gpui_component/theme/

mod.rs

use crate::{
    highlighter::HighlightTheme, list::ListSettings, notification::NotificationSettings,
    scroll::ScrollbarMode, sheet::SheetSettings,
};
use gpui::{
    App, Global, Hsla, IsZero as _, Pixels, SharedString, Window, WindowAppearance,
    prelude::FluentBuilder as _, px,
};
pub use gpui_base::{
    ColorTokens, RadiusTokens, SemanticThemeTokens, ShadowTokens, SpacingTokens, TextStyleToken,
    TypographyTokens,
};
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};
use std::{
    ops::{Deref, DerefMut},
    rc::Rc,
    sync::Arc,
    time::Duration,
};

mod color;
mod mono_font;
mod motion;
mod registry;
mod schema;
mod system_font;
mod theme_color;

pub use color::*;
pub use motion::*;
pub use registry::*;
pub use schema::*;
pub use theme_color::*;

pub fn init(cx: &mut App) {
    registry::init(cx);

    // Ensure theme is loaded directly on startup for WASM compatibility
    Theme::change(ThemeMode::Light, None, cx);
    Theme::sync_scrollbar_appearance(cx);
}

pub trait ActiveTheme {
    fn theme(&self) -> &Theme;
}

impl ActiveTheme for App {
    #[inline(always)]
    fn theme(&self) -> &Theme {
        Theme::global(self)
    }
}

fn default_true() -> bool {
    true
}

/// The radius that rounds a shape as far as its own size allows, giving a
/// circle or a pill. Any value past half the shorter side is clamped by the
/// renderer, so this is simply "as round as it goes".
const RADIUS_FULL: Pixels = px(9999.);

/// How long the scrollbar stays visible after the last scroll, drag, or hover.
const SCROLLBAR_IDLE: Duration = Duration::from_secs(2);
/// How long the scrollbar takes to appear.
const SCROLLBAR_ENTER: Duration = Duration::from_millis(300);
/// How long the scrollbar takes to fade away once the idle hold expires.
const SCROLLBAR_EXIT: Duration = Duration::from_millis(500);
/// How long the thumb takes to reach its hovered or resting width.
const SCROLLBAR_EXPAND: Duration = Duration::from_millis(300);

/// The resting thumb width on iOS and Android, matching the 3pt indicator
/// those platforms draw. Hover and drag keep Base's desktop widths, so a
/// grabbed thumb still grows under the finger.
const MOBILE_SCROLLBAR_THUMB_WIDTH: Pixels = px(3.);
/// How far the resting thumb sits from the edge on iOS and Android. Base's
/// desktop inset leaves a 3px thumb floating too far from the edge.
const MOBILE_SCROLLBAR_THUMB_INSET: Pixels = px(2.);
/// Base's resting thumb width, restated so the hovered thumb keeps it when
/// the mobile resting width would otherwise cascade into it.
const SCROLLBAR_THUMB_HOVER_WIDTH: Pixels = px(6.);
/// Base's dragged thumb width, restated for the same reason.
const SCROLLBAR_THUMB_ACTIVE_WIDTH: Pixels = px(8.);
/// Base's hovered and dragged thumb inset, restated for the same reason.
const SCROLLBAR_THUMB_INSET: Pixels = px(4.);

/// The scrollbar motion this design system projects onto Base.
///
/// Scrolling and track hover reveal a scrollbar by fading it in place. In hover
/// mode, pointing at the thumb slides it in from the nearest edge as it fades.
fn scrollbar_motion(mode: ScrollbarMode) -> gpui_base::ScrollbarMotion {
    gpui_base::ScrollbarMotion::default()
        .with_idle(SCROLLBAR_IDLE)
        .with_enter(SCROLLBAR_ENTER)
        .with_exit(SCROLLBAR_EXIT)
        .with_expand(SCROLLBAR_EXPAND)
        .with_entrance(gpui_base::ScrollbarEntrance::Fade)
        .with_thumb_hover_entrance(match mode {
            ScrollbarMode::Scrolling | ScrollbarMode::Always => gpui_base::ScrollbarEntrance::Fade,
            ScrollbarMode::Hover => gpui_base::ScrollbarEntrance::SlideAndFade,
        })
}

