How to catch key presses in editable QTableWidgetItem?

Question

Now I can process all key presses in my QTableWidget in a function eventFilter() (after calling of myTable->viewport()->installEventFilter(this); in the constructor).

The only place where this doesn't work is editable cell while editing (because it grabs all key presses). To fix it I can't call installEventFilter() for each item in the table, because these items are not QObjects (and also I can't use connect for putting of my processing of key presses).

The only solution I have is to put QLineEdits in these cells and to use event filter to catch key presses while editing. But is it possible to solve it using only standard items? (i.e. only QTableWidgetItem with a flag Qt::ItemIsEditable)

Also I can call grabKeyboard() for my QTableWidget. In this case I'll have all key presses (even while editing of cells by user), but it blocks edit box (i.e. user can't input anything). May be it is possible to fix broken edit boxes after calling of grabKeyboard() for the table?

Answer 1

This so quite ease to achieve. Just subclass QStyledItemDelegate override createEditor method like this:

QWidget *AlterEditorDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const {
    QWidget *result = QStyledItemDelegate::createEditor(parent, option, index);
    result->installEventFilter(new YourEventFilter(result));
    return result;
}

Than replace delegate for your QTableWidget.

Or even better instead subclassing create proxy class which accepts original QAbstractItemDelegate (more writing but much more universal and can be composed with other modifications).

AlterEditorProxyDelegate::AlterEditorProxyDelegate(QAbstractItemDelegate *original, QObject *parent)
    : QAbstractItemDelegate(parent)
    , original(original)
{}

QWidget *AlterEditorProxyDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const {
    QWidget *result = original->createEditor(parent, option, index);
    result->installEventFilter(new YourEventFilter(result));
    return result;
}

// other methods which invokes respective methods for `original` style. 

Answer 2

Since QTableWidgetItem has no function keyEvent() that you can overload this is not possible.

What you have to do is set a delegate with custom editor factory that produces widgets where keyEvent is overloaded.