QTreeWidgetItems, how to make all ttransaprent to see QTreeWidget background

Hello to all, sorry my english =)
My problem is that:
I set a background to my QTreeWidget,
I populate my tree with QTreeWidgetItems and i want to see the background trought the items.
Try with setStyleSheet of the TreeWidget:item : nothing how can i do?
TreeWidget:

Code:

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void qtg_QTreeWidget::paintEvent(QPaintEvent *event)
{
 
 
        QPainter painter(viewport());
        QImage image("./background.png");
        QRect rect(x(),y(),image.height (),image.width());
        qDebug () <<"paint" << x() << y() << image.height () <<image.width();
        painter.drawImage(rect, image);
        painter.end();
        QTreeWidget::paintEvent(event);
};

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TreeWidgetItem

Code:

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gui_laucher::gui_laucher(QWidget *parent)
    : QWidget(parent)
{
    setupTray();
    int y= m_tray->geometry().y() ;
    int x= m_tray->geometry().x() ;
    setGeometry(x+3,y+3,300,320);
    setAttribute(Qt::WA_TranslucentBackground);
    QStringList labels;
    labels << tr("Software");
 
    m_treeWidget = new qtg_QTreeWidget(this);
    setStyleSheet("QTreeView::item {background-color :rgba(255,255,255,0%);}");
    xmlparser();
}

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I also try this:

Code:

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qtg_QTreeWidgetItem::qtg_QTreeWidgetItem(QTreeWidgetItem *parent) :
    QTreeWidgetItem(parent)
{
    m_pProcessPath="nopath";
    m_pStringParameters="noparams";
 
    setBackground(0,QBrush(Qt::transparent));
}

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I never can see the picture trought the item =(

Solved:

Code:

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void qtg_QTreeWidget::drawRow(QPainter* p, const QStyleOptionViewItem &opt, const QModelIndex &idx) const
{
 
/* Altro metodo per disegnare la pixmap:
   la recupero così:
   QTreeWidgetItem * item = this->itemFromIndex(idx);
   la drawo così:
   p->drawPixmap(im,yPixmap,16,16,item->icon(0).pixmap(16,16));
 
*/
     for (int col = 0; col < columnCount(); ++col)
     {
         QModelIndex s = idx.sibling(idx.row(), col);
         if (s.isValid())
         {
             // Recupero il testo dell'item
                QString szText=idx.data(Qt::DisplayRole).toString();
                // Recupero la pixmap dell'item
                QPixmap myPix =  qvariant_cast<QIcon>(idx.data(Qt::DecorationRole)).pixmap(opt.decorationSize);
                // Mi recupero il rettangolo dove disegnare
                int x = visualRect(s).left();
                int y = visualRect(s).top();
                int w = visualRect(s).width();
                int h = visualRect(s).height();
                QRect cRect(x,y,w,h);
                // Mi calcolo la y dell'icona dell'item
                int yPixmap = (y + (h / 2 - 8));
                /* Posso cominciare a disegnare l'item, non disegnerò lo sfondo
                   perchè lo voglio trasparente, altrimenti avrei fatto così:
                   QImage image("percorso");
                   QRect rect(opt.rect);
                   p->drawImage(rect, image);
                */
                // Disegno l'icona
                p->drawPixmap(x,yPixmap,myPix.width(),myPix.height(),myPix);
                // Mi sposto verso destra del rettangolo dell'item della lunghezza della pixmap + 2 per distaccarmi
                // e disegno il testo
                cRect.setLeft(cRect.left() + myPix.width()+2);
                p->drawText(cRect,Qt::AlignLeft | Qt::AlignVCenter,szText);;
                // Mi sposto verso sinistra del rettangolo visuale dell'item sottraendo la lunghezza della mia pixmap + 2
                // e chiamo la funzione delle QT che disegna le branches passandogli il rettangolo giusto
                cRect.setRight(cRect.left() - (myPix.width()+2));
                QTreeView::drawBranches(p,cRect,idx);
          }
 
      }
}

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