/// The global theme configuration.
#[derive(Debug, Clone, Serialize, Deserialize, JsonSchema)]
pub struct Theme {
    pub colors: ThemeColor,
    /// Component-specific resolved tokens retained for legacy compatibility.
    ///
    /// New application-owned presentation should use [`Self::semantic_tokens`]
    /// rather than extending this legacy surface.
    #[serde(default)]
    pub tokens: ThemeTokens,
    pub highlight_theme: Arc<HighlightTheme>,
    pub light_theme: Rc<ThemeConfig>,
    pub dark_theme: Rc<ThemeConfig>,

    pub mode: ThemeMode,
    /// The font family for the application, default is `.SystemUIFont`.
    ///
    /// When the system font resolves to an installed fallback family instead
    /// of itself (Linux desktops without the family GPUI maps it to),
    /// [`Theme::change`] names that family here, so every text lookup hits
    /// the font cache. A family set explicitly is used as-is.
    pub font_family: SharedString,
    /// The base font size for the application, default is 16px.
    pub font_size: Pixels,
    /// The monospace font family for the application.
    ///
    /// Defaults to:
    ///
    /// - macOS: `Menlo`
    /// - Windows: `Consolas`
    /// - Linux: `DejaVu Sans Mono`
    ///
    /// When that default is not installed, [`Theme::change`] swaps it for the
    /// first installed alternative (`Monaco`, `Cascadia Mono`, `Noto Sans Mono`
    /// and the like) and finally `.SystemUIFont`, so a missing font cannot
    /// crash text layout. A family set explicitly is used as-is.
    pub mono_font_family: SharedString,
    /// The monospace font size for the application, default is 13px.
    pub mono_font_size: Pixels,
    /// Radius for the general elements.
    pub radius: Pixels,
    /// Radius for the large elements, e.g.: Dialog, Notification border radius.
    pub radius_lg: Pixels,
    pub shadow: bool,
    /// Whether focused controls draw a ring outside their border, default true.
    ///
    /// The ring is painted outside the element, so any ancestor that clips its
    /// content will cut it off. An application whose layout clips heavily can
    /// turn it off here: focused controls then show only their tinted border,
    /// which costs no space and cannot be clipped.
    #[serde(default = "default_true")]
    pub focus_ring: bool,
    pub transparent: Hsla,
    /// Show the scrollbar mode, default: Scrolling
    #[serde(alias = "scrollbar_show")]
    pub scrollbar_mode: ScrollbarMode,
    /// The notification setting.
    #[serde(skip)]
    pub notification: NotificationSettings,
    /// The list settings.
    pub list: ListSettings,
    /// The sheet settings.
    pub sheet: SheetSettings,
    /// Semantic motion policy for styled components.
    #[serde(skip)]
    pub motion: MotionTokens,
}

impl Default for Theme {
    fn default() -> Self {
        Self::from(&ThemeColor::default())
    }
}

impl Deref for Theme {
    type Target = ThemeColor;

    fn deref(&self) -> &Self::Target {
        &self.colors
    }
}

impl DerefMut for Theme {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.colors
    }
}

impl Global for Theme {}

impl Theme {
    /// Returns the global theme reference
    #[inline(always)]
    pub fn global(cx: &App) -> &Theme {
        cx.global::<Theme>()
    }

    /// Returns the global theme mutable reference.
    ///
    /// An edit made through this reference reaches nothing but the field it
    /// touches: [`Theme::tokens`] keeps the colors it had, and so does the
    /// Base projection until [`Theme::sync_base`] rebuilds it. Prefer
    /// [`Theme::update`], which does both after the edit and refreshes every
    /// window. Keep this for an edit that must not trigger any of that.
    #[inline(always)]
    pub fn global_mut(cx: &mut App) -> &mut Theme {
        cx.global_mut::<Theme>()
    }

    /// Edits the global theme and keeps every copy of it in step.
    ///
    /// The theme holds the same colors twice — [`Theme::colors`] as solid
    /// colors and [`Theme::tokens`] as renderable backgrounds that may carry a
    /// gradient — and the Base layer keeps a projection of its own for the
    /// scrollbar and resize handles. Editing one of them through
    /// [`Theme::global_mut`] leaves the others where they were, so a sidebar
    /// can paint its text from the new colors and its background from the old
    /// tokens. This is the write path that cannot drift:
    ///
    /// ```ignore
    /// Theme::update(cx, |theme| {
    ///     theme.colors = my_colors;
    ///     theme.radius = px(8.);
    /// });
    /// ```
    ///
    /// After the closure returns, a color edited on `colors` replaces its
    /// token (dropping any gradient — the edit asked for that solid color), a
    /// token edited on its own writes its solid color back to `colors`, an
    /// untouched field keeps the gradient a theme file gave it, the Base
    /// projection is rebuilt, and every window is refreshed.
    ///
    /// A field the closure sets to the value it already had counts as
    /// untouched: assigning a whole palette keeps the gradient of any field
    /// whose color did not change. Edit the token to replace one.
    ///
    /// Setting [`Theme::mode`] loads that mode's registered theme, the same
    /// as [`Theme::change`]; that load replaces the colors, so edit colors in
    /// a second `update` after switching mode rather than in the same closure.
    /// [`Theme::apply_config`] installs a theme file and switches to its mode
    /// in one step, and the closure may go on editing after it — nothing is
    /// loaded over its edits.
    pub fn update<R>(cx: &mut App, edit: impl FnOnce(&mut Theme) -> R) -> R {
        Self::edit(cx, false, edit)
    }

