Question

My program consists of a large graphing UI control that I need to spend about 15 seconds re-loading every once in a while. Because the updating code works primarily with the UI control (maybe 90% of it actually sets properties on the control), it would make sense to me to actually let the UI thread handle that. I really don’t want the control to visually re-paint while it is loading in a separate thread from the UI.

I also want a progress bar to update as well that lives in the status bar of the same application window. Is there a way to break the rule in this case and re-paint only the progress bar, or should I just open a new application window for the progress bar to live in?

What would you do in this particular case?

Answer 1

If you can break your primary task (ie. updating the graph) in many steps, you can perform each step as a separate dispatcher message. This will allow other messages to be processed, including giving you the ability to update progress information.

The basic pattern is:

1. Invoke your primary task, passing in zero for the step.
2. Perform the step.
3. If there are more steps, queue another message, passing in step + 1.

You can then add in progress updates at the appropriate points in your code.

PS. Not saying this is your best option – hard to tell without knowing all the details. But this is an option.