设置壁纸方法

通过IActiveDesktop接口来实现

比如设置壁纸，就可以这样

IActiveDesktop *a;
CoInitialize(NULL);
if(SUCCEEDED(CoCreateInstance(Shlobj::CLSID_ActiveDesktop,NULL,CLSCTX_INPROC_SERVER,IID_IActiveDesktop,(void **)&a)))
　 {
　 WideString c = "C:\\My Documents\\yw2.jpg";
　 OleCheck(a->SetWallpaper(c.c_bstr(),0));
　 OleCheck(a->ApplyChanges(AD_APPLY_ALL));
　 a->Release();
}
CoUninitialize();

注意在cpp的第一行加入#define NO_WIN32_LEAN_AND_MEAN

并要#include <shlobj.h>