Using Q_DECLARE_METATYPE

[grsabourin]

Hi,

I'm derivating a class from QGraphicsView. When I add some mouse event function in this class as the following

void mousePressEvent(QMouseEvent *event);
void mouseMoveEvent(QMouseEvent *event);
void mouseReleaseEvent(QMouseEvent *event);

I received the following error

Error C2338 Type is not registered, please use the Q_DECLARE_METATYPE macro to make it known to Qt's meta-object system (compiling source file GeneratedFiles\Debug\moc_MyFile.cpp)

It seems I need to add Q_DECLARE_METATYPE to my code. The compiler error is in the moc file.

1 - Do I need to add it in the moc file or in MyFile.h?

2 -For the mouse event, what metatype I need to define?

[raven-worx]

@grsabourin
no line of code you've posted makes use of any meta-types
So the problem comes from somewhere else in your code i guess

don't declare your mouse-handlers as slots

[dheerendra]

I don't see any issue with your above function. You need to use this macro to register if there is a new user defined data type you are using. We suspect that you are using some User defined data type somewhere. It may be coming from signal/slots.

Please help us with complete class file. It should help us to find the issue.

[raven-worx]

@grsabourin

1 - Do I need to add it in the moc file or in MyFile.h?

you never ever need to edit the moc file, since this is generated again in the next build anyway.

2 -For the mouse event, what metatype I need to define?

The overridden mouse event handlers do not need a meta-type to be registered.

What are you doing in your reimplemented mouse handlers?
A meta type needs to be registered when you want to put a custom type into a QVariant or emit a signal with a custom type parameter via a queued connection.

[grsabourin]

Thank you for your answers. Yes I understand that the moc file will be rewrite at each build

This is complete code of my class. For now it is just a starting point is the class is doing mostly nothing

MyFile.h
#pragma once
#include <QGraphicsView>
#include <QMouseEvent>
#include <QMetaType>
#include <Qt>

#include <fstream>

class MyFile : public QGraphicsView
{
Q_OBJECT

public:
MyFile(QWidget * parent = Q_NULLPTR);
~MyFile();

void LoadViewImage(QImage &in_QImage);
void Refresh();

private slots :
void mousePressEvent(QMouseEvent *event);
void mouseMoveEvent(QMouseEvent *event);
void mouseReleaseEvent(QMouseEvent *event);

private:

QImage m_image;

};

MyFile.cpp
#include "MyFile.h"

MyFile::MyFile(QWidget * parent) : QGraphicsView ( parent )
{

}

MyFile::~MyFile()
{

}

void MyFile::LoadViewImage(QImage &in_image)
{
m_image = in_image;
}

void MyFile::Refresh()
{
resetCachedContent();
QGraphicsScene * graphic = new QGraphicsScene(this);
graphic->addPixmap(QPixmap::fromImage( displayImage ) );
setScene(graphic);
}

void MyFile::mousePressEvent(QMouseEvent *event)
{
if (event->buttons() == Qt::LeftButton)
{

}
else if (event->buttons() == Qt::RightButton)
{
}

}

void ImageView::mouseMoveEvent(QMouseEvent *event)
{
}

void ImageView::mouseReleaseEvent(QMouseEvent *event)
{

}

[raven-worx]

@grsabourin
no line of code you've posted makes use of any meta-types
So the problem comes from somewhere else in your code i guess

don't declare your mouse-handlers as slots

[grsabourin]

You are right. It solve my issue. Thank you for your help.

[aha_1980]

@grsabourin Glad you figured it out. So please mark this topic as SOLVED too.

Thanks!