[Antidelphik]

не понимаю очень многие команды в этом тексте

Код:

unit UnTrafficLight;

interface
  uses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
    Dialogs, DateUtils;

  type
    TTrafficLight = class(TObject)
      private
      { Private declarations }

        fLightRed,                                                                  
        fLightYellow,                                                             
        fLightGreen,                                                             
        fStop

          : boolean;

        fCanvas: TCanvas;                                                          

       public
       { Public declarations }
          property LightRed  : boolean read   fLightRed;                       
          property LightYellow : boolean read fLightYellow;                    
          property LightGreen : boolean read fLightGreen;                      

          constructor Create(Canvas : TCanvas);                                 

          procedure DrawLight(LightColor: TColor; clear: boolean = false);   
          procedure ClearTrafficLight;                                         
          procedure ShowState;                                                 
          procedure Wait(time: integer);                                     
          procedure StopCycle;                                                 
          procedure StartLightCycle;                                          
    end;
implementation

  constructor TTrafficLight.Create(Canvas : TCanvas);                                       
    begin
      inherited Create;
      fCanvas :=  Canvas;
      fCanvas.Brush.Style := bsSolid;
      fLightRed     :=  false;                                                                  
      fLightYellow  :=  false;                                                              
      fLightGreen   :=  false;
      ShowState;
    end;

  procedure TTrafficLight.DrawLight(LightColor: TColor; clear: boolean = false);                      
    begin
      if clear then fCanvas.Brush.Color :=  clSilver
               else fCanvas.Brush.Color :=  LightColor;
      case LightColor of
        clRed     :  fcanvas.Ellipse(35,20,85,70);
        clYellow  :  fcanvas.Ellipse(35,90,85,140);
        clGreen    :  fcanvas.Ellipse(35,160,85,210);
      end;
    end;

  procedure TTrafficLight.ClearTrafficLight;                                             
    begin
      DrawLight(clRed, true);                                         
      DrawLight(clYellow, true);                                   
      DrawLight(clGreen, true);                                      
    end;

  procedure TTrafficLight.ShowState;                                            
    begin
      DrawLight(clRed, not fLightRed);                                         
      DrawLight(clYellow, not fLightYellow);                                  
      DrawLight(clGreen, not fLightGreen);                                   
    end;

  procedure TTrafficLight.Wait(time: integer);
    var h: THandle;
    begin
      h:=CreateEvent(nil,true,false,'');
      WaitForSingleObject(h,time);
      CloseHandle(h);
    end;
 procedure TTrafficLight.StopCycle;                                            
    begin
      fStop := true;
      ClearTrafficLight;
    end;

  procedure TTrafficLight.StartLightCycle;                                  
    var start : TDateTime;
    begin
      fStop :=  false;

      While not fStop do
        begin
          Application.ProcessMessages;
          If fStop then exit;

          //  Исходное состояние - красный свет
          fLightRed     :=  true;                                                                 
          fLightYellow  :=  false;                                                              
          fLightGreen   :=  false;
          ShowState;
          Start :=   now;                                                      
          While SecondsBetween(Start,now) < 15 do                             
            begin
              if fStop then exit;                                               
              ShowState;                                                       
              Application.ProcessMessages;                                     
              Wait(50);
            end;

          //  Включаем желтый и красный, горим 2 секунды
          fLightRed     :=  true;                                               
          fLightYellow  :=  true;                                              
          fLightGreen   :=  false;
          ShowState;
          Start :=   now;                                                    

          While SecondsBetween(Start,now) < 2 do                             
            begin
              if fStop then exit;                                             
              ShowState;                                                       
              Application.ProcessMessages;                                     
              Wait(50);
            end;


          //  Включаем зеленый, горим 30 секунд
          fLightRed     :=  false;                                             
          fLightYellow  :=  false;                                              
          fLightGreen   :=  true;
          ShowState;
          Start :=   now;                                                      

          While SecondsBetween(Start,now) < 30 do                            
            begin
              if fStop then exit;                                              
              ShowState;                                                       
              Application.ProcessMessages;                                     
              Wait(50);
            end;


          //  Зеленый мигает 3 секунд
          Start :=   now;                                                     
          While SecondsBetween(Start,now) < 3 do                              
            begin
              fLightGreen   :=  not fLightGreen;                               
              if fStop then exit;                                              
              ShowState;                                                        
              Application.ProcessMessages;                                      
              Wait(500);
            end;

          //  Включаем желтый, горим 3 секунд
          fLightRed     :=  false;                                             
          fLightYellow  :=  true;                                               
          fLightGreen   :=  false;
          ShowState;
          Start :=   now;                                                     
          While SecondsBetween(Start,now) < 2 do                               
            begin
              if fStop then exit;                                               
              ShowState;                                                      
              Application.ProcessMessages;                                     
              Wait(50);
            end;

        end;

      fLightRed     :=  false;                                                               
      fLightYellow  :=  false;                                                              
      fLightGreen   :=  false;

    end;





end.