winrt::create_instance<IDesktopWallpaper> error

Question

I am completely new to C++/WinRT. I read some articles on winrt::capture and tried the following code:

#include "pch.h"
#include <Shobjidl.h>

// EDIT: use winrt::guid_of<IDesktopWallpaper>.
// Previously I used CLSID_DesktopWallpaper which did not work.
auto d = winrt::create_instance<IDesktopWallpaper>(winrt::guid_of<IDesktopWallpaper>(), CLSCTX_ALL);

Now there is another weird compile error on undefined identifier:

1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\um\shobjidl_core.h(33547,11): error C2061: syntax error: identifier 'CMINVOKECOMMANDINFO'
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\um\shobjidl_core.h(33552,61): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

// Shobjidl_core.h:
/* [local] */ HRESULT STDMETHODCALLTYPE IContextMenu_InvokeCommand_Proxy( 
IContextMenu * This,
/* [annotation][in] */ 
_In_  CMINVOKECOMMANDINFO *pici);

But Shobjidl_core.h does have the following declaration:

typedef struct _CMINVOKECOMMANDINFO
{
DWORD cbSize;
DWORD fMask;
HWND hwnd;
LPCSTR lpVerb;
LPCSTR lpParameters;
LPCSTR lpDirectory;
int nShow;
DWORD dwHotKey;
HANDLE hIcon;
} 	CMINVOKECOMMANDINFO;

OT: When I edit my post, "Edit development language" on code blocks never works for me from the beginning. For example, if I select "C++/WinRT", it will strangely change language to XML!

E.O.F

Answer 1

Hi @Neo , Welcome to Microsoft Q&A!

IDesktopWallpaper Interface only supports desktop apps. If you are using the UWP project, you cannot use it in the UWP project.

If you want to set lock screen image or wallpaper image in UWP project, it is recommended to use UserProfilePersonalizationSettings.TrySetLockScreenImageAsync and UserProfilePersonalizationSettings.TrySetWallpaperImageAsync.

Thank you.

Junjie.

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Answer 2

I just wanted to add that, you use the winrt::create_instance wrong. It's true that UWP does NOT support this interface. But in a winui3 project, this should be

 auto wallpaper = winrt::create_instance<IDesktopWallpaper>(CLSID_DesktopWallpaper, CLSCTX_ALL);