    /// The write path behind [`Theme::update`] and [`Theme::change`].
    ///
    /// `reload_mode` loads the current mode's registered theme even when the
    /// mode did not change, which is what `change` promises: a caller that
    /// swapped [`Theme::light_theme`] or [`Theme::dark_theme`] and then asks
    /// for that mode gets the new theme applied.
    fn edit<R>(cx: &mut App, reload_mode: bool, edit: impl FnOnce(&mut Theme) -> R) -> R {
        let theme = Theme::global_mut(cx);
        let colors_before = theme.colors;
        let tokens_before = theme.tokens;
        let mode_before = theme.mode;
        let light_before = theme.light_theme.clone();
        let dark_before = theme.dark_theme.clone();
        let fonts_before = (theme.font_family.clone(), theme.mono_font_family.clone());

        let result = edit(theme);

        theme
            .tokens
            .reconcile(&mut theme.colors, &colors_before, &tokens_before);
        let mode_changed = theme.mode != mode_before;
        let (config, config_before) = if theme.mode.is_dark() {
            (&theme.dark_theme, &dark_before)
        } else {
            (&theme.light_theme, &light_before)
        };
        // `apply_config` registers the file it applies and switches to its
        // mode, so a mode change that arrives with a newly registered config
        // has already loaded it. Loading it again would put the file's radius,
        // fonts and colors back over whatever the closure edited after it.
        let installed_by_edit = mode_changed && !Rc::ptr_eq(config, config_before);
        if (mode_changed || reload_mode) && !installed_by_edit {
            let config = config.clone();
            theme.apply_config(&config);
        }
        let fonts_changed =
            (&theme.font_family, &theme.mono_font_family) != (&fonts_before.0, &fonts_before.1);
        if mode_changed || reload_mode || fonts_changed {
            system_font::resolve_default_font(cx);
            mono_font::resolve_default_mono_font(cx);
        }
        Self::sync_base(cx);
        cx.refresh_windows();
        result
    }

    /// Returns true if the theme is dark.
    #[inline(always)]
    pub fn is_dark(&self) -> bool {
        self.mode.is_dark()
    }

    /// Returns the current theme name.
    pub fn theme_name(&self) -> &SharedString {
        if self.is_dark() {
            &self.dark_theme.name
        } else {
            &self.light_theme.name
        }
    }

    /// Sync the theme with the system appearance
    pub fn sync_system_appearance(window: Option<&mut Window>, cx: &mut App) {
        // Better use window.appearance() for avoid error on Linux.
        // https://github.com/longbridge/gpui-kit/issues/104
        let appearance = window
            .as_ref()
            .map(|window| window.appearance())
            .unwrap_or_else(|| cx.window_appearance());

        Self::change(appearance, window, cx);
    }

    /// Sync the Scrollbar showing behavior with the system
    pub fn sync_scrollbar_appearance(cx: &mut App) {
        let mode = if cx.should_auto_hide_scrollbars() {
            ScrollbarMode::Scrolling
        } else {
            ScrollbarMode::Hover
        };
        Self::set_scrollbar_mode(mode, cx);
    }

    /// Changes the scrollbar display mode through [`Theme::update`], which
    /// projects it onto the Base scrollbar and refreshes every window.
    pub fn set_scrollbar_mode(mode: ScrollbarMode, cx: &mut App) {
        Self::update(cx, |theme| theme.scrollbar_mode = mode);
    }

    /// Change the theme mode.
    ///
    /// Loads the registered theme for `mode` — even when `mode` is already
    /// current, so a caller that swapped [`Theme::light_theme`] or
    /// [`Theme::dark_theme`] sees the new theme — through [`Theme::update`],
    /// which keeps every copy of the theme in step and refreshes every
    /// window. `window` is accepted for compatibility; every window is
    /// refreshed either way, so it is not read.
    pub fn change(mode: impl Into<ThemeMode>, _window: Option<&mut Window>, cx: &mut App) {
        let mode = mode.into();
        if !cx.has_global::<Theme>() {
            let mut theme = Theme::default();
            theme.light_theme = ThemeRegistry::global(cx).default_light_theme().clone();
            theme.dark_theme = ThemeRegistry::global(cx).default_dark_theme().clone();
            cx.set_global(theme);
        }

