Fix plugin settings sync when multiple monitors use same layout

src/DesktopMagic/BuiltInPlugins/WeatherPlugin.cs

@@ -58,9 +58,6 @@ public class WeatherPlugin : AsyncPlugin
         showTime.OnValueChanged += Application.UpdateWindow;
         fontSizeSlider.OnValueChanged += Application.UpdateWindow;
 
-        await UpdateLocationAndWeather();
-        Application.UpdateWindow();
-
         searchButton.OnClick += () =>
         {
             isLoading = true;
@@ -73,6 +70,9 @@ public class WeatherPlugin : AsyncPlugin
                 Application.UpdateWindow();
             });
         };
+
+        await UpdateLocationAndWeather();
+        Application.UpdateWindow();
     }
 
     public override async Task<Bitmap?> MainAsync(CancellationToken cancellationToken)

src/DesktopMagic/Manager.cs

@@ -291,6 +291,32 @@ public sealed class Manager
         SaveSettings();
     }
 
+    private readonly Dictionary<(Layout, uint), SettingSynchronizer> settingSynchronizers = [];
+
+    /// <summary>
+    /// Gets (or creates) the synchronizer that keeps the settings of all windows showing the
+    /// given plugin in the given layout in sync.
+    /// </summary>
+    internal SettingSynchronizer GetSettingSynchronizer(Layout layout, uint pluginId)
+    {
+        (Layout, uint) key = (layout, pluginId);
+        if (!settingSynchronizers.TryGetValue(key, out SettingSynchronizer? synchronizer))
+        {
+            synchronizer = new SettingSynchronizer();
+            settingSynchronizers.Add(key, synchronizer);
+        }
+
+        return synchronizer;
+    }
+
+    /// <summary>
+    /// Drops the synchronizer for the given plugin in the given layout once no windows use it anymore.
+    /// </summary>
+    internal void ReleaseSettingSynchronizer(Layout layout, uint pluginId)
+    {
+        _ = settingSynchronizers.Remove((layout, pluginId));
+    }
+
     #endregion
 
     #region Settings Management

src/DesktopMagic/Plugins/IPluginWindow.cs

@@ -21,5 +21,8 @@ public interface IPluginWindow
     void Hide();
     void Close();
 
+    void ApplySettingValue(string id, string value);
+    void ApplyButtonClick(string id);
+
     event System.ComponentModel.CancelEventHandler Closing;
 }

src/DesktopMagic/Plugins/PluginWindow.xaml.cs

@@ -9,6 +9,7 @@ using DesktopMagic.Settings;
 using SkiaSharp;
 
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.ComponentModel;
@@ -44,6 +45,7 @@ public partial class PluginWindow : Window, IPluginWindow
     private readonly Rectangle screenBounds;
     private readonly string screenDeviceName;
     private bool isUpdatingPosition = false;
+    private bool _editMode = false;
 
     private CancellationTokenSource? pluginCancellationTokenSource;
     private FileSystemWatcher? pluginFileWatcher;
@@ -58,8 +60,13 @@ public partial class PluginWindow : Window, IPluginWindow
     private readonly PropertyChangedEventHandler themePropertyChangedHandler;
     private Theme? subscribedTheme;
     private NotifyCollectionChangedEventHandler? themesCollectionChangedHandler;
-    private readonly List<Setting> subscribedSettings = [];
+    private readonly List<(Setting Setting, Action Handler)> subscribedSettings = [];
     private readonly List<(Setting Setting, Action Handler)> defaultSettingsSubscriptions = [];
+    private readonly List<(Button Button, Action Handler)> subscribedButtonClicks = [];
+
+    private readonly ConcurrentDictionary<string, Setting> localSettings = [];
+    private SettingSynchronizer? synchronizer;
+    private bool suppressButtonSync = false;
 
     public bool IsRunning { get; private set; } = true;
     public PluginMetadata PluginMetadata { get; private set; }
@@ -121,6 +128,12 @@ public partial class PluginWindow : Window, IPluginWindow
 
         PluginFolderPath = pluginFolderPath;
 
+        if (settings.Owner is not null)
+        {
+            synchronizer = Manager.Instance.GetSettingSynchronizer(settings.Owner, PluginMetadata.Id);
+            synchronizer.Register(this);
+        }
+
         assemblyLoadContext = CreateAssemblyLoadContext();
 
