(DataFlex) Transition from BeginCompressStringENC to FirstChunk/LastChunk

Provides instructions for replacing deprecated BeginCompressStringENC method calls with using FirstChunk/LastChunk properties.

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

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

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSbCompressedBase64
    Handle hoCompress
    Handle hoSbIndex
    Integer i
    String sOriginalText
    Variant vBdCompressed
    Handle hoBdCompressed
    Variant vSbUncompressedChunk
    Handle hoSbUncompressedChunk
    String sTemp1

    Move False To iSuccess

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbCompressedBase64
    If (Not(IsComObjectCreated(hoSbCompressedBase64))) Begin
        Send CreateComObject of hoSbCompressedBase64
    End

    Get Create (RefClass(cComChilkatCompression)) To hoCompress
    If (Not(IsComObjectCreated(hoCompress))) Begin
        Send CreateComObject of hoCompress
    End
    Set ComAlgorithm Of hoCompress To "deflate"
    Set ComCharset Of hoCompress To "utf-8"
    Set ComEncodingMode Of hoCompress To "base64"

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbIndex
    If (Not(IsComObjectCreated(hoSbIndex))) Begin
        Send CreateComObject of hoSbIndex
    End

    // ----------------------------------------------------------------------------------
    // This is the deprecated way of compressing in chunks using Begin/More/End methods..
    // ----------------------------------------------------------------------------------

    For i From 0 To 24
        // Note: It is possible (and normal) for a BeginCompress* or MoreCompress* method to return
        // an empty string (or 0 bytes).  When this happens, the input data is not lost.  It will be flushed
        // in a subsequent call.
        Send ComClear To hoSbIndex
        Get ComAppendInt Of hoSbIndex i To iSuccess
        If (i = 0) Begin
            Get ComBeginCompressStringENC Of hoCompress (ComGetAsString(hoSbIndex)) To sTemp1
            Get ComAppend Of hoSbCompressedBase64 sTemp1 To iSuccess
        End
        Else Begin
            Get ComMoreCompressStringENC Of hoCompress (ComGetAsString(hoSbIndex)) To sTemp1
            Get ComAppend Of hoSbCompressedBase64 sTemp1 To iSuccess
        End

        Get ComMoreCompressStringENC Of hoCompress ": This is a line of data to be compressed..." + (character(13)) + (character(10)) To sTemp1
        Get ComAppend Of hoSbCompressedBase64 sTemp1 To iSuccess
    Loop

    // Flush any remaining output.
    Get ComEndCompressStringENC Of hoCompress To sTemp1
    Get ComAppend Of hoSbCompressedBase64 sTemp1 To iSuccess

    Showln "The base64 encoded compressed text:"
    Get ComGetAsString Of hoSbCompressedBase64 To sTemp1
    Showln sTemp1

    // Decompress in one call:
    Get ComGetAsString Of hoSbCompressedBase64 To sTemp1
    Get ComDecompressStringENC Of hoCompress sTemp1 To sOriginalText
    Showln sOriginalText

    // ----------------------------------------------------------------------------------
    // This is new way of compressing in chunks using FirstChunk and LastChunk properties
    // ----------------------------------------------------------------------------------

    Send ComClear To hoSbCompressedBase64

    Set ComFirstChunk Of hoCompress To True
    Set ComLastChunk Of hoCompress To False

    Get Create (RefClass(cComChilkatBinData)) To hoBdCompressed
    If (Not(IsComObjectCreated(hoBdCompressed))) Begin
        Send CreateComObject of hoBdCompressed
    End
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbUncompressedChunk
    If (Not(IsComObjectCreated(hoSbUncompressedChunk))) Begin
        Send CreateComObject of hoSbUncompressedChunk
    End

    For i From 0 To 24
        If (i = 24) Begin
            Set ComLastChunk Of hoCompress To True
        End

        Send ComClear To hoSbUncompressedChunk
        Get ComAppendInt Of hoSbUncompressedChunk i To iSuccess
        Get ComAppend Of hoSbUncompressedChunk ": This is a line of data to be compressed..." + (character(13)) + (character(10)) To iSuccess

        Get pvComObject of hoSbUncompressedChunk to vSbUncompressedChunk
        Get pvComObject of hoBdCompressed to vBdCompressed
        Get ComCompressSb Of hoCompress vSbUncompressedChunk vBdCompressed To iSuccess

        Set ComFirstChunk Of hoCompress To False
    Loop

    Showln "The base64 encoded compressed text:"
    Get ComGetEncoded Of hoBdCompressed "base64" To sTemp1
    Showln sTemp1

    // Decompress in one call:
    Get ComGetEncoded Of hoBdCompressed "base64" To sTemp1
    Get ComDecompressStringENC Of hoCompress sTemp1 To sOriginalText
    Showln sOriginalText


End_Procedure