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