Printing from TextEdit | QPrinter | QPrintDialog

[Noob]

Hi,

I am trying to get printing service to work in my simple program. I am doing it in this way:

#include <QtPrintSupport/QPrintDialog>
#include <QtPrintSupport/QPrinter>

#include <QtPrintSupport/QPrintDialog>
#include <QtPrintSupport/QPrinter>

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And than I get the code in my print button.

void MainWindow::on_printButton_clicked()
{
    QPrinter printer;
    QPrintDialog printDialog(&printer, this);
    if (printDialog.exec() == QDialog::Accepted) {
       ui->textBox->print(&printer);
    }
}

void MainWindow::on_printButton_clicked()
{
    QPrinter printer;
    QPrintDialog printDialog(&printer, this);
    if (printDialog.exec() == QDialog::Accepted) {
       ui->textBox->print(&printer);
    }
}

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I get a lot of "undefined reference" errors to QPrintDialog and QPrinter.
If You could drop me some hint.