Turn OnClick event on and off in code?(Solved)

[JLWest]

I have a deck of cards named I1..I52.  (TImage)
CardArray[1].Image:=I1..CardArray[52]:=I52
I need to turn the clicked event on while the hands of Bridge are played out and turned off after the last trick.

I suppose I could write;

Code: Pascal  [Select][+][-]

1. procedure Tform1.Onclick(S: Integer);
2.  begin
3.   Case S: begin
4.                 code to turn the event on
5.               end;
6.   end;

Brute force would work but there must be a better way.

[speter]

Do you have a variable representing the state-of-the-game (I usually have a variable called "finished" or "game_over").
If you have something like that you could test it's value at the start of the procedure and exit (if the game is over)...

cheers
S.

[Handoko]

Disabling/Enabling an object's event can be done by:
- Setting the event to nil and point it back to the event (see the first code)
- Using a variable as mentioned by @speter (see the second code)

Solution 1

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, ExtCtrls, StdCtrls;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     btnEnable1: TButton;
16.     btnDisable: TButton;
17.     btnEnable2: TButton;
18.     btnDisable2: TButton;
19.     Label1: TLabel;
20.     Panel1: TPanel;
21.     Panel2: TPanel;
22.     procedure btnDisable2Click(Sender: TObject);
23.     procedure btnDisableClick(Sender: TObject);
24.     procedure btnEnable1Click(Sender: TObject);
25.     procedure btnEnable2Click(Sender: TObject);
26.     procedure Panel1Click(Sender: TObject);
27.     procedure Panel2Click(Sender: TObject);
28.   end;
29.  
30. var
31.   Form1: TForm1;
32.  
33. implementation
34.  
35. {$R *.lfm}
36.  
37. { TForm1 }
38.  
39. procedure TForm1.Panel1Click(Sender: TObject);
40. begin
41.   Panel1.Color := Random($FFFFFF);
42. end;
43.  
44. procedure TForm1.Panel2Click(Sender: TObject);
45. begin
46.   Panel2.Caption := Random($FFFFFF).ToString;
47. end;
48.  
49. procedure TForm1.btnEnable1Click(Sender: TObject);
50. begin
51.   Panel1.OnClick := @Panel1Click;
52. end;
53.  
54. procedure TForm1.btnEnable2Click(Sender: TObject);
55. begin
56.   Panel2.OnClick := @Panel2Click;
57. end;
58.  
59. procedure TForm1.btnDisableClick(Sender: TObject);
60. begin
61.   Panel1.OnClick := nil;
62. end;
63.  
64. procedure TForm1.btnDisable2Click(Sender: TObject);
65. begin
66.   Panel2.OnClick := nil;
67. end;
68.  
69. end.

Pay attention on the @ symbol in the code above (see line #51 & #56).

Solution 2

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, ExtCtrls, StdCtrls;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     btnEnable1: TButton;
16.     btnDisable: TButton;
17.     btnEnable2: TButton;
18.     btnDisable2: TButton;
19.     Label1: TLabel;
20.     Panel1: TPanel;
21.     Panel2: TPanel;
22.     procedure btnDisable2Click(Sender: TObject);
23.     procedure btnDisableClick(Sender: TObject);
24.     procedure btnEnable1Click(Sender: TObject);
25.     procedure btnEnable2Click(Sender: TObject);
26.     procedure FormCreate(Sender: TObject);
27.     procedure Panel1Click(Sender: TObject);
28.     procedure Panel2Click(Sender: TObject);
29.   private
30.     ClickEnabled: array[1..2] of Boolean;
31.   end;
32.  
33. var
34.   Form1: TForm1;
35.  
36. implementation
37.  
38. {$R *.lfm}
39.  
40. { TForm1 }
41.  
42. procedure TForm1.Panel1Click(Sender: TObject);
43. begin
44.   if ClickEnabled[1] then
45.     Panel1.Color := Random($FFFFFF);
46. end;
47.  
48. procedure TForm1.Panel2Click(Sender: TObject);
49. begin
50.   if ClickEnabled[2] then
51.     Panel2.Caption := Random($FFFFFF).ToString;
52. end;
53.  
54. procedure TForm1.FormCreate(Sender: TObject);
55. begin
56.   // Enable OnClick on all panels
57.   ClickEnabled[1] := True;
58.   ClickEnabled[2] := True;
59. end;
60.  
61. procedure TForm1.btnEnable1Click(Sender: TObject);
62. begin
63.   ClickEnabled[1] := True;
64. end;
65.  
66. procedure TForm1.btnEnable2Click(Sender: TObject);
67. begin
68.   ClickEnabled[2] := True;
69. end;
70.  
71. procedure TForm1.btnDisableClick(Sender: TObject);
72. begin
73.   ClickEnabled[1] := False;
74. end;
75.  
76. procedure TForm1.btnDisable2Click(Sender: TObject);
77. begin
78.   ClickEnabled[2] := False;
79. end;
80.  
81. end.

