Crashes on Clearing a QTreeWidget

MasterBlade

Hello I want to clear a QTreeWidget and used

ui->DeckList->clear(); // DeckList is a QTreeWidget

However the program sometimes crashes.

I found that after I clicked on this tree it surely crashes. But if I didn't click the tree it won't crash. What's wrong with it?

I used the following code in the constructor.

ui->DeckList->setColumnWidth(0, 25);
ui->DeckList->setColumnWidth(1, 65);
ui->DeckList->setColumnWidth(2, 140);
ui->DeckList->header()->setStretchLastSection(true);
ui->DeckList->setIndentation(0);

QTreeWidgetItem *md = new QTreeWidgetItem(ui->DeckList);
QTreeWidgetItem *sd = new QTreeWidgetItem(ui->DeckList);
ui->DeckList->insertTopLevelItem(0, md);
ui->DeckList->insertTopLevelItem(1, sd);
md->setText(0, "0");
sd->setText(0, "0");
md->setText(1, "MDeck");
sd->setText(1, "SDeck");
QFont f;
f.setBold(true);
md->setFont(0, f);
sd->setFont(0, f);
md->setFont(1, f);
sd->setFont(1, f);
md->setTextAlignment(0, Qt::AlignCenter);
sd->setTextAlignment(0, Qt::AlignCenter);
md->setTextAlignment(1, Qt::AlignCenter);
sd->setTextAlignment(1, Qt::AlignCenter);

mrjj

Hi
Its not due to clear. ( very unlikely)
Did you apply event filter or anything like that ?
Try a small sample. If you can get that to crash with clear. it might be a bug
but mostly like you are saving QTreeWidgetItem * somewhere and access after its deleted.

MasterBlade

@mrjj said in Crashes on Clearing a QTreeWidget:

Hi
Its not due to clear. ( very unlikely)
Did you apply event filter or anything like that ?
Try a small sample. If you can get that to crash with clear. it might be a bug
but mostly like you are saving QTreeWidgetItem * somewhere and access after its deleted.

But when I was debugging, it always stops at ui->DeckList->clear();

To be more precise, it stopped at qtreewidget.h

Oh I think I know the reason. I also used on_DeckList_currentItemChanged. So the current item did change when the whole tree was deleted. But I still need this function. Is there a way to prevent such conflict?

mrjj

Hi
you need to check if current is null

if (!current) return;

when you clear it, none can be selected and hence its null.

MasterBlade

@mrjj said in Crashes on Clearing a QTreeWidget:

Hi
you need to check if current is null

if (!current) return;

when you clear it, none can be selected and hence its null.

That did help. Thanks!