Solved: QTabObject with QTableWidgetItem crash on delete

SherifOmran

Hello,

I have QTab object and in one tab, i have QTable on it. When the form unloads, it crashes.
The form is called from main as pointer

my h file
@
#ifndef REPORTWIN_H
#define REPORTWIN_H

#include <QDialog>
#include "tmain.h" //1
#include <QCloseEvent>

namespace Ui {
class reportwin;
}

class reportwin : public QDialog
{
Q_OBJECT

public:
explicit reportwin(QWidget *parent = 0);
~reportwin();
TMain *mainparentform; //2

protected:
void closeEvent(QCloseEvent *event); //3

private slots:

private:
Ui::reportwin *ui;
void preparegraph(int graphtype);
void initializeModel(QSqlTableModel *model);
QPointer <QTableWidget> table;
QHBoxLayout *layout;

};

#endif // REPORTWIN_H

@

here is how i create the table

@
layout=new QHBoxLayout(this);
table = new QTableWidget(rows, cols, this);
QStringList Header;
Header << " Date & Time" << " Number " << " Average Typing Speed " << " % Correct " << " % completed";
for (int r=0; r<rows; ++r)
{
for (int c = 0; c < cols; ++c)
{
QString character = Header.at(c);
table->setHorizontalHeaderItem(c, new QTableWidgetItem(character));

    QTableWidgetItem *dateitem = new QTableWidgetItem();
    dateitem->setText(practisedata.datestring.at(r));
    table->setItem( r, 0, dateitem );
    QTableWidgetItem *number = new QTableWidgetItem( practisedata.log1_practisetestnumber.at(r));
    table->setItem( r, 1, number )

}
}
table->setItemPrototype(table->item(rows -1, cols - 1));
table->setGeometry(QRect(55,90,660,300));
//table->show();
layout->addWidget(table);
this->ui->Training_tab1->setLayout(layout);

@

here is my main file
@
QPointer <reportwin> report = new reportwin(0);
report->mainparentform=this;

    //report->deleteLater();
    this->hide();
    report->exec&#40;&#41;;
    report->done(1&#41;;

// //delete report; // still not working, data still exist even after call
// QObjectCleanupHandler *cleaner=new QObjectCleanupHandler;
// cleaner->add(report);
// cleaner->deleteLater();

    qDebug() << " exit report" << report.isNull();

@

I tried delete later but it crashes, i tried the object cleaner but same result. I tried to delete the pointer but the same. I understand from the QT crash report that it has difficulty deleting the QTab or the QTableWidget

Any help is appreciated

Mario84

you should not call "delete report" since report is no pointer but a simple (stack) instance of QPointer. QPointer is an object that holds a pointer and behaves like one.
you could try to call "delete report->data();" but its probably better to use QSopedPointer. This class deletes the pointer it holds automatically in its destructor or when you call "reset()"

SherifOmran

I tried delete report->data(); but same result .. Can you show me how to use QScopedpointer? because i never used it before ..
thanks

SherifOmran

I use this now
@
QScopedPointer<reportwin> report(new reportwin(0));
@
I removed the delete phrase but then it crashes also
@
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 QtGui 0x0000000100cdcaf9 QTableModel::~QTableModel() + 41
1 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
2 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
3 QtGui 0x0000000100cd8a66 QTableWidget::~QTableWidget() + 38
4 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
5 QtGui 0x00000001007b39b9 QWidget::~QWidget() + 713
6 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
7 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
8 QtGui 0x0000000100bad8a9 QStackedWidget::~QStackedWidget() + 41
9 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
10 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
11 QtGui 0x0000000100bbac76 QTabWidget::~QTabWidget() + 38
12 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
13 QtGui 0x00000001007b39b9 QWidget::~QWidget() + 713
14 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
15 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
16 QtGui 0x0000000100bad8a9 QStackedWidget::~QStackedWidget() + 41
17 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
18 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
19 QtGui 0x0000000100bbac76 QTabWidget::~QTabWidget() + 38
20 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
21 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
22 QtGui 0x0000000100b4af49 QFrame::~QFrame() + 41
@

SherifOmran

I found the mistake ..

there must be an empty unfilled row at the end of the table, otherwise it crashes
@
rows=rows+1;
@
@
table = new QTableWidget(rows, cols, this); // note to avoid crashing: there must be 1 empty row at the end
QStringList Header;
Header << " Date & Time" << " Number " << " Average Typing Speed " << " % Correct " << " % completed";
//QTableWidgetItem *dateitem[rows];
qDebug() << "rows=" << rows;
for (int r=0; r<rows-1; r++)
{
for (int c = 0; c <cols; c++)
{
QString character = Header.at(c);
table->setHorizontalHeaderItem(c, new QTableWidgetItem(character));
if (r<=rows-1)
{
QTableWidgetItem *dateitem = new QTableWidgetItem();
dateitem->setText(practisedata.datestring.at(r));
table->setItem( r, 0, dateitem );
QTableWidgetItem *number = new QTableWidgetItem( practisedata.log1_practisetestnumber.at(r));
}

}
}
table->setItemPrototype(table->item(rows -1, cols - 1));
table->setGeometry(QRect(55,90,660,300));
//table->show();
layout->addWidget(table);
this->ui->Training_tab1->setLayout(layout);

@