flatten method

PdfFormFlattenResult flatten({ Iterable<String>? fieldNames, })

Flattens the form fields.

Without fieldNames, flattens all of them. With the list, only the fields whose fully qualified name is in it; the rest stay in the form and the /AcroForm remains in the catalog.

Implementation

PdfFormFlattenResult flatten({Iterable<String>? fieldNames}) {
  // The warnings belong to this call; the collections do not: calling
  // [flatten] again with another list of names has to reuse the content
  // editor already created for each page, otherwise the page would get a
  // second pair of streams wrapping the original content.
  _warnings.clear();

  if (!acroForm.exists) {
    _warnings.add('O documento não tem /AcroForm: nada a achatar.');
    return PdfFormFlattenResult(
      flattened: const <PdfFlattenedField>[],
      warnings: List<String>.unmodifiable(_warnings),
      remainingFields: 0,
      acroFormRemoved: false,
    );
  }

  final selected = fieldNames == null ? null : Set<String>.of(fieldNames);
  final targets = _collectWidgets();

  final flattened = <PdfFlattenedField>[];
  for (final target in targets) {
    if (selected != null && !selected.contains(target.name)) continue;
    final field = _flattenWidget(target);
    if (field != null) flattened.add(field);
  }

  if (selected != null) {
    for (final name in selected) {
      if (targets.any((target) => target.name == name)) continue;
      _warnings.add('Campo "$name" não existe no formulário.');
    }
  }

  // After flattening there is no appearance to regenerate; leaving
  // `/NeedAppearances true` would make the reader try to rebuild fields that
  // no longer exist.
  acroForm.removeNeedAppearances();

  final remaining = acroForm.fields?.values.length ?? 0;
  final removed = options.removeAcroFormWhenEmpty &&
      remaining == 0 &&
      acroForm.removeWhenEmpty();

  return PdfFormFlattenResult(
    flattened: List<PdfFlattenedField>.unmodifiable(flattened),
    warnings: List<String>.unmodifiable(_warnings),
    remainingFields: remaining,
    acroFormRemoved: removed,
  );
}