Package org.loboevolution.pdfview

Class PDFXref

java.lang.Object
org.loboevolution.pdfview.PDFXref
public class PDFXref extends Object
a cross reference representing a line in the PDF cross referencing table.

There are two forms of the PDFXref, destinguished by absolutely nothing. The first type of PDFXref is used as indirect references in a PDFObject. In this type, the id is an index number into the object cross reference table. The id will range from 0 to the size of the cross reference table.

The second form is used in the Java representation of the cross reference table. In this form, the id is the file position of the start of the object in the PDF file. See the use of both of these in the PDFFile.dereference() method, which takes a PDFXref of the first form, and uses (internally) a PDFXref of the second form.

This is an unhappy state of affairs, and should be fixed. Fortunatly, the two uses have already been factored out as two different methods.

Author Mike Wessler

  • Constructor Summary

    Constructors
    Constructor
    Description
    PDFXref(byte[] line)
    create a new PDFXref, given a sequence of bytes representing the fixed-width cross reference table line
    PDFXref(int id, int gen)
    create a new PDFXref, given a parsed id and generation.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    equals(Object obj)
    int
    getFilePos()
    get the character index into the file of the start of this object
    int
    getID()
    get the object number of this object
    int
    getIndex()
    get the generation of this object
    PDFObject
    getObject()
    Get the object this reference refers to, or null if it hasn't been set.
    int
    hashCode()
    void
    setObject(PDFObject obj)
    Set the object this reference refers to.

    Methods inherited from class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • PDFXref

      public PDFXref(int id, int gen)
      create a new PDFXref, given a parsed id and generation.
      Parameters:
      id - a Integer object.
      gen - a Integer object.

    • PDFXref

      public PDFXref(byte[] line)
      create a new PDFXref, given a sequence of bytes representing the fixed-width cross reference table line
      Parameters:
      line - an array of
      invalid reference 
      byte
      objects.

  • Method Details

    • getFilePos

      public int getFilePos()
      get the character index into the file of the start of this object
      Returns:
      a Integer object.

    • getIndex

      public int getIndex()
      get the generation of this object
      Returns:
      a Integer object.

    • getID

      public int getID()
      get the object number of this object
      Returns:
      a Integer object.

    • getObject

      public PDFObject getObject()
      Get the object this reference refers to, or null if it hasn't been set.
      Returns:
      the object if it exists, or null if not

    • setObject

      public void setObject(PDFObject obj)
      Set the object this reference refers to.
      Parameters:
      obj - a PDFObject object.

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object