SystemParameters High Contrast Event

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I'm trying to launch an event whenever the user switches to/from High Contrast Mode in Windows.

I'm currently able to accomplish this by using the SystemEvents.UserPreferenceChanged event. This however fires multiple times and is not just for high contrast. I noticed that .Net 4.5 actually has a SystemParameters.StaticPropertyChanged event but I'm using 4.0 and won't be going to 4.5 anytime soon.

I'm still learning WPF and C# for the most part and was wondering if there's a good clean way to do this?

Posted 6-Sep-12 6:36am

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Sergey Alexandrovich Kryukov · Accepted Answer · 2012-09-06T08:01:00

The problem has nothing to do with WPF itself. I think you still need to handle SystemEvents.UserPreferenceChanging and SystemEvents.UserPreferenceChanged events and ignore the events not related to high contrast. This is the very usual practice. The class Microsoft.Win32.SystemEvents does not provide any filters for the event, but you can filter out the event by the value of the Category property of the event arguments:
http://msdn.microsoft.com/en-us/library/microsoft.win32.userpreferencechangingeventargs.category.aspx[^],
http://msdn.microsoft.com/en-us/library/microsoft.win32.userpreferencechangedeventargs.category.aspx[^],
http://msdn.microsoft.com/en-us/library/microsoft.win32.userpreferencechangedeventargs.aspx[^],
http://msdn.microsoft.com/en-us/library/microsoft.win32.userpreferencechangingeventargs.aspx[^].

Most likely, the only category you need in this case is Microsoft.Win32.UserPreferenceCategory.Accessibility, but you can also handle the cases with Microsoft.Win32.UserPreferenceCategory.Color:
http://msdn.microsoft.com/en-us/library/microsoft.win32.userpreferencecategory.aspx[^].

—SA

SystemParameters High Contrast Event

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