Como mostrar o conteúdo de um campo blob no DBGrid

Eu faco assim :

procedure TFrmCobrancas.DBGrid1DrawColumnCell(Sender: TObject;
const Rect: TRect; DataCol: Integer; Column: TColumn;
State: TGridDrawState);
var
R : TRect;
begin
inherited;
(*exibe campo memo*)

R:=Rect; // declara uma variável local R : TRect
Dec(R.Bottom,2);
if Column.Field=DM.CDSCampoMemo then
begin
if not (gdSelected in State) then
DBGrid1.Canvas.FillRect(Rect);
DrawText(DBGrid1.Canvas.Handle,
pchar(DM.CDSCampoMemo.AsString),
length(DM.CDSCampoMemo.AsString),
R,DT_WORDBREAK);

end;



end;