Package org.apache.pdfbox.pdmodel.graphics.predictor

Class PredictorAlgorithm

java.lang.Object
org.apache.pdfbox.pdmodel.graphics.predictor.PredictorAlgorithm
Direct Known Subclasses:
Average, None, Optimum, Paeth, Sub, Up
public abstract class PredictorAlgorithm extends Object
Implements different PNG predictor algorithms that is used in PDF files.
Version:
$Revision: 1.4 $
Author:
xylifyx@yahoo.co.uk
See Also:

  • Constructor Summary

    Constructors
    Constructor
    Description
    PredictorAlgorithm()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    aboveLeftPixel(byte[] buf, int offset, int dy, int x)
    Get the above-left pixel from the buffer.
    int
    abovePixel(byte[] buf, int offset, int dy, int x)
    Get the above pixel from the buffer.
    void
    checkBufsiz(byte[] src, byte[] dest)
    check that buffer sizes matches width,height,bpp.
    void
    decode(byte[] src, byte[] dest)
    decode a byte array full of image data using the filter that this object implements.
    abstract void
    decodeLine(byte[] src, byte[] dest, int srcDy, int srcOffset, int destDy, int destOffset)
    decode line of pixel data in src from src_offset and width*bpp bytes forward, put the decoded bytes into dest.
    void
    encode(byte[] src, byte[] dest)
    encode a byte array full of image data using the filter that this object implements.
    abstract void
    encodeLine(byte[] src, byte[] dest, int srcDy, int srcOffset, int destDy, int destOffset)
    encode line of pixel data in src from srcOffset and width*bpp bytes forward, put the decoded bytes into dest.
    int
    getBpp()
     
    static PredictorAlgorithm
    getFilter(int predictor)
     
    int
    getHeight()
     
    int
    getWidth()
     
    int
    leftPixel(byte[] buf, int offset, int dy, int x)
    Get the left pixel from the buffer.
    static void
    main(String[] args)
    Simple command line program to test the algorithm.
    void
    setBpp(int newBpp)
     
    void
    setHeight(int newHeight)
     
    void
    setWidth(int newWidth)
     

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • PredictorAlgorithm

      public PredictorAlgorithm()

  • Method Details

    • checkBufsiz

      public void checkBufsiz(byte[] src, byte[] dest)
      check that buffer sizes matches width,height,bpp. This implementation is used by most of the filters, but not Uptimum.
      Parameters:
      src - The source buffer.
      dest - The destination buffer.

    • encodeLine

      public abstract void encodeLine(byte[] src, byte[] dest, int srcDy, int srcOffset, int destDy, int destOffset)
      encode line of pixel data in src from srcOffset and width*bpp bytes forward, put the decoded bytes into dest.
      Parameters:
      src - raw image data
      dest - encoded data
      srcDy - byte offset between lines
      srcOffset - beginning of line data
      destDy - byte offset between lines
      destOffset - beginning of line data

    • decodeLine

      public abstract void decodeLine(byte[] src, byte[] dest, int srcDy, int srcOffset, int destDy, int destOffset)
      decode line of pixel data in src from src_offset and width*bpp bytes forward, put the decoded bytes into dest.
      Parameters:
      src - encoded image data
      dest - raw data
      srcDy - byte offset between lines
      srcOffset - beginning of line data
      destDy - byte offset between lines
      destOffset - beginning of line data

    • main

      public static void main(String[] args)
      Simple command line program to test the algorithm.
      Parameters:
      args - The command line arguments.

    • leftPixel

      public int leftPixel(byte[] buf, int offset, int dy, int x)
      Get the left pixel from the buffer.
      Parameters:
      buf - The buffer.
      offset - The offset into the buffer.
      dy - The dy value.
      x - The x value.
      Returns:
      The left pixel.

    • abovePixel

      public int abovePixel(byte[] buf, int offset, int dy, int x)
      Get the above pixel from the buffer.
      Parameters:
      buf - The buffer.
      offset - The offset into the buffer.
      dy - The dy value.
      x - The x value.
      Returns:
      The above pixel.

    • aboveLeftPixel

      public int aboveLeftPixel(byte[] buf, int offset, int dy, int x)
      Get the above-left pixel from the buffer.
      Parameters:
      buf - The buffer.
      offset - The offset into the buffer.
      dy - The dy value.
      x - The x value.
      Returns:
      The above-left pixel.

    • getBpp

      public int getBpp()
      Returns:
      Returns the bpp.

    • setBpp

      public void setBpp(int newBpp)
      Parameters:
      newBpp - The bpp to set.

    • getHeight

      public int getHeight()
      Returns:
      Returns the height.

    • setHeight

      public void setHeight(int newHeight)
      Parameters:
      newHeight - The height to set.

    • getWidth

      public int getWidth()
      Returns:
      Returns the width.

    • setWidth

      public void setWidth(int newWidth)
      Parameters:
      newWidth - The width to set.

    • encode

      public void encode(byte[] src, byte[] dest)
      encode a byte array full of image data using the filter that this object implements.
      Parameters:
      src - buffer
      dest - buffer

    • decode

      public void decode(byte[] src, byte[] dest)
      decode a byte array full of image data using the filter that this object implements.
      Parameters:
      src - buffer
      dest - buffer

    • getFilter

      public static PredictorAlgorithm getFilter(int predictor)
      Parameters:
      predictor -
      • 1 No prediction (the default value)
      • 2 TIFF Predictor 2
      • 10 PNG prediction (on encoding, PNG None on all rows)
      • 11 PNG prediction (on encoding, PNG Sub on all rows)
      • 12 PNG prediction (on encoding, PNG Up on all rows)
      • 13 PNG prediction (on encoding, PNG Average on all rows)
      • 14 PNG prediction (on encoding, PNG Paeth on all rows)
      • 15 PNG prediction (on encoding, PNG optimum)
      Returns:
      The predictor class based on the predictor code.