SystemParametersInfo

This is a discussion on SystemParametersInfo within the Windows Programming forums, part of the Platform Specific Boards category; Hi. can anyone please help me find out why this code doesn't work: char* nextWpName = "mypic.jpg" SystemParametersInfo (SPI_SETDESKWALLPAPER,0,nextWpName,SPIF_UPDATEINIF ILE); ...

  1. #1
    Registered User
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    Dec 2002
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    SystemParametersInfo

    Hi.

    can anyone please help me find out why this code doesn't work:
    char* nextWpName = "mypic.jpg"
    SystemParametersInfo (SPI_SETDESKWALLPAPER,0,nextWpName,SPIF_UPDATEINIF ILE);

    my wallpaper simply disappears and goes blank.
    help...

  2. #2
    erstwhile
    Join Date
    Jan 2002
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    From msdn:
    ...To specify a wallpaper bitmap, set pvParam to point to a null-terminated string containing the name of a bitmap file....
    So try it with a bitmap and not a jpeg.
    Last edited by Ken Fitlike; 12-28-2002 at 11:53 AM.

  3. #3
    &TH of undefined behavior Fordy's Avatar
    Join Date
    Aug 2001
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    5,789
    If you wish to use JPEGS or GIFS (as the system does when you change wallpaper manually), you need to roll your sleeves up and use a COM interface - IActiveDesktop

    This code opens a dialog allowing you to shose a BMP,GIF or JPEG......then it sets that as wallpaper and stretches it accross the screen...unfortunately, it is targetted at VC++...if you use a different compiler, come back and I will try again

    Code:
    #include <windows.h>//Essential stuff
    #include <wininet.h>//This has to be here...bug!!!!!!
    #include <shlobj.h>//For IActiveDesktop
    #include <comdef.h>//For neat VC++ COM Classes
    
    
    struct COM_INIT{//To manage COM
    	COM_INIT(){CoInitialize(0);}
    	~COM_INIT(){CoUninitialize();}
    }COM_INIT_;
    
    
    int WINAPI WinMain(HINSTANCE hInst,HINSTANCE,LPSTR,int){
    	
    	char szFile[MAX_PATH+1] = {0};
    	OPENFILENAME ofn = {sizeof(OPENFILENAME)};
    	ofn.hInstance = GetModuleHandle(0);
    	ofn.lpstrFilter = "BMP\0*.BMP\0JPeg\0*.JPG\0Gif\0*.GIF\0";
    	ofn.lpstrFile = szFile;
    	ofn.nMaxFile = MAX_PATH+1;
    	ofn.lpstrTitle = "Pick Bitmap, JPeg or Gif to replace wallpaper";
    
    	if(!GetOpenFileName(&ofn))return 0;
    
    	try{
    		
    		WALLPAPEROPT wpo = {sizeof(wpo),WPSTYLE_STRETCH};
    		_com_ptr_t<_com_IIID<IActiveDesktop,
    			&__uuidof(IActiveDesktop)> > lpIAD;
    
    		lpIAD.CreateInstance(CLSID_ActiveDesktop);	
    
    		lpIAD->SetWallpaper(_bstr_t(szFile),0);
    
    		lpIAD->SetWallpaperOptions(&wpo,0);
    
    		lpIAD->ApplyChanges(AD_APPLY_ALL);
    
    
    		MessageBox(0,"Wallpaper changed","",MB_OK);
    
    	}
    	catch(_com_error& e){
    		MessageBox(0,(e.Description().length() ? 
    			e.Description() : "COM Error"),0,MB_OK);
    	}
    
    	return 0;
    }

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