        Self::edit(cx, true, |theme| theme.mode = mode);
    }

    /// This theme projected onto the Base layer, which owns the scrollbar and
    /// resize handles and reads the semantic tokens.
    fn base_theme(&self) -> gpui_base::Theme {
        gpui_base::Theme {
            appearance: if self.mode.is_dark() {
                gpui_base::ThemeAppearance::Dark
            } else {
                gpui_base::ThemeAppearance::Light
            },
            tokens: self.semantic_tokens(),
            scrollbar: gpui_base::ScrollbarTheme::new()
                .with_mode(self.scrollbar_mode)
                .with_motion(scrollbar_motion(self.scrollbar_mode))
                .with_styles(
                    gpui_base::ScrollbarStyles::default()
                        .track(|style| style.bg(self.scrollbar))
                        .track_hover(|style| style.bg(self.scrollbar))
                        .track_active(|style| style.bg(self.scrollbar).border_color(self.border))
                        .thumb(|style| {
                            style
                                .bg(self.tokens.scrollbar_thumb)
                                .radius(self.radius)
                                .when(gpui_base::is_mobile(), |style| {
                                    style
                                        .width(MOBILE_SCROLLBAR_THUMB_WIDTH)
                                        .inset(MOBILE_SCROLLBAR_THUMB_INSET)
                                        .radius(RADIUS_FULL)
                                })
                        })
                        .thumb_hover(|style| {
                            style
                                .bg(self.tokens.scrollbar_thumb_hover)
                                .radius(self.radius)
                                .when(gpui_base::is_mobile(), |style| {
                                    style
                                        .width(SCROLLBAR_THUMB_HOVER_WIDTH)
                                        .inset(SCROLLBAR_THUMB_INSET)
                                })
                        })
                        .thumb_active(|style| {
                            style
                                .bg(self.tokens.scrollbar_thumb_hover)
                                .radius(self.radius)
                                .when(gpui_base::is_mobile(), |style| {
                                    style
                                        .width(SCROLLBAR_THUMB_ACTIVE_WIDTH)
                                        .inset(SCROLLBAR_THUMB_INSET)
                                })
                        }),
                ),
            resizable: gpui_base::ResizableTheme {
                handle: Some(self.border),
                active_handle: Some(self.drag_border),
            },
        }
    }

    /// Push the current theme down to the Base layer.
    ///
    /// The Base layer holds its own copy of the theme — the semantic tokens
    /// plus the scrollbar and resize-handle styles — because it paints those
    /// without going through `gpui-component`. [`Theme::change`] refreshes that
    /// copy, but writing to the theme's public fields directly does not, so a
    /// scrollbar keeps painting with the radius and colors it was last given.
    ///
    /// [`Theme::update`] and [`Theme::change`] call this after their edits.
    /// After editing through [`Theme::global_mut`], call it yourself, then
    /// refresh the windows.
    ///
    /// It rebuilds the Base theme from scratch, so any style written straight
    /// onto the Base global is replaced. It does not touch [`Theme::tokens`].
    pub fn sync_base(cx: &mut App) {
        let theme = Theme::global(cx).clone();
        let base_theme = theme.base_theme();
        cx.set_global(base_theme);
        crate::text::install_text_view_defaults(&theme, cx);
    }

    /// Get the input background color.
    ///
    /// For dark, use a transparent color mixed with the input border: `cx.theme().input`,
    /// otherwise use the `cx.theme().background` color.
    #[inline]
    pub fn input_background(&self) -> Hsla {
        if self.is_dark() {
            self.input.mix_oklab(self.transparent, 0.3)
        } else {
            self.background
        }
    }

    /// Get the editor background color, if not set, use the input background color.
    #[inline]
    pub(crate) fn editor_background(&self) -> Hsla {
        self.highlight_theme
            .style
            .editor_background
            .unwrap_or_else(|| self.input_background())
    }

    /// Returns a snapshot of the semantic design tokens represented by this
    /// theme. The snapshot is computed from the legacy public fields so direct
    /// mutations of those fields are reflected immediately.
    pub fn semantic_tokens(&self) -> SemanticThemeTokens {
        SemanticThemeTokens {
            colors: self.color_tokens(),
            radius: self.radius_tokens(),
            spacing: self.spacing_tokens(),
            typography: self.typography_tokens(),
            shadow: self.shadow_tokens(),
        }
    }

    /// Returns the styled layer's semantic motion policy.
    pub fn motion_tokens(&self) -> &MotionTokens {
        &self.motion
    }

    pub fn color_tokens(&self) -> ColorTokens {
        ColorTokens {
            background: self.background,
            foreground: self.foreground,
            surface: self.popover,
            surface_foreground: self.popover_foreground,
            primary: self.primary,
            primary_foreground: self.primary_foreground,
            secondary: self.secondary,
            secondary_foreground: self.secondary_foreground,
            muted: self.muted,
            muted_foreground: self.muted_foreground,
            accent: self.accent,
            accent_foreground: self.accent_foreground,
            destructive: self.danger,
            destructive_foreground: self.danger_foreground,
            border: self.border,
            input: self.input,
            ring: self.ring,
            selection: self.selection,
        }
    }

    /// The radius of a shape that reads as a circle or a pill — an avatar, a
    /// slider thumb, a badge dot, a pill tab.
    ///
    /// A theme whose [`Theme::radius`] is zero squares these off too, so one
    /// setting governs the whole UI instead of leaving a handful of
    /// permanently round elements behind. Use it in place of
    /// [`gpui::Styled::rounded_full`], or reach for
    /// [`crate::ThemeStyled::rounded_full_style`] when styling an element.
    pub fn radius_full(&self) -> Pixels {
        if self.radius.is_zero() {
            px(0.)
        } else {
            RADIUS_FULL
        }
    }

