notifications: add support for unpackaged apps and protocol activation

installer/PowerToysSetup/Product.wxs

@@ -192,6 +192,13 @@
 
   <Fragment>
     <DirectoryRef Id="INSTALLFOLDER" FileSource="$(var.BinX64Dir)">
+      <Component Id="powertoys_toast_clsid" Win64="yes">
+        <RegistryKey Root="HKCU" Key="Software\Classes\CLSID\{DD5CACDA-7C2E-4997-A62A-04A597B58F76}">
+          <RegistryValue Type="string" Value="PowerToys Toast Notifications Background Activator" />
+          <RegistryValue Type="string" Key="LocalServer32" Value="[INSTALLFOLDER]PowerToys.exe -ToastActivated" />
+          <RegistryValue Type="string" Key="LocalServer32" Name="ThreadingModel" Value="Apartment" />
+        </RegistryKey>
+      </Component>
       <Component Id="powertoys_exe" Guid="A2C66D91-3485-4D00-B04D-91844E6B345B" Win64="yes">
         <File Id="PowerToys.exe" KeyPath="yes" Checksum="yes">
           <Shortcut Id="ApplicationStartMenuShortcut"
@@ -201,7 +208,10 @@
                     WorkingDirectory="INSTALLFOLDER"
                     Icon="powertoys.ico"
                     IconIndex="0"
-                    Advertise="yes" />
+                    Advertise="yes">
+            <ShortcutProperty Key="System.AppUserModel.ID" Value="Microsoft.PowerToysWin32"/>
+            <ShortcutProperty Key="System.AppUserModel.ToastActivatorCLSID" Value="{DD5CACDA-7C2E-4997-A62A-04A597B58F76}"/>
+          </Shortcut>
         </File>
 
         <RemoveFolder Id="DeleteShortcutFolder" Directory="ApplicationProgramsFolder" On="uninstall" />
@@ -209,6 +219,9 @@
       <Component Id="settings_exe" Guid="A5A461A9-7097-4CBA-9D39-3DBBB6B7B80C" Win64="yes">
         <File Id="PowerToysSettings.exe" KeyPath="yes" Checksum="yes" />
       </Component>
+      <Component Id="notifications_dll" Guid="23B25EE4-BCA2-45DF-BBCD-82FBDF01C5AB" Win64="yes">
+        <File Id="Notifications.dll" KeyPath="yes" Checksum="yes" />
+      </Component>
       <Component Id="License_rtf" Guid="3E5AE43B-CFB4-449B-A346-94CAAFF3312E" Win64="yes">
         <File Source="$(var.RepoDir)\License.rtf" Id="License.rtf" KeyPath="yes" />
       </Component>
@@ -292,6 +305,8 @@
   <Fragment>
     <ComponentGroup Id="CoreComponents" Directory="INSTALLFOLDER">
       <ComponentRef Id="powertoys_exe" />
+      <ComponentRef Id="notifications_dll" />
+      <ComponentRef Id="powertoys_toast_clsid" />
       <ComponentRef Id="License_rtf" />
       <ComponentRef Id="PowerToysSvgs" />
       <ComponentRef Id="Module_ShortcutGuide" />

src/common/com_object_factory.h

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <Unknwn.h>
+#include <winrt/base.h>
+#include <atomic>
+
+template<typename T>
+class com_object_factory : public IClassFactory
+{
+public:
+    HRESULT __stdcall QueryInterface(const IID & riid, void** ppv) override
+    {
+        static const QITAB qit[] = {
+            QITABENT(com_object_factory, IClassFactory),
+            { 0 }
+        };
+        return QISearch(this, qit, riid, ppv);
+    }
+
+    ULONG __stdcall AddRef() override
+    {
+        return ++_refCount;
+    }
+
+    ULONG __stdcall Release() override
+    {
+        LONG refCount = --_refCount;
+        return refCount;
+    }
+
+    HRESULT __stdcall CreateInstance(IUnknown* punkOuter, const IID & riid, void** ppv)
+    {
+        *ppv = nullptr;
+        HRESULT hr;
+        if (punkOuter)
+        {
+            hr = CLASS_E_NOAGGREGATION;
+        }
+        else
+        {
+            T* psrm = new (std::nothrow) T();
+            HRESULT hr = psrm ? S_OK : E_OUTOFMEMORY;
+            if (SUCCEEDED(hr))
+            {
+                hr = psrm->QueryInterface(riid, ppv);
+                psrm->Release();
+            }
+            return hr;
+        }
+        return hr;
+    }
+
+    HRESULT __stdcall LockServer(BOOL)
+    {
+        return S_OK;
+    }
+
+private:
+    std::atomic<long> _refCount;
+};

