Not receiving a signal from a subclassed QVideoWidget

Question

I'm developing a video player application, I have subclassed QVideoWidget, then I promoted QWidget in my ui file to this subclassed QVideoWidget.

Now I want to call a function defined in another class by a signal from the subclassed QVideoWidget.

So I defined a signal that I emit when the user presses the videowidget, and connected it to a slot in the other class (the function I want to call), but the slot never gets called.

videowidget.h :

#ifndef VIDEOWIDGET_H
#define VIDEOWIDGET_H

#include <QVideoWidget>
#include <QMouseEvent>
#include <QObject>

class videowidget : public QVideoWidget
{
    Q_OBJECT
public:
     videowidget();
signals:
    void videoClicked();
protected:
    void mouseDoubleClickEvent(QMouseEvent *event) override;
    void mousePressEvent(QMouseEvent *event) override;
};
#endif // VIDEOWIDGET_H

videowidget.cpp :

#include "videowidget.h"
videowidget::videowidget()
{

}

void videowidget::mouseDoubleClickEvent(QMouseEvent *event)
{

    setFullScreen(!isFullScreen());
    event->accept();
}

void videowidget::mousePressEvent(QMouseEvent *event)
{
    if(event->button() == Qt::LeftButton)
    {
        emit videoClicked();
    }
    else
    {
        return;
    }
}

widget.h :

private slots:
     void videoClicked();
private:
   videowidget *videoPlayer;

widget.cpp :

Widget::Widget()
{
    videoPlayer = new videowidget();

    /*Widget*/
    Bottom = ui->Bottom; /*Bottom was declare in Player.h as a QWidget*/
    connect(videoPlayer, &videowidget::videoClicked, this, &Widget::videoClicked);
}

void Widget::videoClicked()
{
    Bottom->setVisible(false);
    qDebug()<<"pressed from slot";
}

If I print something in the function that emits the signal, it works, but the slot from the other class is never called.

I also have tried to directly print a string instead of calling the slot, but it also doesn't work.

Answer 1

Here's a minimal reproducible example with comments to explain what was wrong and how to fix it:

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QVideoWidget>
#include "videowidget.h"

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();

private slots:
    void videoClicked();

private:
    Ui::Widget *ui;
    videowidget *videoPlayer;
    QWidget *Bottom;
};
#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "./ui_widget.h"
#include "videowidget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    
    //The problem's here

    //this new object is unnecessary and it's not being set visible 
    videoPlayer = new videowidget(this);
     
    ui->video_player->show();

    //I removed Bottom because it was an unnecessary intermediate
    //use ui->video_player directly as a sender, since it is the promoted widget
    //and the one being displayed and clicked
    connect(ui->video_player, &videowidget::videoClicked, this, &Widget::videoClicked);
    
    //videoPlayer was not the widget you were clicking, hence why you never got a response
    //connect(videoPlayer, &videowidget::videoClicked, this, &Widget::videoClicked);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::videoClicked()
{
    qDebug()<<"pressed";
    ui->video_player->setVisible(false);
}

videowidget.h

#ifndef VIDEOWIDGET_H
#define VIDEOWIDGET_H

#include <QVideoWidget>
#include <QMouseEvent>

class videowidget : public QVideoWidget
{
    Q_OBJECT

public:
    videowidget(QWidget *parent = nullptr);

signals:
    void videoClicked();

protected:
    void mouseDoubleClickEvent(QMouseEvent *event) override;
    void mousePressEvent(QMouseEvent *event) override;
};

#endif // VIDEOWIDGET_H

videowidget.cpp

#include "videowidget.h"

videowidget::videowidget(QWidget *parent)
{
}

void videowidget::mouseDoubleClickEvent(QMouseEvent *event)
{
    setFullScreen(!isFullScreen());
    event->accept();
}

void videowidget::mousePressEvent(QMouseEvent *event)
{
    if(event->button() == Qt::LeftButton)
    {
        videoClicked();
    }
}