1See below some functions declarations for Visual Basic. 2 3Frequently Asked Question: 4 5Q: Each time I use the compress function I get the -5 error (not enough 6 room in the output buffer). 7 8A: Make sure that the length of the compressed buffer is passed by 9 reference ("as any"), not by value ("as long"). Also check that 10 before the call of compress this length is equal to the total size of 11 the compressed buffer and not zero. 12 13 14From: "Jon Caruana" <jon-net@usa.net> 15Subject: Re: How to port zlib declares to vb? 16Date: Mon, 28 Oct 1996 18:33:03 -0600 17 18Got the answer! (I haven't had time to check this but it's what I got, and 19looks correct): 20 21He has the following routines working: 22 compress 23 uncompress 24 gzopen 25 gzwrite 26 gzread 27 gzclose 28 29Declares follow: (Quoted from Carlos Rios <c_rios@sonda.cl>, in Vb4 form) 30 31#If Win16 Then 'Use Win16 calls. 32Declare Function compress Lib "ZLIB.DLL" (ByVal compr As 33 String, comprLen As Any, ByVal buf As String, ByVal buflen 34 As Long) As Integer 35Declare Function uncompress Lib "ZLIB.DLL" (ByVal uncompr 36 As String, uncomprLen As Any, ByVal compr As String, ByVal 37 lcompr As Long) As Integer 38Declare Function gzopen Lib "ZLIB.DLL" (ByVal filePath As 39 String, ByVal mode As String) As Long 40Declare Function gzread Lib "ZLIB.DLL" (ByVal file As 41 Long, ByVal uncompr As String, ByVal uncomprLen As Integer) 42 As Integer 43Declare Function gzwrite Lib "ZLIB.DLL" (ByVal file As 44 Long, ByVal uncompr As String, ByVal uncomprLen As Integer) 45 As Integer 46Declare Function gzclose Lib "ZLIB.DLL" (ByVal file As 47 Long) As Integer 48#Else 49Declare Function compress Lib "ZLIB32.DLL" 50 (ByVal compr As String, comprLen As Any, ByVal buf As 51 String, ByVal buflen As Long) As Integer 52Declare Function uncompress Lib "ZLIB32.DLL" 53 (ByVal uncompr As String, uncomprLen As Any, ByVal compr As 54 String, ByVal lcompr As Long) As Long 55Declare Function gzopen Lib "ZLIB32.DLL" 56 (ByVal file As String, ByVal mode As String) As Long 57Declare Function gzread Lib "ZLIB32.DLL" 58 (ByVal file As Long, ByVal uncompr As String, ByVal 59 uncomprLen As Long) As Long 60Declare Function gzwrite Lib "ZLIB32.DLL" 61 (ByVal file As Long, ByVal uncompr As String, ByVal 62 uncomprLen As Long) As Long 63Declare Function gzclose Lib "ZLIB32.DLL" 64 (ByVal file As Long) As Long 65#End If 66 67-Jon Caruana 68jon-net@usa.net 69Microsoft Sitebuilder Network Level 1 Member - HTML Writer's Guild Member 70 71 72Here is another example from Michael <michael_borgsys@hotmail.com> that he 73says conforms to the VB guidelines, and that solves the problem of not 74knowing the uncompressed size by storing it at the end of the file: 75 76'Calling the functions: 77'bracket meaning: <parameter> [optional] {Range of possible values} 78'Call subCompressFile(<path with filename to compress> [, <path with 79filename to write to>, [level of compression {1..9}]]) 80'Call subUncompressFile(<path with filename to compress>) 81 82Option Explicit 83Private lngpvtPcnSml As Long 'Stores value for 'lngPercentSmaller' 84Private Const SUCCESS As Long = 0 85Private Const strFilExt As String = ".cpr" 86Private Declare Function lngfncCpr Lib "zlib.dll" Alias "compress2" (ByRef 87dest As Any, ByRef destLen As Any, ByRef src As Any, ByVal srcLen As Long, 88ByVal level As Integer) As Long 89Private Declare Function lngfncUcp Lib "zlib.dll" Alias "uncompress" (ByRef 90dest As Any, ByRef destLen As Any, ByRef src As Any, ByVal srcLen As Long) 91As Long 92 93Public Sub subCompressFile(ByVal strargOriFilPth As String, Optional ByVal 94strargCprFilPth As String, Optional ByVal intLvl As Integer = 9) 95 Dim strCprPth As String 96 Dim lngOriSiz As Long 97 Dim lngCprSiz As Long 98 Dim bytaryOri() As Byte 99 Dim bytaryCpr() As Byte 100 lngOriSiz = FileLen(strargOriFilPth) 101 ReDim bytaryOri(lngOriSiz - 1) 102 Open strargOriFilPth For Binary Access Read As #1 103 Get #1, , bytaryOri() 104 Close #1 105 strCprPth = IIf(strargCprFilPth = "", strargOriFilPth, strargCprFilPth) 106'Select file path and name 107 strCprPth = strCprPth & IIf(Right(strCprPth, Len(strFilExt)) = 108strFilExt, "", strFilExt) 'Add file extension if not exists 109 lngCprSiz = (lngOriSiz * 1.01) + 12 'Compression needs temporary a bit 110more space then original file size 111 ReDim bytaryCpr(lngCprSiz - 1) 112 If lngfncCpr(bytaryCpr(0), lngCprSiz, bytaryOri(0), lngOriSiz, intLvl) = 113SUCCESS Then 114 lngpvtPcnSml = (1# - (lngCprSiz / lngOriSiz)) * 100 115 ReDim Preserve bytaryCpr(lngCprSiz - 1) 116 Open strCprPth For Binary Access Write As #1 117 Put #1, , bytaryCpr() 118 Put #1, , lngOriSiz 'Add the the original size value to the end 119(last 4 bytes) 120 Close #1 121 Else 122 MsgBox "Compression error" 123 End If 124 Erase bytaryCpr 125 Erase bytaryOri 126End Sub 127 128Public Sub subUncompressFile(ByVal strargFilPth As String) 129 Dim bytaryCpr() As Byte 130 Dim bytaryOri() As Byte 131 Dim lngOriSiz As Long 132 Dim lngCprSiz As Long 133 Dim strOriPth As String 134 lngCprSiz = FileLen(strargFilPth) 135 ReDim bytaryCpr(lngCprSiz - 1) 136 Open strargFilPth For Binary Access Read As #1 137 Get #1, , bytaryCpr() 138 Close #1 139 'Read the original file size value: 140 lngOriSiz = bytaryCpr(lngCprSiz - 1) * (2 ^ 24) _ 141 + bytaryCpr(lngCprSiz - 2) * (2 ^ 16) _ 142 + bytaryCpr(lngCprSiz - 3) * (2 ^ 8) _ 143 + bytaryCpr(lngCprSiz - 4) 144 ReDim Preserve bytaryCpr(lngCprSiz - 5) 'Cut of the original size value 145 ReDim bytaryOri(lngOriSiz - 1) 146 If lngfncUcp(bytaryOri(0), lngOriSiz, bytaryCpr(0), lngCprSiz) = SUCCESS 147Then 148 strOriPth = Left(strargFilPth, Len(strargFilPth) - Len(strFilExt)) 149 Open strOriPth For Binary Access Write As #1 150 Put #1, , bytaryOri() 151 Close #1 152 Else 153 MsgBox "Uncompression error" 154 End If 155 Erase bytaryCpr 156 Erase bytaryOri 157End Sub 158Public Property Get lngPercentSmaller() As Long 159 lngPercentSmaller = lngpvtPcnSml 160End Property 161