src/common/common.h

@@ -119,3 +119,11 @@ struct on_scope_exit
         _f();
     }
 };
+
+template<class... Ts>
+struct overloaded : Ts...
+{
+    using Ts::operator()...;
+};
+template<class... Ts>
+overloaded(Ts...)->overloaded<Ts...>;

src/common/common.vcxproj

@@ -105,6 +105,7 @@
     <ClInclude Include="d2d_text.h" />
     <ClInclude Include="d2d_window.h" />
     <ClInclude Include="dpi_aware.h" />
+    <ClInclude Include="com_object_factory.h" />
     <ClInclude Include="notifications.h" />
     <ClInclude Include="window_helpers.h" />
     <ClInclude Include="icon_helpers.h" />

src/common/common.vcxproj.filters

@@ -87,6 +87,9 @@
     <ClInclude Include="notifications.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="com_object_factory.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="d2d_svg.cpp">

src/common/notifications.cpp

@@ -1,4 +1,7 @@
 #include "pch.h"
+
+#include "common.h"
+#include "com_object_factory.h"
 #include "notifications.h"
 
 #include <unknwn.h>
@@ -9,6 +12,13 @@
 #include <winrt/Windows.UI.Notifications.h>
 #include <winrt/Windows.ApplicationModel.Background.h>
 
+#include "winstore.h"
+
+#include <winerror.h>
+#include <NotificationActivationCallback.h>
+
+#include "notifications_winrt/handler_functions.h"
+
 using namespace winrt::Windows::ApplicationModel::Background;
 using winrt::Windows::Data::Xml::Dom::XmlDocument;
 using winrt::Windows::UI::Notifications::ToastNotification;
@@ -19,10 +29,94 @@ namespace
     constexpr std::wstring_view TASK_NAME = L"PowerToysBackgroundNotificationsHandler";
     constexpr std::wstring_view TASK_ENTRYPOINT = L"PowerToysNotifications.BackgroundHandler";
     constexpr std::wstring_view APPLICATION_ID = L"PowerToys";
+
+    constexpr std::wstring_view WIN32_AUMID = L"Microsoft.PowerToysWin32";
+}
+
+static DWORD loop_thread_id()
+{
+    static const DWORD thread_id = GetCurrentThreadId();
+    return thread_id;
+}
+
+class DECLSPEC_UUID("DD5CACDA-7C2E-4997-A62A-04A597B58F76") NotificationActivator : public INotificationActivationCallback
+{
+public:
+    HRESULT __stdcall QueryInterface(_In_ REFIID iid, _Outptr_ void** resultInterface) override
+    {
+        static const QITAB qit[] = {
+            QITABENT(NotificationActivator, INotificationActivationCallback),
+            { 0 }
+        };
+        return QISearch(this, qit, iid, resultInterface);
+    }
+
+    ULONG __stdcall AddRef() override
+    {
+        return ++_refCount;
+    }
+
+    ULONG __stdcall Release() override
+    {
+        LONG refCount = --_refCount;
+        if (refCount == 0)
+        {
+            PostThreadMessage(loop_thread_id(), WM_QUIT, 0, 0);
+            delete this;
+        }
+        return refCount;
+    }
+
+    virtual HRESULT STDMETHODCALLTYPE Activate(
+        LPCWSTR appUserModelId,
+        LPCWSTR invokedArgs,
+        const NOTIFICATION_USER_INPUT_DATA*,
+        ULONG) override
+    {
+        auto lib = LoadLibraryW(L"Notifications.dll");
+        if (!lib)
+        {
+            return 1;
+        }
+        auto dispatcher = reinterpret_cast<decltype(dispatch_to_backround_handler)*>(GetProcAddress(lib, "dispatch_to_backround_handler"));
+        if (!dispatcher)
+        {
+            return 1;
+        }
+
+        dispatcher(invokedArgs);
+
+        return 0;
+    }
+
+private:
+    std::atomic<long> _refCount;
+};
+
+void notifications::run_desktop_app_activator_loop()
+{
+    com_object_factory<NotificationActivator> factory;
+
+    (void)loop_thread_id();
+
+    DWORD token;
+    auto res = CoRegisterClassObject(__uuidof(NotificationActivator), &factory, CLSCTX_LOCAL_SERVER, REGCLS_MULTIPLEUSE, &token);
+    if (!SUCCEEDED(res))
+    {
+        return;
+    }
+
+    run_message_loop();
+    CoRevokeClassObject(token);
 }
 
