Integre fluxos do PDFium VCL Component em aplicações Delphi e C++Builder, ou fluxos do PDFium LCL Component em Lazarus/FPC, com componentes em código-fonte para visualização, renderização, formulários, impressão, relatórios de preflight e validação orientada a padrões.
Este artigo é para developers building PDF data-entry viewers where users need to complete forms accurately. Ele trata form-field navigation and viewer validation como engenharia documental de produção, não como uma chamada isolada de componente.
O risco prático é que users can tab through a form and still submit incorrect or invisible data if field focus, required-state display, export values, and calculated fields are not coordinated. Por isso o fluxo precisa de contrato escrito, diagnósticos observáveis e arquivos de regressão representativos.
Decisões de arquitetura
Make field navigation a first-class viewer feature. tab order, required-field markers, and skip rules for hidden or read-only fields / value conversion for checkboxes, radio groups, combo boxes, and date fields
- tab order, required-field markers, and skip rules for hidden or read-only fields
- value conversion for checkboxes, radio groups, combo boxes, and date fields
- calculation timing and whether scripts are supported, ignored, or blocked
- how invalid fields are highlighted, listed, and returned to the user
Fluxo de implementação
Build a form index before user interaction. The order below keeps the workflow reviewable for Delphi and C++Builder teams.
- scan fields and widgets into a navigation index when the document opens
- connect keyboard traversal, mouse selection, and side-panel selection to the same index
- validate current values before page changes, save, export, or submission
- show field-specific messages that reference the document location and rule
- record validation outcomes for support when users report submission failures
Evidências de validação
Validation signals users and support can understand. Keep these fields with the output or support record.
- field name, type, page, widget bounds, required flag, and current export value
- navigation order and skipped field reasons
- validation rule, failing value, message shown to the user, and time of check
- calculated-field dependencies and whether scripts were allowed
A field is not only a rectangle
A viewer-side form workflow needs field identity, widget geometry, page location, validation messages, current value, export value, and focus behavior. That model should drive both UI navigation and diagnostics.
Review questions before release
Before this reaches production, the team should be able to answer these questions without reading source code.
- Who owns tab order, required-field markers, and skip rules for hidden or read-only fields?
- What evidence proves field name, type, page, widget bounds, required flag, and current export value?
- What happens when radio button groups often share one field name across several widgets?
- Which regression file covers record validation outcomes for support when users report submission failures?
Engineering review notes for form-field navigation and viewer validation
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: tab order, required-field markers, and skip rules for hidden or read-only fields. Implementation pressure point: connect keyboard traversal, mouse selection, and side-panel selection to the same index. Acceptance evidence: validation rule, failing value, message shown to the user, and time of check. Regression trigger: calculated values can become stale when editing jumps across pages
- Decision: value conversion for checkboxes, radio groups, combo boxes, and date fields. Implementation pressure point: validate current values before page changes, save, export, or submission. Acceptance evidence: calculated-field dependencies and whether scripts were allowed. Regression trigger: radio button groups often share one field name across several widgets
Casos limite
- radio button groups often share one field name across several widgets
- required fields hidden by logic still need a policy decision
- date and number formatting should match the document, not only the OS locale
- calculated values can become stale when editing jumps across pages
Delphi / C++Builder notes
PDFium 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 form field, tab order, widget, export value, validation, calculated field.
Exemplo de código Delphi
O esboço Delphi abaixo mostra um limite de serviço prático para este tema. Mantenha checagens de política, logs e validação fora do trecho estreito que chama o produto para que o fluxo continue testável.
procedure TFormHost.BuildFieldNavigation(const FileName: string);
begin
PdfView.LoadFromFile(FileName);
FFields := ExtractInteractiveFields(PdfView);
FFields.SortByPageAndBounds;
ValidateRequiredFieldNames(FFields);
FocusFirstEditableField;
end;Checklist de produção
- 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