cobines wrote:
2010/1/20 Brad Campbell <[email protected]>:
Is QueueAsyncCall() threadsafe?
As far as I know it is not.
Let's say I have a communications child thread and I want to trigger a call
back in the main GUI thread. Traditionally I'd do something ugly like have a
timer polling a variable used as a flag, or polling a RtlEvent on a short
timeout, but this seems like a much nicer solution.
You can call TThread.Synchronize(), your thread will be stopped until
the GUI thread executes your function.
Yeah, but what I'm trying to do is have the main gui thread sit on its hands until it has a message
waiting for it. Then I'd like to have it wakeup on an event rather than spinning or polling, while
still remaining responsive to user input.
Other solution is to create a separate thread for handling such GUI
functions (take a look at attached source); this doesn't stop your
child thread. Be careful however because in this case you don't
control when your method is called (it may be after your thread is
already finished).
That's a really interesting solution. I *thought* the issue was that the update of GUI elements must
only be done in the main thread. I actually don't have a problem running the callbacks from the
comms thread as the callbacks are executed between packets in a polled system, so it's not at all
timing critical. I was more concerned with updating the GUI components in a threadsafe manner.
Unless I'm mistaken (and I'm pretty green at thread stuff still) it looks like you are running a
separate thread that checks a message queue and runs the callbacks from there, so you are possibly
updating gui components from a thread other than the main thread. Is that kosher?
Really appreciate the reply, it has been incredibly helpful.
Regards,
Brad
--
Dolphins are so intelligent that within a few weeks they can
train Americans to stand at the edge of the pool and throw them
fish.
--
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