In what ways can PHP code be integrated into the PDF theme to display additional individual fields on invoices?

To display additional individual fields on invoices in a PDF theme, you can integrate PHP code to fetch the data for those fields and dynamically insert them into the PDF template. This can be achieved by modifying the existing PHP code in the PDF theme to include the additional fields and their corresponding data.

// Fetch additional data for individual fields
$additional_field1 = get_additional_field_data_1();
$additional_field2 = get_additional_field_data_2();

// Insert additional fields into the PDF template
$pdf->SetFont('Arial', '', 12);
$pdf->SetXY(10, 100);
$pdf->Cell(0, 10, 'Additional Field 1: ' . $additional_field1, 0, 1, 'L');
$pdf->SetXY(10, 110);
$pdf->Cell(0, 10, 'Additional Field 2: ' . $additional_field2, 0, 1, 'L');