    /// Returns the next surface radius above the existing `xl` theme tier.
    ///
    /// Larger surface tiers derive from the same application-controlled base
    /// radius, so adjusting or squaring the theme updates every tier together.
    pub fn radius_2xl(&self) -> Pixels {
        self.radius * 2.5
    }

    /// Returns the surface radius above [`Self::radius_2xl`].
    pub fn radius_3xl(&self) -> Pixels {
        self.radius * 3.
    }

    /// Returns the surface radius above [`Self::radius_3xl`].
    pub fn radius_4xl(&self) -> Pixels {
        self.radius * 3.5
    }

    pub fn radius_tokens(&self) -> RadiusTokens {
        RadiusTokens {
            none: px(0.),
            sm: self.radius / 2.,
            md: self.radius,
            lg: self.radius_lg,
            xl: self.radius * 2.,
            full: self.radius_full(),
        }
    }

    pub fn spacing_tokens(&self) -> SpacingTokens {
        SpacingTokens::default()
    }

    pub fn typography_tokens(&self) -> TypographyTokens {
        let mut tokens = TypographyTokens::default();
        tokens.sans = self.font_family.clone();
        tokens.mono = self.mono_font_family.clone();
        tokens.md.size = self.font_size;
        tokens.mono_md.size = self.mono_font_size;
        tokens
    }

    pub fn shadow_tokens(&self) -> ShadowTokens {
        if self.shadow {
            ShadowTokens::elevations(self.transparent.alpha(0.18))
        } else {
            ShadowTokens::default()
        }
    }

    /// Applies the subset of semantic tokens representable by the legacy
    /// theme. Scale-only spacing and elevation details have no legacy storage;
    /// legacy components therefore keep their existing behavior.
    pub fn apply_semantic_tokens(&mut self, tokens: &SemanticThemeTokens) {
        let colors = tokens.colors;
        self.background = colors.background;
        self.foreground = colors.foreground;
        self.popover = colors.surface;
        self.popover_foreground = colors.surface_foreground;
        self.primary = colors.primary;
        self.primary_foreground = colors.primary_foreground;
        self.secondary = colors.secondary;
        self.secondary_foreground = colors.secondary_foreground;
        self.muted = colors.muted;
        self.muted_foreground = colors.muted_foreground;
        self.accent = colors.accent;
        self.accent_foreground = colors.accent_foreground;
        self.danger = colors.destructive;
        self.danger_foreground = colors.destructive_foreground;
        self.border = colors.border;
        self.input = colors.input;
        self.ring = colors.ring;

        self.tokens.background = colors.background.into();
        self.tokens.popover = colors.surface.into();
        self.tokens.primary = colors.primary.into();
        self.tokens.secondary = colors.secondary.into();
        self.tokens.muted = colors.muted.into();
        self.tokens.accent = colors.accent.into();
        self.tokens.danger = colors.destructive.into();

        self.radius = tokens.radius.md;
        self.radius_lg = tokens.radius.lg;
        self.font_family = tokens.typography.sans.clone();
        self.mono_font_family = tokens.typography.mono.clone();
        self.font_size = tokens.typography.md.size;
        self.mono_font_size = tokens.typography.mono_md.size;
        self.shadow = !tokens.shadow.sm.is_empty()
            || !tokens.shadow.md.is_empty()
            || !tokens.shadow.lg.is_empty();
    }

    /// Resolves a standalone semantic configuration over the current legacy
    /// theme without mutating either value.
    pub fn resolve_semantic_config(&self, config: &SemanticThemeConfig) -> SemanticThemeTokens {
        let mut tokens = self.semantic_tokens();
        config.apply_to(&mut tokens);
        tokens
    }

    /// Applies the legacy-representable part of a standalone semantic config
    /// and returns the complete resolved snapshot for application-owned UI.
    pub fn apply_semantic_config(&mut self, config: &SemanticThemeConfig) -> SemanticThemeTokens {
        let tokens = self.resolve_semantic_config(config);
        self.apply_semantic_tokens(&tokens);
        tokens
    }

    /// Parses and applies a standalone `{ "tokens": ... }` semantic theme file.
    pub fn apply_semantic_config_str(
        &mut self,
        content: &str,
    ) -> anyhow::Result<SemanticThemeTokens> {
        let config = serde_json::from_str::<SemanticThemeConfigFile>(content)?;
        Ok(self.apply_semantic_config(&config.tokens))
    }
}

#[cfg(test)]
mod semantic_token_tests {
    use gpui::{Hsla, IsZero as _, px};

    use super::{RADIUS_FULL, Theme};

