Read a Text from TStringGrid cells[aCol,aRow] , which is generated by DrawText function on “OnDrawCell” event

Question

Am having a string grid( TStringGrid ) with 2 column and 1 row ( Property: ColCount = 2 & Rowcount = 1 .

Code for OnDrawCell Event:

procedure TForm1.StringGrid1DrawCell(Sender: TObject; ACol, ARow: Integer;
  Rect: TRect; State: TGridDrawState);
  var
    Parametertext : string;
begin
     case ACol of
     0 : Parametertext := 'Test';
     1 : Parametertext := 'Test1';
     end;
     stringgrid1.Brush.Color := clBtnFace;
     stringgrid1.Font.Color := clWindowText;
     stringgrid1.Canvas.FillRect(Rect);
     DrawText(stringgrid1.Canvas.Handle, PChar(parameterText), -1, Rect,
      DT_SINGLELINE);
end;

When I run the application, I get the below output:

Question:

When I try to get the text using StringGrid1.Cells[0,0] , StringGrid1.Cells[1,0] ,

I except "Test" & "Test1" but it always gives a empty string"".

How can I get the text from string grid using StringGrid.Cells[aCol,aRow] ?

Answer 1

You are generating the text to draw it, but not storing it. You also need to set the stringGrid.Cells value, probably not in the OnDrawCell event, though.

Think about your variable Parametertext. It is a local variable destroyed on exit. Nowhere do you save it anywhere else. So why would you expect it to magically appear in the cells property?

Answer 2

To do what you are asking, you need to actually store the string values in the Cells property, not generate them dynamically in the OnDrawCell event:

procedure TForm1.StringGrid1DrawCell(Sender: TObject; ACol, ARow: Integer;
  Rect: TRect; State: TGridDrawState);
var
  Parametertext : string;
begin
  Parametertext := StringGrid1.Cells[ACol, ARow];
  StringGrid1.Brush.Color := clBtnFace;
  StringGrid1.Font.Color := clWindowText;
  StringGrid1.Canvas.FillRect(Rect);
  DrawText(StringGrid1.Canvas.Handle, PChar(ParameterText), Length(ParameterText), Rect, DT_SINGLELINE);
end;

...

StringGrid1.Cells[0, 0] := 'Test';
StringGrid1.Cells[1, 0] := 'Test1';

If you are not going to use the Cells property to store strings, you may as well have just used TDrawGrid instead.