         // Initialize hot reload watcher if plugin supports unloading and is external
@@ -346,6 +359,8 @@ public partial class PluginWindow : Window, IPluginWindow
 
     public void SetEditMode(bool enabled)
     {
+        _editMode = enabled;
+
         if (enabled)
         {
             Topmost = true;
@@ -645,9 +660,16 @@ public partial class PluginWindow : Window, IPluginWindow
         }
 
         void SetWindowLayer()
+        {
+            if (_editMode)
+            {
+                Topmost = true;
+            }
+            else
             {
                 WindowPos.SetWindowLayer(this, pluginClassInstance.windowLayer.Value);
             }
+        }
 
         void SetRotation()
         {
@@ -686,7 +708,7 @@ public partial class PluginWindow : Window, IPluginWindow
         defaultSettingsSubscriptions.Add((setting, handler));
     }
 
-    private void OnPluginSettingValueChanged()
+    private void OnPluginSettingValueChanged(Setting setting, string id)
     {
         pluginClassInstance?.OnSettingsChanged();
 
@@ -694,6 +716,34 @@ public partial class PluginWindow : Window, IPluginWindow
         {
             pluginClassInstance.Application.UpdateWindow();
         }
+
+        synchronizer?.SettingChanged(this, id, setting.GetJsonValue());
+    }
+
+    public void ApplySettingValue(string id, string value)
+    {
+        if (localSettings.TryGetValue(id, out Setting? setting) && setting.GetJsonValue() != value)
+        {
+            setting.SetJsonValue(value);
+        }
+    }
+
+    public void ApplyButtonClick(string id)
+    {
+        if (!localSettings.TryGetValue(id, out Setting? setting) || setting is not Button button)
+        {
+            return;
+        }
+
+        suppressButtonSync = true;
+        try
+        {
+            button.Click();
+        }
+        finally
+        {
+            suppressButtonSync = false;
+        }
     }
 
     private async Task LoadOptions(object instance)
@@ -713,16 +763,36 @@ public partial class PluginWindow : Window, IPluginWindow
                     {
                         if (attribute is SettingAttribute elementAttribute)
                         {
+                            localSettings[elementAttribute.Id] = element;
+
                             SettingElement settingElement = new SettingElement(element, elementAttribute.Id, elementAttribute.Name, elementAttribute.OrderIndex);
 
                             if (settings.Settings.Exists(e => e.Id == elementAttribute.Id))
                             {
                                 SettingElement settingsSettingElement = settings.Settings.First(e => e.Id == elementAttribute.Id);
-                                settingElement.JsonValue = settingsSettingElement.JsonValue;
+                                string savedValue = settingsSettingElement.JsonValue;
+                                if (!string.IsNullOrEmpty(savedValue) || element is not Label and not Button)
+                                {
+                                    settingElement.JsonValue = savedValue;
+                                }
                             }
 
-                            element.OnValueChanged += OnPluginSettingValueChanged;
-                            subscribedSettings.Add(element);
+                            Action valueChangedHandler = () => OnPluginSettingValueChanged(element, elementAttribute.Id);
+                            element.OnValueChanged += valueChangedHandler;
+                            subscribedSettings.Add((element, valueChangedHandler));
+
+                            if (element is Button button)
+                            {
+                                Action clickHandler = () =>
+                                {
+                                    if (!suppressButtonSync)
+                                    {
+                                        synchronizer?.ButtonClicked(this, elementAttribute.Id);
+                                    }
+                                };
+                                button.OnClick += clickHandler;
+                                subscribedButtonClicks.Add((button, clickHandler));
+                            }
 
                             settingElements.Add(settingElement);
                             break;
@@ -1070,6 +1140,15 @@ public partial class PluginWindow : Window, IPluginWindow
 
         UnsubscribeEvents();
         DetachSettings();
+
+        if (synchronizer is not null && settings.Owner is not null)
+        {
+            if (synchronizer.Unregister(this))
+            {
+                Manager.Instance.ReleaseSettingSynchronizer(settings.Owner, PluginMetadata.Id);
+            }
+            synchronizer = null;
+        }
     }
 
     private void DetachSettings()
@@ -1098,9 +1177,9 @@ public partial class PluginWindow : Window, IPluginWindow
             themesCollectionChangedHandler = null;
         }
 
