Custom QStyledItemDelegate paint function never called

[mattsnowboard]

I have a custom Model, View and Delegate. I am unable to get the Delegate paint function to ever get called. It should print a debug statement, however it behaves as if I never created the delegate Here is a brief part of the code. Please let me know if there are other functions that would be useful to post. Thanks!

class QtCellItemDelegate : public QStyledItemDelegate
{
    Q_OBJECT;
public:
    QtCellItemDelegate( QWidget *parent = NULL );
 
    void paint( QPainter *painter,
                const QStyleOptionViewItem &option,
                const QModelIndex &index );
 
    QSize sizeHint( const QStyleOptionViewItem &option,
                    const QModelIndex & index ) const;
};

class QtCellItemDelegate : public QStyledItemDelegate
{
    Q_OBJECT;
public:
    QtCellItemDelegate( QWidget *parent = NULL );

    void paint( QPainter *painter,
                const QStyleOptionViewItem &option,
                const QModelIndex &index );

    QSize sizeHint( const QStyleOptionViewItem &option,
                    const QModelIndex & index ) const;
};

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QtCellItemDelegate::QtCellItemDelegate( QWidget *parent ) :
    QStyledItemDelegate( parent )
{
    qDebug() << "CONSTRUCT"; // this gets printed, good!
}
 
void QtCellItemDelegate::paint( QPainter *painter,
                                const QStyleOptionViewItem &option,
                                const QModelIndex &index )
{
    //painter->save();
    qDebug() << "Begin Paint"; // this is never printed, function never called
    QStyledItemDelegate::paint( painter, option, index );
 
    qDebug() << "   Begin custom paint";
    // custom stuff...
    qDebug() << "End paint";
    //painter->restore();
}
 
QSize QtCellItemDelegate::sizeHint( const QStyleOptionViewItem &option,
                                     const QModelIndex & index ) const 
{
    return QSize( 60, 60 );
}

QtCellItemDelegate::QtCellItemDelegate( QWidget *parent ) :
    QStyledItemDelegate( parent )
{
    qDebug() << "CONSTRUCT"; // this gets printed, good!
}

void QtCellItemDelegate::paint( QPainter *painter,
                                const QStyleOptionViewItem &option,
                                const QModelIndex &index )
{
    //painter->save();
    qDebug() << "Begin Paint"; // this is never printed, function never called
    QStyledItemDelegate::paint( painter, option, index );
    
    qDebug() << "   Begin custom paint";
    // custom stuff...
    qDebug() << "End paint";
    //painter->restore();
}

QSize QtCellItemDelegate::sizeHint( const QStyleOptionViewItem &option,
                                     const QModelIndex & index ) const 
{
    return QSize( 60, 60 );
}

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class QtDirector : public QObject
{
    Q_OBJECT;
public:
    friend class QtFactory;
 
    int Exec();
 
    ~QtDirector() {}
 
protected:
 
    QtDirector( int &argc, char **arg,
                std::shared_ptr<QtPuzzleModel> puzzleModel );
 
private:
    QtGameApplication *_app;
 
    QTableView *_tableView;
 
    QtMainWindow *_window;
 
    std::shared_ptr<QtPuzzleModel> _model;
    std::shared_ptr<QtCellItemDelegate> _delegate;
};
 
QtDirector::QtDirector( int &argc, char **argv,
                        std::shared_ptr<QtPuzzleModel> puzzleModel )
    : _app( new QtGameApplication( argc, argv ) ),
      _tableView( new QtPuzzleView ),
      _window( new QtMainWindow( _tableView ) ),
      _model( puzzleModel ),
      _delegate( new QtCellItemDelegate( _tableView ) )
{
    if ( !_model )
    {
        throw std::runtime_error(
            "Cannot instantiate with NULL QtPuzzleModel" );
    }
    _tableView->setModel( _model.get() );
    _tableView->setItemDelegate( _delegate.get() );
 
    qDebug() << "My delegate is: " << _delegate.get(); // output of this
    qDebug() << "Table view is using: " << _tableView->itemDelegate(); // and this is the same
 
