2 questions regarding String Grids

[Badger]

I have two questions marginally related.
I have a String Grid on a panel in a scroll box. This is initial the configuration of the attached program.
If you run the program you can scroll up and down with the mouse wheel with the cursor over the scroll box.  You can also scroll with the cursor over the panel.  Normally, if you scroll up and down over the StringGrid it only scrolls the cells.  I have added an OnMouseWheel event to override this.  Unfortunately, the scrollbox keeps on scrolling past its limits. Can anyone give me a fix for this or suggest an alternative way of doing it.
My second question, assuming I can get the scroll box responding properly, is that I I am using the dataUtils unit to create a number of components and do common tasks. (Click the button to activate this) To do complete this I need to add the OnMouseWheel event at run time.  I thought I knew how to do this but it refuses to compile. (Reverse all the commented out code in "DataUtils").

Code: Pascal  [Select][+][-]

1. unit MainUnit;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, ExtCtrls, DataUtils,
9.   Grids, Buttons, StdCtrls, Types;
10.  
11. type
12.  
13.   { TMainForm }
14.  
15.   TMainForm = class(TForm)
16.     Button1: TButton;
17.     Panel1: TPanel;
18.     ScrollBox1: TScrollBox;
19.     StringGrid1: TStringGrid;
20.     procedure Button1Click(Sender: TObject);
21.     procedure StringGrid1MouseWheel(Sender: TObject; Shift: TShiftState;
22.       WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
23.   private
24.  
25.   public
26.  
27.   end;
28.  
29. var
30.   MainForm: TMainForm;
31.   StGrids:Array of TStringGrid;
32.   Panels:Array of TPanel;
33.   Scrolls:Array of TScrollbox;
34.   PageNum:Integer;
35.  
36. implementation
37.  
38. {$R *.lfm}
39.  
40. { TMainForm }
41.  
42.  
43.  
44.  
45. procedure TMainForm.StringGrid1MouseWheel(Sender: TObject; Shift: TShiftState;
46.   WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
47. begin
48.  
49.   Scrollbox1.ScrollBy(0,Wheeldelta div 10);
50. end;
51.  
52.  
53. procedure TMainForm.Button1Click(Sender: TObject);
54. begin
55.   PutScrollboxOnForm(MainForm,PageNum);
56.  
57.   PlacePanelInScrollBox(Scrolls[PageNum],PageNum);
58.  
59.   PutGridOnPanel(Panels[PageNum],PageNum);
60.  
61. end;
62.  
63. end.  

Code: Pascal  [Select][+][-]

1. object MainForm: TMainForm
2.   Left = 346
3.   Height = 496
4.   Top = 119
5.   Width = 714
6.   Caption = 'MainForm'
7.   ClientHeight = 496
8.   ClientWidth = 714
9.   LCLVersion = '2.2.4.0'
10.   object ScrollBox1: TScrollBox
11.     Left = 72
12.     Height = 296
13.     Top = 80
14.     Width = 408
15.     HorzScrollBar.Page = 376
16.     VertScrollBar.Page = 292
17.     ClientHeight = 292
18.     ClientWidth = 387
19.     TabOrder = 0
20.     object Panel1: TPanel
21.       Left = 11
22.       Height = 304
23.       Top = 16
24.       Width = 365
25.       Caption = 'Panel1'
26.       ClientHeight = 304
27.       ClientWidth = 365
28.       TabOrder = 0
29.       object StringGrid1: TStringGrid
30.         Left = 24
31.         Height = 272
32.         Top = 16
33.         Width = 312
34.         TabOrder = 0
35.         OnMouseWheel = StringGrid1MouseWheel
36.       end
37.     end
38.   end
39.   object Button1: TButton
40.     Left = 160
41.     Height = 25
42.     Top = 424
43.     Width = 184
44.     Caption = 'Click to add programatically'
45.     OnClick = Button1Click
46.     TabOrder = 1
47.   end
48. end

Code: Pascal  [Select][+][-]

