{"id":107922,"date":"2023-03-09T07:00:00","date_gmt":"2023-03-09T15:00:00","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/oldnewthing\/?p=107922"},"modified":"2023-03-09T09:11:21","modified_gmt":"2023-03-09T17:11:21","slug":"20230309-00","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20230309-00\/?p=107922","title":{"rendered":"From a Windows app, how can I check whether there is an app installed that implements a particular URI scheme?, part 2"},"content":{"rendered":"

Last time, we looked at detecting packaged apps which support a particular URI scheme<\/a>. Unpackaged apps do not have AppIds (in the Windows Store sense), so some of the operations don’t work.<\/p>\n\n\n\n\n\n\n\n
Function<\/th>\nPackaged apps<\/th>\nUnpackaged apps<\/th>\n<\/tr>\n
Launcher.Find\u00adUri\u00adScheme\u00adHandlers\u00adAsync<\/code><\/td>\nYes<\/td>\nNo<\/td>\n<\/tr>\n
Launcher.Query\u00adUri\u00adSupport\u00adAsync(uri)<\/code><\/td>\nYes<\/td>\nYes<\/td>\n<\/tr>\n
Launcher.Query\u00adUri\u00adSupport\u00adAsync(uri, pfn)<\/code><\/td>\nYes<\/td>\nN\/A<\/td>\n<\/tr>\n
Launcher.Launch\u00adUri\u00adAsync<\/code><\/td>\nYes<\/td>\nYes<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

If you think about it, the reasons for the above entries are obvious:<\/p>\n

    \n
  • Launcher.Find\u00adUri\u00adScheme\u00adHandlers\u00adAsync<\/code> returns a collection of AppInfo<\/code> objects, and AppInfo<\/code> objects describe packaged apps. So it has no way to report an unpackaged app.<\/li>\n
  • Launcher.Query\u00adUri\u00adSupport\u00adAsync(uri)<\/code> just tells you whether the URI can be launched or not. If it can be launched by an unpackaged app, then it will report Available<\/code>, just like the case where it can be launched by a packaged app. It doesn’t tell you which<\/i> app will launch it, so it doesn’t run into the problem of trying to describe something that it has no way to describe.<\/li>\n
  • Launcher.Query\u00adUri\u00adSupport\u00adAsync(uri, pfn)<\/code> takes a package family name, and unpackaged apps don’t have a package family name, so it’s not even possible to specify the unpackaged app you are querying for.<\/li>\n
  • Launcher.Launch\u00adUri\u00adAsync<\/code> tries to launch the URI and tells you whether it succeeded. It doesn’t tell you anything about the app that ultimately handled the URI, so unpackaged apps don’t cause any problems.<\/li>\n<\/ul>\n

    But what if you want to ask about unpackaged apps, too?<\/p>\n

    The SH\u00adAssoc\u00adEnum\u00adHandlers\u00adFor\u00adProtocol\u00adBy\u00adApplication<\/code> function gives you the apps (both packaged and unpackaged) which can launch a particular URI scheme.<\/p>\n

    Today’s smart pointer library will be (rolls dice)\u00b9 WRL.<\/p>\n

    Microsoft::WRL::ComPtr<IEnumAssocHandlers> e;\r\nauto hr = SHAssocEnumHandlersForProtocolByApplication(L\"http\", IID_PPV_ARGS(&e));\r\nif (SUCCEEDED(hr)) {\r\n    Microsoft::WRL::ComPtr<IAssocHandler> handler;\r\n    while (e->Next(1, &handler, nullptr) == S_OK) {\r\n        PWSTR name;\r\n        if (SUCCEEDED(handler->GetUIName(&name))) {\r\n            printf(\"UI Name: %ls\\n\", name);\r\n            CoTaskMemFree(name);\r\n        }\r\n    }\r\n}\r\n<\/pre>\n
    You can even ask pass the URI to a specific handler by calling the Invoke<\/code> method:<\/p>\n
    HRESULT InvokeHandlerOnURI(IAssocHandler* handler, PCWSTR uri)\r\n{\r\n    Microsoft::WRL::ComPtr<IShellItem> item;\r\n    RETURN_IF_FAILED(SHCreateItemFromParsingName(\r\n        L\"http:\/\/msn.com\/\", nullptr, IID_PPV_ARGS(&item)));\r\n    Microsoft::WRL::ComPtr<IDataObject> dto;\r\n    RETURN_IF_FAILED(item->BindToHandler(nullptr,\r\n        BHID_DataObject, IID_PPV_ARGS(&dto)));\r\n    RETURN_IF_FAILED(handler->Invoke(dto.Get()));\r\n    return S_OK;\r\n}\r\n<\/pre>\n
    \u00b9 Dirty secret: The dice are loaded.<\/p>\n","protected":false},"excerpt":{"rendered":"
    Alternatives that work for unpackaged apps.<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[25],"class_list":["post-107922","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"
    Alternatives that work for unpackaged apps.<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/107922","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=107922"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/107922\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=107922"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=107922"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=107922"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}