Package org.openpdf.renderer.decode

Class PNGPredictor

java.lang.Object
org.openpdf.renderer.decode.Predictor
org.openpdf.renderer.decode.PNGPredictor
public class PNGPredictor extends Predictor
Undo prediction based on the PNG algorithm.

  • Field Summary

    Fields inherited from class org.openpdf.renderer.decode.Predictor

    PNG, TIFF

  • Constructor Summary

    Constructors
    Constructor
    Description
    PNGPredictor()
    Creates a new instance of PNGPredictor

  • Method Summary

    Modifier and Type
    Method
    Description
    protected void
    doAverageLine(byte[] curLine, byte[] prevLine)
    Return the value of the average algorithm on the line (compare bytes to the average of the previous byte of the same color and the same byte on the previous line)
    protected void
    doPaethLine(byte[] curLine, byte[] prevLine)
    Return the value of the average algorithm on the line (compare bytes to the average of the previous byte of the same color and the same byte on the previous line)
    protected void
    doSubLine(byte[] curLine)
    Return the value of the Sub algorithm on the line (compare bytes to the previous byte of the same color on this line).
    protected void
    doUpLine(byte[] curLine, byte[] prevLine)
    Return the value of the up algorithm on the line (compare bytes to the same byte in the previous line)
    protected int
    paeth(int left, int up, int upLeft)
    The paeth algorithm
    ByteBuffer
    unpredict(ByteBuffer imageData)
    Undo data based on the png algorithm

    Methods inherited from class org.openpdf.renderer.decode.Predictor

    getAlgorithm, getBitsPerComponent, getColors, getColumns, getPredictor, setBitsPerComponent, setColors, setColumns

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • PNGPredictor

      public PNGPredictor()
      Creates a new instance of PNGPredictor

  • Method Details

    • unpredict

      public ByteBuffer unpredict(ByteBuffer imageData) throws IOException
      Undo data based on the png algorithm
      Specified by:
      unpredict in class Predictor
      Throws:
      IOException

    • doSubLine

      protected void doSubLine(byte[] curLine)
      Return the value of the Sub algorithm on the line (compare bytes to the previous byte of the same color on this line).

    • doUpLine

      protected void doUpLine(byte[] curLine, byte[] prevLine)
      Return the value of the up algorithm on the line (compare bytes to the same byte in the previous line)

    • doAverageLine

      protected void doAverageLine(byte[] curLine, byte[] prevLine)
      Return the value of the average algorithm on the line (compare bytes to the average of the previous byte of the same color and the same byte on the previous line)

    • doPaethLine

      protected void doPaethLine(byte[] curLine, byte[] prevLine)
      Return the value of the average algorithm on the line (compare bytes to the average of the previous byte of the same color and the same byte on the previous line)

    • paeth

      protected int paeth(int left, int up, int upLeft)
      The paeth algorithm