MSIX: implement initial version of notifications library (#1178)

src/common/notifications.cpp

@@ -0,0 +1,89 @@
+#include "pch.h"
+#include "notifications.h"
+
+#include <unknwn.h>
+#include <winrt/base.h>
+#include <winrt/Windows.Foundation.h>
+#include <winrt/Windows.Data.Xml.Dom.h>
+#include <winrt/Windows.Foundation.Collections.h>
+#include <winrt/Windows.UI.Notifications.h>
+#include <winrt/Windows.ApplicationModel.Background.h>
+
+using namespace winrt::Windows::ApplicationModel::Background;
+using winrt::Windows::Data::Xml::Dom::XmlDocument;
+using winrt::Windows::UI::Notifications::ToastNotification;
+using winrt::Windows::UI::Notifications::ToastNotificationManager;
+
+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";
+}
+
+void notifications::register_background_toast_handler()
+{
+    try
+    {
+        // Re-request access to clean up from previous PowerToys installations
+        BackgroundExecutionManager::RemoveAccess();
+        BackgroundExecutionManager::RequestAccessAsync().get();
+
+        BackgroundTaskBuilder builder;
+        ToastNotificationActionTrigger trigger{ APPLICATION_ID };
+        builder.SetTrigger(trigger);
+        builder.TaskEntryPoint(TASK_ENTRYPOINT);
+        builder.Name(TASK_NAME);
+
+        const auto tasks = BackgroundTaskRegistration::AllTasks();
+        const bool already_registered = std::any_of(begin(tasks), end(tasks), [=](const auto& task) {
+            return task.Value().Name() == TASK_NAME;
+        });
+        if (already_registered)
+        {
+            return;
+        }
+        (void)builder.Register();
+    }
+    catch (...)
+    {
+        // Couldn't register the background task, nothing we can do
+    }
+}
+
+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, {}, {});
+}
+
+void notifications::show_toast_background_activated(std::wstring_view message, std::wstring_view background_handler_id, std::vector<std::wstring_view> button_labels)
+{
+    // 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>)";
+    toast_xml += message;
+    toast_xml += L"</text></binding></visual><actions>";
+
+    for (size_t i = 0; i < size(button_labels); ++i)
+    {
+        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 += button_labels[i];
+        toast_xml += LR"("/>)";
+    }
+    toast_xml += L"</actions></toast>";
+
+    XmlDocument toast_xml_doc;
+    toast_xml_doc.LoadXml(toast_xml);
+    ToastNotification notification{ toast_xml_doc };
+
+    const auto notifier = ToastNotificationManager::ToastNotificationManager::CreateToastNotifier();
+    notifier.Show(notification);
+}