Programmatically focus and edit a cell in StringGrid

[FangQ]

hi, I have a StringGrid, and want the user to type only numbers (integers, floating point), so I defined a test in the OnEditingDone event and test if the input is numerical value, if not, I want to give user a warning, and then set focus & enabling editing state of the offending cell. Here is my EditingDone function:

Code: Pascal  [Select][+][-]

1. procedure TfmMCX.sgMediaEditingDone(Sender: TObject);
2. var
3.    grid: TStringGrid;
4.    val: Extended;
5.    ss: string;
6.    rowid, colid: integer;
7. begin
8.   grid:= Sender as TStringGrid;
9.   if(grid = nil) then exit;
10.   try
11.     try
12.         ss:=grid.Cells[grid.Col,grid.Row];
13.         rowid:=grid.Row;
14.         colid:=grid.Col;
15.         if(Length(ss)>0) then
16.             val := StrToFloat(ss);
17.     except
18.         raise Exception.Create('Input is not a number!');
19.     end;
20.   except
21.     On E : Exception do
22.     begin
23.       ShowMessage(E.Message);
24.       grid.Row:=rowid;
25.       grid.Col:=colid;
26.       grid.EditorMode:=true;
27.     end;
28.   end;
29. end;

however, I can only see a warning, but I can not either move the focused cell to the offending one, or enable the editor mode. My StringGrid already has the "goEditing" option enabled.

I am appreciated if you can suggest how to fix this. thanks!

[Handoko]

Use a TTimer. You can download my test.zip to try.

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   SysUtils, Forms, Dialogs, Grids, ExtCtrls, LCLType;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     StringGrid1: TStringGrid;
16.     Timer1: TTimer;
17.     procedure StringGrid1EditingDone(Sender: TObject);
18.     procedure Timer1Timer(Sender: TObject);
19.   public
20.     procedure GotoColRow(Col, Row: Integer);
21.   end;
22.  
23. var
24.   Form1: TForm1;
25.   GotoCol, GotoRow: Integer;
26.  
27. implementation
28.  
29. {$R *.lfm}
30.  
31. { TForm1 }
32.  
33. procedure TForm1.StringGrid1EditingDone(Sender: TObject);
34. var
35.   Z: Integer;
36. begin
37.  
38.   if not(Sender is TStringGrid) then Exit;
39.  
40.   with StringGrid1 do
41.     if not(TryStrToInt(Cells[Col, Row], Z)) then
42.       begin
43.         ShowMessage('Input is not a number!');
44.         GotoColRow(Col, Row);
45.       end;
46. end;
47.  
48. procedure TForm1.Timer1Timer(Sender: TObject);
49. begin
50.   StringGrid1.Col := GotoCol;
51.   StringGrid1.Row := GotoRow;
52.   Timer1.Enabled := False;
53. end;
54.  
55. procedure TForm1.GotoColRow(Col, Row: Integer);
56. begin
57.   GotoCol := Col;
58.   GotoRow := Row;
59.   Timer1.Enabled := True;
60. end;
61.  
62. end.

TStringGris is very customizable, if you want to learn more:
http://forum.lazarus.freepascal.org/index.php/topic,37181.0.html

[FangQ]

thanks Handoko for your prompt reply. I am wondering though why my code (setting grid.Row and grid.Col in the except...end block) does not work as desired? when I type a non-digit input and press enter, I see the exception I generated, but the focus of the cell shifts to the right no matter what I do.

also, can you set the selected cell into edit mode (as if you double clicked on the cell)? thanks

[Handoko]

Done. You can download the test2.zip.

Information about exception:
https://freepascal.org/docs-html/ref/refch17.html

As the page said, exception is used for program to handle error and error recovery, it is not suitable for used in this user input case. I personally will avoid using exception but write my own validation rules and show more friendly messages to users.

This forum has many more experienced seniors, I will let them to answer your question, why exception doesn't work on your code.

The sample I provide should work as what you want. But I noticed something not friendly to users. If user accidentally edits a cell, he/she cannot cancel (or press Esc) until he/she provides a numeric value. It is very annoying, test my code then you will understand what I mean.

