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技術記事

PDFium Component: Delphi での PDF intake and review workbench

PDFium Component

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 teams triaging incoming PDFs before routing them to compliance, support, conversion, or data-entry workflows 向けです。PDF intake and review workbench 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 intake tools become unreliable when preview, metadata, warnings, annotations, security state, and operator decisions live in separate screens 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

Create one intake record per document. intake states such as new, blocked, needs review, ready, rejected, and archived / metadata fields, warnings, thumbnail strategy, and operator notes

  • intake states such as new, blocked, needs review, ready, rejected, and archived
  • metadata fields, warnings, thumbnail strategy, and operator notes
  • routing rules for encrypted, signed, damaged, image-only, or oversized files
  • retention policy for original files, previews, reports, and review decisions

実装フロー

Summarize document risk before routing. The order below keeps the workflow reviewable for Delphi and C++Builder teams.

  1. create an intake record before rendering pages or modifying the file
  2. collect metadata, security state, page count, text availability, and warnings
  3. generate thumbnails and preview pages without changing the source document
  4. surface blockers and recommended routing actions to the operator
  5. store the final decision with enough evidence for downstream teams

検証エビデンス

Intake evidence that supports hand-off. Keep these fields with the output or support record.

  • source path, hash, page count, metadata, encryption status, and signature status
  • warnings for forms, annotations, attachments, damaged objects, or missing text
  • operator decision, routing destination, comment, and time of hand-off
  • preview generation status and reason when a file cannot be previewed

Preview should explain, not just display

A review workbench should make document facts visible: page count, encryption, forms, annotations, attachments, signatures, metadata, text availability, and validation findings. Operators can then route a file without guessing.

サポートパッケージの設計

PDFium Component を展開した後に最も役立つサポートパッケージは、入力、プロファイル、出力、そして失敗した正確な段階を説明するものです

  • source path, hash, page count, metadata, encryption status, and signature status
  • warnings for forms, annotations, attachments, damaged objects, or missing text
  • operator decision, routing destination, comment, and time of hand-off
  • preview generation status and reason when a file cannot be previewed
  • terminology snapshot: intake, review workbench, thumbnail, metadata

PDF intake and review workbench に関する技術レビューの注意点

これらのレビュー項目を使って、機能がデモ段階を超え、リリース、サポート、顧客エスカレーションの場で説明できることを確認します

  • 判断: intake states such as new, blocked, needs review, ready, rejected, and archived. 実装上の焦点: collect metadata, security state, page count, text availability, and warnings. 受け入れ証拠: operator decision, routing destination, comment, and time of hand-off. 回帰の引き金: oversized files need queue limits and operator feedback rather than silent delays
  • 判断: metadata fields, warnings, thumbnail strategy, and operator notes. 実装上の焦点: generate thumbnails and preview pages without changing the source document. 受け入れ証拠: preview generation status and reason when a file cannot be previewed. 回帰の引き金: password-protected files need a secure credential hand-off or a blocked state
  • 判断: routing rules for encrypted, signed, damaged, image-only, or oversized files. 実装上の焦点: surface blockers and recommended routing actions to the operator. 受け入れ証拠: source path, hash, page count, metadata, encryption status, and signature status. 回帰の引き金: image-only files should not be routed to text extraction without a warning
  • 判断: retention policy for original files, previews, reports, and review decisions. 実装上の焦点: store the final decision with enough evidence for downstream teams. 受け入れ証拠: warnings for forms, annotations, attachments, damaged objects, or missing text. 回帰の引き金: signed documents may require read-only review to preserve trust
  • 判断: intake states such as new, blocked, needs review, ready, rejected, and archived. 実装上の焦点: create an intake record before rendering pages or modifying the file. 受け入れ証拠: operator decision, routing destination, comment, and time of hand-off. 回帰の引き金: oversized files need queue limits and operator feedback rather than silent delays

境界ケース

  • password-protected files need a secure credential hand-off or a blocked state
  • image-only files should not be routed to text extraction without a warning
  • signed documents may require read-only review to preserve trust
  • oversized files need queue limits and operator feedback rather than silent delays

Delphi / C++Builder の補足

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. 重要な用語には intake, review workbench, thumbnail, metadata, routing, document risk.

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 TIntakeWorkbench.OpenForReview(const FileName: string);
begin
  PdfView.LoadFromFile(FileName);
  FCaseId := CreateReviewCase(FileName, PdfView.PageCount);
  FFindings := RunIntakeChecks(PdfView);
  RenderThumbnailStrip;
  BindFindingsToGrid(FFindings);
end;

本番チェックリスト

  • ワークフローは、空のファイル、通常の顧客ファイル、最悪ケースのファイルで実行します
  • 生成された PDF は、対象のビューアー、検証ツール、プリンター、または downstream アプリケーションで開きます
  • 製品バージョン、プロファイルバージョン、入力ハッシュ、出力パス、経過時間、警告数を記録します
  • パスワード、証明書、一時ファイル、顧客データは明確な保持ルールの下で管理します
  • 顧客ファイルが新しい境界ケースを示したら、回帰用ドキュメントを追加します

製品ドキュメント

PDFium Component

追加のコード例

procedure CollectIdentity(Pdf: TPdf; const FilePath: string;
  var Rec: TIntakeRecord);
begin
  Rec.Title := Pdf.Title;             // Info dictionary value
  Rec.Author := Pdf.Author;
  Rec.CreatedAt := Pdf.CreationDate;  // raw PDF date string ("D:2026...")

  // An empty Info title does not mean the document is untitled. The
  // component does not expose the XMP packet, so probe the raw file
  // bytes for the dc:title element before trusting the blank.
  if (Rec.Title = '') and FileContainsText(FilePath, 'dc:title') then
    Include(Rec.Flags, ifTitleInXmpOnly);
end;
procedure CollectRiskSignals(Pdf: TPdf; var Rec: TIntakeRecord);
var
  i, PageNo: Integer;
  Ext: string;
begin
  Rec.IsEncrypted := Assigned(FPDF_GetSecurityHandlerRevision) and
    (FPDF_GetSecurityHandlerRevision(Pdf.Document) <> -1);
  Rec.HasForms := Pdf.FormType <> ftNone;
  Rec.IsXfa := Pdf.FormType = ftXfaFull;
  Rec.HasJavaScript := Pdf.JavaScriptActionCount > 0;

  // AnnotationCount is a per-page property; walk the pages to total
  // it. Loading a page object renders nothing, so this stays cheap.
  Rec.Annotations := 0;
  for PageNo := 1 to Pdf.PageCount do
  begin
    Pdf.PageNumber := PageNo;
    Inc(Rec.Annotations, Pdf.AnnotationCount);
  end;

  Rec.Attachments := Pdf.AttachmentCount;

  for i := 0 to Rec.Attachments - 1 do
  begin
    Ext := LowerCase(ExtractFileExt(string(Pdf.AttachmentName[i])));
    if (Ext = '.exe') or (Ext = '.js') or (Ext = '.vbs') or (Ext = '.dll') then
      Include(Rec.Flags, ifDangerousAttachment);
  end;
end;