procedure ImageEnView1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer); inline;
procedure ImageEnView1DrawCanvas(Sender: TObject; ACanvas: TCanvas; ARect: TRect); inline;

procedure TForm1.Button1Click(Sender: TObject);
begin
  ImageEnView1.IO.LoadFromFile( 'D:\im.jpg' );
  ImageEnView1.ShowRulers := [ rdHorizontal, rdVertical ];
  ImageEnView1.Cursor := crNone;
end;

procedure TForm1.ImageEnView1MouseMove(Sender: TObject; Shift: TShiftState; X,
    Y: Integer);
begin
  ImageEnView1.Invalidate();
end;

procedure TForm1.ImageEnView1DrawCanvas(Sender: TObject; ACanvas: TCanvas; ARect: TRect);
var
  P: TPoint;
begin
  GetCursorPos( P );
  P := ImageEnView1.ScreenToClient( P );

  ACanvas.Pen.Color := clYellow;
  ACanvas.MoveTo( P.X, 0 );
  ACanvas.LineTo( P.X, ImageEnView1.ClientHeight - 1 );
  ACanvas.MoveTo( 0, P.Y );
  ACanvas.LineTo( ImageEnView1.ClientWidth - 1, P.Y );
end;