1. unit datautils;
2.  
3. {$mode ObjFPC}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils,Forms, Controls, Printers,
9.   ExtCtrls,
10.    graphics, Grids;
11.  
12.  
13.   Procedure PutScrollboxOnForm(TheForm:TForm;PN:Integer);
14.   Procedure PlacePanelInScrollBox(SB:TScrollBox;PN:Integer);
15.   Procedure PutGridOnPanel(Pan:TPanel;PN:Integer);
16. //  Procedure GridScrolling(Sender: TObject; Shift: TShiftState;
17. //    WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
18.  
19.  
20. implementation
21.  
22. Uses
23.   MainUnit;
24.  
25. procedure PutScrollboxOnForm(TheForm: TForm;PN:Integer);
26. begin
27.   SetLength(Scrolls,PN+1);
28.             Scrolls[PN]:=TScrollBox.Create(TheForm);
29.             with Scrolls[PN] do
30.             begin
31.               Parent:=TheForm;
32.               width:=500;
33.               Height:=400;
34.               Left:=8;
35.               Top:=8;
36.               visible:=True;
37.               refresh;
38.             end;
39. end;
40.  
41. procedure PlacePanelInScrollBox(SB:TScrollBox;PN:Integer);
42. begin
43.   SetLength(Panels,PN+1);
44.   Panels[PN]:=TPanel.Create(MainUnit.Scrolls[PN]);
45.   with Panels[PN] do
46.   begin
47.     Parent:=SB;
48.     width:=300;
49.     Height:=500;
50.     Left:=8;
51.     Top:=8;
52.     color:=clwhite;
53.     visible:=True;
54.     refresh;
55.   end;
56. end;
57.  
58. procedure PutGridOnPanel(Pan: TPanel; PN: Integer);
59. begin
60.   SetLength(StGrids,PN+1);
61.   StGrids[PN]:=TStringGrid.Create(MainUnit.Panels[PN]);
62.   with StGrids[PN] do
63.   begin
64.     Parent:=Pan;
65.     width:=250;
66.     Height:=400;
67.     Left:=8;
68.     Top:=8;
69.     color:=clwhite;
70.     visible:=True;
71.     //OnMouseWheel:=@GridScrolling;
72.     refresh;
73.   end;
74. end;
75. (*
76. procedure GridScrolling(Sender: TObject; Shift: TShiftState;
77.   WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
78. begin
79.   Sender as TStringgrid.Parent.Parent.ScrollBy(WheelDelta);
80. end;
81.     *)
82. end.
83.            

[cdbc]

Hi
This:

Code: Pascal  [Select][+][-]

1. (*
2. procedure GridScrolling(Sender: TObject; Shift: TShiftState;
3.   WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
4. begin
5.   Sender as TStringgrid.Parent.Parent.ScrollBy(WheelDelta);
6. end;
7.     *)

Can't be a simple procedure, it *has* to be a method on an object/class
- - - Stick it in a class or an object and Bob's your uncle - - -
Regards Benny

[cdbc]

Hi ...again
Or you can play dirty like this:

Code: Pascal  [Select][+][-]

1. unit datautils;
2.  
3. {$mode ObjFPC}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils,Forms, Controls, Printers,
9.   ExtCtrls,
10.    graphics, Grids;
11. { Hack start }
12. type
13.   { declare an object to host our method, yes it's a hack :o) }
14.   THack = object
15.     procedure GridScrolling(Sender: TObject;
16.                             Shift: TShiftState;
17.                             WheelDelta: Integer;
18.                             MousePos: TPoint;
19.                             var Handled: Boolean);
20.   end; { THack }
21. { end of hack }
22.  
23.   Procedure PutScrollboxOnForm(TheForm:TForm;PN:Integer);
24.   Procedure PlacePanelInScrollBox(SB:TScrollBox;PN:Integer);
25.   Procedure PutGridOnPanel(Pan:TPanel;PN:Integer);
26.  
27.  
28. implementation
29.  
30. Uses
31.   MainUnit;
32.  
33. var { declare a variable of our object/hack }
34.   Hack: THack;
35.  
36. procedure PutScrollboxOnForm(TheForm: TForm;PN:Integer);
37. begin
38.   SetLength(Scrolls,PN+1);
39.             Scrolls[PN]:=TScrollBox.Create(TheForm);
40.             with Scrolls[PN] do
41.             begin
42.               Parent:=TheForm;
43.               width:=500;
44.               Height:=400;
45.               Left:=8;
46.               Top:=8;
47.               visible:=True;
48.               refresh;
49.             end;
50. end;
51.  
52. procedure PlacePanelInScrollBox(SB:TScrollBox;PN:Integer);
53. begin
54.   SetLength(Panels,PN+1);
55.   Panels[PN]:=TPanel.Create(MainUnit.Scrolls[PN]);
56.   with Panels[PN] do
57.   begin
58.     Parent:=SB;
59.     width:=300;
60.     Height:=500;
61.     Left:=8;
62.     Top:=8;
63.     color:=clwhite;
64.     visible:=True;
65.     refresh;
66.   end;
67. end;
68.  
69. procedure PutGridOnPanel(Pan: TPanel; PN: Integer);
70. begin
71.   SetLength(StGrids,PN+1);
72.   StGrids[PN]:=TStringGrid.Create(MainUnit.Panels[PN]);
73.   with StGrids[PN] do
74.   begin
75.     Parent:=Pan;
76.     width:=250;
77.     Height:=400;
78.     Left:=8;
79.     Top:=8;
80.     color:=clwhite;
81.     visible:=True;
82.     { here we utilize our hack/object to host the event-handler }
83.     OnMouseWheel:=@Hack.GridScrolling;
84.     refresh;
85.   end;
86. end;
87.  
88. { Hack start }
89. { THack is a nifty way of converting a function or a procedure into a method :o) }
90. procedure THack.GridScrolling(Sender: TObject;
91.                               Shift: TShiftState;
92.                               WheelDelta: Integer;
93.                               MousePos: TPoint;
94.                               var Handled: Boolean);
95. begin
96.   Sender as TStringgrid.Parent.Parent.ScrollBy(WheelDelta);
97. end;
98. { end of hack }
99. end.
100.  

