Compressing and decompressing. String input and output

project1.pas

unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    procedure Button1Click(Sender: TObject);
  private

  public

  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

uses
  ZStream
  ;

const BUF_SIZE = 10000;

function CompressString(const S: String): String;
var
  CompStream: TCompressionStream;
  DestStream: TMemoryStream;
  aStringStream: TStringStream;
begin
  DestStream := TMemoryStream.Create;
  aStringStream:=TStringStream.Create(EmptyStr);
  try
    CompStream := TCompressionStream.Create(clDefault, DestStream, True);
    CompStream.Write(S[1], Length(S));
    CompStream.Free;
    aStringStream.LoadFromStream(DestStream);
    Result:=aStringStream.DataString;
  finally
    aStringStream.Free;
    DestStream.Free;
  end;
end;

function DeCompressString(const S: String): String;
var
  DeCompStream: Tdecompressionstream;
  DestStream: TMemoryStream;
  aStringStream: TStringStream;
begin
  DestStream := TMemoryStream.Create;
  aStringStream:=TStringStream.Create(S);
  try
    DeCompStream := Tdecompressionstream.Create(aStringStream, True);
    SetLength(Result, BUF_SIZE);
    SetLength(Result, DeCompStream.read(Result[1], BUF_SIZE));
  finally
    aStringStream.Free;
    DeCompStream.Free;
    DestStream.Free;
  end;
end;

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
begin
  Edit2.Text:=DeCompressString(CompressString(Edit1.Text));
end;

end.