Package com.itextpdf.kernel.pdf

Class PdfXrefTable

  • public class PdfXrefTable
extends java.lang.Object
    A representation of a cross-referenced table of a PDF document.

    • Field Detail

      • MAX_OFFSET_IN_CROSS_REFERENCE_STREAM

        private static final long MAX_OFFSET_IN_CROSS_REFERENCE_STREAM
        The maximum offset in a cross-reference stream. This is a limitation of the PDF specification. SPEC1.7: 7.5.4 Cross reference trailer

        It states that the offset should be a 10-digit byte, so the maximum value is 9999999999. This is the max value that can be represented in 10 bytes.

        See Also:
        Constant Field Values

      • freeXRefEntry

        private static final byte[] freeXRefEntry

      • inUseXRefEntry

        private static final byte[] inUseXRefEntry

      • count

        private int count

      • readingCompleted

        private boolean readingCompleted

      • freeReferencesLinkedList

        private final java.util.TreeMap<java.lang.Integer,​PdfIndirectReference> freeReferencesLinkedList
        Free references linked list is stored in a form of a map, where: key - free reference obj number; value - previous item in the linked list of free references for the object denoted by the key.

    • Constructor Detail

      • PdfXrefTable

        public PdfXrefTable()
        Creates a PdfXrefTable which will be used to store xref structure of the pdf document. Capacity and MemoryLimitsAwareHandler instance would be set by default values.

      • PdfXrefTable

        public PdfXrefTable​(int capacity)
        Creates a PdfXrefTable which will be used to store xref structure of the pdf document.
        Parameters:
        capacity - initial capacity of xref table.

      • PdfXrefTable

        public PdfXrefTable​(int capacity,
                    MemoryLimitsAwareHandler memoryLimitsAwareHandler)
        Creates a PdfXrefTable which will be used to store xref structure of the pdf document.
        Parameters:
        capacity - initial capacity of xref table.
        memoryLimitsAwareHandler - memoryLimitsAwareHandler custom MemoryLimitsAwareHandler to set.

    • Method Detail

      • add

        public PdfIndirectReference add​(PdfIndirectReference reference)
        Adds indirect reference to list of indirect objects.
        Parameters:
        reference - indirect reference to add.
        Returns:
        reference from param

      • size

        public int size()
        Get size of cross-reference table.
        Returns:
        amount of lines including zero-object

      • getCountOfIndirectObjects

        public int getCountOfIndirectObjects()
        Calculates a number of stored references to indirect objects.
        Returns:
        number of indirect objects

      • get

        public PdfIndirectReference get​(int index)
        Get appropriate reference to indirect object.
        Parameters:
        index - is the index of required object
        Returns:
        reference to object with the provided index

      • createNextIndirectReference

        protected PdfIndirectReference createNextIndirectReference​(PdfDocument document)
        Creates next available indirect reference.
        Parameters:
        document - is the current document
        Returns:
        created indirect reference.

      • freeReference

        protected void freeReference​(PdfIndirectReference reference)
        Set the reference to free state.
        Parameters:
        reference - is a reference to be updated.

      • getCapacity

        protected int getCapacity()
        Gets the capacity of xref stream.
        Returns:
        the capacity of xref stream.

      • setCapacity

        protected void setCapacity​(int capacity)
        Increase capacity of the array of indirect references.
        Parameters:
        capacity - is a new capacity to set

      • writeXrefTableAndTrailer

        protected void writeXrefTableAndTrailer​(PdfDocument document,
                                        PdfObject fileId,
                                        PdfObject crypto)
                                 throws java.io.IOException
        Writes cross reference table and trailer to PDF.
        Parameters:
        document - is the current document
        fileId - field id
        crypto - pdf encryption
        Throws:
        java.io.IOException - if any I/O error occurs

      • markReadingCompleted

        void markReadingCompleted()
        Change the state of the cross-reference table to mark that reading of the document was completed.

      • unmarkReadingCompleted

        void unmarkReadingCompleted()
        Change the state of the cross-reference table to unmark that reading of the document was completed.

      • isReadingCompleted

        boolean isReadingCompleted()
        Check if reading of the document was completed.
        Returns:
        true if reading was completed and false otherwise

      • initFreeReferencesList

        void initFreeReferencesList​(PdfDocument pdfDocument)
        Set up appropriate state for the free references list.
        Parameters:
        pdfDocument - is the current document

      • createNewIndirectReference

        PdfIndirectReference createNewIndirectReference​(PdfDocument document)
        Method is used for object streams to avoid reuse existed references.
        Parameters:
        document - is the current document
        Returns:
        created indirect reference to the object stream

      • clear

        void clear()
        Clear the state of the cross-reference table without free references removal.

      • clearAllReferences

        void clearAllReferences()
        Clear the state of the cross-reference table including free references.

      • createSections

        private java.util.List<java.lang.Integer> createSections​(PdfDocument document,
                                                         boolean dropObjectsFromObjectStream)

      • getOffsetSize

        private int getOffsetSize​(long startxref)
        Gets size of the offset. Max size is 2^40, i.e. 1 Tb.

      • removeFreeRefFromList

        private PdfIndirectReference removeFreeRefFromList​(int freeRefObjNr)
        Removes indirect reference from free references linked list. It does not removes it from xref table and affects only the linked list formed by offset values of free references.
        Parameters:
        freeRefObjNr - object number of the reference to be removed. Removes the free reference with the least object number if this parameter is less than zero: this could be used for finding the next free reference for reusing.
        Returns:
        PdfIndirectReference instance of the removed free reference corresponding to the object number passed as parameter. null - if given object number doesn't correspond to free reference or equals to zero.

      • ensureCount

        private void ensureCount​(int count)

      • extendXref

        private void extendXref​(int capacity)