It's your unit, with a few modifications of mine, it should work now...
Just look for the word 'Hack' and you'll find my mods... 
It's a bit /Old School/, but hey... that's fun too  ...and easy.
HTH
Regards Benny

[TRon]

Just look for the word 'Hack' and you'll find my mods... 

I always name the object 'events' or 'eventhandlers' ... no idea it was considered a hack 

It's a bit /Old School/, but hey... that's fun too  ...and easy.

Exactly why I use that all the time: quick and easy.

You can always figure out a more proper solution/location (for the event handlers) when things are working (or just leave it as is).

[jamie]

if I am following this correctly, shouldn't a simple

Code: Pascal  [Select][+][-]

1. Handled := True;
2.  

In the MouseWhile Event for the stringgrid be enough to not send it to the scrollbox ?

[Badger]

I'll give your suggestions a try tonight.

It's a bit /Old School/, but hey... that's fun too  ...and easy.

You don't know the meaning of old school!! I cut my teeth on a PDP11, a Commodore 64 and an Amstrad!

[cdbc]

Hi

Commodore 64

Yup, me too, with tape loading... 
Regards Benny

[Badger]

PDP was toggle switches!

[Badger]

Still got a couple of problems.

Firstly, the  scrollbox in the first part of the program is still scrolling past the ends of the scrollbox 'canvas'.

Secondly, I had to modify the THack.GridScrolling procedure as follows

Code: Pascal  [Select][+][-]

1. procedure THack.GridScrolling(Sender: TObject;
2.                               Shift: TShiftState;
3.                               WheelDelta: Integer;
4.                               MousePos: TPoint;
5.                               var Handled: Boolean);
6. var
7.   APanel:TPanel;
8.   AScroll:TScrollbox;
9. begin
10.   APanel:=TPanel.Create(Sender as TStringgrid) ;
11.  
12.   AScroll:=TScrollbox.Create(APAnel);
13.  
14.   AScroll.ScrollBy(0,WheelDelta);
15. end;  

However, when I run the program I get the error message - TWinControl.ScrollBy_WS: Handle not allocated at the line AScroll.ScrollBy(0,WheelDelta); 

[cdbc]

Hi
Hmmm...
In that handler procedure:

Code: Pascal  [Select][+][-]

1. procedure THack.GridScrolling(Sender: TObject;
2.                               Shift: TShiftState;
3.                               WheelDelta: Integer;
4.                               MousePos: TPoint;
5.                               var Handled: Boolean);
6. var
7.   APanel:TPanel;
8.   AScroll:TScrollbox;
9. begin
10.   APanel:=TPanel.Create(Sender as TStringgrid) ;
11.   // try to set parent for APanel, maybe that will jolt the 'HandleNeeded'
12.   APanel.Parent:= (Sender as TStringgrid){.Parent?!?};
13.   AScroll:=TScrollbox.Create(APAnel);
14.   // dunno 'bout 'parent' business here?!? Trial 'n error...
15.   AScroll.ScrollBy(0,WheelDelta);
16. end;

note: I've got this funny feeling, that something else is wrong... 
Regards Benny