises]

Try this:

class VerdLabel : public QLabel {
        Q_OBJECT
public:
    VerdLabel (QWidget* parent = 0, Qt::WindowFlags f = 0) : QLabel("verdura", parent, f) {}
    VerdLabel (const QString& text, QWidget* parent = 0, Qt::WindowFlags f = 0) : QLabel(text, parent, f) {}
    /* other members and methods */
};

class VerdLabel : public QLabel {
        Q_OBJECT
public:
    VerdLabel (QWidget* parent = 0, Qt::WindowFlags f = 0) : QLabel("verdura", parent, f) {}
    VerdLabel (const QString& text, QWidget* parent = 0, Qt::WindowFlags f = 0) : QLabel(text, parent, f) {}
    /* other members and methods */
};

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in the header file.

Of course, you can use declarations for the constructors and put the definitions in a cpp file if they get more complicated — the idea is to duplicate the same constructors that are defined for QLabel.

QDialog is a subclass of QWidget, so the first constructor will match the call to ‘VerdLabel::VerdLabel(QDialog*&)’, and the initializer will set the initial properties of the QLabel from which your class is derived properly.

[yoyega]

Thank you very much for your reply, everything works now