Chris@43: See below some functions declarations for Visual Basic.
Chris@43: 
Chris@43: Frequently Asked Question:
Chris@43: 
Chris@43: Q: Each time I use the compress function I get the -5 error (not enough
Chris@43:    room in the output buffer).
Chris@43: 
Chris@43: A: Make sure that the length of the compressed buffer is passed by
Chris@43:    reference ("as any"), not by value ("as long"). Also check that
Chris@43:    before the call of compress this length is equal to the total size of
Chris@43:    the compressed buffer and not zero.
Chris@43: 
Chris@43: 
Chris@43: From: "Jon Caruana" <jon-net@usa.net>
Chris@43: Subject: Re: How to port zlib declares to vb?
Chris@43: Date: Mon, 28 Oct 1996 18:33:03 -0600
Chris@43: 
Chris@43: Got the answer! (I haven't had time to check this but it's what I got, and
Chris@43: looks correct):
Chris@43: 
Chris@43: He has the following routines working:
Chris@43:         compress
Chris@43:         uncompress
Chris@43:         gzopen
Chris@43:         gzwrite
Chris@43:         gzread
Chris@43:         gzclose
Chris@43: 
Chris@43: Declares follow: (Quoted from Carlos Rios <c_rios@sonda.cl>, in Vb4 form)
Chris@43: 
Chris@43: #If Win16 Then   'Use Win16 calls.
Chris@43: Declare Function compress Lib "ZLIB.DLL" (ByVal compr As
Chris@43:         String, comprLen As Any, ByVal buf As String, ByVal buflen
Chris@43:         As Long) As Integer
Chris@43: Declare Function uncompress Lib "ZLIB.DLL" (ByVal uncompr
Chris@43:         As String, uncomprLen As Any, ByVal compr As String, ByVal
Chris@43:         lcompr As Long) As Integer
Chris@43: Declare Function gzopen Lib "ZLIB.DLL" (ByVal filePath As
Chris@43:         String, ByVal mode As String) As Long
Chris@43: Declare Function gzread Lib "ZLIB.DLL" (ByVal file As
Chris@43:         Long, ByVal uncompr As String, ByVal uncomprLen As Integer)
Chris@43:         As Integer
Chris@43: Declare Function gzwrite Lib "ZLIB.DLL" (ByVal file As
Chris@43:         Long, ByVal uncompr As String, ByVal uncomprLen As Integer)
Chris@43:         As Integer
Chris@43: Declare Function gzclose Lib "ZLIB.DLL" (ByVal file As
Chris@43:         Long) As Integer
Chris@43: #Else
Chris@43: Declare Function compress Lib "ZLIB32.DLL"
Chris@43:         (ByVal compr As String, comprLen As Any, ByVal buf As
Chris@43:         String, ByVal buflen As Long) As Integer
Chris@43: Declare Function uncompress Lib "ZLIB32.DLL"
Chris@43:         (ByVal uncompr As String, uncomprLen As Any, ByVal compr As
Chris@43:         String, ByVal lcompr As Long) As Long
Chris@43: Declare Function gzopen Lib "ZLIB32.DLL"
Chris@43:         (ByVal file As String, ByVal mode As String) As Long
Chris@43: Declare Function gzread Lib "ZLIB32.DLL"
Chris@43:         (ByVal file As Long, ByVal uncompr As String, ByVal
Chris@43:         uncomprLen As Long) As Long
Chris@43: Declare Function gzwrite Lib "ZLIB32.DLL"
Chris@43:         (ByVal file As Long, ByVal uncompr As String, ByVal
Chris@43:         uncomprLen As Long) As Long
Chris@43: Declare Function gzclose Lib "ZLIB32.DLL"
Chris@43:         (ByVal file As Long) As Long
Chris@43: #End If
Chris@43: 
Chris@43: -Jon Caruana
Chris@43: jon-net@usa.net
Chris@43: Microsoft Sitebuilder Network Level 1 Member - HTML Writer's Guild Member
Chris@43: 
Chris@43: 
Chris@43: Here is another example from Michael <michael_borgsys@hotmail.com> that he
Chris@43: says conforms to the VB guidelines, and that solves the problem of not
Chris@43: knowing the uncompressed size by storing it at the end of the file:
Chris@43: 
Chris@43: 'Calling the functions:
Chris@43: 'bracket meaning: <parameter> [optional] {Range of possible values}
Chris@43: 'Call subCompressFile(<path with filename to compress> [, <path with
Chris@43: filename to write to>, [level of compression {1..9}]])
Chris@43: 'Call subUncompressFile(<path with filename to compress>)
