# 06 - 主题系统示例

演示如何使用 Sharp.Wpf 的主题系统实现浅色/深色主题切换，包括自定义颜色、跟随系统主题等功能。

## 🎯 学习目标

- 使用 `IThemeService` 管理应用主题
- 实现浅色/深色主题切换
- 自定义主题颜色
- 跟随系统主题设置
- 动态主题切换（无需重启）

## 📦 使用的模块

- **Sharp.Wpf** - IThemeService, ThemeService

## 🚀 快速运行

```bash
cd examples/06-Theming
dotnet run
```

## 📝 核心代码讲解

### 1. App.xaml.cs - 注册主题服务

```csharp
using Wpf.Theming;

protected override void OnStartup(StartupEventArgs e)
{
    var services = new ServiceCollection();

    services.AddSharpWpf();  // 自动注册 IThemeService

    services.AddViewModel<MainViewModel>();

    var provider = services.BuildServiceProvider();

    // 应用初始主题
    var themeService = provider.GetRequiredService<IThemeService>();
    themeService.ApplyTheme(Theme.Light);  // 或 Theme.System

    var mainWindow = provider.GetRequiredService<MainWindow>();
    mainWindow.Show();
}
```

### 2. MainViewModel.cs - 主题切换逻辑

```csharp
using Wpf.Theming;

public class MainViewModel : ViewModelBase
{
    private readonly IThemeService _themeService;
    private Theme _currentTheme;

    public Theme CurrentTheme
    {
        get => _currentTheme;
        set
        {
            SetProperty(ref _currentTheme, value);
            _themeService.ApplyTheme(value);
        }
    }

    public ICommand SwitchToLightCommand { get; }
    public ICommand SwitchToDarkCommand { get; }
    public ICommand SwitchToSystemCommand { get; }

    public MainViewModel(IThemeService themeService)
    {
        _themeService = themeService;
        _currentTheme = themeService.CurrentTheme;

        // 监听主题变化
        _themeService.ThemeChanged += (s, theme) =>
        {
            OnPropertyChanged(nameof(CurrentTheme));
        };

        SwitchToLightCommand = new RelayCommand(() =>
        {
            CurrentTheme = Theme.Light;
        });

        SwitchToDarkCommand = new RelayCommand(() =>
        {
            CurrentTheme = Theme.Dark;
        });

        SwitchToSystemCommand = new RelayCommand(() =>
        {
            CurrentTheme = Theme.System;
        });
    }
}
```

### 3. MainWindow.xaml - 使用主题颜色

```xml
<Window x:Class="ThemingExample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="主题系统示例" Height="500" Width="600"
        Background="{DynamicResource BackgroundColor}">  <!-- 使用主题颜色 -->

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!-- 主题切换栏 -->
        <StackPanel Grid.Row="0" Orientation="Horizontal"
                    Background="{DynamicResource PrimaryColor}" Padding="15">
            <TextBlock Text="选择主题:"
                      Foreground="White" VerticalAlignment="Center" Margin="0,0,10,0"/>
            <Button Content="☀️ 浅色" Command="{Binding SwitchToLightCommand}"
                    Margin="0,0,10,0" Padding="15,5"/>
            <Button Content="🌙 深色" Command="{Binding SwitchToDarkCommand}"
                    Margin="0,0,10,0" Padding="15,5"/>
            <Button Content="🖥️ 跟随系统" Command="{Binding SwitchToSystemCommand}"
                    Padding="15,5"/>
        </StackPanel>

        <!-- 内容区域 -->
        <ScrollViewer Grid.Row="1" Padding="20">
            <StackPanel>
                <TextBlock Text="主题颜色预览" FontSize="24" FontWeight="Bold"
                          Foreground="{DynamicResource ForegroundColor}" Margin="0,0,0,20"/>

                <!-- 基础颜色 -->
                <GroupBox Header="基础颜色" Margin="0,0,0,15">
                    <StackPanel>
                        <Border Background="{DynamicResource PrimaryColor}"
                                Height="40" Margin="0,5">
                            <TextBlock Text="PrimaryColor" Foreground="White"
                                      VerticalAlignment="Center" HorizontalAlignment="Center"/>
                        </Border>
                        <Border Background="{DynamicResource BackgroundColor}"
                                BorderBrush="{DynamicResource BorderColor}" BorderThickness="1"
                                Height="40" Margin="0,5">
                            <TextBlock Text="BackgroundColor"
                                      Foreground="{DynamicResource ForegroundColor}"
                                      VerticalAlignment="Center" HorizontalAlignment="Center"/>
                        </Border>
                    </StackPanel>
                </GroupBox>

                <!-- 状态颜色 -->
                <GroupBox Header="状态颜色" Margin="0,0,0,15">
                    <StackPanel>
                        <Border Background="{DynamicResource SuccessColor}"
                                Height="40" Margin="0,5">
                            <TextBlock Text="✓ Success" Foreground="White"
                                      VerticalAlignment="Center" HorizontalAlignment="Center"/>
                        </Border>
                        <Border Background="{DynamicResource WarningColor}"
                                Height="40" Margin="0,5">
                            <TextBlock Text="⚠ Warning" Foreground="White"
                                      VerticalAlignment="Center" HorizontalAlignment="Center"/>
                        </Border>
                        <Border Background="{DynamicResource ErrorColor}"
                                Height="40" Margin="0,5">
                            <TextBlock Text="✗ Error" Foreground="White"
                                      VerticalAlignment="Center" HorizontalAlignment="Center"/>
                        </Border>
                        <Border Background="{DynamicResource InfoColor}"
                                Height="40" Margin="0,5">
                            <TextBlock Text="ℹ Info" Foreground="White"
                                      VerticalAlignment="Center" HorizontalAlignment="Center"/>
                        </Border>
                    </StackPanel>
                </GroupBox>

                <!-- 控件预览 -->
                <GroupBox Header="控件预览" Margin="0,0,0,15">
                    <StackPanel>
                        <!-- 按钮 -->
                        <Button Content="普通按钮" Margin="0,5" Padding="10,5"
                                Background="{DynamicResource ButtonBackgroundColor}"
                                Foreground="{DynamicResource ForegroundColor}"/>

                        <!-- 输入框 -->
                        <TextBox Text="输入框示例" Margin="0,5" Padding="5"
                                Background="{DynamicResource InputBackgroundColor}"
                                BorderBrush="{DynamicResource InputBorderColor}"/>

                        <!-- 复选框 -->
                        <CheckBox Content="复选框示例" Margin="0,5"
                                 Foreground="{DynamicResource ForegroundColor}"/>

                        <!-- 单选按钮 -->
                        <RadioButton Content="单选按钮示例" Margin="0,5"
                                    Foreground="{DynamicResource ForegroundColor}"/>
                    </StackPanel>
                </GroupBox>

                <!-- 文本示例 -->
                <GroupBox Header="文本示例">
                    <StackPanel>
                        <TextBlock Text="这是标题文本" FontSize="20" FontWeight="Bold"
                                  Foreground="{DynamicResource ForegroundColor}" Margin="0,5"/>
                        <TextBlock Text="这是正文文本。主题切换后，所有使用 DynamicResource 的颜色都会自动更新，无需重启应用。"
                                  TextWrapping="Wrap" Foreground="{DynamicResource ForegroundColor}"
                                  Margin="0,5"/>
                        <TextBlock Text="这是次要文本" FontSize="12" FontStyle="Italic"
                                  Foreground="Gray" Margin="0,5"/>
                    </StackPanel>
                </GroupBox>
            </StackPanel>
        </ScrollViewer>
    </Grid>
</Window>
```

