Class PdfXrefLookup

constructor

• new PdfXrefLookup(
      options?: {
          object?:
              | PdfXRefTable
              | PdfIndirectObject<PdfStream<PdfDictionary<PdfDictionaryEntries>>>;
          prev?: PdfXrefLookup;
          trailerDict?: PdfDictionary<PdfTrailerEntries>;
          type?: "stream" | "table";
      },
  ): PdfXrefLookup

  Creates a new xref lookup instance.

  Parameters

  • Optionaloptions: {
        object?:
            | PdfXRefTable
            | PdfIndirectObject<PdfStream<PdfDictionary<PdfDictionaryEntries>>>;
        prev?: PdfXrefLookup;
        trailerDict?: PdfDictionary<PdfTrailerEntries>;
        type?: "stream" | "table";
    }

    Configuration options

    • Optionalobject?: PdfXRefTable | PdfIndirectObject<PdfStream<PdfDictionary<PdfDictionaryEntries>>>

      Pre-existing xref table or stream object

    • Optionalprev?: PdfXrefLookup

      Previous xref lookup to link to

    • OptionaltrailerDict?: PdfDictionary<PdfTrailerEntries>

      Pre-existing trailer dictionary

    • Optionaltype?: "stream" | "table"

      Type of xref ('table' or 'stream')

  Returns PdfXrefLookup

entries

object

Optionalprev

trailerDict

entriesValues

• get entriesValues(): PdfXRefStreamEntry[]

  Gets all xref entries as an array.

  Returns PdfXRefStreamEntry[]

offset

• get offset(): Ref<number>

  Gets the byte offset of the xref object.

  Returns Ref<number>

• set offset(value: Ref<number>): void

  Sets the byte offset of the xref object.

  Parameters

  • value: Ref<number>

  Returns void

size

• get size(): number

  Gets the size of the xref table (highest object number + 1). Ensures size is at least as large as the previous revision.

  Returns number

• set size(value: number): void

  Sets the size of the xref table.

  Parameters

  • value: number

  Returns void

addObject

• addObject(
      newObject: PdfIndirectObject,
      options?: { indexInStream?: number; parentObjectNumber?: number },
  ): void

  Adds an indirect object to the xref lookup. Assigns an object number if not already set.

  Parameters

  • newObject: PdfIndirectObject

    The indirect object to add

  • Optionaloptions: { indexInStream?: number; parentObjectNumber?: number }

    Options for compressed objects

    • OptionalindexInStream?: number

      Index within the object stream

    • OptionalparentObjectNumber?: number

      Object number of the containing object stream

  Returns void

  Throws

  Error if trying to add compressed object with non-zero generation number

getObject

• getObject(objectNumber: number): PdfXRefStreamEntry | undefined

  Gets an xref entry by object number. Falls back to the previous xref if not found in current entries.

  Parameters

  • objectNumber: number

    The object number to look up

  Returns PdfXRefStreamEntry | undefined

  The xref entry or undefined if not found

linkIndirectObjects

• linkIndirectObjects(objects: PdfIndirectObject<PdfObject>[]): void

  Links xref entries to their corresponding indirect objects. Updates byte offset references to point to actual object offsets.

  Parameters

  • objects: PdfIndirectObject<PdfObject>[]

    Array of indirect objects to link

  Returns void

linkPrev

• linkPrev(objects: PdfXrefLookup[]): void

  Links this xref to a previous xref lookup based on the Prev trailer entry.

  Parameters

  • objects: PdfXrefLookup[]

    Array of xref lookups to search for the previous one

  Returns void

removeObject

• removeObject(object: PdfIndirectObject): void

  Removes an indirect object from the xref lookup. Also removes any trailer references to the object.

  Parameters

  • object: PdfIndirectObject

    The indirect object to remove

  Returns void

setPrev

• setPrev(xref: PdfXrefLookup): void

  Links this xref to a previous xref lookup. Copies missing trailer entries from the previous xref.

  Parameters

  • xref: PdfXrefLookup

    The previous xref lookup to link to

  Returns void

  Throws

  Error if trying to set self as previous (would create circular reference) or if offsets match (would create ambiguous or invalid xref chain)

toTrailerSection

• toTrailerSection(): PdfObject[]

  Generates the trailer section objects for this xref. Includes xref table/stream, trailer (if using table), startxref, and EOF.

  Returns PdfObject[]

  Array of objects forming the trailer section

update

• update(): PdfXRefTable | PdfIndirectObject<PdfXRefStream>

  Updates the xref object with current entries. Handles both table and stream formats, including hybrid documents.

  Returns PdfXRefTable | PdfIndirectObject<PdfXRefStream>

  The updated xref object

StaticfromObjects

• fromObjects(objects: PdfObject[]): PdfXrefLookup

  Creates xref lookups from an array of PDF objects. Parses both xref tables and xref streams, linking them via the Prev chain.

  Parameters

  • objects: PdfObject[]

    Array of PDF objects to parse

  Returns PdfXrefLookup

  The most recent xref lookup with linked previous lookups

StaticfromXrefStream

• fromXrefStream(
      streamObject: PdfIndirectObject<
          PdfStream<PdfDictionary<PdfDictionaryEntries>>,
      >,
  ): PdfXrefLookup

  Creates an xref lookup from an xref stream object.

  Parameters

  • streamObject: PdfIndirectObject<PdfStream<PdfDictionary<PdfDictionaryEntries>>>

    The indirect object containing the xref stream

  Returns PdfXrefLookup

  A new PdfXrefLookup instance

StaticfromXrefTable

• fromXrefTable(
      xrefTable: PdfXRefTable,
      trailer: PdfTrailer,
      objects?: PdfObject[],
  ): PdfXrefLookup

  Creates an xref lookup from a traditional xref table and trailer. Handles hybrid xref documents with both table and stream entries.

  Parameters

  • xrefTable: PdfXRefTable

    The xref table object

  • trailer: PdfTrailer

    The trailer object

  • Optionalobjects: PdfObject[]

    Optional array of objects for resolving hybrid xref streams

  Returns PdfXrefLookup

  A new PdfXrefLookup instance