Debug output when calling QToolBar::addAction()

[Perdrix]

I'm getting a debug output message:

QObject::connect: Use the SLOT or SIGNAL macro to connect DEditStars::dragButtonPressed

when I do:

    QToolBar t(&w);
    QIcon dragRect("C:/Users/amonra/Documents/GitHub/DSS/DeepSkyStacker/Buttons/ButtonSelect_Up.bmp");
    t.setOrientation(Qt::Vertical);
    t.addAction(dragRect, "", &editor, "dragButtonPressed");

clearly Qt doesn't love me a lot, but why?

[JonB]

@Perdrix said in Debug output when calling QToolBar::addAction():
Just to be 100% clear, and get you on the right track of new syntax so you will like it(!), as @Pl45m4 has said the whole line needs to be:

t.addAction(dragRect, "", &editor, &DEditStars::dragButtonPressed);

Page https://wiki.qt.io/New_Signal_Slot_Syntax gives you comparative examples.

[Bonnie]

because you didn't give it a slot, but a normal string...

[Pl45m4]

@Perdrix

Is DEditStars a QObject? Do you have Q_OBJECT macro in this class? Is your function dragButtonPressed a slot?

And dont put the function name in double quotes, like @Bonnie already said

https://doc.qt.io/qt-5/qtoolbar.html#addAction-3

[Perdrix]

Yes, yes and yes!

#include <QObject>
class DEditStars :
    public QObject
{
    Q_OBJECT

typedef QObject
        Inherited;

public:
    DEditStars() :
        QObject()
    {
    };

    virtual ~DEditStars() {};

public slots:
    void mousePressEvent(QMouseEvent* e);
    void mouseMoveEvent(QMouseEvent* e);
    void mouseReleaseEvent(QMouseEvent* e);

    void dragButtonPressed();

};

Don't put function name in "" ??? The function sig:

QAction *QToolBar::addAction(const QIcon &icon, const QString &text, const QObject *receiver, const char *member)

requires it to be in ""

David

[JonB]

@Perdrix

• What type is your editor?
• Do a delete of all files in your debug/release directory, and rebuild. Qt can get in a mess over its Q_OBJECT macros and other things, sometimes this happens and this fixes.
• typedef QObject Inherited;: probably irrelevant, just wondering whether this could have any detrimental effect on moc etc.
• dragButtonPressed is a slot of your own you have created?

Oh, you didn't make clear:

I'm getting a debug output message:

QObject::connect: Use the SLOT or SIGNAL macro to connect DEditStars::dragButtonPressed

At first I thought you meant at compile-time, now I'm thinking you mean at runtime when the addAction() is hit?

In any case please do the complete rebuild before going any further....

[Perdrix]

Editor is of type DEditStars as you might hope.

Never had a problem using that sort of typedef before.

Yes this is at RUNTIME when addAction is invoked (after a full cleanup and rebuild):

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QPixmap p("C:\\Users\\amonra\\Documents\\Astrophotography\\NGC 7789 Caroline's Rose or Herschel's Spiral Cluster\\NGC7789 Edited large.png");
    DSSImageWidget w(p);
    DEditStars editor;
    QObject::connect(&w, &DSSImageWidget::Image_mousePressEvent, &editor, &DEditStars::mousePressEvent);
    QToolBar t(&w);
    QIcon dragRect("C:/Users/amonra/Documents/GitHub/DSS/DeepSkyStacker/Buttons/ButtonSelect_Up.bmp");
    t.setOrientation(Qt::Vertical);
    t.addAction(dragRect, "", &editor, "dragButtonPressed()");
    //t.setFixedSize(50, 50);
    t.setIconSize(QSize(48, 48));
    w.setToolBar(&t);
    w.show();
    return a.exec();
}

Debug log snippet:

'DSSImageWidget.exe' (Win32): Loaded 'C:\Qt\5.15.0\msvc2019_64\plugins\imageformats\qwebpd.dll'. Symbols loaded.
QObject::connect: Use the SLOT or SIGNAL macro to connect DEditStars::dragButtonPressed()
'DSSImageWidget.exe' (Win32): Loaded 'C:\Windows\System32\d3d9.dll'. 

