unit ProductDetailScherm;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls,
  Subscherm, Main, ApplicationContext,
  ObserverPattern;

type
  TFormProductDetail = class(TFormSubscherm)
    LabelOmschrijving1: TLabel;
    LabelOmschrijving2: TLabel;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    FProductDetailsSubject: TSubject;
    FProductDetailsSubjectObserver: TSubjectObserver;
    procedure UpdateGui(Sender: TObject);
  public
    Constructor Create(AOwner: TComponent; Navigator: INavigator; ApplicationContext: TApplicationContext;
      ProductDetailsSubject: TSubject);
  end;

implementation

{$R *.dfm}

Constructor TFormProductDetail.Create(AOwner: TComponent; Navigator: INavigator; ApplicationContext: TApplicationContext;
  ProductDetailsSubject: TSubject);
begin
  inherited Create(AOwner, Navigator, ApplicationContext);
  self.FProductDetailsSubject := ProductDetailsSubject;
  self.FProductDetailsSubjectObserver := TSubjectObserver.Create(self);
  self.FProductDetailsSubjectObserver.OnChange := UpdateGui;
end;

procedure TFormProductDetail.FormCreate(Sender: TObject);
begin
  FProductDetailsSubject.RegisterObserver(FProductDetailsSubjectObserver);
end;

procedure TFormProductDetail.FormDestroy(Sender: TObject);
begin
  FProductDetailsSubject.UnregisterObserver(FProductDetailsSubjectObserver);
end;

procedure TFormProductDetail.UpdateGui(Sender: TObject);
begin
  if ApplicationContext.ProductDetailContext.GeselecteerdProduct <> nil then
  begin
    // Update with data from ApplicationContext
    LabelOmschrijving1.Caption := ApplicationContext.ProductDetailContext.GeselecteerdProduct.Omschrijving1;
    LabelOmschrijving2.Caption := ApplicationContext.ProductDetailContext.GeselecteerdProduct.Omschrijving2;
  end;
end;

end.