Delphi: Close all forms (except MainForm), but, ignore any OnCloseQuery dialogs

Question

Basically, I'm using a TTimer event to close all the open forms and bring the user back to the main form. I could iterate through Screen.Forms:

for i := 0 to Screen.Formcount - 1 do
  Screen.Forms[i].close;

The problem is the OnCloseQuery events on some of those forms - they pop up MessageDlg's which interrupt this process :(

I'm trying to avoid having to 'hack' the 'OnCloseQuery' event of all the forms. Also, when a MessageDlg pops up, this can count as a 'new' form, which was not in the "close" loop before, so it has to be closed manually. — Richard Woolf
If they're interrupting the process for a reason, then they shouldn't be closed. If there's no reason for them to not to close then they shouldn't be interrupting the process (they shouldn't set 'CanClose'). — Sertac Akyuz
The OnCloseQuery events frequently contain MessageDlgs saying "Are you sure you want to cancel this activity?" Yes / No --I don't want to even offer them such a choice -- I want to close, without OnCloseQuery. — Richard Woolf
So you're asking the user if there's a reason for not to close. I would just be sure that there's a visual indication that there's an activity and leave the rest to the user. But maybe that's just me.. — Sertac Akyuz
Seems like you need to refactor your app. "Close handling logic" could be delegated to a single place that has all the information it needs. Much nicer than a global boolean hack. — Warren P

Sertac Akyuz Sertac Akyuz · Accepted Answer · 2012-06-03T14:54:30

You can use a flag in your main form that your other forms would check before asking the user whether to proceed or not. Something like this:

unit1

type
  TForm1 = class(TForm)
    ..
  public
    UnconditinalClose: Boolean;
  end;

..

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  UnconditinalClose := True;
end;

unit 2:

implementation

uses
  unit1;

procedure TForm2.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
  CanClose := unit1.Form1.UnconditinalClose;
  if not CanClose then
    // ask the user if he/she's sure he/she wants to close
end;

One other solution could be detaching OnCloseQuery event handlers of other forms. ~~This would only be practical if these other forms are released (freed) when closing, not hidden~~ (edited to reflect Rob's comment):

procedure TForm1.Timer1Timer(Sender: TObject);
var
  i: Integer;
  SaveHandler: TCloseQueryEvent;
begin
  for i := 0 to Screen.Formcount - 1 do
    if Screen.Forms[i] <> Self then begin
      SaveHandler := Screen.Forms[i].OnCloseQuery;
      Screen.Forms[i].OnCloseQuery := nil;
      Screen.Forms[i].Close;
      Screen.Forms[i].OnCloseQuery := SaveHandler;
    end;
end;

Delphi: Close all forms (except MainForm), but, ignore any OnCloseQuery dialogs

2 Answers