Heres a couple of classes the compress and decompress data:
'DATACOMPRESS CLASS - VB.Net
'**********************************************************************************************************
' METHODS:
' CompressBytes(Source ByteArray, Optional Temporay Byte Array
' Compresses ByteArray into Temporary Byte Array or into
ByteArray if Temporary Byte Array not input
'
' DeCompressBytes (Source ByteArray, Original Array Size before
compression as integer, Optional Temporary Byte Array)
' Decompresses ByteArray into Temporary Byte Array or into
ByteArray if Temporary Byte Array not input
'
'***********************************************************************************************************
Imports System.Runtime.InteropServices
Public Class CompressData
'Declare zlib functions "Compress" and "Uncompress" for compressing Byte
Arrays
<DllImport("zlib.DLL", EntryPoint:="compress")> _
Private Shared Function CompressByteArray(ByVal dest As Byte(), ByRef
destLen As Integer, ByVal src As Byte(), ByVal srcLen As Integer) As Integer
' Leave function empty - DLLImport attribute forwards calls to
CompressByteArray to compress in zlib.dLL
End Function
<DllImport("zlib.DLL", EntryPoint:="uncompress")> _
Private Shared Function UncompressByteArray(ByVal dest As Byte(), ByRef
destLen As Integer, ByVal src As Byte(), ByVal srcLen As Integer) As Integer
' Leave function empty - DLLImport attribute forwards calls to
UnCompressByteArray to Uncompress in zlib.dLL
End Function
Public Sub New()
MyBase.New()
End Sub
Public Function CompressBytes(ByRef Data() As Byte, Optional ByRef
TempBuffer() As Byte = Nothing) As Integer
'Compresses Data into a temp buffer
'Returns compressed Data in Data if TempBuff not specified
'Returns Result = Size of compressed data if ok, -1 if compression
failed
Dim OriginalSize As Long = UBound(Data) + 1
'Allocate temporary Byte Array for storage
Dim result As Integer
Dim usenewstorage As Boolean
If TempBuffer Is Nothing Then usenewstorage = False Else
usenewstorage = True
Dim BufferSize As Integer = UBound(Data) + 1
BufferSize = CInt(BufferSize + (BufferSize * 0.01) + 12)
ReDim TempBuffer(BufferSize)
'Compress data byte array
result = CompressByteArray(TempBuffer, BufferSize, Data,
UBound(Data) + 1)
'Store results
If result = 0 Then
If usenewstorage Then
'Return results in TempBuffer
ReDim Preserve TempBuffer(BufferSize - 1)
Else
'Return compressed Data in original Data Array
' Resize original data array to compressed size
ReDim Data(BufferSize - 1)
' Copy Array to original data array
Array.Copy(TempBuffer, Data, BufferSize)
'Release TempBuffer STorage
TempBuffer = Nothing
End If
Return BufferSize
Else
Return -1
End If
End Function
Public Function DeCompressBytes(ByRef Data() As Byte, ByVal Origsize As
Integer, Optional ByRef TempBuffer() As Byte = Nothing) As Integer
'DeCompresses Data into a temp buffer..note that Origsize must be
the size of the original data before compression
'Returns compressed Data in Data if TempBuff not specified
'Returns Result = Size of decompressed data if ok, -1 if not
'Allocate memory for buffers
Dim result As Integer
Dim usenewstorage As Boolean
Dim Buffersize As Integer = CInt(Origsize + (Origsize * 0.01) + 12)
If TempBuffer Is Nothing Then usenewstorage = False Else
usenewstorage = True
ReDim TempBuffer(Buffersize)
'Decompress data
result = UncompressByteArray(TempBuffer, Origsize, Data,
UBound(Data) + 1)
'Truncate buffer to compressed size
If result = 0 Then
If usenewstorage Then
'Return decoompressed data in TempBuffer
ReDim Preserve TempBuffer(Origsize - 1)
Else
'Return decompressed data in original source data file
' Truncate to compressed size
ReDim Data(Origsize - 1)
' Copy Array to original data array
Array.Copy(TempBuffer, Data, Origsize)
'Release TempBuffer STorage
TempBuffer = Nothing
End If
Return Origsize
Else
Return -1
End If
End Function
Protected Overrides Sub Finalize()
MyBase.Finalize()
End Sub
'Test routines for this class:
'Testing - Remove
'Dim sdata As Byte() = New Byte() {}
'Dim fs As FileStream = New FileStream("C:\Programming\VS-Help Docs\Misc
NewsGroup Articles.doc", FileMode.Open, FileAccess.Read)
'Dim rnew As BinaryReader = New BinaryReader(fs)
' sdata = rnew.ReadBytes(CInt(fs.Length))
' r.Close()
' fs.Close()
'Dim ucomp As Integer = UBound(sdata, 1) + 1
'Dim compsize As Integer = cmp.CompressBytes(sdata)
'Dim uncompsize As Integer = cmp.DeCompressBytes(sdata, ucomp)
'End TEsting
End Class
"M. Posseth" wrote:
>
> Hello Crouchie
>
> Thanks for the link this code should not be so difficult to convert to
> VB.Net ,, i was already thinking about the huffman algorythm as i know
> that it is verry strong on string values
> and as far as i know it should also be possible to make it easily in Delphi
>
>
> Well i will probably end up in writing one in VB.Net and Delphi as you
> just saved me the VB6 version :-)
>
> when it is finished i will post the link were to download it
>
>
> Michel Posseth
>
>
>
>
>
>
> "Crouchie1998" <(E-Mail Removed)> wrote in message
> news:e$P0m$(E-Mail Removed)...
> > If you want a compression then I suggest Huffman compression, but there
> are
> > no examples of this in VB.NET, but there are in VB6. If you do convert it
> to
> > VB.NET then please post the code here.
> >
> > Here's a link to a VB6 project if you want to convert it:
> >
> >
> http://www.planet-source-code.com/vb...11000&lngWId=1
> >
> > I hope this is of help to you
> >
> >
>
>
>
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