    connect( _window->GetLoadAction(), SIGNAL( triggered() ),
             _model.get(), SLOT( LoadPuzzle() ) );
    connect( _window->GetNewAction(), SIGNAL( triggered() ),
             _model.get(), SLOT( NewPuzzle() ) );
    connect( _window->GetUndoAction(), SIGNAL( triggered() ),
             _model.get(), SLOT( Undo() ) );
    connect( _window->GetRedoAction(), SIGNAL( triggered() ),
             _model.get(), SLOT( Redo() ) );
    connect( _window->GetMarkHintsAction(), SIGNAL( triggered() ),
             _model.get(), SLOT( MarkPuzzleHints() ) );
 
    connect( _model.get(), SIGNAL( hasPuzzle(bool) ),
             _window->GetMarkHintsAction(), SLOT( setEnabled( bool ) ) );
 
    connect( this, SIGNAL( canUndo( bool ) ),
             _window->GetUndoAction(), SLOT( setEnabled( bool ) ) );
 
    connect( this, SIGNAL( canRedo( bool ) ),
             _window->GetRedoAction(), SLOT( setEnabled( bool ) ) );
 
    _window->setWindowTitle(
        QApplication::translate("windowlayout", "Sudoku"));
    _window->show();
}

class QtDirector : public QObject
{
    Q_OBJECT;
public:
    friend class QtFactory;

    int Exec();

    ~QtDirector() {}

protected:

    QtDirector( int &argc, char **arg,
                std::shared_ptr<QtPuzzleModel> puzzleModel );

private:
    QtGameApplication *_app;

    QTableView *_tableView;

    QtMainWindow *_window;

    std::shared_ptr<QtPuzzleModel> _model;
    std::shared_ptr<QtCellItemDelegate> _delegate;
};

QtDirector::QtDirector( int &argc, char **argv,
                        std::shared_ptr<QtPuzzleModel> puzzleModel )
    : _app( new QtGameApplication( argc, argv ) ),
      _tableView( new QtPuzzleView ),
      _window( new QtMainWindow( _tableView ) ),
      _model( puzzleModel ),
      _delegate( new QtCellItemDelegate( _tableView ) )
{
    if ( !_model )
    {
        throw std::runtime_error(
            "Cannot instantiate with NULL QtPuzzleModel" );
    }
    _tableView->setModel( _model.get() );
    _tableView->setItemDelegate( _delegate.get() );

    qDebug() << "My delegate is: " << _delegate.get(); // output of this
    qDebug() << "Table view is using: " << _tableView->itemDelegate(); // and this is the same

    connect( _window->GetLoadAction(), SIGNAL( triggered() ),
             _model.get(), SLOT( LoadPuzzle() ) );
    connect( _window->GetNewAction(), SIGNAL( triggered() ),
             _model.get(), SLOT( NewPuzzle() ) );
    connect( _window->GetUndoAction(), SIGNAL( triggered() ),
             _model.get(), SLOT( Undo() ) );
    connect( _window->GetRedoAction(), SIGNAL( triggered() ),
             _model.get(), SLOT( Redo() ) );
    connect( _window->GetMarkHintsAction(), SIGNAL( triggered() ),
             _model.get(), SLOT( MarkPuzzleHints() ) );

    connect( _model.get(), SIGNAL( hasPuzzle(bool) ),
             _window->GetMarkHintsAction(), SLOT( setEnabled( bool ) ) );

    connect( this, SIGNAL( canUndo( bool ) ),
             _window->GetUndoAction(), SLOT( setEnabled( bool ) ) );

    connect( this, SIGNAL( canRedo( bool ) ),
             _window->GetRedoAction(), SLOT( setEnabled( bool ) ) );

    _window->setWindowTitle(
        QApplication::translate("windowlayout", "Sudoku"));
    _window->show();
}

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class QtPuzzleModel : public QAbstractTableModel, public Sudoku::ICellObserver
{
    Q_OBJECT;
public:
//    typedef std::map<Sudoku::Position, int > CellModelMap;
 
