HotPDF — нативная VCL PDF-библиотека для приложений Delphi и C++Builder, которым нужны прямое создание и редактирование PDF, формы, аннотации, шифрование, цифровые подписи, Unicode-шрифты, вывод с учетом стандартов и preflight-отчеты без внешнего PDF-runtime.
Эта статья предназначена для teams receiving mixed form documents that must be archived, reviewed, or converted by a Delphi workflow. Она рассматривает XFA, AcroForm, and flattening decisions как промышленную инженерию документов, а не как одиночный вызов компонента.
Практический риск состоит в том, что dynamic XFA, static XFA, and AcroForm fields behave differently, so a naive flattening step can lose values or preserve hidden state unexpectedly. Поэтому процессу нужны письменный контракт, наблюдаемая диагностика и реалистичные регрессионные файлы.
Архитектурные решения
Identify the form technology before changing it. how to classify AcroForm, static XFA, dynamic XFA, and hybrid forms / whether unsupported dynamic behavior blocks processing or creates a warning
- how to classify AcroForm, static XFA, dynamic XFA, and hybrid forms
- whether unsupported dynamic behavior blocks processing or creates a warning
- appearance refresh policy for changed values and calculated fields
- retention of original form data after a flattened archive copy is produced
Порядок реализации
Refresh visible appearances before flattening. The order below keeps the workflow reviewable for Delphi and C++Builder teams.
- inspect the document catalog and form dictionaries before loading values
- classify the form model and choose a profile that matches the business goal
- apply values, refresh appearances, and validate required fields
- flatten only the fields approved by policy and verify remaining interactivity
- save the classification and flattening result in the support report
Доказательства проверки
Flattening evidence for auditors and support. Keep these fields with the output or support record.
- form model classification, field count, XFA presence, and unsupported feature list
- appearance refresh status for every field changed by the workflow
- flattened field count, remaining interactive field count, and output hash
- side-by-side viewer result for at least one customer-like form
Flattening is a finalization step
Flattening should happen only after the workflow knows which form model owns the value, which appearance is authoritative, and whether the resulting PDF must remain interactive or become a static record.
Regression files worth keeping
Keep more than successful samples. A useful XFA, AcroForm, and flattening decisions regression set contains normal files, boundary files, and intentional failure files so the behavior is stable across releases.
- dynamic XFA forms may depend on behavior outside normal AcroForm processing
- hidden fields can contain values that should not appear in a flattened copy
- flattening invalid values can make correction impossible for downstream users
- different viewers may choose different appearances when streams are stale
- inspect the document catalog and form dictionaries before loading values
- classify the form model and choose a profile that matches the business goal
Engineering review notes for XFA, AcroForm, and flattening decisions
Use these review notes to make sure the feature has moved beyond a demo and can be defended during release, support, and customer escalation.
- Decision: how to classify AcroForm, static XFA, dynamic XFA, and hybrid forms. Implementation pressure point: classify the form model and choose a profile that matches the business goal. Acceptance evidence: flattened field count, remaining interactive field count, and output hash. Regression trigger: different viewers may choose different appearances when streams are stale
- Decision: whether unsupported dynamic behavior blocks processing or creates a warning. Implementation pressure point: apply values, refresh appearances, and validate required fields. Acceptance evidence: side-by-side viewer result for at least one customer-like form. Regression trigger: dynamic XFA forms may depend on behavior outside normal AcroForm processing
- Decision: appearance refresh policy for changed values and calculated fields. Implementation pressure point: flatten only the fields approved by policy and verify remaining interactivity. Acceptance evidence: form model classification, field count, XFA presence, and unsupported feature list. Regression trigger: hidden fields can contain values that should not appear in a flattened copy
- Decision: retention of original form data after a flattened archive copy is produced. Implementation pressure point: save the classification and flattening result in the support report. Acceptance evidence: appearance refresh status for every field changed by the workflow. Regression trigger: flattening invalid values can make correction impossible for downstream users
- Decision: how to classify AcroForm, static XFA, dynamic XFA, and hybrid forms. Implementation pressure point: inspect the document catalog and form dictionaries before loading values. Acceptance evidence: flattened field count, remaining interactive field count, and output hash. Regression trigger: different viewers may choose different appearances when streams are stale
Пограничные случаи
- dynamic XFA forms may depend on behavior outside normal AcroForm processing
- hidden fields can contain values that should not appear in a flattened copy
- flattening invalid values can make correction impossible for downstream users
- different viewers may choose different appearances when streams are stale
Delphi / C++Builder notes
HotPDF Component should sit behind a small service boundary that receives files, streams, profiles, and credentials, then returns output paths, warnings, metrics, and validation status. Important terms include XFA, AcroForm, flattening, appearance stream, field value, archive copy.
Пример кода Delphi
Следующий эскиз Delphi показывает практическую границу сервиса для этой темы. Оставляйте проверки политики, журналирование и валидацию вне узкого блока вызова продукта, чтобы сценарий было проще тестировать.
procedure FlattenIncomingForm(const InputFile, OutputFile: string; const Policy: TFormPolicy);
var
Pdf: THotPDF;
begin
Pdf := THotPDF.Create(nil);
try
LoadCustomerForm(Pdf, InputFile);
NormalizeXfaPackets(Pdf, Policy);
FlattenVisibleAcroFormFields(Pdf);
SaveFlattenedCopy(Pdf, OutputFile);
VerifyNoEditableFields(OutputFile);
finally
Pdf.Free;
end;
end;Производственный чек-лист
- Run the workflow on an empty file, a normal customer file, and a worst-case file
- Open the generated PDF with the target viewer, validator, printer, or downstream application
- Log product version, profile version, input hash, output path, elapsed time, and warning count
- Keep passwords, certificates, temporary files, and customer data under explicit retention rules
- Add regression documents when a customer file exposes a new edge case