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   SysUtils, Forms, Dialogs, Grids, ExtCtrls, LCLType;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     StringGrid1: TStringGrid;
16.     Timer1: TTimer;
17.     procedure StringGrid1EditingDone(Sender: TObject);
18.     procedure Timer1Timer(Sender: TObject);
19.   public
20.     procedure GotoColRow(Col, Row: Integer);
21.   end;
22.  
23. var
24.   Form1: TForm1;
25.   GotoCol, GotoRow: Integer;
26.  
27. implementation
28.  
29. {$R *.lfm}
30.  
31. { TForm1 }
32.  
33. procedure TForm1.StringGrid1EditingDone(Sender: TObject);
34. var
35.   Z: Integer;
36. begin
37.  
38.   if not(Sender is TStringGrid) then Exit;
39.  
40.   with StringGrid1 do
41.     if not(TryStrToInt(Cells[Col, Row], Z)) then
42.       begin
43.         ShowMessage('Input is not a number!');
44.         GotoColRow(Col, Row);
45.       end;
46. end;
47.  
48. procedure TForm1.Timer1Timer(Sender: TObject);
49. begin
50.   Timer1.Enabled := False;
51.   StringGrid1.Col := GotoCol;
52.   StringGrid1.Row := GotoRow;
53.   StringGrid1.EditorMode := True;
54. end;
55.  
56. procedure TForm1.GotoColRow(Col, Row: Integer);
57. begin
58.   GotoCol := Col;
59.   GotoRow := Row;
60.   Timer1.Enabled := True;
61. end;
62.  
63. end.

[FangQ]

Done. You can download the test2.zip.

really appreciated! tried it and worked like a charm.

I suppose my old approach of modifying the selection/editormode failed to work because it was inside the OnEditDone event, which must have followed by another function that sets the focus. Anyways. It works now.

On a side note, I want to apply this test for more than 1 StringGrids. I currently added another global variable to save the Goto-grid, but keep wondering if there is a way I can avoid using global variables. Tried setting Timer1's Owner to the stringgrid, but it turns out to be read-only. any method that does not require global variables?

[Handoko]

You may try to write a new TTimer. You can download the test3.zip. Here are the improvements:

- Support multiple StringGrids
- Instead using global variables, it uses TGotoTimer
- TGotoTimer will be freed automatically
- The validation rules now accept empty input

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   SysUtils, Forms, Dialogs, Grids, ExtCtrls, LCLType, StdCtrls, Classes;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     Label1: TLabel;
16.     Label2: TLabel;
17.     StringGrid1: TStringGrid;
18.     StringGrid2: TStringGrid;
19.     procedure StringGrid1EditingDone(Sender: TObject);
20.     procedure StringGrid2EditingDone(Sender: TObject);
21.   end;
22.  
23.   { TGotoTimer }
24.  
25.   TGotoTimer = class(TTimer)
26.   private
27.     TargetGrid: TStringGrid;
28.     TargetCol: Integer;
29.     TargetRow: Integer;
30.     procedure GotoColRow(Sender: TObject);
31.   public
32.     constructor Create(Grid: TStringGrid; Col, Row: Integer); overload;
33.   end;
34.  
35. var
36.   Form1: TForm1;
37.  
38. implementation
39.  
40. {$R *.lfm}
41.  
42. { TGotoTimer }
43.  
44. procedure TGotoTimer.GotoColRow(Sender: TObject);
45. begin
46.   Enabled := False;
47.   TargetGrid.SetFocus;
48.   TargetGrid.Col := TargetCol;
49.   TargetGrid.Row := TargetRow;
50.   TargetGrid.EditorMode := True;
51.   Form1.RemoveComponent(Self);
52. end;
53.  
54. constructor TGotoTimer.Create(Grid: TStringGrid; Col, Row: Integer);
55. begin
56.   inherited Create(Form1);
57.   TargetGrid := Grid;
58.   TargetCol := Col;
59.   TargetRow := Row;
60.   OnTimer := @GotoColRow;
61.   Interval := 20;
62. end;
63.  
64. { TForm1 }
65.  
66. procedure TForm1.StringGrid1EditingDone(Sender: TObject);
67. var
68.   S: string;
69.   Z: Integer;
70. begin
71.   with StringGrid1 do
72.   begin
73.     S := Cells[Col, Row];
74.     if not(TryStrToInt(S, Z)) and (S <> '') then
75.     begin
76.       ShowMessage('Input is not a number!');
77.       TGotoTimer.Create(StringGrid1, Col, Row);
78.     end;
79.   end;
80. end;
81.  
82. procedure TForm1.StringGrid2EditingDone(Sender: TObject);
83. var
84.   S: string;
85. begin
86.   with StringGrid2 do
87.   begin
88.     S := Cells[Col, Row];
89.     if (Length(S) <> 4) and (S <> '') then
90.     begin
91.       ShowMessage('Input must be 4 characters!');
92.       TGotoTimer.Create(StringGrid2, Col, Row);
93.     end;
94.   end;
95. end;
96.  
97. end.

[FangQ]

wonderful! that's an elegant solution, thank you very much!