 void notifications::register_background_toast_handler()
 {
+    if (!winstore::running_as_packaged())
+    {
+        // The WIX installer will have us registered via the registry
+        return;
+    }
     try
     {
         // Re-request access to clean up from previous PowerToys installations
@@ -54,36 +148,89 @@ void notifications::register_background_toast_handler()
 void notifications::show_toast(std::wstring_view message)
 {
     // The toast won't be actually activated in the background, since it doesn't have any buttons
-    show_toast_background_activated(message, {}, {});
+    show_toast_with_activations(message, {}, {});
 }
 
-void notifications::show_toast_background_activated(std::wstring_view message, std::wstring_view background_handler_id, std::vector<std::wstring_view> button_labels)
+inline void xml_escape(std::wstring data)
+{
+    std::wstring buffer;
+    buffer.reserve(data.size());
+    for (size_t pos = 0; pos != data.size(); ++pos)
+    {
+        switch (data[pos])
+        {
+        case L'&':
+            buffer.append(L"&amp;");
+            break;
+        case L'\"':
+            buffer.append(L"&quot;");
+            break;
+        case L'\'':
+            buffer.append(L"&apos;");
+            break;
+        case L'<':
+            buffer.append(L"&lt;");
+            break;
+        case L'>':
+            buffer.append(L"&gt;");
+            break;
+        default:
+            buffer.append(&data[pos], 1);
+            break;
+        }
+    }
+    data.swap(buffer);
+}
+
+void notifications::show_toast_with_activations(std::wstring_view message, std::wstring_view background_handler_id, std::vector<button_t> buttons)
 {
     // DO NOT LOCALIZE any string in this function, because they're XML tags and a subject to
     // https://docs.microsoft.com/en-us/windows/uwp/design/shell/tiles-and-notifications/toast-xml-schema
 
     std::wstring toast_xml;
     toast_xml.reserve(1024);
-    toast_xml += LR"(<?xml version="1.0"?><toast><visual><binding template="ToastGeneric"><text>PowerToys</text><text>)";
+    std::wstring title{L"PowerToys"};
+    if (winstore::running_as_packaged())
+    {
+        title += L" (Experimental)";
+    }
+
+    toast_xml += LR"(<?xml version="1.0"?><toast><visual><binding template="ToastGeneric"><text>)";
+    toast_xml += title;
+    toast_xml += L"</text><text>";
     toast_xml += message;
     toast_xml += L"</text></binding></visual><actions>";
 
