On Tue, 30 Aug 2005 11:09:30 +0200 (Romance Daylight Time)
Michael Van Canneyt <[EMAIL PROTECTED]> wrote:
> On Tue, 30 Aug 2005, Micha Nelissen wrote:
>
> > What do you mean with Idle handler? TApplication.OnIdle ? In any sane app,
> > that is only called once when the user goes idle; after that, the app is
> > blocked waiting for user input.
>
> Hm.
>
> So that is not usable.
>
> On Unix, it's easy:
>
> I once wrote a GTK version of a debug server.
> You can tell GTK to watch for input on a file descriptor in it's main loop.
> If there is input on your descriptor, a callback you specify is called.
Yes, this is used in the gtk widgetset interface in the LCL too, now;
that's what WakeMainThread does there (send a byte down that pipe).
> In windows, it's slightly more difficult (surprise, surprise :-) )
>
> You can use MsgWaitForMultipleObjects to do this for a windows
> handle, or use WaitForSingleObject on a simple file handle.
You can't "wait" for file handles in windows.
OTOH, the backend of the IPC server will use messages to copy things
around ? So the message queue would be woken up that way.
> (Why they made this two separate functions is a mystery to me,
> it makes things horribly complicated...)
Some threads have no message queue, so MsgWait... is more expensive, would
require a message queue to be created.
> So in fact, what we'd need is a pair of calls in TApplication :
>
> TApplication.AddWatch(AHandle: THandle; Handler : TNotifyEvent);
> TApplication.RemoveWatch(AHandle: THandle);
>
> Which would handle both things transparantly in the message loop.
> (the standard IsWindow function of Windows could be used to determine what
> kind of handle it is in a windows app)
>
> This would come in handy in many applications.
Hmm, I'm not sure. Can you give examples? A THandle is a widget-specific
thingy, it doesn't have the same semantics on various platforms, so it's not
directly usable by users of LCL (if you want one source code base).
Things you could use this function for: file change notifications,
events, ... all have to be seperately implemented in the FCL/LCL to make
them work "universally" and well.
Micha
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