How does one detect when the wallpaper has changed (Windows XP or greater)?

Question

I have figured out how to change the desktop wallpaper (there are dozens of examples on the Internet.)

One thing that still eludes me: how do I detect when the wallpaper has changed? (Say via the Display control panel or another program changing it.)

What programming language/environment? .Net? MFC? Win32? – Joel Coehoorn Jan 06 '10 at 16:47 — Joel Coehoorn, Jan 06 '10 at 16:47

Hans Passant · Answer 1 · 2010-01-06T18:39:37.707

8

Add a message handler for WM_SETTINGCHANGE, SystemEvents.UserPreferenceChanged in .NET. Check if the wallpaper is still the same.

edited Jan 06 '10 at 18:39

answered Jan 06 '10 at 17:19

Hans Passant

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It's `WM_SETTINGCHANGE`, but yes, I would say that this is a good way to be notified. – Aaron Klotz Jan 06 '10 at 18:36

score 5 · Answer 2 · edited Feb 17 '12 at 17:55

Here is an example in C# to retrieve the wallpaper. All you would need to add is some additional code to store the last wallpaper and check to see if it is different.

RegistryKey wallpaper = Registry.CurrentUser.OpenSubKey("Control Panel\\Desktop",false);
string wallpapername = wallpaper.GetValue("wallpaper").ToString();          
wallpaper.Close();

If you were writing something in a non .net language you could use the Win32 API RegNotifyChangeKeyValue function to check to see if this value has changed:

HKEY_CURRENT_USER\Control Panel\Desktop\Wallpaper

How does one detect when the wallpaper has changed (Windows XP or greater)?

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