THPDFDocumentHandlerRegistry Class

THPDFDocumentHandlerRegistry = class
  function RegisterHandler(const Handler: IHPDFDocumentHandler;
    ReplaceExisting: boolean = false): boolean;
  function UnregisterHandler(const HandlerName: string): boolean;
  procedure Clear;
  function GetHandlerCount: Integer;
  function GetHandlerName(Index: Integer): string;
  procedure RegisterStandardHandlers(ReplaceExisting: boolean = false);
  function OpenFromStream(Source: TStream; const SourceName,
    MIMEType: string; const Options: THPDFDocumentHandlerOptions;
    out Document: IHPDFHandledDocument;
    out Info: THPDFDocumentHandlerInfo): boolean;
  function OpenFromFile(const FileName, MIMEType: string;
    const Options: THPDFDocumentHandlerOptions;
    out Document: IHPDFHandledDocument;
    out Info: THPDFDocumentHandlerInfo): boolean;
end;

Registration, replacement, removal, snapshots, and lookup are thread-safe, with at most 32 handlers and one case-insensitive slot per handler name

Recognition runs outside the registry lock against a stable interface snapshot, and equal scores retain registration order

RegisterStandardHandlers opts into XPS, EPUB, and CBZ support without changing PDF-specific loading APIs

Optional Document Handlers