NeoKolors.Tui.Lifecycle.Apps 2026.4.0-preview.2

NeoKolors.Tui.Lifecycle.Apps

NeoKolors.Tui.Lifecycle.Apps provides the application hosting infrastructure, execution loop strategies, window focus management, and view binding for interactive TUI applications.

Key Components

1. Application Host (AppLifecycleHost)

AppLifecycleHost coordinates application states:

• Activation State: AppActivationState (ACTIVE, INACTIVE, SUSPENDED).
• Focus Management: Automatically manages whether the terminal has OS window focus (HasFocus).
• Terminal Resizing: Responds to terminal resize events (NotifyWindowResized(width, height)).
• Graceful Termination: Handles close requests (RequestClose(), CloseRequested event with cancellation option).

using NeoKolors.Tui.Lifecycle.Apps;

var host = new AppLifecycleHost();

host.CloseRequested += (sender, e) => {
    if (HasUnsavedChanges()) {
        e.Cancel = true; // Prevent shutdown
        ShowUnsavedDialog();
    }
};

host.Start();

2. View Presenter (NKAppView)

NKAppView connects a root IElement layout tree to an ICharScreen and HitMap:

• Manages dirty tracking (Invalidate(), IsDirty, ResetDirty()).
• Fires lifecycle events: BeforeRender, Render, AfterRender.
• Replaces or updates the active UI hierarchy seamlessly (view.RootElement = BuildUi()).

using NeoKolors.Tui.Lifecycle.Apps;

var view = new NKAppView(rootElement, screen, hitMap);

// Trigger re-render whenever state changes
stateSignal.Changed += () => {
    view.RootElement = BuildUpdatedUi();
    view.Invalidate();
};

3. Rendering Loop Strategies (IAppLoopStrategy)

ThrottledAppLoopStrategy

Maintains high frame rates when the application is focused, and throttles down when the application loses focus:

• ActiveFps: Target FPS when focused (e.g. 60 FPS).
• BackgroundFps: Target FPS when inactive (e.g. 10 FPS) to drastically reduce CPU usage.
• RenderOnlyWhenDirty: Only renders frames if view.IsDirty is true.
• SignalWakeup(): Thread-safe signal to immediately awaken the loop from sleeping on user interaction.

var loopStrategy = new ThrottledAppLoopStrategy {
    ActiveFps = 60,
    BackgroundFps = 10,
    RenderOnlyWhenDirty = true
};

while (host.State != LifecycleState.STOPPED) {
    loopStrategy.Tick(host, view);
}

LazyAppLoopStrategy

Designed for classic terminal utilities:

• Remains completely asleep until an input event, resize notification, or wakeup signal is dispatched.
• Uses 0% CPU while idle.

Complete Boilerplate Example

See Examples/ExampleApp.cs for a complete production-grade application loop using AppLifecycleHost, NKAppView, and ThrottledAppLoopStrategy.