Re: Progress dialog for compute-intensive task

• Subject: Re: Progress dialog for compute-intensive task
• From: Ken Turkowski <email@hidden>
• Date: Fri, 24 Dec 2004 23:33:21 -0800
• Delivered-to: email@hidden
• Delivered-to: email@hidden

On Dec 23, 2004, at 2:48 AM, email@hidden wrote:

On 23 Dec 2004, at 08:04, Ken Turkowski wrote:

I've got a simple application with a minimal interface that opens a
"job file" and performs a compute intensive function. I would like to
provide a progress dialog with progress bar, message, and a cancel
button.

Currently, I have my compute-intensive function call a progress
callback function that updates the progress bar and message text. (I
don't have the cancel button wired up yet)

I have a couple of problems with my current implementation.
(1) The progress bar is updated continuously, but the message is not.
(2) The dialog is not activated when brought to the foreground

What is the minimum I need to do to get this functionality?

Do I need to fork off a few threads?
Do I need to call ReceiveNextEvent() in my progress bar updater?

Ideally you'd do the long task in a background thread and tell the
progress bar to update by sending Carbon Events back to the main
thread. This is actually very easy, so if you don't have other
constraints, I'd go that way.

returns componentNotThreadSafeErr

I thought that QuickTime was supposed to be thread safe in OS 10.3.

If you need to do the progress callback thing, you need to dispatch
events in your callback procedure to allow window activates and static
text controls to work. Something like this:

	while (::ReceiveNextEvent(0, NULL, 0, true, &event) == noErr) {
		::SendEventToEventTarget(event, GetEventDispatcherTarget());
		::ReleaseEvent(event);
	}

Make your progress window modal so that mouse clicks don't end up going
where they shouldn't.

Thanks!

--
Ken Turkowski                    email@hidden
Engineer/Scientist   http://www.worldserver.com/turk/
Independent Consultant      Industrial Grade Software
Computer Graphics     2D     3D     Immersive Imagery
Photo-mosaicing       Panoramas       Computer Vision
Applied Mathematics  Numerical Analysis  Optimization

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