DataFlex

Compress and Decompress Base64

See more Compression Examples

This example demonstrates how to compress and decompress binary data using the Chilkat.Compression class with the BinData object.

The input data is provided as a Base64-encoded string. It is first decoded into raw bytes and loaded into a BinData object. The example then compresses the data in-place using the deflate algorithm. Because compressed data is binary, it is re-encoded to Base64 for easy display and transport.

To verify correctness, the example performs the reverse operation: it decodes the compressed Base64 back to bytes, decompresses the data, and encodes the result to Base64 again. The final Base64 output is compared with the original input to confirm that the compression and decompression process preserved the data exactly.

This example highlights:

• Using BinData to hold and transform binary data
• In-place compression and decompression with CompressBd and DecompressBd
• Converting between binary data and Base64 for display or transmission
• Verifying round-trip integrity after compression and decompression

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    String sOriginalBase64
    Handle hoCompress
    Variant vBinData
    Handle hoBinData
    String sCompressedBase64
    String sDecompressedBase64
    String sTemp1

    Move False To iSuccess

    // This example assumes the Chilkat API has already been unlocked.
    // See Global Unlock Sample for sample code.

    // This is the original data, encoded as base64.
    // It decodes to plain text containing several repeated lines.
    Move "VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZWQgb3ZlciB0aGUgbGF6eSBkb2cuDQpUaGUgcXVpY2sgYnJvd24gZm94IGp1bXBlZCBvdmVyIHRoZSBsYXp5IGRvZy4NClRoZSBxdWljayBicm93biBmb3gganVtcGVkIG92ZXIgdGhlIGxhenkgZG9nLg0KVGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZWQgb3ZlciB0aGUgbGF6eSBkb2cuDQpUaGUgcXVpY2sgYnJvd24gZm94IGp1bXBlZCBvdmVyIHRoZSBsYXp5IGRvZy4NCg0K" To sOriginalBase64

    Get Create (RefClass(cComChilkatCompression)) To hoCompress
    If (Not(IsComObjectCreated(hoCompress))) Begin
        Send CreateComObject of hoCompress
    End
    Set ComAlgorithm Of hoCompress To "deflate"

    // Load the original base64 data into a BinData object.
    // AppendEncoded decodes the base64 and stores the decoded bytes in binData.
    Get Create (RefClass(cComChilkatBinData)) To hoBinData
    If (Not(IsComObjectCreated(hoBinData))) Begin
        Send CreateComObject of hoBinData
    End
    Get ComAppendEncoded Of hoBinData sOriginalBase64 "base64" To iSuccess
    If (iSuccess = False) Begin
        Showln "Failed to decode the original base64 data."
        Procedure_Return
    End

    // Compress the bytes contained in binData.
    // CompressBd modifies binData in-place, replacing the original bytes
    // with the compressed bytes.
    Get pvComObject of hoBinData to vBinData
    Get ComCompressBd Of hoCompress vBinData To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCompress To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Show the compressed result as base64 so it can be printed as text.
    Get ComGetEncoded Of hoBinData "base64" To sCompressedBase64

    Showln "Compressed data, base64 encoded:"
    Showln sCompressedBase64

    // Expected compressed base64:
    // C8lIVSgszUzOVkgqyi/PU0jLr1DIKs0tSE1RyC9LLVIoAcrnJFZVKqTkp+vxcoUMYeW8XAA=

    // --------------------------------------------------------------------
    // Decompress the data to verify that we get back the original bytes.
    // --------------------------------------------------------------------

    // Start with a fresh BinData object containing the compressed bytes.
    // The compressed data is currently represented as base64 text, so decode it
    // back to bytes before calling DecompressBd.
    Get ComClear Of hoBinData To iSuccess
    Get ComAppendEncoded Of hoBinData sCompressedBase64 "base64" To iSuccess
    If (iSuccess = False) Begin
        Showln "Failed to decode the compressed base64 data."
        Procedure_Return
    End

    // DecompressBd also modifies binData in-place, replacing the compressed bytes
    // with the decompressed bytes.
    Get pvComObject of hoBinData to vBinData
    Get ComDecompressBd Of hoCompress vBinData To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCompress To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Encode the decompressed bytes as base64 so we can compare them with the
    // original base64 input.
    Get ComGetEncoded Of hoBinData "base64" To sDecompressedBase64

    Showln "Decompressed data, base64 encoded:"
    Showln sDecompressedBase64

    // The decompressed base64 should match the original base64 input.
    If (sDecompressedBase64 = sOriginalBase64) Begin
        Showln "Success. The decompressed data matches the original data."
    End
    Else Begin
        Showln "Failure. The decompressed data does not match the original data."
    End



End_Procedure