unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls,Zlib;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit_dxg: TEdit;
    Button2: TButton;
    OpenDialog1: TOpenDialog;
    SaveDialog1: TSaveDialog;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    procedure CompressStream(inpStream, outStream: TStream);
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
  ms1,ms2:TMemoryStream;
begin
  ms1 := TMemoryStream.Create;
  ms2 := TMemoryStream.Create;
  try
    try
      ms1.LoadFromFile(OpenDialog1.FileName);
      CompressStream(ms1, ms2);
      if SaveDialog1.Execute then ms2.SaveToFile(SaveDialog1.FileName);
    finally
      ms1.Free;
    end;
  finally
    ms2.Free;
  end;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  if OpenDialog1.Execute then Edit_dxg.Text:=OpenDialog1.FileName;
end;

procedure Tform1.CompressStream(inpStream, outStream: TStream);
var
  InpBuf, OutBuf    : Pointer;
  InpBytes, OutBytes: Integer;
begin
  InpBuf := nil;
  OutBuf := nil;
  try
    GetMem(InpBuf, inpStream.Size);
    inpStream.Position := 0;
    InpBytes := inpStream.Read(InpBuf^, inpStream.Size);
    CompressBuf(InpBuf, InpBytes, OutBuf, OutBytes);
    outStream.Write(OutBuf^, OutBytes);
  finally
    if InpBuf <> nil then
      FreeMem(InpBuf);
    if OutBuf <> nil then
      FreeMem(OutBuf);
  end;
end;

end.