One day,I want to set the desktop wallpaper by the application which
I wrote using Win32 in c++.First,I used the api
SystemParametersInfo(SPI_SETDESKWALLPAPER,TRUE,(LPVOID)"E:\\my_docs\\test.jpg",SPIF_SENDWININICHANGE| SPIF_UPDATEINIFILE);
But it can not work.So I checked with MSDN:
SPI_SETDESKWALLPAPER
Sets the desktop wallpaper. The value of the pvParam parameter determines the new wallpaper. To specify a wallpaper bitmap, set pvParam to point to a null-terminated string containing the full path to the bitmap file. Setting pvParam to "" removes the wallpaper. Setting pvParam to SETWALLPAPER_DEFAULT or NULL reverts to the default wallpaper.
Starting with Windows Vista, pvParam can specify a .jpg file.
So I tried the Google,it told me as below and that can be worked normally.
139 BOOL SetWPByActiveDesktop(LPCTSTR lpszPath)
140 {
141 if ( lpszPath == NULL )
142 return FALSE ;
143 #if 1
144 CoInitialize(NULL);
145
146 HRESULT hr;
147 IActiveDesktop* pIAD;
148 hr = CoCreateInstance( CLSID_ActiveDesktop, NULL, CLSCTX_INPROC_SERVER,IID_IActiveDesktop, (void**)&pIAD);
149
150 if ( !SUCCEEDED(hr) )
151 return FALSE;
152
153 //set activedesktop options,turn on the AD.
154 COMPONENTSOPT co = {0};
155 co.dwSize = sizeof(COMPONENTSOPT);
156 co.fEnableComponents = TRUE;
157 co.fActiveDesktop = TRUE;
158 hr = pIAD->SetDesktopItemOptions(&co, 0);
159 if ( !SUCCEEDED(hr) )
160 return FALSE;
161
162 //pay attention the parameter passed to IActiveDesktop.if app is unicode,ignore
163 WCHAR wszPath[MAX_PATH]={0};
164 //LPTSTR lpStr = strPath.GetBuffer(strPath.GetLength());
165 MultiByteToWideChar(CP_ACP, 0, lpszPath, -1, wszPath, MAX_PATH);
166 //strPath.ReleaseBuffer();
167
168 //set the wallpaper
169 hr = pIAD->SetWallpaper(wszPath, 0);
170 if ( !SUCCEEDED(hr) )
171 return FALSE;
172
173 // Set wallpaper style such as title,center,stretch
174 WALLPAPEROPT wp = {0};
175 wp.dwSize = sizeof(WALLPAPEROPT);
176 wp.dwStyle |= WPSTYLE_CENTER;
177 hr = pIAD->SetWallpaperOptions(&wp, 0);
178 if ( !SUCCEEDED(hr) )
179 return FALSE;
180
181 // 应用改变
182 hr = pIAD->ApplyChanges(AD_APPLY_ALL);
183 if ( !SUCCEEDED(hr) )
184 return FALSE;
185
186 // RELEASE
187 pIAD->Release();
188
189 CoUninitialize();
190 #endif
191
192 return TRUE;
193 }
Testing passed in VC++6 SP6-win32 application.