(PureBasic) 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 v9.5.0.67 or greater.

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IncludeFile "CkBinData.pb"
IncludeFile "CkFileAccess.pb"
IncludeFile "CkZip.pb"
IncludeFile "CkStream.pb"
IncludeFile "CkTask.pb"
IncludeFile "CkZipEntry.pb"

Procedure ChilkatExample()

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

    zip.i = CkZip::ckCreate()
    If zip.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; First open a .zip.
    success.i = CkZip::ckOpenZip(zip,"qa_data/zips/big.zip")
    If success <> 1
        Debug CkZip::ckLastErrorText(zip)
        CkZip::ckDispose(zip)
        ProcedureReturn
    EndIf

    ; Get the entry to be unzipped to a stream..
    entry.i = CkZip::ckGetEntryByIndex(zip,0)
    If CkZip::ckLastMethodSuccess(zip) <> 1
        Debug CkZip::ckLastErrorText(zip)
        CkZip::ckDispose(zip)
        ProcedureReturn
    EndIf

    dataStream.i = CkStream::ckCreate()
    If dataStream.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    unzipTask.i = CkZipEntry::ckUnzipToStreamAsync(entry,dataStream)
    If CkZipEntry::ckLastMethodSuccess(entry) <> 1
        Debug CkZipEntry::ckLastErrorText(entry)
        CkZipEntry::ckDispose(entry)

        CkZip::ckDispose(zip)
        CkStream::ckDispose(dataStream)
        ProcedureReturn
    EndIf

    ; Start the background unzip thread.
    CkTask::ckRun(unzipTask)

    ; We'll read the uncompressed data chunk-by-chunk and write to an output file.
    fac.i = CkFileAccess::ckCreate()
    If fac.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkFileAccess::ckOpenForWrite(fac,"qa_output/out.dat")
    If success <> 1
        Debug CkFileAccess::ckLastErrorText(fac)
        CkZipEntry::ckDispose(entry)

        CkZip::ckDispose(zip)
        CkStream::ckDispose(dataStream)
        CkFileAccess::ckDispose(fac)
        ProcedureReturn
    EndIf

    ; Read the stream.  (this is reading the unzipped file data)
    bd.i = CkBinData::ckCreate()
    If bd.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    While CkStream::ckEndOfStream(dataStream) <> 1
        ; Get the next chunk of decompressed bytes.
        CkStream::ckReadBd(dataStream,bd)
        ; Do something with it..
        ; In this simple example, we'll just write to the file.
        CkFileAccess::ckFileWriteBd(fac,bd,0,0)
        ; Clear for the next read.
        CkBinData::ckClear(bd)
    Wend

    CkFileAccess::ckFileClose(fac)

    CkZipEntry::ckDispose(entry)

    CkTask::ckDispose(unzipTask)

    Debug "Success."


    CkZip::ckDispose(zip)
    CkStream::ckDispose(dataStream)
    CkFileAccess::ckDispose(fac)
    CkBinData::ckDispose(bd)


    ProcedureReturn
EndProcedure