delphi custom component with default popupmenu item

Question

I use a custom listview component and I need it to have a popupmenu item "copy data to clipboard". If there is no assigned popup, I create one and add the menuitem, if there is already a menu assigned, add the item to the current popup. Tried to put the code in the constructor, but then I realized, that popupmenu is still not created or associated to my listview. So any idea when to create my default item?

constructor TMyListView.Create(AOwner: TComponent);
var
  FpopupMenu: TPopupMenu;
begin
  inherited;
  .....
  FPopUpMenuItem := TMenuItem.Create(self);
  FPopUpMenuItem.Caption := 'Copy data to clipboard';
  FPopUpMenuItem.OnClick := PopupMenuItemClick;
  if assigned(PopupMenu) then begin
    popupMenu.Items.Add(FPopUpMenuItem);
  end
  else begin
    FpopupMenu := TPopupMenu.Create(self);
    FpopupMenu.Items.Add(FPopUpMenuItem);
    PopupMenu := FpopupMenu;
  end;
...
end;

Answer 1

Override the virtual TControl.DoContextPopup() method, eg:

type
  TMyListView = class(TListView)
  protected
    ...
    procedure DoContextPopup(MousePos: TPoint; var Handled: Boolean); override;
    ...
  end;

procedure TMyListView.DoContextPopup(MousePos: TPoint; var Handled: Boolean);
var
  LPopupMenu: TPopupMenu;
  LItem: TMenuItem;

  function IsSameEvent(const E1, E2: TNotifyEvent): Boolean;
  begin
    Result := (TMethod(E1).Code = TMethod(E2).Code) and
              (TMethod(E1).Data = TMethod(E2).Data);
  end;

begin
  inherited DoContextPopup(MousePos, Handled);
  if Handled then Exit;

  LPopupMenu := PopupMenu;
  if not Assigned(LPopupMenu) then
  begin
    LPopupMenu := TPopupMenu.Create(Self);
    PopupMenu := LPopupMenu;
  end;

  for I := 0 to LPopupMenu.Items.Count-1 do
  begin
    LItem := LPopupMenu.Items[I];
    if IsSameEvent(LItem.OnClick, PopupMenuItemClick) then
      Exit;
  end;

  LItem := TMenuItem.Create(Self);
  LItem.Caption := 'Copy data to clipboard';
  LItem.OnClick := PopupMenuItemClick;
  LPopupMenu.Items.Add(LItem);
end;