\nSometimes software development is inventing new stuff.\nBut often, it’s just putting together the stuff you already have.\nToday’s puzzle is one of the latter type of problem.\n<\/p>\n
\nGiven a window handle, you can you determine (1) whether it is\nan Explorer window, and if so (2) what folder it is viewing, and\n(3) what item is currently focused.\n<\/p>\n
\nThis is not an inherently difficult task.\nYou just have to put together lots of small pieces.\n<\/p>\n
\nStart with\n\nthe ShellWindows object<\/a>\nwhich represents all the open shell windows.\nYou can enumerate through them all with\nthe Item property<\/a>.\nThis is rather clumsy from C++ because the ShellWindows object\nwas designed for use by a scripting language like JScript or Visual Basic.\n<\/p>\n \nFrom each item, we can ask it for its window handle and see if it’s the one\nwe want.<\/p>\n \nOkay, now that we have found the folder via its IWebBrowserApp,\nwe need to get to the top shell browser. This is done by\nquerying for the SID_STopLevelBrowser service and asking for\n\nthe IShellBrowser interface<\/a>.\n<\/p>\n \nFrom the IShellBrowser, we can ask for the current shell view\nvia\n\nthe QueryActiveShellView method<\/a>.\n<\/p>\n \nOf course, what we really want is\n\nthe IFolderView interface<\/a>,\nwhich is the automation object that contains all the real goodies.\n<\/p>\n \nOkay, now we’re golden. What do you want to get from the view?\nHow about the location of the IShellFolder being viewed.\nTo do that, we need to use\n\nIPersistFolder2<\/a>::GetCurFolder<\/a>.\n\nThe GetFolder method<\/a> will give us access to the shell folder,\nfrom which we ask for IPersistFolder2.\n(Most of the time you want the IShellFolder interface,\nsince that’s where most of the cool stuff hangs out.)\n<\/p>\n \nLet’s convert that \nWhat else can we do with what we’ve got? Oh right, let’s see what the\ncurrently-focused object is.\n<\/p>\n \nLet’s display the name of the focused item.\nTo do that we need the item’s pidl and the IShellFolder.\n(See, I told you the IShellFolder is where the cool stuff is.)\nThe item comes from\n\nthe Item method<\/a> (surprisingly enough).\n<\/p>\n \n(If we had wanted a list of selected items we could have used\n\nthe Items method<\/a>, passing SVGIO_SELECTION.)\n<\/p>\n \nAfter we get the item’s pidl, we also need the IShellFolder:\n<\/p>\n \nThen we put the two together to get the item’s display name,\nwith the help of\n\nthe GetDisplayNameOf method<\/a>.\n<\/p>\n \nWe can use the helper function\n\nStrRetToBuf<\/a> to convert the kooky\n\nSTRRET structure<\/a> into\na boring string buffer.\n(The history of the kooky STRRET structure will have to wait for\nanother day.)\n<\/p>\n \nOkay, let’s put this all together.\nIt looks rather ugly because I put everything into one huge\nfunction instead of breaking them out into subfunctions.\nIn “real life” I would have broken things up into little helper\nfunctions to make things more manageable.\n<\/p>\n\n IShellWindows *psw;\n if (SUCCEEDED(CoCreateInstance(CLSID_ShellWindows, NULL, CLSCTX_ALL,\n IID_IShellWindows, (void**)&psw))) {\n VARIANT v;\n V_VT(&v) = VT_I4;\n IDispatch *pdisp;\n BOOL fFound = FALSE;\n for (V_I4(&v) = 0; !fFound && psw->Item(v, &pdisp) == S_OK;\n V_I4(&v)++) {\n ...\n pdisp->Release();\n }\n psw->Release();\n }\n<\/pre>\n\n IWebBrowserApp *pwba;\n if (SUCCEEDED(pdisp->QueryInterface(IID_IWebBrowserApp, (void**)&pwba))) {\n HWND hwndWBA;\n if (SUCCEEDED(pwba->get_HWND((LONG_PTR*)&hwndWBA)) &&\n hwndWBA == hwndFind) {\n fFound = TRUE;\n ...\n }\n pwba->Release();\n }\n<\/pre>\n\n IServiceProvider *psp;\n if (SUCCEEDED(pwba->QueryInterface(IID_IServiceProvider, (void**)&psp))) {\n IShellBrowser *psb;\n if (SUCCEEDED(psp->QueryService(SID_STopLevelBrowser,\n IID_IShellBrowser, (void**)&psb))) {\n ...\n psb->Release();\n }\n psp->Release();\n }\n<\/pre>\n\n IShellView *psv;\n if (SUCCEEDED(psb->QueryActiveShellView(&psv))) {\n ...\n psv->Release();\n }\n<\/pre>\n\n IFolderView *pfv;\n if (SUCCEEDED(psv->QueryInterface(IID_IFolderView,\n (void**)&pfv))) {\n ...\n pfv->Release();\n }\n<\/pre>\n\n IPersistFolder2 *ppf2;\n if (SUCCEEDED(pfv->GetFolder(IID_IPersistFolder2,\n (void**)&ppf2))) {\n LPITEMIDLIST pidlFolder;\n if (SUCCEEDED(ppf2->GetCurFolder(&pidlFolder))) {\n ...\n CoTaskMemFree(pidlFolder);\n }\n ppf2->Release();\n }\n<\/pre>\npidl<\/code> into a path, for display purposes.\n<\/p>\n\n if (!SHGetPathFromIDList(pidlFolder, g_szPath)) {\n lstrcpyn(g_szPath, TEXT(\"<not a directory>\"), MAX_PATH);\n }\n ...\n<\/pre>\n\n int iFocus;\n if (SUCCEEDED(pfv->GetFocusedItem(&iFocus))) {\n ...\n }\n<\/pre>\n\n LPITEMIDLIST pidlItem;\n if (SUCCEEDED(pfv->Item(iFocus, &pidlItem))) {\n ...\n CoTaskMemFree(pidlItem);\n }\n<\/pre>\n\n IShellFolder *psf;\n if (SUCCEEDED(ppf2->QueryInterface(IID_IShellFolder,\n (void**)&psf))) {\n ...\n psf->Release();\n }\n<\/pre>\n\n STRRET str;\n if (SUCCEEDED(psf->GetDisplayNameOf(pidlItem,\n SHGDN_INFOLDER,\n &str))) {\n ...\n }\n<\/pre>\n\n StrRetToBuf(&str, pidlItem, g_szItem, MAX_PATH);\n<\/pre>\n