cannam@128: See below some functions declarations for Visual Basic.
cannam@128: 
cannam@128: Frequently Asked Question:
cannam@128: 
cannam@128: Q: Each time I use the compress function I get the -5 error (not enough
cannam@128:    room in the output buffer).
cannam@128: 
cannam@128: A: Make sure that the length of the compressed buffer is passed by
cannam@128:    reference ("as any"), not by value ("as long"). Also check that
cannam@128:    before the call of compress this length is equal to the total size of
cannam@128:    the compressed buffer and not zero.
cannam@128: 
cannam@128: 
cannam@128: From: "Jon Caruana" <jon-net@usa.net>
cannam@128: Subject: Re: How to port zlib declares to vb?
cannam@128: Date: Mon, 28 Oct 1996 18:33:03 -0600
cannam@128: 
cannam@128: Got the answer! (I haven't had time to check this but it's what I got, and
cannam@128: looks correct):
cannam@128: 
cannam@128: He has the following routines working:
cannam@128:         compress
cannam@128:         uncompress
cannam@128:         gzopen
cannam@128:         gzwrite
cannam@128:         gzread
cannam@128:         gzclose
cannam@128: 
cannam@128: Declares follow: (Quoted from Carlos Rios <c_rios@sonda.cl>, in Vb4 form)
cannam@128: 
cannam@128: #If Win16 Then   'Use Win16 calls.
cannam@128: Declare Function compress Lib "ZLIB.DLL" (ByVal compr As
cannam@128:         String, comprLen As Any, ByVal buf As String, ByVal buflen
cannam@128:         As Long) As Integer
cannam@128: Declare Function uncompress Lib "ZLIB.DLL" (ByVal uncompr
cannam@128:         As String, uncomprLen As Any, ByVal compr As String, ByVal
cannam@128:         lcompr As Long) As Integer
cannam@128: Declare Function gzopen Lib "ZLIB.DLL" (ByVal filePath As
cannam@128:         String, ByVal mode As String) As Long
cannam@128: Declare Function gzread Lib "ZLIB.DLL" (ByVal file As
cannam@128:         Long, ByVal uncompr As String, ByVal uncomprLen As Integer)
cannam@128:         As Integer
cannam@128: Declare Function gzwrite Lib "ZLIB.DLL" (ByVal file As
cannam@128:         Long, ByVal uncompr As String, ByVal uncomprLen As Integer)
cannam@128:         As Integer
cannam@128: Declare Function gzclose Lib "ZLIB.DLL" (ByVal file As
cannam@128:         Long) As Integer
cannam@128: #Else
cannam@128: Declare Function compress Lib "ZLIB32.DLL"
cannam@128:         (ByVal compr As String, comprLen As Any, ByVal buf As
cannam@128:         String, ByVal buflen As Long) As Integer
cannam@128: Declare Function uncompress Lib "ZLIB32.DLL"
cannam@128:         (ByVal uncompr As String, uncomprLen As Any, ByVal compr As
cannam@128:         String, ByVal lcompr As Long) As Long
cannam@128: Declare Function gzopen Lib "ZLIB32.DLL"
cannam@128:         (ByVal file As String, ByVal mode As String) As Long
cannam@128: Declare Function gzread Lib "ZLIB32.DLL"
cannam@128:         (ByVal file As Long, ByVal uncompr As String, ByVal
cannam@128:         uncomprLen As Long) As Long
cannam@128: Declare Function gzwrite Lib "ZLIB32.DLL"
cannam@128:         (ByVal file As Long, ByVal uncompr As String, ByVal
cannam@128:         uncomprLen As Long) As Long
cannam@128: Declare Function gzclose Lib "ZLIB32.DLL"
cannam@128:         (ByVal file As Long) As Long
cannam@128: #End If
cannam@128: 
cannam@128: -Jon Caruana
cannam@128: jon-net@usa.net
cannam@128: Microsoft Sitebuilder Network Level 1 Member - HTML Writer's Guild Member
cannam@128: 
cannam@128: 
cannam@128: Here is another example from Michael <michael_borgsys@hotmail.com> that he
cannam@128: says conforms to the VB guidelines, and that solves the problem of not
cannam@128: knowing the uncompressed size by storing it at the end of the file:
cannam@128: 
cannam@128: 'Calling the functions:
cannam@128: 'bracket meaning: <parameter> [optional] {Range of possible values}
cannam@128: 'Call subCompressFile(<path with filename to compress> [, <path with
cannam@128: filename to write to>, [level of compression {1..9}]])
cannam@128: 'Call subUncompressFile(<path with filename to compress>)
