QT OpenCV Play Pause and Stop Video

Stevendragoes

maybe @J.Hilk could help me?

jsulm

@Stevendragoes Can you show the destructor of your MainWindow?
Also, when closing your app you should first stop the playback if active.

Stevendragoes

@jsulm this is my destructor

MainWindow::~MainWindow()
{
    cap.release();
    delete ui;
}

Stevendragoes

@jsulm I have also attached the close event captured for reference

void MainWindow::closeEvent(QCloseEvent *event)    //To confirm that the user really wants to quit the application
{
    QMessageBox::StandardButton exitBtn = QMessageBox::question( this, "MainWindow",tr("Are you sure you want to exit?\n"), QMessageBox::Cancel | QMessageBox::No | QMessageBox::Yes,QMessageBox::Yes);
    if (exitBtn == QMessageBox::Yes) {
        event->accept();
    } else {
        event->ignore();
    }
}

jsulm

@Stevendragoes I would stop the timer in closeEvent if it is running and user wants to quit.

Stevendragoes

Hi @jsulm I have implemented timer->stop() but it still gives me the same error. I am not too sure why.

Stevendragoes

Hi @jsulm
I think i have solved the problem

w.setAttribute(Qt::WA_DeleteOnClose, true);

this was inside the main.cpp. I am not sure why this happens.

jsulm

@Stevendragoes said in QT OpenCV Play Pause and Stop Video:

w.setAttribute

What is w? Maybe it was double delete?

jsulm

@Stevendragoes said in QT OpenCV Play Pause and Stop Video:

w.set

Now I see the problem: w is allocated on the stack and there is no need to delete it explicitly (what Qt::WA_DeleteOnClose does), so it was double delete.

Stevendragoes

@jsulm I suspect is double delete. w is the MainWindow Setup in the main.cpp
The Code is as follows

#include "mainwindow.h"
#include <QApplication>                                         //Widgets Events Handling, Mouse Movements


int main(int argc, char *argv[])                                //All Executions are going to begin
{
    QApplication a(argc, argv);                                 //Create the QApplication Object to Handle Events etc.
    MainWindow w;
    w.showMaximized();
    w.show();
    return a.exec();
}

on other hand, do u mind if use my solution to mark it as solved?

Stevendragoes

@jsulm
Thank you so much for your assistance in these few days. Now I need to move on to interfacing with an inbuilt camera or USB connected camera to do my object tracking.

jsulm

@Stevendragoes There is no need for Qt::WA_DeleteOnClose, see my previous comment.