I downloaded the source code for IUP 3.26 and 3.27 from SourceForge to see if I
could work out what was going wrong. I haven’t been able to work out why
sometimes IUP scripts cause the application to close – even, in some cases, if
it’s not running under a Lua debugger. But I have spotted some behaviour that
looks clearly wrong to me, which I believe can be easily fixed, and which if
fixed should solve the problem. In both 3.2.6 and 3.2.7 there is one and only
call to PostQuitMessage and only one place where the WM_QUIT message is
mentioned (and for that matter, only one place where ‘GetMessage’ is called),
and it’s in the file iupwin_loop.c. The 3.2.6 and 3.2.7 versions of this file
are identical.
I believe that the following 3 small changes would fix the problem:
(1) Insert this line to the top of iupwin_loop.c (at say line 26): “static
UINT win_quit_msg_id = 0;”
(2) The IupExitLoop function currently looks like this:
void IupExitLoop(void)
{
char* exit_loop = IupGetGlobal("EXITLOOP");
if (win_main_loop > 1 || !exit_loop || iupStrBoolean(exit_loop))
PostQuitMessage(0);
}
… and should be changed to this:
void IupExitLoop(void)
{
if (win_quit_msg_id == 0)
win_quit_msg_id = ::RegisterWindowMessage("IUP Quit Message");
char* exit_loop = IupGetGlobal("EXITLOOP");
if (win_main_loop > 1 || !exit_loop || iupStrBoolean(exit_loop))
PostMessage(NULL, win_quit_msg_id, 0, 0L);
}
(3) The winLoopProcessMessage function currently looks like this:
static int winLoopProcessMessage(MSG* msg)
{
if (msg->message == WM_QUIT) /* IUP_CLOSE returned in a callback or IupHide
in a popup dialog or all dialogs closed */
return IUP_CLOSE;
else
{
TranslateMessage(msg);
DispatchMessage(msg);
return IUP_DEFAULT;
}
}
… and should be changed to this:
static int winLoopProcessMessage(MSG* msg)
{
if (win_quit_msg_id == 0)
{
win_quit_msg_id = ::RegisterWindowMessage("IUP Quit Message");
if (win_quit_msg_id == 0)
return IUP_CLOSE;
}
if (msg->message == win_quit_msg_id) /* IUP_CLOSE returned in a callback or
IupHide in a popup dialog or all dialogs closed */
return IUP_CLOSE;
else
{
TranslateMessage(msg);
DispatchMessage(msg);
return IUP_DEFAULT;
}
}
That’s it – except that there are a couple of comments in the same file /*
WM_QUIT */ that can simply be removed. The code in each case is fine as it is
and does not need to be changed. Probably you should define “IUP Quit Message”
(or whatever your preferred string is) as a constant string at the top of the
file, for greater robustness.
Theoretically you could use WM_USER + ? as the message id, but it’s more robust
to use a registered message. That way you can be 100% sure that there won’t be
a conflict with any application-defined messages, which there could be if you
took the WM_USER approach.
The Windows documentation says that the PostQuitMessage function “Indicates to
the system that a thread has made a request to terminate (quit)”. That is
clearly not the case here, so PostQuitMessage should not be used.
Any thoughts anyone? Scuri?
Simon
From: Antonio Scuri [mailto:[email protected]]
Sent: 24 June 2019 6:27 PM
To: IUP discussion list.
Subject: Re: [Iup-users] FW: IUP crash in Debug Mode
> Is there any way I can stop it doing that?
No
> Has IUP always posted WM_QUIT messages?
I think Yes
> I wasn’t clear from your reply what you think needs to be done.
Actually neither I...
> From my point-of-view, I don’t want IUP to ever close down my application in
> any circumstances.
Yes, it wasn't meant to do that. When you are showing an IUP dialog the
iup.MainLoop will hold the execution until a WM_QUIT message is posted. The
same happens when iup.Popup is called, but in this case there is a secondary
message loop, when the quit message is posted it returns to the mainloop. The
idea, and it works when not debugging, is that IUP receive the quit message,
and returns the control to the application just like a secondary message loop.
The problem is that your application loop is intercepting our quit message in
debug, apparently because of the message pump process. Notice that IUP has its
own way to message pump by using IupLoopStep. We use that to implement the Lua
debugger in the IupLuaScripterDlg predefined dialog.
To be more specific and not being, I think something in the message pump
should be changed, but I'm not sure what.
Best,
Scuri
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