(Visual FoxPro) Unzip Binary File to Stream

Demonstrates how to unzip a large binary file to a stream to allow the application to process the uncompressed bytes chunk by chunk.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lnSuccess
LOCAL loZip
LOCAL loEntry
LOCAL loDataStream
LOCAL loUnzipTask
LOCAL loFac
LOCAL loBd

lnSuccess = 0

* This requires the Chilkat Zip API to have been previously unlocked.
* See Unlock Chilkat Zip for sample code.

loZip = CreateObject('Chilkat.Zip')

* First open a .zip.
lnSuccess = loZip.OpenZip("qa_data/zips/big.zip")
IF (lnSuccess = 0) THEN
    ? loZip.LastErrorText
    RELEASE loZip
    CANCEL
ENDIF

* Get the entry to be unzipped to a stream..
loEntry = CreateObject('Chilkat.ZipEntry')
lnSuccess = loZip.EntryAt(0,loEntry)
IF (lnSuccess = 0) THEN
    ? loZip.LastErrorText
    RELEASE loZip
    RELEASE loEntry
    CANCEL
ENDIF

loDataStream = CreateObject('Chilkat.Stream')

loUnzipTask = loEntry.UnzipToStreamAsync(loDataStream)
IF (loEntry.LastMethodSuccess <> 1) THEN
    ? loEntry.LastErrorText
    RELEASE loZip
    RELEASE loEntry
    RELEASE loDataStream
    CANCEL
ENDIF

* Start the background unzip thread.
loUnzipTask.Run()

* We'll read the uncompressed data chunk-by-chunk and write to an output file.
loFac = CreateObject('Chilkat.FileAccess')
lnSuccess = loFac.OpenForWrite("qa_output/out.dat")
IF (lnSuccess <> 1) THEN
    ? loFac.LastErrorText
    RELEASE loZip
    RELEASE loEntry
    RELEASE loDataStream
    RELEASE loFac
    CANCEL
ENDIF

* Read the stream.  (this is reading the unzipped file data)
loBd = CreateObject('Chilkat.BinData')
DO WHILE loDataStream.EndOfStream <> 1
    * Get the next chunk of decompressed bytes.
    loDataStream.ReadBd(loBd)
    * Do something with it..
    * In this simple example, we'll just write to the file.
    loFac.FileWriteBd(loBd,0,0)
    * Clear for the next read.
    loBd.Clear()
ENDDO

loFac.FileClose()

RELEASE loUnzipTask
? "Success."

RELEASE loZip
RELEASE loEntry
RELEASE loDataStream
RELEASE loFac
RELEASE loBd