Problem in printing barcode

Hi

Lydia is a problem in printing barcode where I want to print on the posters Allbeckod
And the size of poster Width 4 cm, height 2.5 cm, but I could not control
Paper size and margins of the paper where all Print print does not come in the mid-poster
Comes from the right or the north and you print two posters. I am with you select the paper size
Settings in the printer, but the problem did not persist.
The code used

void MyClase::print( ) {

( I do I view the page to be printed in the BrwoserText Bsthaddam HTML )
QTextDocmant docmant = Gui.BrwoserText->docmant();
Qprinter printer;

printer.setFullpag(true);
printer.setPageSize( Qprinter:: ... ); ( All sizes provided by the Class printer to Ataatmac with the size of the poster )

QprintDialog *printdialog = new QprintDialog(&printer, this);

if( printdialog ->exec() != QDialog::Accepted) return

docmant.print(&printer);

}