progress bar in separate window

Question

(WPF) We have been asked to build a little window that pops up when the app is busy (instead of or in addition to a wait cursor). We put a textblock in the window, and a ProgressBar with IsIndeterminate = true.

We call show on the little window, and then start up our long-running process, calling Close on the little window when we are through. However, during the long-running process, the ProgressBar does not show any activity, and the little window shows (Not Responding) in its title.

Is this even possible? A better idea?

Answer 1

You need to look into using another thread (or multiple threads) to do the heavy processing that could take longer than 100ms (100ms and above can cause this 'hanging' appearence before 'Not Responding' appears.)

You could create a new thread using a BackgroundWorker object and subscribe to the OnProgressChanged event to indicate a progress bar update. This does not however get around the problem of accessing the main (UI) threads Progress Bar. You would have to check if an Invoke is required and then invoke a piece of code responsible for updating the Progress Bar.

Here is a StackOverflow question that shows a nice Extension Method in the accepted answer for invoking a method call on a control:

Invoking

Hopefully that helps!!

Answer 2

The problem is most likely that whatever is causing the app to be "busy" is being run in the main thread of the app. So, the app stops responding, including responding to layout and painting requests from the OS. So, when the app is "busy", it's too busy to paint the new window.

The solution is to move as much "heavy lifting" as possible into background threads, so the main thread and thus the UI remain responsive.