[JonB]

@Perdrix

• So editor is of type DEditStars and not DEditStars *, right?

• I certainly would not expect it to work with "dragButtonPressed()", it would need to be "dragButtonPressed" as you showed originally.

• (Temporarily) give up on this constructor. Create the action with an overload which does not take that, and set the signal/slot on the QAction's triggered after it is created. Can you get that to work?

P.S.
[signal]void QAction::triggered(bool checked = false)

Your problem may (well?) be that you need your dragButtonPressed() slot to be declared with that (optional) parameter, in order to match correctly?

[jsulm]

@Perdrix said in Debug output when calling QToolBar::addAction():

QObject::connect: Use the SLOT or SIGNAL macro to connect DEditStars::dragButtonPressed()

This tells you exactly what the problem is.
It should be:

t.addAction(dragRect, "", &editor, SLOT(dragButtonPressed()));

[JonB]

@jsulm
The OP is trying to use the following overload:

QAction *QToolBar::addAction(const QIcon &icon, const QString &text, const QObject *receiver, const char *member)

https://doc.qt.io/qt-5/qtoolbar.html#addAction-3

The action's triggered() signal is connected to member in receiver.

Note how the last argument is of type const char *, for the name of a member function.

[jsulm]

@JonB He still has to use SLOT, see https://doc.qt.io/qt-5/qobject.html#connect - it has char* also, but you have to use SLOT/SIGNAL macros, not just plain string containing slot/signal name.

[JonB]

@jsulm

but you have to use SLOT/SIGNAL macros, not just plain string containing slot name.

Ohhh, well that's not very clear from the docs: "the name of a member function" :) I took the docs as indicating as he did in his original post!

@Perdrix
So follow @jsulm's answer! Though TBH you would be far better getting rid of all SIGNAL/SLOT() macros/methods, and doing it new-style, as I say over & over in this forum :) Then the issue would not arise....

P.S.
That would be template <typename Functor> QAction *QToolBar::addAction(const QIcon &icon, const QString &text, const QObject *context, Functor functor), overload https://doc.qt.io/qt-5/qtoolbar.html#addAction-7.

[jsulm]

@JonB said in Debug output when calling QToolBar::addAction():

getting rid of all SIGNAL/SLOT()

this!

[Perdrix]

In the context of that code I tried:

t.addAction(dragRect, "", &editor, &DEditStars::dragButtonPressed());

and was awarded this nastygram:

1>C:\Users\amonra\Documents\source\repos\QImageView\QImageView\main.cpp(17,53): error C2352: 'DEditStars::dragButtonPressed': illegal call of non-static member function
1>C:\Users\amonra\Documents\source\repos\QImageView\QImageView\deditstars.h(61): message : see declaration of 'DEditStars::dragButtonPressed'

trying with:

t.addAction(dragRect, "", &editor, &editor.dragButtonPressed());

got me:

1>C:\Users\amonra\Documents\source\repos\QImageView\QImageView\main.cpp(17): error C2102: '&' requires l-value

This:

    t.addAction(dragRect, "", &editor, SLOT(dragButtonPressed()));

Does work, but it definitely is NOT clear that what you need to code from the docs. If you want me to use the other formats - how do they go?
So hows it supposed to go?

[Bonnie]

@Perdrix
Do you know how to call connect?
It is exactly the same...

[Pl45m4]

@Perdrix

&DEditStars::dragButtonPressed

New syntax without ( )

[JonB]

@Perdrix said in Debug output when calling QToolBar::addAction():
Just to be 100% clear, and get you on the right track of new syntax so you will like it(!), as @Pl45m4 has said the whole line needs to be:

t.addAction(dragRect, "", &editor, &DEditStars::dragButtonPressed);

Page https://wiki.qt.io/New_Signal_Slot_Syntax gives you comparative examples.