(Delphi DLL) Compress and Decompress Hex String

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.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, BinData, Compression;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
strHex: PWideChar;
compress: HCkCompression;
binDat: HCkBinData;
compressedHex: PWideChar;
compressedBase64: PWideChar;
decompressedHex: PWideChar;

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

strHex := '54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A';

compress := CkCompression_Create();
CkCompression_putAlgorithm(compress,'deflate');

binDat := CkBinData_Create();
// Load the hex string into a BinData object.
// This decodes the hexidecimal. The decoded bytes will be contained in the BinData.
CkBinData_AppendEncoded(binDat,strHex,'hex');

// Compress the BinData.
CkCompression_CompressBd(compress,binDat);

// Get the compressed data in hex format:
compressedHex := CkBinData__getEncoded(binDat,'hex');
Memo1.Lines.Add('compressed hex:');
Memo1.Lines.Add(compressedHex);

// The compressed hex is: 0BC94855282CCD4CCE56482ACA2FCF5348CBAF50C82ACD2D484D51C82F4B2D522801CAE72456552AA4E4A7EBF172850C61E5BC5C00

// Even better, get the compressed data in base64 format:
// (base64url and modbase64 are other valid choices...)
compressedBase64 := CkBinData__getEncoded(binDat,'base64');
Memo1.Lines.Add('compressed base64:');
Memo1.Lines.Add(compressedBase64);

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

// Now decompress:
CkBinData_Clear(binDat);
CkBinData_AppendEncoded(binDat,compressedHex,'hex');
CkCompression_DecompressBd(compress,binDat);

decompressedHex := CkBinData__getEncoded(binDat,'hex');
Memo1.Lines.Add('decompressed hex:');
Memo1.Lines.Add(decompressedHex);

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

CkCompression_Dispose(compress);
CkBinData_Dispose(binDat);

end;