Method saveInternal

src/api/pdf.ts:3197–3341

* Internal save that returns full result including xref offset. * Used by signing to chain incremental updates.

(options: SaveOptions = {})

   * Used by signing to chain incremental updates.
   */
  private saveInternal(options: SaveOptions = {}): { bytes: Uint8Array; xrefOffset: number } {
    // Finalize embedded fonts (creates PDF objects, optionally subsets)
    this.fonts.finalize(options.subsetFonts ?? false);

    const wantsIncremental = options.incremental ?? false;
    const blocker = this.canSaveIncrementally();

    // Check if incremental is requested but not possible
    if (wantsIncremental && blocker !== null) {
      this.ctx.registry.addWarning(
        `Incremental save not possible (${blocker}), performing full save`,
      );
    }

    const useIncremental = wantsIncremental && blocker === null;

    // If no changes and no security changes, return original bytes
    const hasSecurityChanges = this._pendingSecurity.action !== "none";

    if (!this.hasChanges() && !this.fonts.hasEmbeddedFonts && !hasSecurityChanges) {
      return {
        bytes: this.originalBytes,
        xrefOffset: this.originalXRefOffset,
      };
    }

    // Get root reference from trailer
    const root = this.ctx.info.trailer.getRef("Root");

    if (!root) {
      throw new Error("Document has no catalog (missing /Root in trailer)");
    }

    // Get optional info reference
    const infoRef = this.ctx.info.trailer.getRef("Info");

    // Handle encryption based on pending security state
    let encryptRef: PdfRef | undefined;
    let fileId: [Uint8Array, Uint8Array] | undefined;
    let securityHandler: StandardSecurityHandler | undefined;

    if (this._pendingSecurity.action === "encrypt" && this._pendingSecurity.options) {
      // Generate new encryption
      const encryption = generateEncryption(this._pendingSecurity.options);

      // Register the encrypt dictionary
      encryptRef = this.ctx.registry.register(encryption.encryptDict);
      fileId = encryption.fileId;
      securityHandler = encryption.securityHandler;
    } else if (this._pendingSecurity.action === "none" && this.isEncrypted) {
      // Re-encrypt with original security - preserve encryption when saving encrypted documents
      const handler = this.ctx.info.securityHandler;

      if (handler) {
        // Reconstruct the encrypt dict from the parsed encryption parameters
        // We can't resolve the original encrypt ref because it would try to decrypt it
        // (the encrypt dict is never encrypted in the PDF)
        const reconstructedDict = reconstructEncryptDict(handler.encryption);