Q_PROPERTY with binding to designer

[Big_Stone88]

Hello to all:-)

I have a question about the Q_PROPERTY macro.
In Qt-documentation
(http://doc.qt.io/qt-4.8/http://doc.qt.io/qt-4.8/properties.html#requirements-for-declaring-properties),
they tell about the "DISIGNABLE"-attribute:

The DESIGNABLE attribute indicates whether the property should be visible in the property editor of GUI design tool (e.g., Qt Designer). Most properties are DESIGNABLE (default true). Instead of true or false, you can specify a boolean member function.

Now, i simply built a small test-widget with a label and a Pushbutton. In the code, i have a QString-property "smallText"

.h-file

namespace Ui {
class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
    Q_PROPERTY(QString smallText READ smallText WRITE setSmallText NOTIFY smallTextChanged)
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
    QString smallText() const
    {
        return m_smallText;
    }
 
public slots:
    void setSmallText(QString smallText);
    {
        if (m_smallText == smallText)
            return;
 
        m_smallText = smallText;
        emit smallTextChanged(smallText);
    }
signals:
    void smallTextChanged(QString smallText);
 
private slots:
    void on_pushButton_clicked();
 
private:
    Ui::MainWindow *ui;
    QString m_smallText;
};

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT
    Q_PROPERTY(QString smallText READ smallText WRITE setSmallText NOTIFY smallTextChanged)

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

    QString smallText() const
    {
        return m_smallText;
    }

public slots:
    void setSmallText(QString smallText);
    {
        if (m_smallText == smallText)
            return;
        
        m_smallText = smallText;
        emit smallTextChanged(smallText);
    }
signals:
    void smallTextChanged(QString smallText);

private slots:
    void on_pushButton_clicked();

private:
    Ui::MainWindow *ui;
    QString m_smallText;
};

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when i click on the Pushbutton, the Property "smallText" is changed, but where can I tell the label to change?
Of course, I could move the definition of "setSmallText" to the *.cpp-file and add

ui->label->setText(smallText);

ui->label->setText(smallText);

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, but is there any possibility to use the the "DESIGNABLE"-attribute?

I unfortunately have to use Qt4.5.2 with Qt-Creator
Thanks for any help
Robby

[anda_skoa]

If you want "ui->label" to change when smallText is changed, simply connect smallTextChanged() to the label's setText() slot.

Cheers,
_

[Big_Stone88]

Thanks for your answer

Yeah.....

sure, that would be a simple solution...
But what is the function of the mentioned "DISIGNABLE"-attribute then?

Robby

[anda_skoa]

As the documentation says: properties that are marked as designable (most of them), will be displayed in the QtDesigner's property editor.

Cheers,
_

[Big_Stone88]

What the documentation doesn't give away:
WHERE will it be displayed in the QtDesigner's property editor?

Robby

[anda_skoa]

I am not sure what you mean.

The property editor iterates over the properties and displays them grouped by the class they are declared in, starting with QObject, ending with the actual class itself.

E.g. if you look at the properties of a QPushButton, the first section has the properties of QObject, then QWidget, then QAbstractButton, then QPushButton.

So if you derive from QPushButton and add another property, it will be in its own section, following the QPushButton section.

Cheers,
_

[Big_Stone88]

That's exactly my problem:
My ui is a

mainWindow : QMainWindow

mainWindow : QMainWindow

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when I select the mainWindow in the object-tree, there are only three categories in the property editor: QObject, QWidget and QMainWindow. There is no Category as the name of my class "mainWindow" (see following pic).
PropertyEditor.PNG
even if I build two new classes (Form1 : QWidget AND Form2 : Form1) and i set a Q_Property with the name smallText in Form1, i see in the property-editor of "Form2" neither a category "Form1" nor a property "smallText" in any other category.

What am i doing wrong?
Thanks for your help

Robby

[anda_skoa]

That's exactly my problem:
My ui is a

mainWindow : QMainWindow

mainWindow : QMainWindow

To copy to clipboard, switch view to plain text mode 

when I select the mainWindow in the object-tree, there are only three categories in the property editor: QObject, QWidget and QMainWindow. There is no Category as the name of my class "mainWindow" (see following pic).

The type is QMainWindow, as you can see in the second column in the object tree view.

even if I build two new classes (Form1 : QWidget AND Form2 : Form1) and i set a Q_Property with the name smallText in Form1, i see in the property-editor of "Form2" neither a category "Form1" nor a property "smallText" in any other category.

Does the designer plugin that provides "Form1" create instances of Form1 or maybe just QWidget?
Does Form1 have the Q_OBJECT macro additional to the Q_PROPERTY macro?

Cheers,
_