vb6 - Zipping and Unzipping using Shell32

This one requires a reference to shell32.dll.

Option Explicit

'//source was in C# from urls:
'//http://www.codeproject.com/csharp/CompressWithWinShellAPICS.asp
'//http://www.codeproject.com/csharp/DecompressWinShellAPICS.asp

'//set reference to "Microsoft Shell Controls and Automation"


'http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=1090552&SiteID=1
'Be aware when using the shell automation interface to unzip files as it
'leaves copies of the zip files in the temp directory (defined by %TEMP%).
'Folders named "Temporary Directory X for demo.zip" are generated where X
'is a sequential number from 1 - 99. When it reaches 99 you will then get
'a error dialog saying "The file exists" and it will not continue.
'I 've no idea why Windows doesn't clean up after itself when unzipping files,
'but it is most annoying...


'//CopyHere options
'0 Default. No options specified.
'4 Do not display a progress dialog box.
'8 Rename the target file if a file exists at the target location with the same name.
'16 Click "Yes to All" in any dialog box displayed.
'64 Preserve undo information, if possible.
'128 Perform the operation only if a wildcard file name (*.*) is specified.
'256 Display a progress dialog box but do not show the file names.
'512 Do not confirm the creation of a new directory if the operation requires one to be created.
'1024 Do not display a user interface if an error occurs.
'4096 Disable recursion.
'9182 Do not copy connected files as a group. Only copy the specified files.

Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)

Private Sub Zip_Activity(Action As String, sFileSource As String, sFileDest As String)

'//copies contents of folder to zip file
Dim ShellClass As Shell32.Shell
Dim Filesource As Shell32.Folder
Dim Filedest As Shell32.Folder
Dim Folderitems As Shell32.Folderitems

If sFileSource = "" Or sFileDest = "" Then GoTo EH

Select Case UCase$(Action)

Case "ZIPFILE"

If Right$(UCase$(sFileDest), 4) <> ".ZIP" Then
sFileDest = sFileDest & ".ZIP"
End If

If Not Create_Empty_Zip(sFileDest) Then
GoTo EH
End If

Set ShellClass = New Shell32.Shell
Set Filedest = ShellClass.NameSpace(sFileDest)

Call Filedest.CopyHere(sFileSource, 20)

Case "ZIPFOLDER"

If Right$(UCase$(sFileDest), 4) <> ".ZIP" Then
sFileDest = sFileDest & ".ZIP"
End If

If Not Create_Empty_Zip(sFileDest) Then
GoTo EH
End If

'//Copy a folder and its contents into the newly created zip file
Set ShellClass = New Shell32.Shell
Set Filesource = ShellClass.NameSpace(sFileSource)
Set Filedest = ShellClass.NameSpace(sFileDest)
Set Folderitems = Filesource.Items

Call Filedest.CopyHere(Folderitems, 20)

Case "UNZIP"

If Right$(UCase$(sFileSource), 4) <> ".ZIP" Then
sFileSource = sFileSource & ".ZIP"
End If

Set ShellClass = New Shell32.Shell
Set Filesource = ShellClass.NameSpace(sFileSource) '//should be zip file
Set Filedest = ShellClass.NameSpace(sFileDest) '//should be directory
Set Folderitems = Filesource.Items '//copy zipped items to directory

Call Filedest.CopyHere(Folderitems, 20)

Case Else

End Select

'//Ziping a file using the Windows Shell API creates another thread where the zipping is executed.
'//This means that it is possible that this console app would end before the zipping thread
'//starts to execute which would cause the zip to never occur and you will end up with just
'//an empty zip file. So wait a second and give the zipping thread time to get started.

Call Sleep(1000)

EH:

If Err.Number <> 0 Then
MsgBox Err.Description, vbExclamation, "error"
End If

Set ShellClass = Nothing
Set Filesource = Nothing
Set Filedest = Nothing
Set Folderitems = Nothing

End Sub

Private Function Create_Empty_Zip(sFileName As String) As Boolean

Dim EmptyZip() As Byte
Dim J As Integer

On Error GoTo EH
Create_Empty_Zip = False

'//create zip header
ReDim EmptyZip(1 To 22)

EmptyZip(1) = 80
EmptyZip(2) = 75
EmptyZip(3) = 5
EmptyZip(4) = 6

For J = 5 To UBound(EmptyZip)
EmptyZip(J) = 0
Next

'//create empty zip file with header
Open sFileName For Binary Access Write As #1

For J = LBound(EmptyZip) To UBound(EmptyZip)
Put #1, , EmptyZip(J)
Next

Close #1

Create_Empty_Zip = True

EH:

If Err.Number <> 0 Then
MsgBox Err.Description, vbExclamation, "Error"
End If

End Function