Xojo Plugin

Compress and Decompress Hex String

See more Compression Examples

Imagine we have data represented as a hex string. This example demonstrates how to decode, compress, and re-encode to a smaller hex string representing the compressed data. An even better choice is to re-encode to a more compact encoding such as base64.

Note: This example requires Chilkat v9.5.0.66 or greater.

Xojo Plugin

Dim success As Boolean
success = False

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

Dim strHex As String
strHex = "54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A"

Dim compress As New Chilkat.Compression
compress.Algorithm = "deflate"

Dim binDat As New Chilkat.BinData
// Load the hex string into a BinData object.
// This decodes the hexidecimal. The decoded bytes will be contained in the BinData.
success = binDat.AppendEncoded(strHex,"hex")

// Compress the BinData.
success = compress.CompressBd(binDat)

// Get the compressed data in hex format:
Dim compressedHex As String
compressedHex = binDat.GetEncoded("hex")
System.DebugLog("compressed hex:")
System.DebugLog(compressedHex)

// The compressed hex is: 0BC94855282CCD4CCE56482ACA2FCF5348CBAF50C82ACD2D484D51C82F4B2D522801CAE72456552AA4E4A7EBF172850C61E5BC5C00

// Even better, get the compressed data in base64 format:
// (base64url and modbase64 are other valid choices...)
Dim compressedBase64 As String
compressedBase64 = binDat.GetEncoded("base64")
System.DebugLog("compressed base64:")
System.DebugLog(compressedBase64)

// The compressed base64 is: C8lIVSgszUzOVkgqyi/PU0jLr1DIKs0tSE1RyC9LLVIoAcrnJFZVKqTkp+vxcoUMYeW8XAA=

// Now decompress:
success = binDat.Clear()
success = binDat.AppendEncoded(compressedHex,"hex")
success = compress.DecompressBd(binDat)

Dim decompressedHex As String
decompressedHex = binDat.GetEncoded("hex")
System.DebugLog("decompressed hex:")
System.DebugLog(decompressedHex)

// The output is the original hex string:
// 54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A