(Delphi ActiveX) Compress Text Feed to Binary

This example receives incoming text data in chunks, compresses as a stream, and accumulates the compressed binary data.

The purpose is to demonstrate the BeginCompressString, MoreCompressString, and EndCompressString methods.

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
compressedData: TChilkatBinData;
compressedBytes: Array of Byte;
compress: TChilkatCompression;
sbIndex: TChilkatStringBuilder;
i: Integer;
originalText: WideString;

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

compressedData := TChilkatBinData.Create(Self);

compress := TChilkatCompression.Create(Self);
compress.Algorithm := 'deflate';
compress.Charset := 'utf-8';

sbIndex := TChilkatStringBuilder.Create(Self);

for i := 0 to 24 do
  begin
    // 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.
    sbIndex.Clear();
    sbIndex.AppendInt(i);
    if (i = 0) then
      begin
        compressedBytes := compress.BeginCompressString(sbIndex.GetAsString());
      end
    else
      begin
        compressedBytes := compress.MoreCompressString(sbIndex.GetAsString());
      end;
    compressedData.AppendBinary(compressedBytes);
    compressedBytes := compress.MoreCompressString(': This is a line of data to be compressed...' + #13#10);
    compressedData.AppendBinary(compressedBytes);
  end;

// Flush any remaining output.
compressedBytes := compress.EndCompressString();
compressedData.AppendBinary(compressedBytes);

// Show the compressed data in hex format:
Memo1.Lines.Add('The hex encoded compressed text:');
Memo1.Lines.Add(compressedData.GetEncoded('hex'));

// Now decompress in one call:
compressedBytes := compressedData.GetBinary();
originalText := compress.DecompressString(compressedBytes);
Memo1.Lines.Add(originalText);
end;