#include <QStyledItemDelegate>
#include <QTreeView>
#include <QPainter>
#include <QApplication>
#include <QStringListModel>
#include <QHeaderView>

class WordWrapItemDelegate final
	:	public QStyledItemDelegate
{
public:
	WordWrapItemDelegate( QTreeView * parent = nullptr )
		:	QStyledItemDelegate( parent )
		,	m_parent( parent )
	{
	}

	QSize sizeHint( const QStyleOptionViewItem & option,
		const QModelIndex & index ) const override
	{
		return option.fontMetrics.boundingRect(
			QRect( 0, 0, m_parent->header()->sectionSize( index.column() ), 0 ),
			Qt::AlignLeft | Qt::TextWordWrap,
			index.data( Qt::DisplayRole ).toString() ).size();
	}

	void paint( QPainter * painter, const QStyleOptionViewItem & option,
		const QModelIndex & index) const override
	{
		QStyledItemDelegate::paint( painter, option, QModelIndex() );

		painter->drawText( option.rect,
		Qt::AlignLeft | Qt::TextWordWrap | Qt::AlignVCenter,
		index.data( Qt::DisplayRole ).toString() );
	}

private:
	QTreeView * m_parent;
};


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

	QStringListModel m;
	m.setStringList( QStringList() << "QWERTY QWERTY QWERTY QWERTY QWERTY QWERTY"
		<< "ASDFG ASDFG ASDFG ASDFG ASDFG ASDFG"
		<< "ZXCVB ZXCVB ZXCVB ZXCVB ZXCVB ZXCVB" );

	QTreeView v;
	v.resize( 150, 200 );
	v.setRootIsDecorated( false );
	v.setSortingEnabled( true );
	v.setSelectionMode( QAbstractItemView::ExtendedSelection );
	v.setSelectionBehavior( QAbstractItemView::SelectRows );
	v.setWordWrap( true );
	v.setDragDropMode( QAbstractItemView::DragOnly );
	v.setAllColumnsShowFocus( true );
	v.show();

	v.setModel( &m );

	WordWrapItemDelegate d( &v );
	v.setItemDelegate( &d );

	return QApplication::exec();
}