### 4. 自定义主题颜色

```csharp
public class CustomThemeViewModel : ViewModelBase
{
    private readonly IThemeService _themeService;

    public ICommand ChangePrimaryColorCommand { get; }

    public CustomThemeViewModel(IThemeService themeService)
    {
        _themeService = themeService;

        ChangePrimaryColorCommand = new RelayCommand(() =>
        {
            // 打开颜色选择器（可以使用第三方库或自定义）
            var color = Colors.DeepSkyBlue;  // 示例：选择的颜色

            // 更新主题颜色
            _themeService.SetColor("PrimaryColor", color);
        });
    }
}
```

### 5. 主题资源字典（可选 - 高级用法）

可以创建独立的资源字典文件：

**Themes/LightTheme.xaml**:
```xml
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <SolidColorBrush x:Key="PrimaryColor" Color="#0078D7"/>
    <SolidColorBrush x:Key="BackgroundColor" Color="White"/>
    <SolidColorBrush x:Key="ForegroundColor" Color="Black"/>
    <!-- ... 其他颜色 -->
</ResourceDictionary>
```

**Themes/DarkTheme.xaml**:
```xml
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <SolidColorBrush x:Key="PrimaryColor" Color="#0078D7"/>
    <SolidColorBrush x:Key="BackgroundColor" Color="#202020"/>
    <SolidColorBrush x:Key="ForegroundColor" Color="White"/>
    <!-- ... 其他颜色 -->
</ResourceDictionary>
```

## 🎓 练习建议

### 练习1：添加更多预设主题
添加"高对比度"主题，适合视力不佳的用户。

### 练习2：主题动画过渡
在切换主题时添加颜色渐变动画，而非瞬间切换。

### 练习3：保存主题偏好
将用户选择的主题保存到配置文件，下次启动时自动应用。

### 练习4：自定义主题编辑器
创建一个界面，允许用户自定义每种颜色，并导出/导入主题配置。

## 💡 常见问题

**Q: StaticResource 和 DynamicResource 的区别？**
A:
- `StaticResource`: 编译时绑定，主题切换后不会更新
- `DynamicResource`: 运行时绑定，主题切换后自动更新（推荐用于主题）

**Q: 主题切换后部分控件没变化？**
A: 确保使用了 `{DynamicResource}` 而非 `{StaticResource}`。

**Q: 如何跟随 Windows 系统主题？**
A: 使用 `Theme.System`，Sharp.Wpf 会自动检测系统主题设置。

**Q: 能否为不同的窗口设置不同主题？**
A: 可以，但不推荐。可以为每个 Window 设置独立的 ResourceDictionary。

## 📚 延伸阅读

- [WPF 资源](https://learn.microsoft.com/zh-cn/dotnet/desktop/wpf/systems/xaml-resources-overview)
- [WPF 样式和模板](https://learn.microsoft.com/zh-cn/dotnet/desktop/wpf/controls/styles-templates-overview)
- [Windows 主题检测](https://learn.microsoft.com/zh-cn/windows/apps/desktop/modernize/apply-windows-themes)
- 综合示例：[11-FullStackDemo](../11-FullStackDemo/README.md)

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