Application crashes when mouse moves

SherifOmran

When i run through the debugger it says the inferior stopped because
it received a signal from the os
EXC_bad_access
could not access memory

Mac os: 10.7.5
QT creator : 2.4.1
based on 4.7.6
build on jan 25 12

SGaist

You should have a backtrace of what is happening when the crash occurred, what is it ?

SherifOmran

the object window -> creates another highlighting object
at some instance which i don't know when (may be when writing in high speed), the highlighting object is called, it tries to make the paint event but at the same time, there might be other events (i don't know what is it) and they crash together ..

It seems that some object is not correctly deleted ... i don't know how to find it ..

SherifOmran

I installed valgrind in /usr/bin/ i see in it a file called vgrind
but when i do in QT - Analyze - Valgrind analyze memory or function i get

Analyzing memory of /login
** Error: "valgrind" could not be started: No such file or directory **
** Analyzing finished **

I installed valgrind this way

cd /Volumes/Macintosh\ HD/Users/so/Downloads/valgrind-3.9.0
./configure --prefix=/usr/bin
make
sudo make install

SGaist

Try giving the full path in Qt Creator.

Are you using delete on these objects or call deleteLater ?

SherifOmran

yes i use delete after the object finishes ..
I managed to install valgrind correctly and now i have the analyze-memory and function working .. which one should i use to find what hangs up while deleting the object?

SGaist

If these are QObject derived classes you should rather use deleteLater

SherifOmran

Lets try to find the mistake because i am struggling since 2 days and don't see it ..

Header file
@
#ifndef PRACTISING_H
#define PRACTISING_H

#include <QKeyEvent>
#include <QWidget>

#include "highlighter.h"
#include "typingtutormain.h" //1
#include "keygramform.h"

#include <QBitArray>
#include "keyboardmap.h"
#include "practisehandwin.h"
//#include "qgarbagecollector.h"

namespace Ui {
class practising;

}

class practising : public QDialog
{
Q_OBJECT

public:
practising(bool traintestmode, int mintext, int maxtext, QWidget *parent);
~practising();
TypingTutorMain *mainparentform; //2
void handwindowcloseevent();
inline void setWindowPositionAndSize(const QRect& fg) {resize(fg.size()); move(fg.topLeft());}
inline QRect windowPositionAndSize() const { return QRect(pos(), size()); }

private slots:
void on_previous_Btn_clicked();
void on_next_Btn_clicked();
void on_start_Btn__clicked();
void on_stop_Btn_clicked();
void timercount(void);
void lostfocus();

private:
Ui::practising *ui;
QPointer <Highlighter> highlighter;
QPointer <KeyBoardMap> kbmap;
QPointer <QDesktopWidget> d; // for window size
QTime PracticeTimer; // Timer in the practise (Stop watch)
QPointer <QTimer> PractiseTimerFire; // Timer fireing each 1 sec to count the stop watch
// QScopedPointer <QTimer> PractiseTimerFire;
QPointer <practisehandwin> handpop;
QPointer <QScrollBar> sb;

};

#endif // PRACTISING_H

@

Highlighter class
@
class Highlighter : public QSyntaxHighlighter
{
Q_OBJECT
public:
@

keyboard map class
@

class KeyBoardMap : public QDialog
{
Q_OBJECT

public:

@

@
practising::~practising()
{

qDebug() << "practise done return";
done(1);
qDebug() << "practising::~practising";

//delete ui; // it will be deleted there in the calling form

}

void practising::closeEvent(QCloseEvent *event)
{
qDebug()<< "practising::closeEvent";

PractiseTimerFire->stop();
QObject::disconnect(PractiseTimerFire,0);

qDebug()<<"to delete highlighter";
delete highlighter;

qDebug() << "to delete keyboard map ";
delete kbmap;

qDebug() << "to delete timer";
delete PractiseTimerFire;

qDebug() << "to delete handpop";
delete handpop;

qDebug() << " delete scroll bar";
delete sb;

qDebug() << " ------------";


if (handwindowenabled==true) //if handwindow is open
{
   qDebug() << "practising:close-1";
   //handpop.data()->close();
   //QMetaObject::invokeMethod(handpop, "close", Qt::QueuedConnection);//important line
   //delete handpop;
   //handpop.data()->deleteLater();
}
this->mainparentform->show();
//event->accept();

qDebug() << "closesevent - first part pass" << handpop.isNull();



delete d;
//delete inst_speed;
//delete inst_speed_correct;
//delete inst_speed_correct_diff;
//delete inst_speed_timepassd;

//Practise_AddToDataBase(); // Add data to dB

qDebug() << "closever 2";
//Q_UNUSED(event); //unreferenced formal parameter
qDebug() << "closever 3";
quitpractise = true;

//delete ui;

}

@

SherifOmran

should QSyntaxHighlighter be also treated with deletelater?

SGaist

You are doing things in a pretty unusual way.

Why use closeEvent to destroy everything ? In your case the destructor is there for that.

Why are you using QPointer for everything ? It's not it's purpose

Also, you are probably deleting objects that have parent that would be destroyed automatically when "practicing" is destroyed.

Also, why windowPositionAndSize ? look at QWidget::geometry()

SherifOmran

I am still learning QT ... I will take the pointer one by one for me to learn ..
First, lets take the QTimer, i want to get initialized when i press on start button
@
QTimer *PractiseTimerFire = new QTimer(this);
connect(PractiseTimerFire, SIGNAL(timeout()),this, SLOT(timercount()));
PractiseTimerFire->start(1000);
@

I need to disable it when i click on the Stop button, but it is then not defined .. I need to cast it but don't know how .. Could you please help me?

