setData problem at QStandardItemModel first visible item!!!

[josentop]

Hi,
I have created a QStandardItemModel for QTreeView and will update some item's data when some data changed. Everything is ok except when set data to the first visible item, it will cause the program exit in abnormal. the code as below:

QString tag = tagitem->data(Qt::DisplayRole).toString();
if (tag == QString("Width") || tag == QString("Height"))
{
	QString val = item->data(Qt::DisplayRole).toString();
	int t = QLocale().toInt(val);
	QRectF rect = panel->rect();
	if (tag == QString("Width")) rect.setWidth(t);
	else rect.setHeight(t);
	panel->setRect(rect);
 
	QString s = QLocale().toString(rect.width()) +
			QString("x") +
			QLocale().toString(rect.height());
 
	rootItems.at(1)->setData(s, Qt::DisplayRole);
 
        qDebug() << rootItems.at(0)->data(Qt::DisplayRole).toString() << ":" << rootItems.at(1)->data(Qt::DisplayRole).toString();
	scene->update();		
}

QString tag = tagitem->data(Qt::DisplayRole).toString();
if (tag == QString("Width") || tag == QString("Height"))
{
	QString val = item->data(Qt::DisplayRole).toString();
	int t = QLocale().toInt(val);
	QRectF rect = panel->rect();
	if (tag == QString("Width")) rect.setWidth(t);
	else rect.setHeight(t);
	panel->setRect(rect);

	QString s = QLocale().toString(rect.width()) +
			QString("x") +
			QLocale().toString(rect.height());

	rootItems.at(1)->setData(s, Qt::DisplayRole);
                        
        qDebug() << rootItems.at(0)->data(Qt::DisplayRole).toString() << ":" << rootItems.at(1)->data(Qt::DisplayRole).toString();
	scene->update();		
}

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I just want to update the panel data (1920x1080) according panel's width or height change. I'm sure rootItems.at(1) is pointed to the data (1920x1080), please see below picture,
error.png

anyone has suggestion? thanks.