Desktop wallpaper and openinputdesktop

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I wrote a desktop wallpaper program using the

C++

IActiveDesktop

interface. I have also been using Visual Studio 2019 Community Edition as my programing environment. Now I want to make some changes to the wallpaper program and even with including the stated header files for IActiveDesktop (

C++

wininet.h

and

C++

shlopj.h

)

C++

IActiveDesktop *m_pActiveDesktop;

still generates an error. The Microsoft reference indicates that the IActiveDesktop interface is a legacy interface and it seems like it's been replaced with Windows Station and Desktop. However, in the reference material to these things I can find no reference to the desktop wallpaper.

What I have tried:

Can anyone give me an idea of how to access the desktop wallpaper with the new version of Visual Studio 2019?

Much appreciated. Thanks.
Ron

Posted 23-May-21 5:16am

rbrunton

Updated 23-May-21 7:10am

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2 solutions

Solution 1

See IActiveDesktop (shlobj_core.h) - Win32 apps | Microsoft Docs[^]. It would also help if you actually explained what error you see.

[edit]

shlopj.h

The correct header is shlobj_core.h
[/edit]

Posted 23-May-21 6:25am

Richard MacCutchan

Updated 23-May-21 6:27am

v2

Comments

rbrunton 23-May-21 12:40pm

Sorry for not being clear. I have tried including shlobj_core.h, but it did not resolve the problem. The problem is that IActiveDesktop is not recognized as a valid symbol/class. So, despite including the noted header files - wininet.h first, followed by shlobj_core.h and/or shlobj.h, the compiler (the latest version of VS 2019) generates an error that IActiveDesktop is an unidentified class: "Identifier "IActiveDesktop" is undefined."

Richard MacCutchan 23-May-21 13:02pm

IActiveDesktop is an interface, so it may need to be instantiated via COM. You need to examine the header file.

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rbrunton · Accepted Answer · 2021-05-23T07:10:00

I have subsequently looked at using the IDesktopWallpaper interface that I think has superseded the IActiveDesktop and I have been able to successfully change the wallpaper. This requires first:

C++

HRESULT hr = CoInitialize(nullptr);
IDesktopWallpaper* pDesktopWallpaper = nullptr;
hr = CoCreateInstance(__uuidof(DesktopWallpaper), nullptr, CLSCTX_ALL, IID_PPV_ARGS(&pDesktopWallpaper));

and then calls to

C++

pDesktopWallpaper->SetPosition(position);

and

C++

pDesktopWallpaper->SetWallpaper(NULL, lpcwstrFile);

are successful.

(Note: I had the

C++

CoInitialize

and

C++

CoCreateInstance

when trying to work with IActiveDesktop.)