procedure TProgram.Run;
begin
  Execute;
end;

function TGroup.Execute: Word;
var
  E: TEvent;
begin
  repeat
    EndState := 0;
    repeat
      GetEvent(E);
      HandleEvent(E);
      if E.What <> evNothing then EventError(E);
    until EndState <> 0;
  until Valid(EndState);
  Execute := EndState;
end;

type

{ Event record }

  PEvent = ^TEvent;
  TEvent = record
    What: Word;
    case Word of
      evNothing: ();
      evMouse: (
        Buttons: Byte;
        Double: Boolean;
        Where: TPoint);
      evKeyDown: (
        case Integer of
          0: (KeyCode: Word);
          1: (CharCode: Char;
              ScanCode: Byte));
      evMessage: (
        Command: Word;
        case Word of
          0: (InfoPtr: Pointer);
          1: (InfoLong: Longint);
          2: (InfoWord: Word);
          3: (InfoInt: Integer);
          4: (InfoByte: Byte);
          5: (InfoChar: Char));
  end;



procedure TProgram.GetEvent(var Event: TEvent);
var
  R: TRect;

function ContainsMouse(P: PView): Boolean; far;
begin
  ContainsMouse := (P^.State and sfVisible <> 0) and
    P^.MouseInView(Event.Where);
end;

begin
  if Pending.What <> evNothing then
  begin
    Event := Pending;
    Pending.What := evNothing;
  end else
  begin
    GetMouseEvent(Event);
    if Event.What = evNothing then
    begin
      GetKeyEvent(Event);
      if Event.What = evNothing then Idle;
    end;
  end;
  if StatusLine <> nil then
    if (Event.What and evKeyDown <> 0) or
      (Event.What and evMouseDown <> 0) and
      (FirstThat(@ContainsMouse) = PView(StatusLine)) then
      StatusLine^.HandleEvent(Event);
end;

procedure TProgram.HandleEvent(var Event: TEvent);
var
  I: Word;
  C: Char;
begin
  if Event.What = evKeyDown then
  begin
    C := GetAltChar(Event.KeyCode);
    if (C >= '1') and (C <= '9') then
      if Message(Desktop, evBroadCast, cmSelectWindowNum,
        Pointer(Byte(C) - $30)) <> nil then ClearEvent(Event);
  end;
  TGroup.HandleEvent(Event);
  if Event.What = evCommand then
    if Event.Command = cmQuit then
    begin
      EndModal(cmQuit);
      ClearEvent(Event);
    end;
end;


procedure TProgram.Idle;
begin
  if StatusLine <> nil then StatusLine^.Update;
  if CommandSetChanged then
  begin
    Message(@Self, evBroadcast, cmCommandSetChanged, nil);
    CommandSetChanged := False;
  end;
end

procedure TTVDemo.GetEvent(var Event: TEvent);
var   W: PWindow;  HFile: PHelpFile;  HelpStrm: PDosStream;
const
  HelpInUse: Boolean = False;
begin
  inherited GetEvent(Event);
  case Event.What of
    evCommand:
      if (Event.Command = cmHelp) and not HelpInUse then
      begin
        HelpInUse := True;
        HelpStrm := New(PDosStream, Init(CalcHelpName, stOpenRead));
        HFile := New(PHelpFile, Init(HelpStrm));
        if HelpStrm^.Status <> stOk then
        begin
          MessageBox('Could not open help file.', nil, mfError + mfOkButton);
          Dispose(HFile, Done);
        end
        else
        begin
          W := New(PHelpWindow,Init(HFile, GetHelpCtx));
          if ValidView(W) <> nil then
          begin
            ExecView(W);
            Dispose(W, Done);
          end;
          ClearEvent(Event);
        end;
        HelpInUse := False;
      end;
    evMouseDown:
      if Event.Buttons <> 1 then Event.What := evNothing;
  end;
end;

procedure TTVDemo.HandleEvent(var Event: TEvent);
begin
  inherited HandleEvent(Event);
  case Event.What of
    evCommand:
      begin
        case Event.Command of
          cmOpen: FileOpen('*.*');
          cmNew: FileNew;
          cmShowClip: ShowClip;
          cmChangeDir: ChangeDir;
          cmAbout: About;
          cmPuzzle: Puzzle;
          cmCalendar: Calendar;
          cmAsciiTab: AsciiTab;
          cmCalculator: Calculator;
          cmColors: Colors;
          cmMouse: Mouse;
          cmSaveDesktop: SaveDesktop;
          cmRetrieveDesktop: RetrieveDesktop;
        else
          Exit;
        end;
        ClearEvent(Event);
      end;
  end;
end

procedure TApplication.HandleEvent(var Event: TEvent);
begin
  inherited HandleEvent(Event);
  case Event.What of
    evCommand:
      begin
        case Event.Command of
          cmTile: Tile;
          cmCascade: Cascade;
          cmDosShell: DosShell;
        else
          Exit;
        end;
        ClearEvent(Event);
      end;
  end;
end;

procedure TProgram.HandleEvent(var Event: TEvent);
var
  I: Word;
  C: Char;
begin
  if Event.What = evKeyDown then
  begin
    C := GetAltChar(Event.KeyCode);
    if (C >= '1') and (C <= '9') then
      if Message(Desktop, evBroadCast, cmSelectWindowNum,
        Pointer(Byte(C) - $30)) <> nil then ClearEvent(Event);
  end;
  TGroup.HandleEvent(Event);
  if Event.What = evCommand then
    if Event.Command = cmQuit then
    begin
      EndModal(cmQuit);
      ClearEvent(Event);
    end;
end;


procedure TGroup.HandleEvent(var Event: TEvent);

procedure DoHandleEvent(P: PView); far;
begin
  if (P = nil) or ((P^.State and sfDisabled <> 0)
    and (Event.What and (PositionalEvents or FocusedEvents) <> 0)) then Exit;
  case Phase of
    phPreProcess: if P^.Options and ofPreProcess = 0 then Exit;
    phPostProcess: if P^.Options and ofPostProcess = 0 then Exit;
  end;
  if Event.What and P^.EventMask <> 0 then P^.HandleEvent(Event);
end;

function ContainsMouse(P: PView): Boolean; far;
begin
  ContainsMouse := (P^.State and sfVisible <> 0) and
    P^.MouseInView(Event.Where);
end;

begin
  TView.HandleEvent(Event);
  if Event.What and FocusedEvents <> 0 then
  begin
    Phase := phPreProcess;
    ForEach(@DoHandleEvent);
    Phase := phFocused;
    DoHandleEvent(Current);
    Phase := phPostProcess;
    ForEach(@DoHandleEvent);
  end else
  begin
    Phase := phFocused;
    if (Event.What and PositionalEvents <> 0) then
      DoHandleEvent(FirstThat(@ContainsMouse)) else
      ForEach(@DoHandleEvent);
  end;
end;

function Message(Receiver: PView; What, Command: Word;
  InfoPtr: Pointer): Pointer;
var
  Event: TEvent;
begin
  Message := nil;
  if Receiver <> nil then
  begin
    Event.What := What;
    Event.Command := Command;
    Event.InfoPtr := InfoPtr;
    Receiver^.HandleEvent(Event);
    if Event.What = evNothing then Message := Event.InfoPtr;
  end;
end;


procedure TView.GetEvent(var Event: TEvent);
begin
  if Owner <> nil then Owner^.GetEvent(Event);
end;