SherifOmran

I use the widget::close event because the widget is a second window called from a first window , and i want the first window to be visible back, so i made a parent child mechanism ..

SherifOmran

I have it now solved ... I sent a message from the child to a parent method called (closepractise) in order to close the child .. it worked ..

Vielen Dank .. Allerdings ich brauche Unterstützung in der Zukunft

SGaist

Depending on how you create the dialog you should not even need that

SherifOmran

I want to ask a simple question because i don't know its answer, Please ..

lets says in mainwindow, i create a new window called A
QWidget A=new QWidget(0)

Inside A, i want to create a new window that is located beside A and it should be a child ..
If i say
QWidget B=new QWidget (A) -> it will be inside window A
so i must call it
QWidget B=new QWidget (0) -> to make a new window
but then B is not a child of A and will not close if A is closed ..

SGaist

Then it all depends on how you use that window. Is B a member of A ? If so you can e.g. reimplement closeEvent and also close B in there. If not create a signal that you emit from A when it's closing and connect it to B's close slot

SherifOmran

What you mean by B member of A? B is a window, A is also a window
I imlemented your signalling idea but i want ask : I used to do it the following way, is it correct?

@
qPointer <handpop> qWidget;
QWidget handpop = new QWidget (0);

if (!handpop.isNull())
{
    handpop.data()->close();
}
delete handpop;

@

SherifOmran

I tested the signal method but it is not good, it breaks
in practising i create a handwindow
@
handpop = new practisehandwin(0);
connect(this,SIGNAL(destroyed()),handpop.data(),SLOT(close()));
@

I tested also with by emitting a signal to the handpop to close it self ..

SherifOmran

In the main module called typingmain, i do the following with the practiseform

typingmain.cpp
@
QPointer <practising> practiseform = new practising(true,1,0,0); // practise mode, default lesson min=1, lessonmax=0, new parent window=0
practiseform->mainparentform=this; connect(practiseform.data(),SIGNAL(ToTypingDeletePractise(int)),this,SLOT(CloseChild(int));
this->hide();
int x=practiseform->exec();
if (qDebugDemo>=2) {qDebug() << "returned back";}
this->show();
if (qDebugDemo>=1) {qDebug () << "practise finished with return =" << x << " is window reset?" << practiseform.isNull();}
if (! practiseform.isNull())
{
qDebug() << "delete practiseform";
//delete practiseform;
}
@

In practising, i load the handpop when a button is clicked
practising.cpp
@
if (!handwindowenabled)
{
handpop = new practisehandwin(0);
//connect(this,SIGNAL(destroyed()),handpop.data(),SLOT(close()));
//QScopedPointer<practisehandwin> handpop(new practisehandwin(0));
}
@

Then when it closes, i delete the handpop and emit a signal back to typingmain to delete the practising pointer
@
void practising::closeEvent(QCloseEvent *event)
{
if (qDebugDemo>=2)
{ qDebug()<< "practising::closeEvent";
qDebug() << "to delete handpop";
}
if (!handpop.isNull())
{
//emit(this->ToHandWindowDeleteYourSelf());
handpop.data()->close();
}
delete handpop;

PractiseTimerFire->stop();
disconnect(PractiseTimerFire,0);

if (qDebugDemo>=2) {qDebug()<<"to delete highlighter";}
delete highlighter;

if (qDebugDemo>=2) {qDebug() << "to delete keyboard map ";}
delete kbmap;

if (qDebugDemo>=2) {qDebug() << "to delete timer";}
delete PractiseTimerFire;



if (qDebugDemo>=2) {qDebug() << " delete scroll bar";}
delete sb;

if (qDebugDemo>=2) {qDebug() << " ------------";}

this->done(1);
emit(this->ToTypingDeletePractise(1));
if (qDebugDemo>=2) {qDebug() << "practise close me signal emitted";}



//this->mainparentform->show();
//event->accept();

qDebug() << "closesevent - first part pass" << handpop.isNull();


//delete inst_speed;
//delete inst_speed_correct;
//delete inst_speed_correct_diff;
//delete inst_speed_timepassd;

//Practise_AddToDataBase(); // Add data to dB

//Q_UNUSED(event); //unreferenced formal parameter
//qDebug() << "closever 3";
quitpractise = true;
//delete ui;
//event->ignore();

}
@

in typingmain
@
void TypingTutorMain::CloseChild(int childnumber)
{
switch (childnumber)
{
case 1:
if (! practiseform.isNull())
{
qDebug()<<"signal received delete practise follows";
practiseform.data()->deleteLater();
qDebug() << "is practise deleted?"<< practiseform.isNull();
}
}
}
@

Note that if i use
//QScopedPointer<practising> practiseform(new practising(true,1,0,0));
it which is the same as QPointer but it deletes it self automatic, it crashes, even if i disable emiting the ToTypingDeletePractise signal

I don't know if i close the handpop correctly

SGaist

It looks like your are using dialogs and not just widget and you only use them locally. So just don't create pointers to QDialogs if the logic is:

Create dialog

Ask something to the user

Get result

Delete dialog

You really should first go through the examples in Qt's documentation. You are starting to write code that is going to be a nightmare to follow and maintain.