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c# – How do I Refresh Excel whilst Debugging

Posted by: admin April 23, 2020 Leave a comment

Questions:

If I am debugging (in this case a Visual Studio assembly called by Excel) and the code updates the Excel worksheet, how do I get Excel to redraw the current sheet / window whilst paused in the debugger?

How to&Answers:

If you are calling Excel cross-process (e.g. via Automation) then Excel should automatically show any changes as the calls are made, unless you set xlApp.ScreenUpdating = False. If this is the case, then you would probably be best off to use a conditional to not set xlApp.ScreenUpdating = False if running in Debug mode when you have break points set up. Otherwise, you’d have to set xlApp.ScreenUpdating = True from some other process (using GetObject(), or something similar, so that you can grab the same Excel Application instance).

However, if your code is being called in-process (for example, if your code is running as an add-in) then your code is being triggered via a hot-key combination, CommandBar button, Ribbon control callback or the like. In this case, Excel is single-threaded and your code is halting all Excel execution. The only thing I could think of, in this case, would be to use “edit and continue”, adding the line xlApp.ScreenUpdating = True and then stepping into this next line. (Remember to remove this line afterward, though!)

If you are not using xlApp.ScreenUpdating = False, then I don’t really know what your issue is, and you’d have to provide more details on your code…