Ensure DevDiagnostics' owned windows honor theme changes

tools/DevDiagnostics/DevHome.DevDiagnostics/Controls/ThemeAwareWindow.cs

@@ -0,0 +1,183 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Collections.Generic;
+using System.Diagnostics;
+using Microsoft.UI;
+using Microsoft.UI.Dispatching;
+using Microsoft.UI.Windowing;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Media;
+using Windows.UI;
+using Windows.UI.ViewManagement;
+using WinUIEx;
+
+namespace DevHome.DevDiagnostics.Controls;
+
+/* This class encapsulates the theme-awareness logic, including support for custom chrome buttons.
+ * The main BarWindow derives from ThemeAwareWindow. All internal tool windows and any other owned windows
+ * must follow the theme of the main BarWindow. To achieve this:
+ * 1. Derive the tool window from ThemeAwareWindow.
+ * 2. Define a grid or panel for the icon and title (because this window sets ExtendsContentIntoTitleBar
+ *    and HideIconAndSystemMenu).
+ * 3. Add the tool window to the list of related windows for the BarWindow by calling AddRelatedWindow.
+ * 4. Remove the tool window from the list of related windows for the BarWindow when the tool window is closed.
+ * 5. See ClipboardMonitoringWindow for an example.
+ */
+
+public class ThemeAwareWindow : WindowEx
+{
+    private readonly SolidColorBrush _darkModeActiveCaptionBrush;
+    private readonly SolidColorBrush _darkModeInactiveCaptionBrush;
+    private readonly SolidColorBrush _nonDarkModeActiveCaptionBrush;
+    private readonly SolidColorBrush _nonDarkModeInactiveCaptionBrush;
+    private readonly UISettings _uiSettings = new();
+    private readonly DispatcherQueue _dispatcher;
+
+    private WindowActivationState _currentActivationState = WindowActivationState.Deactivated;
+
+    private List<ThemeAwareWindow> RelatedWindows { get; set; } = [];
+
+    internal List<Button> CustomTitleBarButtons { get; private set; } = [];
+
+    internal ElementTheme Theme { get; set; }
+
+    public ThemeAwareWindow()
+    {
+        _dispatcher = DispatcherQueue.GetForCurrentThread();
+
+        // Precreate the brushes for the caption buttons.
+        // In Dark Mode, the active state is white, and the inactive state is translucent white.
+        // In Light Mode, the active state is black, and the inactive state is translucent black.
+        var color = Colors.White;
+        _darkModeActiveCaptionBrush = new SolidColorBrush(color);
+        color.A = 0x66;
+        _darkModeInactiveCaptionBrush = new SolidColorBrush(color);
+
+        color = Colors.Black;
+        _nonDarkModeActiveCaptionBrush = new SolidColorBrush(color);
+        color.A = 0x66;
+        _nonDarkModeInactiveCaptionBrush = new SolidColorBrush(color);
+
+        ExtendsContentIntoTitleBar = true;
+        AppWindow.TitleBar.IconShowOptions = IconShowOptions.HideIconAndSystemMenu;
+
+        Closed += ThemeAwareWindow_Closed;
+        Activated += Window_Activated;
+        _uiSettings.ColorValuesChanged += UiSettings_ColorValuesChanged;
+    }
+
+    // Invoked when the user changes system-wide personalization settings.
+    private void UiSettings_ColorValuesChanged(UISettings sender, object args)
+    {
+        _dispatcher.TryEnqueue(ApplySystemThemeToCaptionButtons);
+    }
+
+    private void ThemeAwareWindow_Closed(object sender, WindowEventArgs args)
+    {
+        Activated -= Window_Activated;
+        _uiSettings.ColorValuesChanged -= UiSettings_ColorValuesChanged;
+    }
+
+    internal void Window_Activated(object sender, WindowActivatedEventArgs args)
+    {
+        // This follows the design guidance of dimming our title bar elements when the window isn't activated.
+        // https://learn.microsoft.com/en-us/windows/apps/develop/title-bar#dim-the-title-bar-when-the-window-is-inactive
+        _currentActivationState = args.WindowActivationState;
+
+        if (CustomTitleBarButtons.Count > 0)
+        {
