New ProviderStateTrigger

CommunityToolkit.Graph.Uwp/CommunityToolkit.Graph.Uwp.csproj

@@ -49,6 +49,10 @@
       <Generator>MSBuild:Compile</Generator>
     </Page>
   </ItemGroup>
+
+  <ItemGroup>
+    <Folder Include="Triggers\" />
+  </ItemGroup>
 
   <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0.17763'">
     <DefineConstants Condition="'$(DisableImplicitFrameworkDefines)' != 'true'">$(DefineConstants);WINRT</DefineConstants>

CommunityToolkit.Graph.Uwp/Triggers/ProviderStateTrigger.cs

@@ -0,0 +1,77 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using CommunityToolkit.Authentication;
+using Microsoft.Toolkit.Uwp;
+using Microsoft.Toolkit.Uwp.Helpers;
+using Windows.System;
+using Windows.UI.Xaml;
+
+namespace CommunityToolkit.Graph.Uwp
+{
+    /// <summary>
+    /// A StateTrigger for detecting when the global authentication provider has been signed in.
+    /// </summary>
+    public class ProviderStateTrigger : StateTriggerBase
+    {
+        /// <summary>
+        /// Identifies the <see cref="ActiveState"/> DependencyProperty.
+        /// </summary>
+        public static readonly DependencyProperty ActiveStateProperty =
+            DependencyProperty.Register(nameof(ActiveState), typeof(ProviderState), typeof(ProviderStateTrigger), new PropertyMetadata(null, OnStateChanged));
+
+        private static void OnStateChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+        {
+            if (d is ProviderStateTrigger instance)
+            {
+                instance.UpdateState();
+            }
+        }
+
+        private readonly DispatcherQueue _dispatcherQueue;
+
+        /// <summary>
+        /// Gets or sets the expected ProviderState.
+        /// </summary>
+        public ProviderState? ActiveState
+        {
+            get => (ProviderState?)GetValue(ActiveStateProperty);
+            set => SetValue(ActiveStateProperty, value);
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ProviderStateTrigger"/> class.
+        /// </summary>
+        public ProviderStateTrigger()
+        {
+            _dispatcherQueue = DispatcherQueue.GetForCurrentThread();
+            var weakEvent =
+                new WeakEventListener<ProviderStateTrigger, object, ProviderUpdatedEventArgs>(this)
+                {
+                    OnEventAction = (instance, source, args) => OnProviderUpdated(source, args),
+                    OnDetachAction = (weakEventListener) => ProviderManager.Instance.ProviderUpdated -= weakEventListener.OnEvent,
+                };
+            ProviderManager.Instance.ProviderUpdated += weakEvent.OnEvent;
+            UpdateState();
+        }
+
+        private void OnProviderUpdated(object sender, ProviderUpdatedEventArgs e)
+        {
+            _ = _dispatcherQueue.EnqueueAsync(UpdateState, DispatcherQueuePriority.Normal);
+        }
+
+        private void UpdateState()
+        {
+            var provider = ProviderManager.Instance.GlobalProvider;
+            if (ActiveState != null && provider?.State != null)
+            {
+                SetActive(provider?.State == ActiveState);
+            }
+            else
+            {
+                SetActive(false);
+            }
+        }
+    }
+}