CODEWITHSUNDEEP
c++qtcheckboxsignals-slotsqtreewidgetitem
Robert Whitley
Robert Whitley

Reputation: 1081

Is it possible to create a signal for when a QTreeWidgetItem checkbox is toggled?

I've created a checkbox that's also a QTreeWidgetItem using the code below. 

//Populate list
QTreeWidgetItem *program = createCheckedTreeItem(QString::fromStdString(itr->first), true);
treePrograms->addTopLevelItem(program);

QTreeWidgetItem* ConfigDialog::createCheckedTreeItem(QString name,bool checkBoxState)
{
  QTreeWidgetItem *item = new QTreeWidgetItem(QStringList(name));
  item->setFlags(item->flags()|Qt::ItemIsUserCheckable);
  if (checkBoxState)
  {
    item->setCheckState(0,Qt::Unchecked);
  }
  else
  {
    item->setCheckState(0,Qt::Checked);
  }
  return item;
}

I need a way of connecting a signal and slot for when the state of this checkbox is changed. The current way I've implemented this is below but unfortunately doesn't work. Can someone explain what I'm doing wrong and what I need to do in order to get it to connect?

connect(program, SIGNAL(toggled(bool)), this, SLOT(programChecked(bool)));

Upvotes: 13

Views: 17791

Answers (5)

afs_mp
afs_mp

Reputation: 77

Add this signal to your QTreeWidget object:

connect(ui->treeWidget, &QTreeWidget::itemChanged, this, &YourDialog::treeWidgetItemChanged);

so you can use this slot to receive the signal:

void YourDialog::treeWidgetItemChanged(QTreeWidgetItem *TWI, int column)
{
    //Do some staff
}

Upvotes: 0

David Faure
David Faure

Reputation: 1997

The best solution we found was to reimplement setData in an item subclass:

void MyItem::setData(int column, int role, const QVariant& value)
{
    const bool isCheckChange = column == 0
        && role == Qt::CheckStateRole
        && data(column, role).isValid() // Don't "change" during initialization
        && checkState(0) != value;
    QTreeWidgetItem::setData(column, role, value);
    if (isCheckChange) {
        MyTree *tree = static_cast<MyTree *>(treeWidget);
        emit tree->itemCheckStateChanged(this, checkState(0) == Qt::Checked);
    }
}

It would really be convenient to have this in Qt indeed, it makes me think about contributing a itemCheckStateChanged signal there directly :)

PS: setting Qt::ItemIsUserCheckable is unnecessary, this flag is on by default for all QTreeWidgetItems.

Upvotes: 3

G Hx
G Hx

Reputation: 1147

Connect to the signal itemClicked(QTreeWidgetItem* item, int column) of the tree. When handling the signal, just verify item->checkState(column).

Upvotes: 6

Masci
Masci

Reputation: 6074

You have to grab the signal itemChanged ( QTreeWidgetItem * item, int column ) coming from QTreeWidget.

Upvotes: 8

Chris Browet
Chris Browet

Reputation: 4266

Your QTreeWidgetItem is directly linked to your model data, so you should connect to your QTreeWidget's model's QAbstractItemModel::dataChanged signal to be notified of the change.

Upvotes: 5

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