Avalonia 动态设置主题和色彩

四套主题Default、Forest、Lavender、Nighttime，2种色彩Dark和Light

不同主题下需要显示的颜色不同，不同的色彩需要显示的图标颜色不同。

首先需要4个主题样式文件 Default.axmal、Forest.axmal、Lavender.axmal、Nighttime.axmal

2套图标资源，Dark和Light

动态实现：
1.资源(举个例子)

<Design.PreviewWith>

</Design.PreviewWith>

<ResourceDictionary.ThemeDictionaries>

avares://YourProjectName/Assets/Dark/default.png
avares://YourProjectName/Assets/Dark/auto.png
avares://YourProjectName/Assets/Dark/close.png

</ResourceDictionary.ThemeDictionaries>

2.动态加载资源：

region 定义主题色切换方法

///

/// 切换为浅色主题
///

public void SwitchToThemeColor(bool isDark)
{
if (Application.Current is { } app)
{
if (isDark)
{
app.RequestedThemeVariant = ThemeVariant.Dark;
}
else
{
app.RequestedThemeVariant = ThemeVariant.Light;
}
ThemeColorInit(isDark);
}
}
///

/// 主题色切换
///

/// 主题名称
/// 色彩类型
public void SwitchToTheme(string themeName, bool isDark)
{
if (StyleIncludes.ContainsKey(themeName))
{
var styleInclude = StyleIncludes[themeName];

    // 清空所有旧样式Application.Current.Styles.Clear();// 加载主题样式Application.Current.Styles.Add(styleInclude);Application.Current.Styles.Add(DefultStyle);if (isDark){Application.Current.RequestedThemeVariant = ThemeVariant.Dark;}else{Application.Current.RequestedThemeVariant = ThemeVariant.Light;}ThemeColorInit(isDark);
}

}
///

/// 通过选择的颜色主题，动态载入资源字典
///

private void ThemeColorInit(bool isDark)
{
try
{
var resources = App.Current.Resources.MergedDictionaries;

    // 清除现有资源字典resources.Clear();// 加载新的资源字典string sourceUri = isDark? "avares://YourProjectName/Resources/DarkResource.axaml": "avares://YourProjectName/Resources/LightResource.axaml";var newResources = new ResourceInclude(new Uri(sourceUri)){Source = new Uri(sourceUri)};resources.Add(newResources);
}
catch(Exception ex)
{Debug.WriteLine(ex.Message);
}

}

endregion

2.Image 绑定
2.1(硬绑定)

2.2 动态绑定(根据当前设置的色彩动态更新)

ResourceKeyConverter的实现(Conver文件)
///

/// ResourceKey״̬
///

public class ResourceKeyConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is string resourceKey)
{
// 获取当前主题
var currentTheme = Application.Current.RequestedThemeVariant;
// 根据当前主题获取相应的资源字典
string themeKey = currentTheme == ThemeVariant.Dark ? "Dark" : "Light";

        if (Application.Current?.Resources.TryGetResource(resourceKey, currentTheme, out var resource) == true){return resource;}}return null;
}public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{throw new NotImplementedException();
}

}