How to Notify Controller of View Changes

[Weitentaaal]

Hello ,

Here My Problem:

I Have a ComboBox and implemented its OnChange Event:

Code: Pascal  [Select][+][-]

1. procedure TFormSW.CmbOpeningChange(Sender: TObject);
2. begin
3.    case CmbOpening.ItemIndex of
4.       0: begin // volle Öffnung
5.          Label46.Visible := True;
6.          Label19.Visible := True;
7.          Label20.Visible := True;
8.          Label50.Visible := True;
9.          Label51.Visible := True;
10.          Command5.Visible := False;
11.          Command6.Visible := False;
12.       end;
13.       1: begin // halbe Öffnung oben
14.          Label46.Visible := True;
15.          Label19.Visible := True;
16.          Label20.Visible := True;
17.          Label50.Visible := True;
18.          Label51.Visible := True;
19.          Command5.Visible := True;
20.          Command6.Visible := True;
21.       end;
22.       2: begin // halbe Öffnung unten
23.          Label46.Visible := True;
24.          Label19.Visible := True;
25.          Label20.Visible := True;
26.          Label50.Visible := True;
27.          Label51.Visible := True;
28.          Command5.Visible := True;
29.          Command6.Visible := True;
30.       end;
31.       3: begin // keine Öffnung
32.          TxBtDp.Text:= '0';
33.          Label46.Visible := False;
34.          Label19.Visible := False;
35.          Label20.Visible := False;
36.          Label50.Visible := False;
37.          Label51.Visible := False;
38.          Command5.Visible := False;
39.          Command6.Visible := False;
40.       end;
41.    end;
42. end;
43.  

and i Have another Class which is My Controller

Code: Pascal  [Select][+][-]

1. procedure OeffnungChanged();
2. begin
3.       Case OeffIND Of
4.          0: CalcOpening0(KlapIND, AnordIND);
5.          1: CalcOpening1(KlapIND, AnordIND);
6.          2: CalcOpening2(KlapIND, AnordIND);
7.          3: begin // keine Öffnung
8.             KpX1:= 0;
9.             KpX2:= 0;
10.             KpY1:= 0;
11.             KpY2:= 0;
12.             KpZ1:= 0;
13.             KpZ2:= 0;
14.          end;
15.       End;
16. end;
17.  

How do i Notify the Controller about  the Changes ?

i currently do it like this:
Cntlr.OeffnungChanged; //Cntlr = Controller

Anyway this seems not that effective.

i tried to use Observers but thats still a bit too complex for me. Then i was trying to do it via TNotifyEvent, but i was also to stupid to understand how this will work.

Could Someone provide a Sollution how to hande this interface between this classes ?

I would like to achieve something similar to MVC or MVVM to make my code more readable and easier to use. Got a Model, View and Controller, but i don't realy know how to handle the Connections between them. I ask myself a lot how to pass Data, how to Notify any of those classes or how to access those classes. i always end up with the same messy Code.

[cdbc]

Hi
The "TObserved" is already implemented in TPersistent.
All you need to do is implement the observer and connect it, maybe 15 lines of code...

Code: Pascal  [Select][+][-]

1.   THKObserver = class(TInterfacedObject,IFPObserver)
2.   private
3.     fDs: THKCollection;
4.     fGrid: TStringGrid;
5.   public
6.     constructor Create(aGrid: TStringGrid);
7.     procedure ClearGrid;
8.     procedure CreateGridHeaders;
9.     procedure PopulateGrid;
10.     Procedure FPOObservedChanged(ASender : TObject; Operation : TFPObservedOperation; Data : Pointer);
11.   end;
12.  
13. procedure THKObserver.FPOObservedChanged(ASender: TObject;Operation: TFPObservedOperation; Data: Pointer);
14. var
15.   HkCount: ptrint;
16. begin
17. //  if Data <> nil then HkItem:= THKCollectionItem(Data);
18.   case Operation of
19.     ooChange: ; //todo
20.     ooFree: ; //todo
21.     ooAddItem: {showmessage('Observer notified: Item added...')}; // todo
22.     ooDeleteItem: ; // todo
23.     ooCustom: begin // triggered after EndUpdate...
24.                 HkCount:= ptrint(Data);
25.                 fmMain.Caption:= MainTitle+' - [Kontakte in Database: '+inttostr(HkCount)+']';
26.                 fDs:= THKCollection(ASender);
27.                 PopulateGrid;
28.               end;
29.   end;
30.  
31. end;
32.  
33.  

Something like this.
Regards Benny

[Weitentaaal]

So im going to Notify all my Observers in the ViewModel from my Form when Something changed, and with the Sender i cant identify what component changed ?

Data is obviously gonna be the Changed Value i guess.

So its gonna be Something like this: (i don't know how to accept Data and Send it. How do i know what Changed)?

 

Code: Pascal  [Select][+][-]

1. //In my View
2. procedure Combo1Changed(Sender: tObject);
3. begin
4.   //How do i notify my Observers Here ?
5.   TObservable.NotifyObservers;
6. end;
7.  
8. //In my ModelView
9. procedure THKObserver.FPOObservedChanged(ASender: TObject;Operation: TFPObservedOperation; Data: Pointer); //ASender will be Combo1 //Data will be Combo1.Text
10. var
11.   Newtext: String;
12. begin
13.    //  if Data <> nil then HkItem:= THKCollectionItem(Data);
14.   case Operation of
15.     ooChange: ; //todo
16.     ooFree: ; //todo
17.     ooAddItem: {showmessage('Observer notified: Item added...')}; // todo
18.     ooDeleteItem: ; // todo
19.     ooCustom: begin // triggered after EndUpdate...
20.                 NewText:= Data;
21.                 //Do Something with New Data and then Send Changes back
22.                 fDs:= THKCollection(ASender);
23.               end;
24.   end;
25.  
26. end;
27.  

[cdbc]

Hi
Easiest way, define a record and send it along in the data-pointer, @DataRec.... You can put all sorts of stuff in there...
Regards Benny