Add dark mode toggle with ThemeState service

Implement dark mode support using a new ThemeState service that manages theme switching and integrates with DevExpress Blazor theming. Update App.razor to apply the theme globally, enhance MainLayout with a toggle button and dynamic CSS classes, and add dark mode styles to CSS files. Register ThemeState as a scoped service in Program.cs.

DbFirst.BlazorWebApp/Components/App.razor

@@ -5,7 +5,10 @@
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <base href="/" />
-    @DxResourceManager.RegisterTheme(Themes.Fluent)
+    @DxResourceManager.RegisterTheme(Themes.Fluent.Clone(properties =>
+    {
+        properties.ApplyToPageElements = true;
+    }))
     @DxResourceManager.RegisterScripts()
 
     <link href="_content/DevExpress.Blazor.Dashboard/ace.css" rel="stylesheet" />

DbFirst.BlazorWebApp/Components/Layout/MainLayout.razor

@@ -1,12 +1,15 @@
 @inherits LayoutComponentBase
+@implements IDisposable
+@inject ThemeState ThemeState
 
-<div class="page">
+<div class="page @(ThemeState.IsDarkMode ? "app-dark" : "app-light")">
     <div class="sidebar">
         <NavMenu />
     </div>
 
     <main>
         <div class="top-row px-4">
+            <DxButton Text="@(ThemeState.IsDarkMode ? "Dark Mode aus" : "Dark Mode an")" Click="ToggleTheme" />
             <a href="https://learn.microsoft.com/aspnet/core/" target="_blank">About</a>
         </div>
 
@@ -21,3 +24,20 @@
     <a href="" class="reload">Reload</a>
     <a class="dismiss">🗙</a>
 </div>
+
+@code {
+    protected override void OnInitialized()
+    {
+        ThemeState.OnChange += StateHasChanged;
+    }
+
+    private void ToggleTheme()
+    {
+        ThemeState.SetDarkMode(!ThemeState.IsDarkMode);
+    }
+
+    public void Dispose()
+    {
+        ThemeState.OnChange -= StateHasChanged;
+    }
+}

DbFirst.BlazorWebApp/Components/Layout/MainLayout.razor.css

@@ -4,14 +4,27 @@
     flex-direction: column;
 }
 
+.page.app-dark {
+    background-color: #1b1b1b;
+    color: #f1f1f1;
+}
+
 main {
     flex: 1;
 }
 
+.page.app-dark main {
+    background-color: #1b1b1b;
+}
+
 .sidebar {
     background-image: linear-gradient(180deg, rgb(5, 39, 103) 0%, #3a0647 70%);
 }
 
+.page.app-dark .sidebar {
+    background-image: linear-gradient(180deg, #171717 0%, #0f2a46 70%);
+}
+
 .top-row {
     background-color: #f7f7f7;
     border-bottom: 1px solid #d6d5d5;
@@ -21,6 +34,11 @@ main {
     align-items: center;
 }
 
+.page.app-dark .top-row {
+    background-color: #222;
+    border-bottom-color: #3d3d3d;
+}
+
     .top-row ::deep a, .top-row ::deep .btn-link {
         white-space: nowrap;
         margin-left: 1.5rem;

DbFirst.BlazorWebApp/Program.cs

@@ -9,6 +9,7 @@ builder.Services.AddRazorComponents()
     .AddInteractiveServerComponents();
 
 builder.Services.AddDevExpressBlazor(options => options.BootstrapVersion = BootstrapVersion.v5);
+builder.Services.AddScoped<ThemeState>();
 
 var apiBaseUrl = builder.Configuration["ApiBaseUrl"];
 if (!string.IsNullOrWhiteSpace(apiBaseUrl))

DbFirst.BlazorWebApp/Services/ThemeState.cs

@@ -0,0 +1,35 @@
+using DevExpress.Blazor;
+
+namespace DbFirst.BlazorWebApp.Services;
+
+public class ThemeState
+{
+    private readonly IThemeChangeService themeChangeService;
+
+    public ThemeState(IThemeChangeService themeChangeService)
+    {
+        this.themeChangeService = themeChangeService;
+    }
+
+    public bool IsDarkMode { get; private set; }
+
+    public event Action? OnChange;
+
+    public void SetDarkMode(bool isDarkMode)
+    {
+        if (IsDarkMode == isDarkMode)
+        {
+            return;
+        }
+
+        IsDarkMode = isDarkMode;
+        var theme = Themes.Fluent.Clone(properties =>
+        {
+            properties.Mode = isDarkMode ? ThemeMode.Dark : ThemeMode.Light;
+            properties.ApplyToPageElements = true;
+        });
+
+        themeChangeService.SetTheme(theme);
+        OnChange?.Invoke();
+    }
+}

DbFirst.BlazorWebApp/wwwroot/app.css

@@ -2,10 +2,19 @@ html, body {
     font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
 }
 
+.app-dark {
+    background-color: #1b1b1b;
+    color: #f1f1f1;
+}
+
 a, .btn-link {
     color: #006bb7;
 }
 
+.app-dark a, .app-dark .btn-link {
+    color: #6cb6ff;
+}
+
 .btn-primary {
     color: #fff;
     background-color: #1b6ec2;
@@ -37,7 +46,7 @@ h1:focus {
 }
 
 .blazor-error-boundary {
-    background: url(data:image/svg+xml;base64,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) no-repeat 1rem/1.8rem, #b32121;
+    background: url(data:image/svg+xml;base64,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) no-repeat 1rem/1.8rem, #b32121;
     padding: 1rem 1rem 1rem 3.7rem;
     color: white;
 }