Crash application after delete window

[ecspertiza]

I have interesting example. We are have qml form, and button. After click need close window and delete window. Simple. But application stable crash. Example:

main.cpp

#include <QApplication>
 
#include "windowmanager.h"
 
int main(int argc, char *argv[])
{
 * *QApplication a(argc, argv);
 
 * *WindowManager manager;
 * *manager.showWindow();
 
 * *return a.exec();
}

#include <QApplication>

#include "windowmanager.h"

int main(int argc, char *argv[])
{
 * *QApplication a(argc, argv);

 * *WindowManager manager;
 * *manager.showWindow();

 * *return a.exec();
}

To copy to clipboard, switch view to plain text mode 

windowmanager.h

#ifndef WINDOWMANAGER_H
#define WINDOWMANAGER_H
 
#include <QObject>
#include <QDeclarativeView>
 
class WindowManager : public QObject
{
 * *Q_OBJECT
 * *public:
 * * * *explicit WindowManager(QObject *parent = 0);
 
 * * * *void showWindow();
 * * * *Q_INVOKABLE void closeWindow();
 
 * * * *QDeclarativeView *window();
 
 * *private:
 * * * *QDeclarativeView *m_window;
 
};
 
#endif // WINDOWMANAGER_H

#ifndef WINDOWMANAGER_H
#define WINDOWMANAGER_H

#include <QObject>
#include <QDeclarativeView>

class WindowManager : public QObject
{
 * *Q_OBJECT
 * *public:
 * * * *explicit WindowManager(QObject *parent = 0);

 * * * *void showWindow();
 * * * *Q_INVOKABLE void closeWindow();

 * * * *QDeclarativeView *window();

 * *private:
 * * * *QDeclarativeView *m_window;

};

#endif // WINDOWMANAGER_H

To copy to clipboard, switch view to plain text mode 

windowmanager.cpp

#include "windowmanager.h"
 
#include <QDeclarativeContext>
 
WindowManager::WindowManager(QObject *parent) : QObject(parent), m_window(0)
{
}
 
void WindowManager::showWindow()
{
 * *window()->show();
}
 
void WindowManager::closeWindow()
{
 * *m_window->close();
 
 * *if (m_window != 0) {
 * * * *delete m_window;
 * * * *m_window = 0;
 * *}
}
 
QDeclarativeView *WindowManager::window()
{
 * *if (m_window == 0) {
 * * * *m_window = new QDeclarativeView(0);
 
 * * * *m_window->rootContext()->setContextProperty("manager",this);
 * * * *m_window->setSource(QUrl("qrc:/main.qml"));
 * *}
 
 * *return m_window;
}

#include "windowmanager.h"

#include <QDeclarativeContext>

WindowManager::WindowManager(QObject *parent) : QObject(parent), m_window(0)
{
}

void WindowManager::showWindow()
{
 * *window()->show();
}

void WindowManager::closeWindow()
{
 * *m_window->close();

 * *if (m_window != 0) {
 * * * *delete m_window;
 * * * *m_window = 0;
 * *}
}

QDeclarativeView *WindowManager::window()
{
 * *if (m_window == 0) {
 * * * *m_window = new QDeclarativeView(0);

 * * * *m_window->rootContext()->setContextProperty("manager",this);
 * * * *m_window->setSource(QUrl("qrc:/main.qml"));
 * *}

 * *return m_window;
}

To copy to clipboard, switch view to plain text mode 

main.qml

import QtQuick 1.1
 
Item {
 * *width: 500
 * *height: 500
 
 * *Rectangle {
 * * * *width: 200
 * * * *height: 200
 
 * * * *anchors.centerIn: parent
 
 * * * *color: "red"
 
 * * * *Text {
 * * * * * *anchors.centerIn: parent
 * * * * * *color: "white"
 
 * * * * * *text: "Click for crash"
 * * * *}
 
 * * * *MouseArea {
 * * * * * *anchors.fill: parent
 
 * * * * * *onClicked: {
 * * * * * * * *manager.closeWindow();
 * * * * * *}
 * * * *}
 * *}
}

import QtQuick 1.1

Item {
 * *width: 500
 * *height: 500

 * *Rectangle {
 * * * *width: 200
 * * * *height: 200

 * * * *anchors.centerIn: parent

 * * * *color: "red"

 * * * *Text {
 * * * * * *anchors.centerIn: parent
 * * * * * *color: "white"

 * * * * * *text: "Click for crash"
 * * * *}

 * * * *MouseArea {
 * * * * * *anchors.fill: parent

 * * * * * *onClicked: {
 * * * * * * * *manager.closeWindow();
 * * * * * *}
 * * * *}
 * *}
}

To copy to clipboard, switch view to plain text mode 

If i use, deleteLater() then applicaition crash in 20% users. If i user hotkey for delete window, all work is good, but why app crash in click button?

[anda_skoa]

I would definitely use deleteLater() since otherwise you are basically doing a "delete this" (code in Window and its QML engine still being executed at time of delete).

You will have to debug the crash to see where it happens, though.
E.g. run the application in a debugger.

The user closing the window manually is different, as this doesn't delete the window.

Cheers,
_

[ecspertiza]

Initially im use deleteLater() and in 80% of cases application work is wery good. But on mac os 20% users catch crash. delete - help for me localization problem. In debug i see, application crash in

QCoreApplication::notifyInternal(QObject *, QEvent *)

and delete and deleteLater().

[anda_skoa]

Hmm, that is indeed not a lot to go on.

Do you need to delete the window?

I.e. it is not being deleted when the user closes it, so I am wondering why you need to delete it when you are closing it from code.

Cheers,
_

[ecspertiza]

I`m find solution. I`m delete window not after close() are before show()

if (window != 0) {
  delete window;
  window = 0;
}
 
window = new QDeclarativeView();
window->show();

if (window != 0) {
  delete window;
  window = 0;
}

window = new QDeclarativeView();
window->show();

To copy to clipboard, switch view to plain text mode 

[anda_skoa]

you can call delete window even without the check for != 0 first,
Delete is defined to do nothing on a null pointer.

Cheers,
_