Shadows under StringGrid

Question

I have a form. On formshow, I initialize values of a field into stringgrid cells, but it shows a shadow under cell's texts. I've used Persian charaters for field's values.
I did the same with english values, but it works fine.
I appreciate any suggestions.

example of the output:

Answer 1

With enaabled DefaultDrawing the text will be already rendered if you enter OnDrawCell.

Since you are calculating the needed rowheight in painting using DT_CALCRECT of DrawText you will have to calculated the Rect wich shall be filled/cleared with FillRect.
You can use UnionRect to get the final Rect which has to be filled (FillRect in the example).

procedure TForm1.FormCreate(Sender: TObject);
begin
  StringGrid1.Cells[1,1] := 'Hallo'#13'World';
  StringGrid1.Cells[2,2] := 'اهای' +13# + 'جهان';
end;

procedure TForm1.StringGrid1DrawCell(Sender: TObject; ACol, ARow: Integer;
  Rect: TRect; State: TGridDrawState);
var
  S:String;
  drawrect,Fillrect : TRect;
begin
  s := (Sender as TStringGrid).Cells[ACol, ARow];
  drawrect := Rect;
  DrawText((Sender as TStringGrid).Canvas.handle, Pchar(s), Length(s),
      drawrect, DT_CALCRECT or DT_WORDBREAK or DT_LEFT);
  if (drawrect.bottom - drawrect.Top) > (Sender as TStringGrid)
      .RowHeights[ARow] then (Sender as TStringGrid)
      .RowHeights[ARow] := (drawrect.bottom - drawrect.Top);
  UnionRect(FillRect,Rect,DrawRect);
  (Sender as TStringGrid).Canvas.FillRect(FillRect);
  DrawText((Sender as TStringGrid).Canvas.handle, Pchar(s), Length(s),
        drawrect, DT_WORDBREAK or DT_LEFT);
end;