Chris@43: 
Chris@43: Option Explicit
Chris@43: Private lngpvtPcnSml As Long 'Stores value for 'lngPercentSmaller'
Chris@43: Private Const SUCCESS As Long = 0
Chris@43: Private Const strFilExt As String = ".cpr"
Chris@43: Private Declare Function lngfncCpr Lib "zlib.dll" Alias "compress2" (ByRef
Chris@43: dest As Any, ByRef destLen As Any, ByRef src As Any, ByVal srcLen As Long,
Chris@43: ByVal level As Integer) As Long
Chris@43: Private Declare Function lngfncUcp Lib "zlib.dll" Alias "uncompress" (ByRef
Chris@43: dest As Any, ByRef destLen As Any, ByRef src As Any, ByVal srcLen As Long)
Chris@43: As Long
Chris@43: 
Chris@43: Public Sub subCompressFile(ByVal strargOriFilPth As String, Optional ByVal
Chris@43: strargCprFilPth As String, Optional ByVal intLvl As Integer = 9)
Chris@43:     Dim strCprPth As String
Chris@43:     Dim lngOriSiz As Long
Chris@43:     Dim lngCprSiz As Long
Chris@43:     Dim bytaryOri() As Byte
Chris@43:     Dim bytaryCpr() As Byte
Chris@43:     lngOriSiz = FileLen(strargOriFilPth)
Chris@43:     ReDim bytaryOri(lngOriSiz - 1)
Chris@43:     Open strargOriFilPth For Binary Access Read As #1
Chris@43:         Get #1, , bytaryOri()
Chris@43:     Close #1
Chris@43:     strCprPth = IIf(strargCprFilPth = "", strargOriFilPth, strargCprFilPth)
Chris@43: 'Select file path and name
Chris@43:     strCprPth = strCprPth & IIf(Right(strCprPth, Len(strFilExt)) =
Chris@43: strFilExt, "", strFilExt) 'Add file extension if not exists
Chris@43:     lngCprSiz = (lngOriSiz * 1.01) + 12 'Compression needs temporary a bit
Chris@43: more space then original file size
Chris@43:     ReDim bytaryCpr(lngCprSiz - 1)
Chris@43:     If lngfncCpr(bytaryCpr(0), lngCprSiz, bytaryOri(0), lngOriSiz, intLvl) =
Chris@43: SUCCESS Then
Chris@43:         lngpvtPcnSml = (1# - (lngCprSiz / lngOriSiz)) * 100
Chris@43:         ReDim Preserve bytaryCpr(lngCprSiz - 1)
Chris@43:         Open strCprPth For Binary Access Write As #1
Chris@43:             Put #1, , bytaryCpr()
Chris@43:             Put #1, , lngOriSiz 'Add the the original size value to the end
Chris@43: (last 4 bytes)
Chris@43:         Close #1
Chris@43:     Else
Chris@43:         MsgBox "Compression error"
Chris@43:     End If
Chris@43:     Erase bytaryCpr
Chris@43:     Erase bytaryOri
Chris@43: End Sub
Chris@43: 
Chris@43: Public Sub subUncompressFile(ByVal strargFilPth As String)
Chris@43:     Dim bytaryCpr() As Byte
Chris@43:     Dim bytaryOri() As Byte
Chris@43:     Dim lngOriSiz As Long
Chris@43:     Dim lngCprSiz As Long
Chris@43:     Dim strOriPth As String
Chris@43:     lngCprSiz = FileLen(strargFilPth)
Chris@43:     ReDim bytaryCpr(lngCprSiz - 1)
Chris@43:     Open strargFilPth For Binary Access Read As #1
Chris@43:         Get #1, , bytaryCpr()
Chris@43:     Close #1
Chris@43:     'Read the original file size value:
Chris@43:     lngOriSiz = bytaryCpr(lngCprSiz - 1) * (2 ^ 24) _
Chris@43:               + bytaryCpr(lngCprSiz - 2) * (2 ^ 16) _
Chris@43:               + bytaryCpr(lngCprSiz - 3) * (2 ^ 8) _
Chris@43:               + bytaryCpr(lngCprSiz - 4)
Chris@43:     ReDim Preserve bytaryCpr(lngCprSiz - 5) 'Cut of the original size value
Chris@43:     ReDim bytaryOri(lngOriSiz - 1)
Chris@43:     If lngfncUcp(bytaryOri(0), lngOriSiz, bytaryCpr(0), lngCprSiz) = SUCCESS
Chris@43: Then
Chris@43:         strOriPth = Left(strargFilPth, Len(strargFilPth) - Len(strFilExt))
Chris@43:         Open strOriPth For Binary Access Write As #1
Chris@43:             Put #1, , bytaryOri()
Chris@43:         Close #1
Chris@43:     Else
Chris@43:         MsgBox "Uncompression error"
Chris@43:     End If
Chris@43:     Erase bytaryCpr
Chris@43:     Erase bytaryOri
Chris@43: End Sub
Chris@43: Public Property Get lngPercentSmaller() As Long
Chris@43:     lngPercentSmaller = lngpvtPcnSml
Chris@43: End Property