-        foreach (Setting setting in subscribedSettings)
+        foreach ((Setting Setting, Action Handler) subscription in subscribedSettings)
         {
-            setting.OnValueChanged -= OnPluginSettingValueChanged;
+            subscription.Setting.OnValueChanged -= subscription.Handler;
         }
         subscribedSettings.Clear();
 
@@ -1109,6 +1188,14 @@ public partial class PluginWindow : Window, IPluginWindow
             subscription.Setting.OnValueChanged -= subscription.Handler;
         }
         defaultSettingsSubscriptions.Clear();
+
+        foreach ((Button Button, Action Handler) subscription in subscribedButtonClicks)
+        {
+            subscription.Button.OnClick -= subscription.Handler;
+        }
+        subscribedButtonClicks.Clear();
+
+        localSettings.Clear();
     }
 
     private void UpdatePosition()

src/DesktopMagic/Plugins/SettingSynchronizer.cs

@@ -0,0 +1,110 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Windows.Threading;
+
+namespace DesktopMagic.Plugins;
+
+/// <summary>
+/// Keeps the per-instance plugin settings of every window sharing the same layout in sync.
+/// Each window owns its own <see cref="DesktopMagic.Api.Settings.Setting"/> objects (plugins
+/// hold them in readonly fields and subscribe to them in Start), so a value change on one
+/// window has to be mirrored onto the sibling windows.
+/// </summary>
+internal sealed class SettingSynchronizer
+{
+    private readonly object _lock = new();
+    private readonly List<IPluginWindow> windows = [];
+    private readonly HashSet<(IPluginWindow Window, string Id)> inFlight = [];
+
+    /// <summary>
+    /// Registers a window so it receives mirrored settings from the other windows of this layout.
+    /// </summary>
+    public void Register(IPluginWindow window)
+    {
+        lock (_lock)
+        {
+            if (!windows.Contains(window))
+            {
+                windows.Add(window);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Unregisters a window and returns whether no windows remain.
+    /// </summary>
+    public bool Unregister(IPluginWindow window)
+    {
+        lock (_lock)
+        {
+            windows.Remove(window);
+            return windows.Count == 0;
+        }
+    }
+
+    /// <summary>
+    /// Mirrors a setting value change onto every other registered window.
+    /// </summary>
+    public void SettingChanged(IPluginWindow origin, string id, string value)
+    {
+        Mirror(origin, id, window => window.ApplySettingValue(id, value));
+    }
+
+    /// <summary>
+    /// Mirrors a button click onto every other registered window.
+    /// </summary>
+    public void ButtonClicked(IPluginWindow origin, string id)
+    {
+        Mirror(origin, id, window => window.ApplyButtonClick(id));
+    }
+
+    private void Mirror(IPluginWindow origin, string id, Action<IPluginWindow> apply)
+    {
+        IPluginWindow[] snapshot;
+        lock (_lock)
+        {
+            snapshot = windows.ToArray();
+        }
+
+        foreach (IPluginWindow window in snapshot)
+        {
+            if (ReferenceEquals(window, origin) || !window.IsRunning)
+            {
+                continue;
+            }
+
+            lock (_lock)
+            {
+                if (!inFlight.Add((window, id)))
+                {
+                    continue;
+                }
+            }
+
+            if (window is not DispatcherObject dispatcherObject)
+            {
+                lock (_lock)
+                {
+                    inFlight.Remove((window, id));
+                }
+                continue;
+            }
+
+            _ = dispatcherObject.Dispatcher.InvokeAsync(() =>
+            {
+                try
+                {
+                    apply(window);
+                }
+                finally
+                {
+                    lock (_lock)
+                    {
+                        inFlight.Remove((window, id));
+                    }
+                }
+            });
+        }
+    }
+}

src/DesktopMagic/Plugins/WebPluginWindow.xaml.cs

@@ -6,6 +6,7 @@ using DesktopMagic.Settings;
 using Microsoft.Web.WebView2.Core;
 
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.IO;
@@ -41,6 +42,10 @@ public partial class WebPluginWindow : Window, IPluginWindow
     private readonly List<(Setting Setting, Action Handler)> subscribedSettings = [];
     private readonly List<(Button Button, Action Handler)> subscribedButtonClicks = [];
 
+    private readonly ConcurrentDictionary<string, Setting> localSettings = [];
+    private SettingSynchronizer? synchronizer;
+    private bool suppressButtonSync = false;
+
     public bool IsRunning { get; private set; } = true;
     public PluginMetadata PluginMetadata { get; private set; }
     public string PluginFolderPath { get; private set; }
@@ -101,6 +106,12 @@ public partial class WebPluginWindow : Window, IPluginWindow
 
