Dart

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.

Dart

import 'package:chilkat/chilkat.dart';

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

  final strHex = '54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A';

  final compress = CkCompression();
  compress.algorithm = 'deflate';

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

  // Compress the BinData.
  compress.compressBd(binDat);

  // Get the compressed data in hex format:
  final compressedHex = binDat.getEncoded('hex');
  print('compressed hex:');
  print(compressedHex);

  // The compressed hex is: 0BC94855282CCD4CCE56482ACA2FCF5348CBAF50C82ACD2D484D51C82F4B2D522801CAE72456552AA4E4A7EBF172850C61E5BC5C00

  // Even better, get the compressed data in base64 format:
  // (base64url and modbase64 are other valid choices...)
  final compressedBase64 = binDat.getEncoded('base64');
  print('compressed base64:');
  print(compressedBase64);

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

  // Now decompress:
  binDat.clear();
  binDat.appendEncoded(compressedHex, 'hex');
  compress.decompressBd(binDat);

  final decompressedHex = binDat.getEncoded('hex');
  print('decompressed hex:');
  print(decompressedHex);

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