-    for (size_t i = 0; i < size(button_labels); ++i)
+    for (size_t i = 0; i < size(buttons); ++i)
     {
-        toast_xml += LR"(<action activationType="background" arguments=")";
+        std::visit(overloaded{
-        toast_xml += L"button_id=" + std::to_wstring(i); // pass the button ID
+                       [&](const link_button& b) {
-        toast_xml += L"&amp;handler=";
+                           toast_xml += LR"(<action activationType="protocol" arguments=")";
-        toast_xml += background_handler_id;
+                           toast_xml += b.url;
-        toast_xml += LR"(" content=")";
+                           toast_xml += LR"(" content=")";
-        toast_xml += button_labels[i];
+                           toast_xml += b.label;
-        toast_xml += LR"("/>)";
+                           toast_xml += LR"("/>)";
+                       },
+                       [&](const background_activated_button& b) {
+                           toast_xml += LR"(<action activationType="background" arguments=")";
+                           toast_xml += L"button_id=" + std::to_wstring(i); // pass the button ID
+                           toast_xml += L"&amp;handler=";
+                           toast_xml += background_handler_id;
+                           toast_xml += LR"(" content=")";
+                           toast_xml += b.label;
+                           toast_xml += LR"("/>)";
+                       },
+                   },
+                   buttons[i]);
     }
     toast_xml += L"</actions></toast>";
 
     XmlDocument toast_xml_doc;
+    xml_escape(toast_xml);
     toast_xml_doc.LoadXml(toast_xml);
     ToastNotification notification{ toast_xml_doc };
 
-    const auto notifier = ToastNotificationManager::ToastNotificationManager::CreateToastNotifier();
+    const auto notifier = winstore::running_as_packaged() ? ToastNotificationManager::ToastNotificationManager::CreateToastNotifier() :
+                                                            ToastNotificationManager::ToastNotificationManager::CreateToastNotifier(WIN32_AUMID);
     notifier.Show(notification);
 }

src/common/notifications.h

@@ -2,12 +2,29 @@
 
 #include <string_view>
 #include <vector>
+#include <variant>
 
 namespace notifications
 {
+    constexpr inline const wchar_t TOAST_ACTIVATED_LAUNCH_ARG[] = L"-ToastActivated";
+
     void register_background_toast_handler();
 
-    // Make sure your plaintext_message argument is properly XML-escaped
+    void run_desktop_app_activator_loop();
+
+    struct link_button
+    {
+        std::wstring_view label;
+        std::wstring_view url;
+    };
+
+    struct background_activated_button
+    {
+        std::wstring_view label;
+    };
+
+    using button_t = std::variant<link_button, background_activated_button>;
+
     void show_toast(std::wstring_view plaintext_message);
-    void show_toast_background_activated(std::wstring_view plaintext_message, std::wstring_view background_handler_id, std::vector<std::wstring_view> plaintext_button_labels);
+    void show_toast_with_activations(std::wstring_view plaintext_message, std::wstring_view background_handler_id, std::vector<button_t> buttons);
 }

src/common/notifications/notifications.def

@@ -3,3 +3,4 @@ DllCanUnloadNow = WINRT_CanUnloadNow                    PRIVATE
 DllGetActivationFactory = WINRT_GetActivationFactory    PRIVATE
 DllRegisterServer                                       PRIVATE
 DllUnregisterServer                                     PRIVATE
+dispatch_to_backround_handler                           PRIVATE

src/common/notifications_winrt/BackgroundHandler.cpp

@@ -8,7 +8,6 @@ namespace winrt::PowerToysNotifications::implementation
 {
     using Windows::ApplicationModel::Background::IBackgroundTaskInstance;
     using Windows::UI::Notifications::ToastNotificationActionTriggerDetail;
-    using Windows::Foundation::WwwFormUrlDecoder;
 
     void BackgroundHandler::Run(IBackgroundTaskInstance bti)
     {
@@ -18,10 +17,6 @@ namespace winrt::PowerToysNotifications::implementation
             return;
         }
 
