QCompleter behvaiour in table view

[ChrisW67]

I have a similar problem to the one back in this thread although the code is C++ (below) not Python. A QLineEdit with completer in a table view only displays expected completion behaviour under some circumstances.

If you double-click or enter edit mode explicitly (F2 on Linux) the completer works correctly on the cell. If you trigger edit mode by just typing with a current cell selected this is the debug output:

// Starting point: shot0.png
// I type 'b' into the current cell
CompleterDelegate::createEditor() called for QWidget(0x83582e0, name = "qt_scrollarea_viewport") QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(, ) 
CompleterDelegate::updateEditorGeometry() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  
CompleterDelegate::setEditorData() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(, ) 
CompleterDelegate::setModelData() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(, ) 
CompleterDelegate::setEditorData() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(QString, "b") 
// result: shot1.png
// the cell does not display as an active editor, no completer visible: middle screen shot
// type 'a'
CompleterDelegate::createEditor() called for QWidget(0x83582e0, name = "qt_scrollarea_viewport") QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(QString, "b") 
CompleterDelegate::updateEditorGeometry() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  
CompleterDelegate::setEditorData() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(QString, "b") 
// result: shot3.png
// setEditorText() called with 'b' but active editor displaying 'a', no completer popup

// Starting point: shot0.png
// I type 'b' into the current cell
CompleterDelegate::createEditor() called for QWidget(0x83582e0, name = "qt_scrollarea_viewport") QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(, ) 
CompleterDelegate::updateEditorGeometry() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  
CompleterDelegate::setEditorData() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(, ) 
CompleterDelegate::setModelData() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(, ) 
CompleterDelegate::setEditorData() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(QString, "b") 
// result: shot1.png
// the cell does not display as an active editor, no completer visible: middle screen shot
// type 'a'
CompleterDelegate::createEditor() called for QWidget(0x83582e0, name = "qt_scrollarea_viewport") QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(QString, "b") 
CompleterDelegate::updateEditorGeometry() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  
CompleterDelegate::setEditorData() called for QModelIndex(0,0,0x8359818,QStandardItemModel(0xbf9858a4) )  QVariant(QString, "b") 
// result: shot3.png
// setEditorText() called with 'b' but active editor displaying 'a', no completer popup

To copy to clipboard, switch view to plain text mode 

Shot3.png is the behaviour expected and seen if you explicitly enter edit mode.
tile.png

The cycle through setEditor, setModel, the setEditor at 5-7 of the debug out is telltale. Wysota mentioned something about focus and event filters in the old thread. I have briefly (minutes not hours) looked at the find completer stuff in Qt Creator but did not find event filter actions related to focus on arbitrary key presses.

Can anyone shed light on how to get correct behaviour here?

#include <QtGui>
#include <QDebug>
 
class CompleterDelegate : public QStyledItemDelegate
{
public:
    CompleterDelegate(QObject* parent = 0) : QStyledItemDelegate(parent) { }
 
    QWidget* createEditor(QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index) const
    {
        qDebug() << "CompleterDelegate::createEditor() called for" << parent << index << index.data(Qt::EditRole);
        QLineEdit* lineEdit = new QLineEdit(parent);
        QStringList stringList = QStringList() << "foo" << "bar" << "baz";
        QCompleter* completer = new QCompleter(stringList, lineEdit);
            completer->setCompletionMode(QCompleter::PopupCompletion);
                completer->setCaseSensitivity(Qt::CaseInsensitive);
 
        lineEdit->setCompleter(completer);
        return lineEdit;
    }
    void setEditorData(QWidget *editor, const QModelIndex &index) const
    {
        qDebug() << "CompleterDelegate::setEditorData() called for" << index << index.data(Qt::EditRole);
        QStyledItemDelegate::setEditorData(editor, index);
    }
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
    {
        qDebug() << "CompleterDelegate::setModelData() called for" << index << index.data(Qt::EditRole);
        QStyledItemDelegate::setModelData(editor, model, index);
    }
    void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const
    {
        qDebug() << "CompleterDelegate::updateEditorGeometry() called for" << index;
        QStyledItemDelegate::updateEditorGeometry(editor, option, index);
    }
};
 
 
int main(int argc, char* argv[])
{
    QApplication app(argc, argv);
 