    QtPuzzleModel( QObject *parent,
                   std::shared_ptr<Sudoku::IPuzzleAccess> access,
                   std::shared_ptr<Sudoku::GameController> gameController,
                   std::shared_ptr<Sudoku::PuzzleController> puzzleController,
                   std::shared_ptr<Sudoku::CellController> cellController );
    int rowCount( const QModelIndex &parent = QModelIndex() ) const;
    int columnCount( const QModelIndex &parent = QModelIndex() ) const;
    // read data
    QVariant data( const QModelIndex &index, int role = Qt::DisplayRole ) const;
    // edit data
    bool setData( const QModelIndex & index,
                  const QVariant & value,
                  int role = Qt::EditRole );
    Qt::ItemFlags flags( const QModelIndex & index ) const;
 
    // disable some stuff
    QVariant headerData( int section,
                         Qt::Orientation orientation,
                         int role ) const;
 
    void Update( const Sudoku::Cell &c );
 
public slots:
    void NewPuzzle();
    bool LoadPuzzle();
    void MarkPuzzleHints();
    void Undo();
    void Redo();
 
signals:
    void ValueChanged( int x, int y, int value );
    void hasPuzzle( bool yes );
 
private:
    std::shared_ptr<Sudoku::IPuzzleAccess> _access;
    std::shared_ptr<Sudoku::GameController> _gameController;
    std::shared_ptr<Sudoku::PuzzleController> _puzzleController;
    std::shared_ptr<Sudoku::CellController> _cellController;
};

class QtPuzzleModel : public QAbstractTableModel, public Sudoku::ICellObserver
{
    Q_OBJECT;
public:
//    typedef std::map<Sudoku::Position, int > CellModelMap;

    QtPuzzleModel( QObject *parent,
                   std::shared_ptr<Sudoku::IPuzzleAccess> access,
                   std::shared_ptr<Sudoku::GameController> gameController,
                   std::shared_ptr<Sudoku::PuzzleController> puzzleController,
                   std::shared_ptr<Sudoku::CellController> cellController );
    int rowCount( const QModelIndex &parent = QModelIndex() ) const;
    int columnCount( const QModelIndex &parent = QModelIndex() ) const;
    // read data
    QVariant data( const QModelIndex &index, int role = Qt::DisplayRole ) const;
    // edit data
    bool setData( const QModelIndex & index,
                  const QVariant & value,
                  int role = Qt::EditRole );
    Qt::ItemFlags flags( const QModelIndex & index ) const;

    // disable some stuff
    QVariant headerData( int section,
                         Qt::Orientation orientation,
                         int role ) const;

    void Update( const Sudoku::Cell &c );

public slots:
    void NewPuzzle();
    bool LoadPuzzle();
    void MarkPuzzleHints();
    void Undo();
    void Redo();

signals:
    void ValueChanged( int x, int y, int value );
    void hasPuzzle( bool yes );

private:
    std::shared_ptr<Sudoku::IPuzzleAccess> _access;
    std::shared_ptr<Sudoku::GameController> _gameController;
    std::shared_ptr<Sudoku::PuzzleController> _puzzleController;
    std::shared_ptr<Sudoku::CellController> _cellController;
};

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class QtPuzzleView : public QTableView
{
    Q_OBJECT;
public:
    QtPuzzleView( QWidget *parent = NULL );
 
    virtual void setModel( QAbstractItemModel *model );
 
protected:
    void resizeRows( int rowCount );
    void resizeCols( int colCount );
 
protected slots:
    void columnCountChanged( int oldCount, int newCount );
    void rowCountChanged( int oldCount, int newCount );
};

class QtPuzzleView : public QTableView
{
    Q_OBJECT;
public:
    QtPuzzleView( QWidget *parent = NULL );

    virtual void setModel( QAbstractItemModel *model );

protected:
    void resizeRows( int rowCount );
    void resizeCols( int colCount );

protected slots:
    void columnCountChanged( int oldCount, int newCount );
    void rowCountChanged( int oldCount, int newCount );
};

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[wysota]

Make sure the delegate doesn't get destroyed before it is ever used. And make sure you have some data in the model, otherwise there is nothing to paint.

[d_stranz]

That's not the problem. QStyledItemDelegate:: paint() is a virtual const method. His is not, so the signatures don't match.