The code above uses an array to remember which item is turn on or off, see line #30. Usually programmers count from 0 for arrays but to make it easier to understand, I used 1 in the code above.

[JLWest]

Hi
Hi Handoko

The following code get an error that it's not a member. @CardArray.Image.Click; I tried @CardArray.Image.Click; and @CardArray.ImageClick;

Code: Pascal  [Select][+][-]

1. procedure TForm1.CardEventOn;
2.  Var
3.   i : Integer;
4.   Image : TImage;
5.  begin
6.   for i := 1 to 52 do begin
7.      CardArray[i].Image.OnClick:=@CardArray[i].Image.Click;   // Error
8.   end;
9.  end;  

[Handoko]

Try this demo:

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, Forms, Controls, ExtCtrls, StdCtrls;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     btnDisable1: TButton;
16.     btnDisable2: TButton;
17.     btnDisable3: TButton;
18.     ImageList1: TImageList;
19.     Label1: TLabel;
20.     procedure CardOnClickEvent(Sender: TObject);
21.     procedure FormCreate(Sender: TObject);
22.     procedure btnDisable1Click(Sender: TObject);
23.     procedure btnDisable2Click(Sender: TObject);
24.     procedure btnDisable3Click(Sender: TObject);
25.   private
26.     Cards: array[1..3] of TImage;
27.   end;
28.  
29. var
30.   Form1: TForm1;
31.  
32. implementation
33.  
34. {$R *.lfm}
35.  
36. { TForm1 }
37.  
38. procedure TForm1.CardOnClickEvent(Sender: TObject);
39. var
40.   Current: TImage;
41. begin
42.   if not(Sender is TImage) then Exit; // Prevent posible error
43.   Current := Sender as TImage;
44.   Current.Picture.Clear;
45.   Application.ProcessMessages;
46.   Sleep(100);
47.   ImageList1.GetBitmap(Random(3), Current.Picture.Bitmap);
48. end;
49.  
50. procedure TForm1.FormCreate(Sender: TObject); // Generate and show the cards
51. var
52.   i: Integer;
53. begin
54.   for i := 1 to 3 do
55.   begin
56.     // Generate the card
57.     Cards[i] := TImage.Create(Self);
58.     Cards[i].Width   := 86;
59.     Cards[i].Height  := 125;
60.     // Get a random image from ImageList1
61.     ImageList1.GetBitmap(Random(3), Cards[i].Picture.Bitmap);
62.     // Show the card
63.     Cards[i].Parent  := Self;
64.     Cards[i].Top     := 40;
65.     Cards[i].Left    := i * 130 - 60;
66.     // Link the CardOnClicEvent to the card, see line #38
67.     Cards[i].OnClick := @CardOnClickEvent;
68.   end;
69. end;
70.  
71. procedure TForm1.btnDisable1Click(Sender: TObject);
72. begin
73.   case (Cards[1].OnClick <> nil) of
74.     True:   begin
75.               btnDisable1.Caption := 'Click to' + #10 + 'Enable';
76.               Cards[1].OnClick    := nil;               // Disable OnClick
77.             end;
78.     False:  begin
79.               btnDisable1.Caption := 'Click to' + #10 + 'Disable';
80.               Cards[1].OnClick    := @CardOnClickEvent; // Encable OnClick
81.             end;
82.   end;
83. end;
84.  
85. procedure TForm1.btnDisable2Click(Sender: TObject);
86. begin
87.   case (Cards[2].OnClick <> nil) of
88.     True:   begin
89.               btnDisable2.Caption := 'Click to' + #10 + 'Enable';
90.               Cards[2].OnClick    := nil;               // Disable OnClick
91.             end;
92.     False:  begin
93.               btnDisable2.Caption := 'Click to' + #10 + 'Disable';
94.               Cards[2].OnClick    := @CardOnClickEvent; // Encable OnClick
95.             end;
96.   end;
97. end;
98.  
99. procedure TForm1.btnDisable3Click(Sender: TObject);
100. begin
101.   case (Cards[3].OnClick <> nil) of
102.     True:   begin
103.               btnDisable3.Caption := 'Click to' + #10 + 'Enable';
104.               Cards[3].OnClick    := nil;               // Disable OnClick
105.             end;
106.     False:  begin
107.               btnDisable3.Caption := 'Click to' + #10 + 'Disable';
108.               Cards[3].OnClick    := @CardOnClickEvent; // Encable OnClick
109.             end;
110.   end;
111. end;
112.  
113. end.

[JLWest]

@Handoko

Yea, I see how you did this.

Thanks