Thread: 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...

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;
}