cannam@128: 
cannam@128: Option Explicit
cannam@128: Private lngpvtPcnSml As Long 'Stores value for 'lngPercentSmaller'
cannam@128: Private Const SUCCESS As Long = 0
cannam@128: Private Const strFilExt As String = ".cpr"
cannam@128: Private Declare Function lngfncCpr Lib "zlib.dll" Alias "compress2" (ByRef
cannam@128: dest As Any, ByRef destLen As Any, ByRef src As Any, ByVal srcLen As Long,
cannam@128: ByVal level As Integer) As Long
cannam@128: Private Declare Function lngfncUcp Lib "zlib.dll" Alias "uncompress" (ByRef
cannam@128: dest As Any, ByRef destLen As Any, ByRef src As Any, ByVal srcLen As Long)
cannam@128: As Long
cannam@128: 
cannam@128: Public Sub subCompressFile(ByVal strargOriFilPth As String, Optional ByVal
cannam@128: strargCprFilPth As String, Optional ByVal intLvl As Integer = 9)
cannam@128:     Dim strCprPth As String
cannam@128:     Dim lngOriSiz As Long
cannam@128:     Dim lngCprSiz As Long
cannam@128:     Dim bytaryOri() As Byte
cannam@128:     Dim bytaryCpr() As Byte
cannam@128:     lngOriSiz = FileLen(strargOriFilPth)
cannam@128:     ReDim bytaryOri(lngOriSiz - 1)
cannam@128:     Open strargOriFilPth For Binary Access Read As #1
cannam@128:         Get #1, , bytaryOri()
cannam@128:     Close #1
cannam@128:     strCprPth = IIf(strargCprFilPth = "", strargOriFilPth, strargCprFilPth)
cannam@128: 'Select file path and name
cannam@128:     strCprPth = strCprPth & IIf(Right(strCprPth, Len(strFilExt)) =
cannam@128: strFilExt, "", strFilExt) 'Add file extension if not exists
cannam@128:     lngCprSiz = (lngOriSiz * 1.01) + 12 'Compression needs temporary a bit
cannam@128: more space then original file size
cannam@128:     ReDim bytaryCpr(lngCprSiz - 1)
cannam@128:     If lngfncCpr(bytaryCpr(0), lngCprSiz, bytaryOri(0), lngOriSiz, intLvl) =
cannam@128: SUCCESS Then
cannam@128:         lngpvtPcnSml = (1# - (lngCprSiz / lngOriSiz)) * 100
cannam@128:         ReDim Preserve bytaryCpr(lngCprSiz - 1)
cannam@128:         Open strCprPth For Binary Access Write As #1
cannam@128:             Put #1, , bytaryCpr()
cannam@128:             Put #1, , lngOriSiz 'Add the the original size value to the end
cannam@128: (last 4 bytes)
cannam@128:         Close #1
cannam@128:     Else
cannam@128:         MsgBox "Compression error"
cannam@128:     End If
cannam@128:     Erase bytaryCpr
cannam@128:     Erase bytaryOri
cannam@128: End Sub
cannam@128: 
cannam@128: Public Sub subUncompressFile(ByVal strargFilPth As String)
cannam@128:     Dim bytaryCpr() As Byte
cannam@128:     Dim bytaryOri() As Byte
cannam@128:     Dim lngOriSiz As Long
cannam@128:     Dim lngCprSiz As Long
cannam@128:     Dim strOriPth As String
cannam@128:     lngCprSiz = FileLen(strargFilPth)
cannam@128:     ReDim bytaryCpr(lngCprSiz - 1)
cannam@128:     Open strargFilPth For Binary Access Read As #1
cannam@128:         Get #1, , bytaryCpr()
cannam@128:     Close #1
cannam@128:     'Read the original file size value:
cannam@128:     lngOriSiz = bytaryCpr(lngCprSiz - 1) * (2 ^ 24) _
cannam@128:               + bytaryCpr(lngCprSiz - 2) * (2 ^ 16) _
cannam@128:               + bytaryCpr(lngCprSiz - 3) * (2 ^ 8) _
cannam@128:               + bytaryCpr(lngCprSiz - 4)
cannam@128:     ReDim Preserve bytaryCpr(lngCprSiz - 5) 'Cut of the original size value
cannam@128:     ReDim bytaryOri(lngOriSiz - 1)
cannam@128:     If lngfncUcp(bytaryOri(0), lngOriSiz, bytaryCpr(0), lngCprSiz) = SUCCESS
cannam@128: Then
cannam@128:         strOriPth = Left(strargFilPth, Len(strargFilPth) - Len(strFilExt))
cannam@128:         Open strOriPth For Binary Access Write As #1
cannam@128:             Put #1, , bytaryOri()
cannam@128:         Close #1
cannam@128:     Else
cannam@128:         MsgBox "Uncompression error"
cannam@128:     End If
cannam@128:     Erase bytaryCpr
cannam@128:     Erase bytaryOri
cannam@128: End Sub
cannam@128: Public Property Get lngPercentSmaller() As Long
cannam@128:     lngPercentSmaller = lngpvtPcnSml
cannam@128: End Property