Wallpaper Woes

**TheSquid** · 12-20-2004

I know there is probably something out there that does this already, but I'm working on a program that selects a random wallpaper from a user-defined list each time Windows starts. I assumed the best way to do this is by replacing the path to the current wallpaper in the registry so I searched for any key that contained "wallpaper" or the name of my current image and started experimenting.

The problem is the only key that seems to cause any change is WallpaperStyle (0 centered, 1 tiled, 2 stretched,) and nothing else seems to have any affect even after a restart. I have listed the keys I have played around with below. Does anyone know of any keys that I have missed or something else I can try?

Code:

HKEY_CURRENT_USER\Control Panel\Desktop\
	ConvertedWallpaper
	ConvertedWallpaper Last Write Time
	TileWallpaper
	WallpaperStyle

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Themes\LastTheme

HKEY_USERS\ <some long #> \Control Panel\Desktop\
	ConvertedWallpaper
	ConvertedWallpaper Last Write Time
		
HKEY_USERS\ <another long #> \Microsoft\Windows\CurrentVersion\Themes\
	LastTheme

**anonytmouse** · 12-20-2004

I assumed the best way to do this is by replacing the path to the current wallpaper in the registry so I searched for any key that contained "wallpaper" or the name of my current image and started experimenting.

Unfortunately, that approach is all too common. Unless documented, values in the registry should be considered internal to Windows and may change from version to version.

The best approach is to search for 'change desktop wallpaper code' which will give you several good results on the first page. Make sure you also search google groups which will often give you better results than a web search.

**andyhunter** · 12-20-2004

I also found this at MSDN:

Code:

int nAction = com.ms.win32.win.SPI_SETDESKWALLPAPER;
String strBMP = "c:\\winnt\\Blue Lace 16.bmp";
int bSaveChange = 0;
SystemParametersInfo(nAction,0,strBMP,nSaveChange);

**Fordy** · 12-21-2004

Originally Posted by andyhunter

I also found this at MSDN:

Code:

 
int nAction = com.ms.win32.win.SPI_SETDESKWALLPAPER;
String strBMP = "c:\\winnt\\Blue Lace 16.bmp";
int bSaveChange = 0;
SystemParametersInfo(nAction,0,strBMP,nSaveChange);

I tried to use that method via windows scripting host once and it isnt too reliable. Sometimes it works, sometimes it doesnt.

The best route is to rely on the IActiveDesktop interface. If you have VC++, then this should be what you need - http://cboard.cprogramming.com/showt...ight=wallpaper

**bithub** · 12-21-2004

Give this a try:

Code:

int SetWallpaper(LPCTSTR szPath) 
{
	HKEY hkRoot,hSubKey;
	TCHAR szItemKey[256];
	TCHAR szValue[MAX_PATH];
	long cb;

	char szTargetName[MAX_PATH];        //target file name
	char szWinPath[MAX_PATH];  //Windows path

	//Get the Windows path
	GetWindowsDirectory(szWinPath,MAX_PATH);  

	//Generate the full path of the target file 
	_stprintf(szTargetName, _T("%s\\WallPaper.BMP"), szWinPath);

	//Copy the selected picture to Windows path
	if(!CopyFile(szPath,szTargetName,FALSE))
	{
		::MessageBox(NULL,_T("Unable to copy file"),_T("ERROR"),MB_OK);
		return 0;
	}
     
	//Update the registry
	_tcscpy(szItemKey,"Wallpaper");
	_tcsncpy(szValue,szTargetName);
	cb=_tcslen(szValue);
     
	if(RegOpenKey(HKEY_CURRENT_USER,NULL,&hkRoot)==ERROR_SUCCESS)
	{
		if(RegOpenKeyEx(hkRoot,
			_T("Control Panel\\Desktop\\"),
			0,
			KEY_ALL_ACCESS,
			&hSubKey)==ERROR_SUCCESS)
		{
			RegSetValueEx(hSubKey, (LPCTSTR)szItemKey,
				0, REG_SZ,(CONST BYTE *)szValue,cb);
		}
		else
		{
			::MessageBox(NULL, _T("Failed to update the registry!"), _T("Error"), MB_OK);
			return 0;
		}
	}
	else
	{
		MessageBox(NULL, _T("Failed to open the registry!"), _T("Error"), MB_OK);
		return 0;
	}

	//Notify Wondows to update the wallpaper
	SystemParametersInfo(SPI_SETDESKWALLPAPER,0,NULL,SPIF_SENDCHANGE);

	//Close registry
	RegCloseKey(hSubKey);
	RegCloseKey(hkRoot);
	return 1;
}

**anonytmouse** · 12-21-2004

bithub, did you write that code? It differs from your typically excellent posts, in that there appears to be a few problems, not the least of which is an obvious buffer overrun.

**bithub** · 12-21-2004

bithub, did you write that code?

No, that code was posted from a google search. All I did was put it in a compiler, and verify that it did indeed change the wallpaper. I'll edit the code to make it a bit safer though

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