Delphi/C++Builder には PDFium VCL Component のワークフローを、Lazarus/FPC には PDFium LCL Component のワークフローを組み込み、表示、レンダリング、フォーム、印刷、プリフライトレポート、標準対応の検証をソースコード付きコンポーネントで実装できます。
この記事は developers building PDF data-entry viewers where users need to complete forms accurately 向けです。form-field navigation and viewer validation を単なるコンポーネント呼び出しではなく、本番向けのドキュメントエンジニアリングとして扱います。
実務上のリスクは 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 です。そのため、明確な契約、観測可能な診断、実際の顧客ファイルに近い回帰サンプルが必要です。
アーキテクチャ上の判断
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
実装フロー
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
検証エビデンス
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
境界ケース
- 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.
Delphi コード例
次の Delphi スケッチは、このテーマに対する実用的なサービス境界を示します。ポリシー確認、ログ記録、検証を製品呼び出しの狭い部分の外側に置くと、ワークフローをテストしやすくなります。
procedure TFormHost.BuildFieldNavigation(const FileName: string);
begin
PdfView.LoadFromFile(FileName);
FFields := ExtractInteractiveFields(PdfView);
FFields.SortByPageAndBounds;
ValidateRequiredFieldNames(FFields);
FocusFirstEditableField;
end;本番チェックリスト
- 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