    #[test]
    fn semantic_colors_are_a_live_projection_of_legacy_fields() {
        let mut theme = Theme::default();
        let primary = Hsla::default().alpha(0.42);
        theme.primary = primary;

        assert_eq!(theme.color_tokens().primary, primary);
        assert_eq!(theme.semantic_tokens().colors.primary, primary);
    }

    #[test]
    fn applying_semantic_tokens_only_updates_generic_legacy_colors() {
        let mut theme = Theme::default();
        let component_color = theme.button_primary;
        let mut tokens = theme.semantic_tokens();
        tokens.colors.primary = Hsla::default().alpha(0.25);
        tokens.colors.destructive = Hsla::default().alpha(0.75);
        tokens.radius.md = px(10.);

        theme.apply_semantic_tokens(&tokens);

        assert_eq!(theme.primary, tokens.colors.primary);
        assert_eq!(theme.tokens.primary.color, tokens.colors.primary);
        assert_eq!(theme.danger, tokens.colors.destructive);
        assert_eq!(theme.radius, px(10.));
        assert_eq!(theme.button_primary, component_color);
    }

    #[test]
    fn square_themes_square_off_pills_and_circles() {
        let mut theme = Theme::default();
        assert_eq!(theme.radius_full(), RADIUS_FULL);
        assert_eq!(theme.radius_tokens().full, RADIUS_FULL);

        // An application asking for square corners gets them everywhere, not
        // just on the elements whose radius happens to come from `radius`.
        theme.radius = px(0.);
        assert_eq!(theme.radius_full(), px(0.));
        assert_eq!(theme.radius_tokens().full, px(0.));
    }

    #[test]
    fn larger_surface_radii_follow_the_theme_radius() {
        let mut theme = Theme::default();
        assert!(theme.radius_tokens().xl < theme.radius_2xl());
        assert!(theme.radius_2xl() < theme.radius_3xl());
        assert!(theme.radius_3xl() < theme.radius_4xl());

        theme.radius = px(10.);
        assert_eq!(theme.radius_2xl(), px(25.));
        assert_eq!(theme.radius_3xl(), px(30.));
        assert_eq!(theme.radius_4xl(), px(35.));

        theme.radius = px(0.);
        assert_eq!(theme.radius_2xl(), px(0.));
        assert_eq!(theme.radius_3xl(), px(0.));
        assert_eq!(theme.radius_4xl(), px(0.));
    }

    #[test]
    fn base_projection_carries_a_square_radius_to_the_scrollbar() {
        let mut theme = Theme::default();
        assert!(!theme.base_theme().tokens.radius.md.is_zero());

        // The scrollbar paints from the Base layer's copy of the theme, so a
        // square theme has to reach it or the thumb stays a pill.
        theme.radius = px(0.);
        assert!(theme.base_theme().tokens.radius.md.is_zero());
    }

    #[test]
    fn disabled_legacy_shadows_project_to_empty_elevations() {
        let mut theme = Theme::default();
        theme.shadow = false;

        let shadows = theme.shadow_tokens();
        assert!(shadows.sm.is_empty());
        assert!(shadows.md.is_empty());
        assert!(shadows.lg.is_empty());
    }
}

impl From<&ThemeColor> for Theme {
    fn from(colors: &ThemeColor) -> Self {
        Theme {
            mode: ThemeMode::default(),
            transparent: Hsla::transparent_black(),
            font_family: ".SystemUIFont".into(),
            font_size: px(16.),
            mono_font_family: mono_font::default_mono_font_family(),
            mono_font_size: px(13.),
            radius: px(6.),
            radius_lg: px(8.),
            shadow: true,
            focus_ring: true,
            scrollbar_mode: ScrollbarMode::default(),
            notification: NotificationSettings::default(),
            list: ListSettings::default(),
            colors: *colors,
            tokens: ThemeTokens::from(colors),
            light_theme: Rc::new(ThemeConfig::default()),
            dark_theme: Rc::new(ThemeConfig::default()),
            highlight_theme: HighlightTheme::default_light(),
            sheet: SheetSettings::default(),
            motion: MotionTokens::default(),
        }
    }
}

#[derive(
    Debug,
    Clone,
    Copy,
    Default,
    PartialEq,
    PartialOrd,
    Eq,
    Ord,
    Hash,
    Serialize,
    Deserialize,
    JsonSchema,
)]
#[serde(rename_all = "snake_case")]
pub enum ThemeMode {
    #[default]
    Light,
    Dark,
}

impl ThemeMode {
    #[inline(always)]
    pub fn is_dark(&self) -> bool {
        matches!(self, Self::Dark)
    }

