On 2 Jan 2013, at 11:12, claude roux wrote:
> Hello,
>
> The way I use FLTK encompasses some level of re-entrance. However, I
> discovered a little problem in the way add_timeout is used on Windows. If I
> initialize a first timeout, it works like a charm... If I try to relaunch a
> new timeout within the same application, then it does not work anymore.
>
> I have investigated a little bit, and I have discovered that in order to
> re-use a timer in the same application, I needed to reset the value of
> s_TimerWnd to 0 in fl_win32.cxx.
>
> For the moment, I have implemented a small function, which does that (the
> variable is static)
>
> void FlResetTimer() {
> if (s_TimerWnd)
> s_TimerWnd=0;
> }
>
> I suppose there is a better way to have this variable reset in a different
> place, but for the moment, it seems to suffice.
Hm, I'm not keen on that approach - it looks to me as if it is "cancelling" the
timer, but not clearing out the action associated with timer, which may be
messy down the line.
I think the preferred approach, if you may have reentrancy on your timers, is
just to call Fl::remove_timeout() first, before you re-add it. Note that
calling Fl::remove_timeout() on a "not-added" timer is harmless.
Though, to be honest, where I've hit this issue, I've just had a state variable
that I check before doing the add call; if it is clear I add the timer and set
the flag. If it is already set, I can decide whether to remove it, or to allow
the extant timer event to occur.
The flag is of course cleared by the function that runs when the timer fires.
Since the code is pretty much single threaded, this is more or less safe...!
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