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## org.apache.poi.hdgf
Class HDGFLZW

    java.lang.Object
      org.apache.poi.util.LZWDecompresser
          org.apache.poi.hdgf.HDGFLZW

    public class HDGFLZW

extends LZWDecompresser

A decoder for the crazy LZW implementation used in Visio. According to VSDump, "it's a slightly perverted version of LZW compression, with inverted meaning of flag byte and 0xFEE as an 'initial shift'". It uses 12 bit codes (http://www.gnome.ru/projects/vsdump_en.html) Two good resources on LZW are: http://en.wikipedia.org/wiki/LZW http://marknelson.us/1989/10/01/lzw-data-compression/

Constructor Summary
`HDGFLZW()`

Method Summary
`protected int` | `adjustDictionaryOffset(int pntr)` We have a slight shift by 18 bytes
`byte[]` | `compress(java.io.InputStream src)` Compress the given input stream, returning the array of bytes of the compressed input
`void` | `compress(java.io.InputStream src, java.io.OutputStream res)` Performs the Visio compatible streaming LZW compression.
`protected int` | `populateDictionary(byte[] dict)` We want an empty dictionary, so do nothing

Methods inherited from class org.apache.poi.util.LZWDecompresser
`decompress, decompress, fromByte, fromInt`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### HDGFLZW

    public HDGFLZW()

Method Detail

### compress

    public byte[] compress(java.io.InputStream src)
                    throws java.io.IOException

  Compress the given input stream, returning the array of bytes of the compressed input

  Throws:
    `java.io.IOException`

### adjustDictionaryOffset

    protected int adjustDictionaryOffset(int pntr)

  We have a slight shift by 18 bytes

  Specified by:
    `adjustDictionaryOffset` in class `LZWDecompresser`

### populateDictionary

    protected int populateDictionary(byte[] dict)

  We want an empty dictionary, so do nothing

  Specified by:
    `populateDictionary` in class `LZWDecompresser`

### compress

    public void compress(java.io.InputStream src,
                         java.io.OutputStream res)
                  throws java.io.IOException

  Performs the Visio compatible streaming LZW compression.

  Throws:
    `java.io.IOException`

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Copyright 2017 The Apache Software Foundation or its licensors, as applicable.