pdf_util.dart

class PdfUtil {
  final doc = pdf.Document();
  final PdfPageFormat? formatPage;
  PdfUtil(this.formatPage);
  
  Future<Uint8List> buildPdf(pdf.Widget widget) {
    doc.addPage(pdf.Page(
      build: (pdf.Context context) => widget,
      pageFormat: formatPage,
    ));
    return doc.save();
  }

  Future<void> printLayoutPdf(pdf.Widget widget) async {
    await Printing.layoutPdf(onLayout: (format) => buildPdf(widget));
  }
}

//example
void main() {
  final pdf = PdfUtil(PdfPageFormat.a3);
  final widget = pw.Center(
        child: pw.Text('Hello World', style: pw.TextStyle(font: ttf, fontSize: 40)),
      );
  await pdf.buildPdf(widget);
  
  //if u want printing
  await pdf.printLayoutPdf(widget);
}