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AuthorForum: PowerTCP Zip Compression for ActiveX
Topic: DartStreams - cannot uncompress
N/A posted May 22, 2002 9:30 PM

Hi,

I'm having trouble using the DartStream object to compress/uncompress data in memory. The source data is in a file so I add that to the FileStore, instantiate a DartStream and
call the FileStore.Zip method with the destination being my DartStream. This works fine, I can dump the compressed data into a local string variable and store it.
However, I cannot UNcompress this data: I create a new stream and use the .Write method to put the contents of the string onto the DartStream. Then I add the DartStream to the FileStore object and call Extract with the destination being a further DartStream. No error message is raised, but there is no data in the destination DartStream.
Can someone tell me where I'm going wrong? Below is sample code that duplicates this problem,
Thanks

- Phil

Dim objZip As Zip
Dim strFilename As String
Dim StreamZipped As DartStream
Dim StreamUnZipped As DartStream
Dim strTest As String

  strFilename = App.Path & "\<SOMEFILE>"
  Set objZip = New Zip
  objZip.FileStore.Add strFilename
  Set StreamZipped = New DartStream
  objZip.FileStore.Zip StreamZipped
  StreamZipped.Position = 0
  strTest = StreamZipped.ReadString      '* Store the Stream data in a string
  Set StreamZipped = Nothing
  Set objZip = Nothing
  Set objZip = New Zip
  Set StreamZipped = New DartStream
  StreamZipped.Write strTest         '* Drop the string into the stream
  StreamZipped.Position = 0
  objZip.FileStore.Add StreamZipped
  strTest = ""                '* Blank the temporary string
  Set StreamUnZipped = New DartStream
  objZip.FileStore(1).Extract StreamUnZipped
  StreamUnZipped.Position = 0
  StreamUnZipped.Write strTest  '* No data returned in strTest

N/A posted May 23, 2002 9:24 AM


Hi,
It looks like you are trying to extract an unzipped file. Below I have code that should do what you are attempting.
Hope it helps,
-ken

Option Explicit
  Private WithEvents objZip As Zip

Private Sub Command1_Click()
  Set objZip = New Zip
  Dim dsZipped As New DartStream
  Dim dsUnzipped As New DartStream
  Dim strTest As String
  
  objZip.FileStore.Add App.Path & "\<SOMEFILE>"
  objZip.FileStore.Zip dsZipped
  objZip.FileStore.Clear
  objZip.FileStore.Load dsZipped
  objZip.FileStore(1).Extract dsUnzipped
  dsUnzipped.Position = 0
  strTest = dsUnzipped.ReadString
End Sub

K M Drake
Dart Tech Support
Phil

From: Auckland, New Zealand
Posts: 1
Member Since: 05/27/02
posted May 27, 2002 4:20 PM

Thanks, Ken, that did the trick.
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