+            UpdateCustomTitleBarButtonsTextColor();
+        }
+    }
+
+    // Invoked when the user changes theme preference in this app's settings.
+    internal void SetRequestedTheme(ElementTheme theme)
+    {
+        Theme = theme;
+
+        if (Content is FrameworkElement rootElement)
+        {
+            rootElement.RequestedTheme = theme;
+
+            if (theme == ElementTheme.Dark)
+            {
+                SetCaptionButtonColors(Colors.White);
+            }
+            else if (theme == ElementTheme.Light)
+            {
+                SetCaptionButtonColors(Colors.Black);
+            }
+            else
+            {
+                ApplySystemThemeToCaptionButtons();
+            }
+        }
+
+        foreach (var window in RelatedWindows)
+        {
+            window.SetRequestedTheme(theme);
+        }
+    }
+
+    // AppWindow.TitleBar doesn't update caption button colors correctly when changed while app is running.
+    // https://task.ms/44172495
+    internal void ApplySystemThemeToCaptionButtons()
+    {
+        if (Content is FrameworkElement rootElement)
+        {
+            Color foregroundColor;
+            if (rootElement.ActualTheme == ElementTheme.Dark)
+            {
+                foregroundColor = Colors.White;
+            }
+            else
+            {
+                foregroundColor = Colors.Black;
+            }
+
+            SetCaptionButtonColors(foregroundColor);
+        }
+    }
+
+    internal void SetCaptionButtonColors(Color color)
+    {
+        AppWindow.TitleBar.ButtonForegroundColor = color;
+        if (CustomTitleBarButtons.Count > 0)
+        {
+            UpdateCustomTitleBarButtonsTextColor();
+        }
+    }
+
+    internal void UpdateCustomTitleBarButtonsTextColor()
+    {
+        var rootElement = Content as FrameworkElement;
+        Debug.Assert(rootElement != null, "Expected Content to be a FrameworkElement");
+
+        foreach (var button in CustomTitleBarButtons)
+        {
+            if (_currentActivationState == WindowActivationState.Deactivated)
+            {
+                var brush = (rootElement.ActualTheme == ElementTheme.Dark) ? _darkModeInactiveCaptionBrush : _nonDarkModeInactiveCaptionBrush;
+                button.Foreground = brush;
+            }
+            else
+            {
+                var brush = (rootElement.ActualTheme == ElementTheme.Dark) ? _darkModeActiveCaptionBrush : _nonDarkModeActiveCaptionBrush;
+                button.Foreground = brush;
+            }
+        }
+    }
+
+    internal void AddRelatedWindow(ThemeAwareWindow window)
+    {
+        RelatedWindows.Add(window);
+        window.SetRequestedTheme(Theme);
+    }
+
+    internal void RemoveRelatedWindow(ThemeAwareWindow window)
+    {
+        RelatedWindows.Remove(window);
+    }
+}

tools/DevDiagnostics/DevHome.DevDiagnostics/Helpers/ClipboardMonitorInternalTool.cs

@@ -1,14 +1,13 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-using System;
+using DevHome.Common.Extensions;
 using DevHome.DevDiagnostics.Properties;
 using DevHome.DevDiagnostics.Views;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.UI.Xaml.Media;
 using Windows.Graphics;
-using Windows.Win32.Foundation;
 
 namespace DevHome.DevDiagnostics.Helpers;
 
@@ -38,6 +37,11 @@ internal override void InvokeTool(ToolLaunchOptions options)
         if (_clipboardMonitoringWindow is null || _clipboardMonitoringWindow.AppWindow is null)
         {
             _clipboardMonitoringWindow = new ClipboardMonitoringWindow();
+
+            // Add this window to the list of related windows for the BarWindow,
+            // so that we can ensure that any BarWindow theme changes are also propagated to this window.
+            var barWindow = Application.Current.GetService<PrimaryWindow>().DBarWindow;
+            barWindow?.AddRelatedWindow(_clipboardMonitoringWindow);
         }
 
         if (options.ParentWindow is not null)