unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    Button2: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

  TMemoWithUnicod = class(TCustomMemo)
  private
    FMemStream: TMemoryStream;
  public
    procedure LoadFromUnicodFile(const FileName: string);
    procedure SaveToUnicodFile(const FileName: string);

    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

var
  MemoWithUnicod:TMemoWithUnicod;

constructor TMemoWithUnicod.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  FMemStream := TMemoryStream.Create;
end;

destructor TMemoWithUnicod.Destroy;
begin
  FMemStream.Free;
  inherited Destroy;
end;

procedure TMemoWithUnicod.LoadFromUnicodFile(const FileName: string);
var
  wbuf: PChar;
  zag: Word;
begin
  FMemStream.LoadFromFile(FileName);
  If FMemStream.Size < 2 then
  exit;
  FMemStream.Position := 0;
  FMemStream.Read(zag, 2);
  If zag <> $FEFF then
  exit;

  FMemStream.Position := 2;
  wbuf := StrAlloc(FMemStream.Size);
  try
    ZeroMemory(wbuf, FMemStream.Size);
    FMemStream.Read(wbuf^, FMemStream.Size-2);
    Lines.Text := WideCharToString(PWideChar(wbuf));
  finally
    StrDispose(wbuf);
  end;
end;

procedure TMemoWithUnicod.SaveToUnicodFile(const FileName: string);
var
  dest: PWideChar;
  zag: Word;
begin
  FMemStream.Clear;
  FMemStream.Position := 0;
  zag := $FEFF;
  FMemStream.Write(zag, 2);

  FMemStream.Position := 2;
  GetMem(dest, (Length(Lines.Text)+1)*2);
  try
    ZeroMemory(dest, (Length(Lines.Text)+1)*2);
    StringToWideChar(Lines.Text, dest, Length(Lines.Text)+1);
    FMemStream.Write(dest^, Length(Lines.Text)*2);
    FMemStream.SaveToFile(FileName);
  finally
    FreeMem(dest);
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
MemoWithUnicod := TMemoWithUnicod.Create(Self);
MemoWithUnicod.Parent := Self;
MemoWithUnicod.Left := 20;
MemoWithUnicod.Top := 20;
MemoWithUnicod.ScrollBars := ssVertical;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
MemoWithUnicod.LoadFromUnicodFile('MyUnicodFile.txt');
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
MemoWithUnicod.SaveToUnicodFile('MyUnicodFile.txt');
end;

end.