HowTo draw pixmap in QHeaderView section using delegate? - qt

Question

Problem: I need to draw small pixmap to QHeaderView section like presented on this figure (pixmap located on the right corner of the section, marked with red square):
As I understand, there is two ways to do that:
reimplement QHeaderView's paintSection() method.
create an delegate from QStyledItemDelegate class and reimplement paint() method.
If I tried (1) variant with this code below, filter pixmap are not shown at all:
void DecorativeHeaderView::paintSection( QPainter* painter, const QRect& rect, int logicalIndex ) const
{
if( !rect.isValid() )
{
return;
}
// get the state of the section
QStyleOptionHeader option;
initStyleOption( &option );
// setup the style options structure
option.rect = rect;
option.section = logicalIndex;
option.iconAlignment = Qt::AlignVCenter | Qt::AlignHCenter;
QVariant variant = model()->headerData( logicalIndex, orientation(), Qt::DecorationRole );
option.icon = qvariant_cast< QIcon >( variant );
if( option.icon.isNull() )
{
option.icon = qvariant_cast< QPixmap >( variant );
}
// draw the section
if( !option.icon.isNull() )
{
style()->drawControl( QStyle::CE_Header, &option, painter, this );
}
else
{
QHeaderView::paintSection( painter, rect, logicalIndex );
// HERE is where I'm trying to draw my filter picture!!!
if( logicalIndex == filteredLogicalIndex_ )
{
QPixmap pixmap( ":/spreadsheet/images/spreadsheet/filter_icon_table.png" );
int x = rect.right() - pixmap.width();
int y = rect.top() + ( rect.height() - pixmap.height() ) / 2;
painter->drawPixmap( QPoint( x, y ), pixmap );
}
}
}
The (2) variant is this:
class HeaderDelegate : public QStyledItemDelegate
{
Q_OBJECT
Q_DISABLE_COPY( HeaderDelegate )
public:
HeaderDelegate( QObject* parent = 0 ) : QStyledItemDelegate( parent ) {}
virtual ~HeaderDelegate() {}
virtual void paint( QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index ) const;
}; // HeaderDelegate
void HeaderDelegate::paint( QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index ) const
{
// THIS method never starts!!!
if( index.column() == 2 )
{
QPixmap pixmap( ":/spreadsheet/images/spreadsheet/filter_icon_table.png" );
int x = option.rect.right() - pixmap.width();
int y = option.rect.top() + ( option.rect.height() - pixmap.height() ) / 2;
painter->save();
painter->drawPixmap( QPoint( x, y ), pixmap );
painter->restore();
}
QStyledItemDelegate::paint( painter, option, index );
}
DecorativeHeaderView::DecorativeHeaderView( Qt::Orientation orientation, QWidget* parent /* = 0 */ )
: QHeaderView( orientation, parent )
, filteredLogicalIndex_( -1 )
{
setItemDelegate( new HeaderDelegate( this ) );
}
Delegate created, but function did not start the paint() method!
Any help?
Thanks!

Answer 1

It Seems like it isn't possible at this time.
From Qt documentation:
Note: Each header renders the data for each section itself, and does not rely on a delegate. As a result, calling a header's setItemDelegate() function will have no effect.
How to have dynamic pixmap in a QHeaderView item
But you may override QHeaderView::paintSection method.
subclassing-QHeaderView
class HeaderView : public QHeaderView {
Q_OBJECT
public:
HeaderView(Qt::Orientation orientation, QWidget * parent = 0)
: QHeaderView(orientation, parent), p("333222.jpeg") {
}
int sectionSizeHint ( int /*logicalIndex*/ ) const { return p.width(); }
protected:
void paintSection(QPainter * painter, const QRect & rect, int /*logicalIndex*/) const {
painter->drawPixmap(rect, p);
}
private:
QPixmap p;
};