Styling & Themes

XenoAtom.Terminal.UI uses a theme/style model built on ANSI colors and cell styling.

Theming

Theme

Theme is a set of style values used as the default environment for visuals.

Fullscreen apps typically use Theme.Default (RGB scheme).
Inline/live widgets typically use Theme.Terminal (uses terminal default colors).

Themes are resolved from the environment (Visual.GetTheme()), and can be overridden per subtree.

Applying a theme

using XenoAtom.Terminal.UI.Controls;
using XenoAtom.Terminal.UI.Styling;

var themed = new Group(new TextArea("Themed region"))
    .Style(Theme.FromScheme(ColorScheme.CherryDark));

What a Theme contains

Theme is intentionally “semantic”: controls mostly consume design tokens such as:

Surface, PopupSurface: background surfaces
ControlFill, ControlFillHover, ControlFillPressed: button-like fills
InputFill, InputFillFocused: text input surfaces
Border, FocusBorder: stroke colors
Accent, Selection: key interaction colors

For RGB schemes, many tokens are derived using subtle alpha overlays. This is how the default theme achieves “lifted” panels and soft hover effects without hard-coded colors.

Styles

Controls obtain their styles from the environment:

new Button("OK").Style(new ButtonStyle { Tone = ControlTone.Primary })

Styles can also be resolved dynamically from a factory (dependency-tracked):

var danger = new State<bool>(false);

new Button("Deploy")
    .Style(() => danger.Value
        ? (ButtonStyle.Default with { ShowBorder = true })
        : ButtonStyle.Default);

And styles can come from a binding:

var buttonStyle = new State<ButtonStyle>(ButtonStyle.Default);

new Button("Apply").Style(buttonStyle);

Style resolution follows normal environment lookup rules: nearest visual with a local value wins. Values set by Style(...), SetStyle(...), factories, and bindings all participate in this lookup.

Styles are records, so variations can be created with with:

var danger = ButtonStyle.Default with { Tone = ControlTone.Error };

Brushes and gradients

Brushes provide per-cell gradient colors while keeping the core Style representation compact.

Supported brush kinds:

Brush.Solid(...)
Brush.LinearGradient(...)

Controls with direct brush support:

TextBlockStyle.ForegroundBrush / TextBlockStyle.BackgroundBrush
TextFigletStyle.ForegroundBrush / TextFigletStyle.BackgroundBrush
TextBoxStyle.ForegroundBrush / TextBoxStyle.BackgroundBrush

Example:

var brush = Brush.LinearGradient(
    new GradientPoint(0f, 0f),
    new GradientPoint(1f, 0f),
    [new GradientStop(0f, Colors.DeepSkyBlue), new GradientStop(1f, Colors.White)]);

new TextBlock("Gradient text")
    .Style(TextBlockStyle.Default with { ForegroundBrush = brush });

The default interpolation space comes from Theme.GradientMixSpace (default ColorMixSpace.Oklab). Set mixSpaceOverride on a brush when a specific interpolation mode is required.

Color schemes

ColorScheme represents a 16-color scheme. Schemes can be:

terminal-indexed (Color.Basic16(...))
RGB (Color.Rgb(...) / Color.RgbA(...))

Root Loops schemes (built-in + generator)

XenoAtom.Terminal.UI ships with a set of curated color schemes generated with Root Loops:

Website: https://rootloops.sh by Ham Vocke
Generator code: ColorScheme.Generate(...)
Predefined schemes: ColorScheme.GetPredefinedSchemes()

Rootloops

Theme.Default and Theme.DefaultLight are built from:

ColorScheme.RootLoopsDark
ColorScheme.RootLoopsLight

You can list all built-in schemes (for example in a demo):

var schemes = ColorScheme.GetPredefinedSchemes();

Alpha blending (RGBA)

XenoAtom.Terminal.UI supports alpha-aware colors via Color.RgbA(r,g,b,a). Even though the terminal ultimately renders a single color per cell, alpha colors are blended during rendering so overlays and lifted surfaces look consistent.

Guidance:

Use low alpha for hover/focus overlays (e.g. 0x10 to 0x40).
Prefer themes for most colors; use raw RGB(A) for special-purpose visuals.

Glyphs

Rendering glyphs (borders, scrollbars, etc.) are stored in styles using Rune so controls can be re-themed without changing behavior.