    QStandardItemModel model(4, 2);
    QTableView tv;
    tv.setWindowTitle("View");
    // default edit triggers are:
    tv.setEditTriggers(QAbstractItemView::DoubleClicked
                       | QAbstractItemView::EditKeyPressed
                       | QAbstractItemView::AnyKeyPressed );
    tv.setModel(&model);
    tv.setItemDelegate(new CompleterDelegate(&tv));
    tv.show();
 
    return app.exec();
}

#include <QtGui>
#include <QDebug>

class CompleterDelegate : public QStyledItemDelegate
{
public:
    CompleterDelegate(QObject* parent = 0) : QStyledItemDelegate(parent) { }

    QWidget* createEditor(QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index) const
    {
        qDebug() << "CompleterDelegate::createEditor() called for" << parent << index << index.data(Qt::EditRole);
        QLineEdit* lineEdit = new QLineEdit(parent);
        QStringList stringList = QStringList() << "foo" << "bar" << "baz";
        QCompleter* completer = new QCompleter(stringList, lineEdit);
            completer->setCompletionMode(QCompleter::PopupCompletion);
                completer->setCaseSensitivity(Qt::CaseInsensitive);

        lineEdit->setCompleter(completer);
        return lineEdit;
    }
    void setEditorData(QWidget *editor, const QModelIndex &index) const
    {
        qDebug() << "CompleterDelegate::setEditorData() called for" << index << index.data(Qt::EditRole);
        QStyledItemDelegate::setEditorData(editor, index);
    }
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
    {
        qDebug() << "CompleterDelegate::setModelData() called for" << index << index.data(Qt::EditRole);
        QStyledItemDelegate::setModelData(editor, model, index);
    }
    void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const
    {
        qDebug() << "CompleterDelegate::updateEditorGeometry() called for" << index;
        QStyledItemDelegate::updateEditorGeometry(editor, option, index);
    }
};


int main(int argc, char* argv[])
{
    QApplication app(argc, argv);

    QStandardItemModel model(4, 2);
    QTableView tv;
    tv.setWindowTitle("View");
    // default edit triggers are:
    tv.setEditTriggers(QAbstractItemView::DoubleClicked
                       | QAbstractItemView::EditKeyPressed
                       | QAbstractItemView::AnyKeyPressed );
    tv.setModel(&model);
    tv.setItemDelegate(new CompleterDelegate(&tv));
    tv.show();

    return app.exec();
}

To copy to clipboard, switch view to plain text mode 

[ChrisW67]

Further tinkering shows that the editor is destroyed after line 7 of the debug output before user control is returned.

A normal editor creation without completer looks like:

DummyDelegate::createEditor() called for QWidget(0x9663a98, name = "qt_scrollarea_viewport") QModelIndex(0,0,0x9665138,QStandardItemModel(0xbfd09674) )  
DummyDelegate::updateEditorGeometry() called for QModelIndex(0,0,0x9665138,QStandardItemModel(0xbfd09674) )  
DummyDelegate::setEditorData() called for QModelIndex(0,0,0x9665138,QStandardItemModel(0xbfd09674) )

DummyDelegate::createEditor() called for QWidget(0x9663a98, name = "qt_scrollarea_viewport") QModelIndex(0,0,0x9665138,QStandardItemModel(0xbfd09674) )  
DummyDelegate::updateEditorGeometry() called for QModelIndex(0,0,0x9665138,QStandardItemModel(0xbfd09674) )  
DummyDelegate::setEditorData() called for QModelIndex(0,0,0x9665138,QStandardItemModel(0xbfd09674) )

To copy to clipboard, switch view to plain text mode