-        WwwFormUrlDecoder decoder{details.Argument()};
+        dispatch_to_backround_handler(details.Argument());
-
-        const size_t button_id = std::stoi(decoder.GetFirstValueByName(L"button_id").c_str());
-        auto handler = decoder.GetFirstValueByName(L"handler");
-        dispatch_to_backround_handler(std::move(handler), std::move(bti), button_id);
     }
 }

src/common/notifications_winrt/handler_functions.cpp

@@ -2,19 +2,26 @@
 
 #include "handler_functions.h"
 
-using handler_function_t = void (*)(IBackgroundTaskInstance, const size_t button_id);
+#include <winrt/Windows.System.h>
+
+using handler_function_t = void (*)(const size_t button_id);
 
 namespace
 {
     const std::unordered_map<std::wstring_view, handler_function_t> handlers_map;
 }
 
-void dispatch_to_backround_handler(std::wstring_view background_handler_id, IBackgroundTaskInstance bti, const size_t button_id)
+void dispatch_to_backround_handler(std::wstring_view argument)
 {
-    const auto found_handler = handlers_map.find(background_handler_id);
+    winrt::Windows::Foundation::WwwFormUrlDecoder decoder{ argument };
+
+    const size_t button_id = std::stoi(decoder.GetFirstValueByName(L"button_id").c_str());
+    auto handler = decoder.GetFirstValueByName(L"handler");
+
+    const auto found_handler = handlers_map.find(handler);
     if (found_handler == end(handlers_map))
     {
         return;
     }
-    found_handler->second(std::move(bti), button_id);
+    found_handler->second(button_id);
 }

src/common/notifications_winrt/handler_functions.h

@@ -1,5 +1,5 @@
 #pragma once
 
-using winrt::Windows::ApplicationModel::Background::IBackgroundTaskInstance;
+#include <string_view>
 
-void dispatch_to_backround_handler(std::wstring_view background_handler_id, IBackgroundTaskInstance bti, const size_t button_id);
+void dispatch_to_backround_handler(std::wstring_view argument);

src/runner/main.cpp

@@ -120,10 +120,7 @@ int runner(bool isProcessElevated)
     int result = -1;
     try
     {
-        if (winstore::running_as_packaged())
+        notifications::register_background_toast_handler();
-        {
-            notifications::register_background_toast_handler();
-        }
 
         chdir_current_executable();
         // Load Powertyos DLLS
@@ -165,8 +162,46 @@ int runner(bool isProcessElevated)
     return result;
 }
 
+// If the PT runner is launched as part of some action and manually by a user, e.g. being activated as a COM server
+// for background toast notification handling, we should execute corresponding code flow instead of the main code flow.
+enum class SpecialMode
+{
+    None,
+    Win32ToastNotificationCOMServer
+};
+
+SpecialMode should_run_in_special_mode()
+{
+    int nArgs;
+    LPWSTR* szArglist = CommandLineToArgvW(GetCommandLineW(), &nArgs);
+    for (size_t i = 1; i < nArgs; ++i)
+    {
+        if (!wcscmp(notifications::TOAST_ACTIVATED_LAUNCH_ARG, szArglist[i]))
+            return SpecialMode::Win32ToastNotificationCOMServer;
+    }
+
+    return SpecialMode::None;
+}
+
+int win32_toast_notification_COM_server_mode()
+{
+    notifications::run_desktop_app_activator_loop();
+    return 0;
+}
+
 int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
 {
+    winrt::init_apartment();
+
+    switch (should_run_in_special_mode())
+    {
+    case SpecialMode::Win32ToastNotificationCOMServer:
+        return win32_toast_notification_COM_server_mode();
+    case SpecialMode::None:
+        // continue as usual
+        break;
+    }
+
     wil::unique_mutex_nothrow msi_mutex;
     wil::unique_mutex_nothrow msix_mutex;
 
@@ -235,12 +270,9 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine
     int result = 0;
     try
     {
-        winrt::init_apartment();
 
         if (winstore::running_as_packaged())
         {
-            notifications::register_background_toast_handler();
-
             std::thread{ [] {
                 start_msi_uninstallation_sequence();
             } }.detach();