    /// Return lower_case theme name: `light`, `dark`.
    pub fn name(&self) -> &'static str {
        match self {
            ThemeMode::Light => "light",
            ThemeMode::Dark => "dark",
        }
    }
}

impl From<WindowAppearance> for ThemeMode {
    fn from(appearance: WindowAppearance) -> Self {
        match appearance {
            WindowAppearance::Dark | WindowAppearance::VibrantDark => Self::Dark,
            WindowAppearance::Light | WindowAppearance::VibrantLight => Self::Light,
        }
    }
}

#[cfg(test)]
mod update_tests {
    use super::*;
    use gpui::{TestAppContext, linear_color_stop, linear_gradient};

    fn gradient(from: Hsla, to: Hsla) -> ThemeToken {
        ThemeToken::new(
            from,
            linear_gradient(135., linear_color_stop(from, 0.), linear_color_stop(to, 1.)),
        )
    }

    /// A color edited on `colors` reaches the token the components paint
    /// with, and the Base projection the scrollbar paints with.
    #[gpui::test]
    fn editing_colors_updates_the_tokens_and_the_base_projection(cx: &mut TestAppContext) {
        cx.update(|cx| {
            init(cx);
            let sidebar = gpui::rgb(0x123456).into();
            let primary = gpui::rgb(0xabcdef).into();

            Theme::update(cx, |theme| {
                theme.sidebar = sidebar;
                theme.colors.primary = primary;
                theme.radius = px(0.);
            });

            let theme = Theme::global(cx);
            assert_eq!(theme.tokens.sidebar.color, sidebar);
            assert_eq!(theme.tokens.sidebar.background, sidebar.into());
            assert_eq!(theme.tokens.primary.color, primary);
            assert_eq!(gpui_base::Theme::global(cx).tokens.colors.primary, primary);
            assert!(gpui_base::Theme::global(cx).tokens.radius.md.is_zero());
        });
    }

    /// Replacing the whole `colors` struct, as an application installing its
    /// own palette does, rewrites every token.
    #[gpui::test]
    fn replacing_the_palette_rewrites_every_token(cx: &mut TestAppContext) {
        cx.update(|cx| {
            init(cx);
            let palette = *ThemeColor::dark();

            Theme::update(cx, |theme| theme.colors = palette);

            assert_eq!(Theme::global(cx).tokens, ThemeTokens::from(palette));
        });
    }

    /// A gradient a theme file gave a token survives edits to other fields;
    /// editing that field's color replaces the gradient with the solid color.
    #[gpui::test]
    fn a_gradient_survives_until_its_own_color_is_edited(cx: &mut TestAppContext) {
        cx.update(|cx| {
            init(cx);
            let from = gpui::rgb(0x4f46e5).into();
            let to = gpui::rgb(0x06b6d4).into();
            let token = gradient(from, to);
            Theme::update(cx, |theme| theme.tokens.primary = token);
            // The token's solid color is written back, so text painted with
            // `theme.primary` matches the gradient's representative color.
            assert_eq!(Theme::global(cx).primary, from);

            Theme::update(cx, |theme| theme.secondary = gpui::rgb(0x222222).into());
            assert_eq!(Theme::global(cx).tokens.primary, token);

            let solid = gpui::rgb(0x999999).into();
            Theme::update(cx, |theme| theme.primary = solid);
            assert_eq!(Theme::global(cx).tokens.primary, solid.into());
        });
    }

    /// Setting `mode` through `update` loads that mode's theme, the same as
    /// `change`, and the Base projection follows.
    #[gpui::test]
    fn setting_the_mode_loads_that_modes_theme(cx: &mut TestAppContext) {
        cx.update(|cx| {
            init(cx);
            let light_background = Theme::global(cx).background;

            Theme::update(cx, |theme| theme.mode = ThemeMode::Dark);

            let theme = Theme::global(cx);
            assert!(theme.is_dark());
            assert_ne!(theme.background, light_background);
            assert_eq!(theme.tokens.background.color, theme.background);
            assert_eq!(
                gpui_base::Theme::global(cx).appearance,
                gpui_base::ThemeAppearance::Dark
            );
            assert_eq!(
                gpui_base::Theme::global(cx).tokens.colors.background,
                theme.background
            );
        });
    }

    /// Applying a theme file through `update` keeps the gradients it
    /// declares: the config sets `colors` and `tokens` to one color, which is
    /// not a conflict to resolve.
    #[gpui::test]
    fn applying_a_config_keeps_its_gradients(cx: &mut TestAppContext) {
        cx.update(|cx| {
            init(cx);
            let config: ThemeConfig = serde_json::from_value(serde_json::json!({
                "name": "Gradient",
                "mode": "light",
                "colors": {
                    "primary": "#4F46E5",
                    "primary.background": "linear-gradient(135deg, #4F46E5, #06B6D4)"
                }
            }))
            .unwrap();
            let config = Rc::new(config);

            Theme::update(cx, |theme| theme.apply_config(&config));

            let theme = Theme::global(cx);
            assert_eq!(theme.tokens.primary.color, theme.primary);
            assert_ne!(
                theme.tokens.primary.background,
                theme.primary.into(),
                "the gradient must survive the reconcile"
            );
        });
    }

