Add theme mode api functions

Author: Jack251970

Flow.Launcher.Plugin/Interfaces/IPublicAPI.cs

@@ -595,5 +595,16 @@ public interface IPublicAPI
         /// </summary>
         /// <returns>The time taken to execute the method in milliseconds</returns>
         public Task<long> StopwatchLogInfoAsync(string className, string message, Func<Task> action, [CallerMemberName] string methodName = "");
+
+        /// <summary>
+        /// Representing whether the application is using a dark theme
+        /// </summary>
+        /// <returns></returns>
+        bool IsApplicationDarkTheme();
+
+        /// <summary>
+        /// Invoked when the actual theme of the application has changed. Currently, the plugin will continue to be subscribed even if it is turned off. 
+        /// </summary>
+        event ActualApplicationThemeChangedEventHandler ActualApplicationThemeChanged;
     }
 }

Flow.Launcher/PublicAPIInstance.cs

@@ -14,23 +14,24 @@
 using System.Windows.Media;
 using CommunityToolkit.Mvvm.DependencyInjection;
 using Flow.Launcher.Core;
+using Flow.Launcher.Core.ExternalPlugins;
 using Flow.Launcher.Core.Plugin;
 using Flow.Launcher.Core.Resource;
-using Flow.Launcher.Core.ExternalPlugins;
 using Flow.Launcher.Core.Storage;
 using Flow.Launcher.Helper;
 using Flow.Launcher.Infrastructure;
-using Flow.Launcher.Infrastructure.Http;
 using Flow.Launcher.Infrastructure.Hotkey;
+using Flow.Launcher.Infrastructure.Http;
 using Flow.Launcher.Infrastructure.Image;
 using Flow.Launcher.Infrastructure.Logger;
 using Flow.Launcher.Infrastructure.Storage;
 using Flow.Launcher.Infrastructure.UserSettings;
 using Flow.Launcher.Plugin;
-using Flow.Launcher.Plugin.SharedModels;
 using Flow.Launcher.Plugin.SharedCommands;
+using Flow.Launcher.Plugin.SharedModels;
 using Flow.Launcher.ViewModel;
 using JetBrains.Annotations;
+using ModernWpf;
 using Squirrel;
 using Stopwatch = Flow.Launcher.Infrastructure.Stopwatch;
 
@@ -587,6 +588,17 @@ public long StopwatchLogInfo(string className, string message, Action action, [C
         public Task<long> StopwatchLogInfoAsync(string className, string message, Func<Task> action, [CallerMemberName] string methodName = "") =>
             Stopwatch.InfoAsync(className, message, action, methodName);
 
+        public bool IsApplicationDarkTheme()
+        {
+            return ThemeManager.Current.ActualApplicationTheme == ApplicationTheme.Dark;
+        }
+
+        public event ActualApplicationThemeChangedEventHandler ActualApplicationThemeChanged
+        {
+            add => _mainVM.ActualApplicationThemeChanged += value;
+            remove => _mainVM.ActualApplicationThemeChanged -= value;
+        }
+
         #endregion
 
         #region Private Methods