avalonia-app-development

Avalonia App Development

Overview

Avalonia app entry: Program.cs builds and runs an AppBuilder. App.axaml + App.axaml.cs is the root. Platform lifetime determines how the app runs (Desktop vs Single-view for mobile/WASM).

Program.cs

using Avalonia;
// using ReactiveUI.Avalonia;  // (12.0+) ReactiveUI.Avalonia package — only if using ReactiveUI
// using Avalonia.ReactiveUI;  // (11.x) Avalonia.ReactiveUI package, last release 11.3.x

class Program
{
    [STAThread]
    public static void Main(string[] args) => BuildAvaloniaApp()
        .StartWithClassicDesktopLifetime(args);

    public static AppBuilder BuildAvaloniaApp()
        => AppBuilder.Configure<App>()
            .UsePlatformDetect()
            .WithInterFont()
            .LogToTrace();
            // .UseReactiveUI(_ => { }).RegisterReactiveUIViewsFromEntryAssembly() // (12.0+) ReactiveUI.Avalonia
            // .UseReactiveUI() // (11.x) Avalonia.ReactiveUI
}

UsePlatformDetect() configures Skia + HarfBuzz. With explicit .UseSkia() in 12, also call .UseHarfBuzz() (Avalonia.HarfBuzz package) or startup throws No text shaping system configured. (12.0+)

Dev tools: Avalonia.Diagnostics + AttachDevTools() (11.x) → AvaloniaUI.DiagnosticsSupport package + AttachDeveloperTools() in App.OnFrameworkInitializationCompleted (12.0+).

App.axaml

<Application xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="MyApp.App"
             RequestedThemeVariant="Default">
    <Application.DataTemplates>
        <local:ViewLocator/>
    </Application.DataTemplates>
    <Application.Styles>
        <FluentTheme/>
    </Application.Styles>
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceInclude Source="avares://MyApp/Assets/Colors.axaml"/>
            </ResourceDictionary.MergedDictionaries>
            <SolidColorBrush x:Key="AccentBrush" Color="#FF5722"/>
        </ResourceDictionary>
    </Application.Resources>
</Application>