         PluginFolderPath = pluginFolderPath;
 
+        if (settings.Owner is not null)
+        {
+            synchronizer = Manager.Instance.GetSettingSynchronizer(settings.Owner, PluginMetadata.Id);
+            synchronizer.Register(this);
+        }
+
         if (pluginMetadata.SupportsUnloading && !string.IsNullOrEmpty(pluginFolderPath))
         {
             InitializeHotReload();
@@ -157,6 +168,32 @@ public partial class WebPluginWindow : Window, IPluginWindow
         }
     }
 
+    public void ApplySettingValue(string id, string value)
+    {
+        if (localSettings.TryGetValue(id, out Setting? setting) && setting.GetJsonValue() != value)
+        {
+            setting.SetJsonValue(value);
+        }
+    }
+
+    public void ApplyButtonClick(string id)
+    {
+        if (!localSettings.TryGetValue(id, out Setting? setting) || setting is not Button button)
+        {
+            return;
+        }
+
+        suppressButtonSync = true;
+        try
+        {
+            button.Click();
+        }
+        finally
+        {
+            suppressButtonSync = false;
+        }
+    }
+
     protected override void OnSourceInitialized(EventArgs e)
     {
         base.OnSourceInitialized(e);
@@ -290,6 +327,15 @@ public partial class WebPluginWindow : Window, IPluginWindow
 
         UnsubscribeEvents();
 
+        if (synchronizer is not null && settings.Owner is not null)
+        {
+            if (synchronizer.Unregister(this))
+            {
+                Manager.Instance.ReleaseSettingSynchronizer(settings.Owner, PluginMetadata.Id);
+            }
+            synchronizer = null;
+        }
+
         try
         {
             if (isInitialized && webView.CoreWebView2 != null)
@@ -324,6 +370,8 @@ public partial class WebPluginWindow : Window, IPluginWindow
             button.OnClick -= handler;
         }
         subscribedButtonClicks.Clear();
+
+        localSettings.Clear();
     }
 
     private void UpdatePosition()
@@ -450,12 +498,18 @@ public partial class WebPluginWindow : Window, IPluginWindow
                     continue;
                 }
 
+                localSettings[id] = setting;
+
                 SettingElement settingElement = new(setting, id, name, orderIndex);
 
                 if (settings.Settings.Exists(e => e.Id == id))
                 {
                     SettingElement saved = settings.Settings.First(e => e.Id == id);
-                    settingElement.JsonValue = saved.JsonValue;
+                    string savedValue = saved.JsonValue;
+                    if (!string.IsNullOrEmpty(savedValue) || setting is not Label and not Button)
+                    {
+                        settingElement.JsonValue = savedValue;
+                    }
                 }
 
                 string capturedId = id;
@@ -463,6 +517,11 @@ public partial class WebPluginWindow : Window, IPluginWindow
                 {
                     Action clickHandler = () =>
                     {
+                        if (!suppressButtonSync)
+                        {
+                            synchronizer?.ButtonClicked(this, capturedId);
+                        }
+
                         _ = webView.Dispatcher.InvokeAsync(async () =>
                         {
                             try
@@ -481,6 +540,8 @@ public partial class WebPluginWindow : Window, IPluginWindow
 
                 Action valueChangedHandler = () =>
                 {
+                    synchronizer?.SettingChanged(this, capturedId, setting.GetJsonValue());
+
                     _ = webView.Dispatcher.InvokeAsync(async () =>
                     {
                         try

src/DesktopMagicPluginAPI/Settings/Button.cs

@@ -46,4 +46,14 @@ public class Button : Setting
     {
         OnClick?.Invoke();
     }
+
+    internal override string GetJsonValue()
+    {
+        return Value;
+    }
+
+    internal override void SetJsonValue(string value)
+    {
+        Value = value;
+    }
 }

src/DesktopMagicPluginAPI/Settings/Label.cs

@@ -38,4 +38,14 @@ public class Label : Setting
         Value = value;
         Bold = bold;
     }
+
+    internal override string GetJsonValue()
+    {
+        return Value;
+    }
+
+    internal override void SetJsonValue(string value)
+    {
+        Value = value;
+    }
 }