Arredondamento TEdit

procedure ArredondarComponente(Componente: TWinControl; const Radius: SmallInt);
var
  R : TRect;
  Rgn : HRGN;
begin
  with Componente do
  begin
    R := ClientRect;
    Rgn := CreateRoundRectRgn(R.Left, R.Top, R.Right, R.Bottom, Radius, Radius);
    Perform(EM_GETRECT, 0, lParam(@R));
    InflateRect(R, -5, -5);

    Perform(EM_SETRECTNP, 0, lParam(@R));
    SetWindowRgn(Handle, Rgn, True);
    Invalidate;
  end;
end;

procedure TfrmPrincipal.Button1Click(Sender: TObject);
begin
  ArredondarComponente(Edit1,10);
end;