Flow.Launcher/Flow.Launcher.Avalonia/codemap.md

Flow.Launcher.Avalonia/

Responsibility

The Flow.Launcher.Avalonia directory is the core of the Avalonia-based UI implementation for Flow Launcher. It handles the application lifecycle, the primary search interface, and provides compatibility layers for existing plugins that were originally designed for the WPF version. It serves as the main entry point for the Avalonia flavor of the application.

Design

• MVVM (Model-View-ViewModel): Separation of UI (MainWindow.axaml) and logic (MainViewModel.cs).
• Dependency Injection (DI): Uses Microsoft.Extensions.DependencyInjection and CommunityToolkit.Mvvm's Ioc for service management.
• Bridge Pattern: AvaloniaPublicAPI adapts the IPublicAPI interface to work with Avalonia's infrastructure, allowing plugins to function without major modifications.
• Singleton: Core services like Settings, MainViewModel, and Internationalization are registered as singletons within the DI container.
• WPF Compatibility Shim: A unique architectural decision to run a background WPF Application instance to support legacy plugins that rely on System.Windows.Application.Current.

Key Classes

Class	Purpose
Program.cs	Entry point. Initializes a background WPF Application instance for plugin compatibility before starting the Avalonia app.
App.axaml.cs	Manages application lifecycle, DI container configuration, settings loading, and plugin initialization.
MainWindow.axaml.cs	Code-behind for the primary search window. Handles window positioning, focus management, and keyboard shortcuts (Escape, Arrows).
AvaloniaPublicAPI.cs	Implementation of IPublicAPI. Provides plugins with access to Flow Launcher's core functionality (Querying, UI control, Clipboard, etc.) in the Avalonia context.

Flow

Application Startup

1. Program.Main: Initializes System.Windows.Application (WPF) to provide Application.Current.Resources for legacy plugins.
2. App.Initialize:
   • Loads user settings from JSON via FlowLauncherJsonStorage.
   • Configures the DI container (ConfigureDI).
   • Injects translations into application resources.
3. App.OnFrameworkInitializationCompleted:
   • Resolves MainViewModel from DI.
   • Instantiates MainWindow.
   • Starts asynchronous plugin initialization (InitializePluginsAsync).

Search Execution

1. User input in MainWindow's QueryTextBox updates MainViewModel.QueryText via binding.
2. MainViewModel (in Flow.Launcher.Avalonia/ViewModel) triggers PluginManager to query active plugins.
3. Results are returned and displayed in the UI.

Integration

• Flow.Launcher.Core: Directly integrates with PluginManager for plugin lifecycle and Internationalization for multi-language support.
• Flow.Launcher.Infrastructure: Relies on UserSettings, Logger, and StringMatcher (fuzzy search logic).
• Flow.Launcher.Plugin: Implements the IPublicAPI interface to allow plugins to interact with the Avalonia-hosted app.
• WPF Ecosystem: Maintains a runtime dependency on WPF (System.Windows) to ensure that plugins using WPF-specific resources or Application.Current do not crash.

Avalonia vs WPF Implementation Details

• WPF Shim: Unlike the original WPF version, the Avalonia version must manually spin up a WPF environment in Program.cs to maintain plugin compatibility.
• Window Positioning: MainWindow uses Avalonia's Screens API to center itself at 25% from the top of the primary screen, mimicking the WPF behavior.
• Event Handling: Uses Avalonia-specific events like Deactivated and PointerPressed for window management and dragging.
• DI Strategy: Uses a modern ServiceCollection-based DI approach compared to the older WPF implementation's service resolution.