    /// `apply_config` switches to the file's mode itself, so `edit` must not
    /// load that mode's theme a second time over what the closure went on to
    /// set — the same closure has to land the same result from either mode.
    #[gpui::test]
    fn edits_after_applying_a_config_of_the_other_mode_survive(cx: &mut TestAppContext) {
        cx.update(|cx| {
            init(cx);
            let config: ThemeConfig = serde_json::from_value(serde_json::json!({
                "name": "Rounded Dark",
                "mode": "dark",
                "radius": 12,
                "colors": { "primary": "#4F46E5" }
            }))
            .unwrap();
            let config = Rc::new(config);
            assert!(!Theme::global(cx).is_dark());

            let red = gpui::red();
            Theme::update(cx, |theme| {
                theme.apply_config(&config);
                theme.radius = px(0.);
                theme.colors.primary = red;
            });

            let theme = Theme::global(cx);
            assert!(theme.is_dark());
            assert!(Rc::ptr_eq(&theme.dark_theme, &config));
            assert_eq!(theme.radius, px(0.), "the file's radius must not reload");
            assert_eq!(theme.primary, red);
            assert_eq!(theme.tokens.primary, red.into());
            assert_eq!(gpui_base::Theme::global(cx).tokens.colors.primary, red);
        });
    }

    #[gpui::test]
    fn update_returns_the_closure_result(cx: &mut TestAppContext) {
        cx.update(|cx| {
            init(cx);
            let radius = Theme::update(cx, |theme| {
                theme.radius = px(6.);
                theme.radius
            });
            assert_eq!(radius, px(6.));
        });
    }
}

#[cfg(test)]
mod base_theme_projection_tests {
    use super::*;
    use gpui::TestAppContext;

    #[gpui::test]
    fn base_theme_tracks_initialization_and_mode_changes(cx: &mut TestAppContext) {
        cx.update(|cx| {
            init(cx);
            assert_styled_projection(cx);

            Theme::change(ThemeMode::Dark, None, cx);
            assert_styled_projection(cx);

            Theme::set_scrollbar_mode(ScrollbarMode::Always, cx);
            assert_eq!(Theme::global(cx).scrollbar_mode, ScrollbarMode::Always);
            assert_eq!(
                gpui_base::Theme::global(cx).scrollbar.mode(),
                gpui_base::ScrollbarMode::Always
            );
            assert_styled_projection(cx);
        });
    }

    #[gpui::test]
    fn scrollbar_motion_is_owned_here_and_projected_onto_base(cx: &mut TestAppContext) {
        cx.update(|cx| {
            init(cx);

            // Base itself ships none of this timing.
            let bare = gpui_base::ScrollbarMotion::default();
            assert_eq!(bare.enter(), Duration::ZERO);
            assert_eq!(bare.exit(), Duration::ZERO);
            assert_eq!(bare.expand(), Duration::ZERO);

            Theme::set_scrollbar_mode(ScrollbarMode::Scrolling, cx);
            let motion = gpui_base::Theme::global(cx).scrollbar.motion();
            assert_eq!(motion.idle(), SCROLLBAR_IDLE);
            assert_eq!(motion.enter(), SCROLLBAR_ENTER);
            assert_eq!(motion.exit(), SCROLLBAR_EXIT);
            assert_eq!(motion.expand(), SCROLLBAR_EXPAND);
            assert_eq!(
                motion.entrance(),
                gpui_base::ScrollbarEntrance::Fade,
                "scroll-revealed scrollbars fade in without sliding"
            );

            Theme::set_scrollbar_mode(ScrollbarMode::Hover, cx);
            let motion = gpui_base::Theme::global(cx).scrollbar.motion();
            assert_eq!(motion.entrance(), gpui_base::ScrollbarEntrance::Fade);
            assert_eq!(
                motion.thumb_hover_entrance(),
                gpui_base::ScrollbarEntrance::SlideAndFade
            );
        });
    }

    #[test]
    fn default_motion_tokens_form_a_coherent_semantic_scale() {
        let theme = Theme::default();
        let motion = theme.motion_tokens();

        assert_eq!(motion.duration_instant, Duration::ZERO);
        assert!(motion.duration_fast < motion.duration_normal);
        assert!(motion.duration_normal < motion.duration_slow);
        assert!(motion.distance_short.0 < motion.distance_medium.0);
        assert_eq!(motion.easing_enter.sample(0.0), 0.0);
        assert_eq!(motion.easing_enter.sample(1.0), 1.0);
    }

    fn assert_styled_projection(cx: &App) {
        let theme = Theme::global(cx);
        let base = gpui_base::Theme::global(cx);

        assert_eq!(base.tokens, theme.semantic_tokens());
        assert_eq!(base.scrollbar.mode(), theme.scrollbar_mode);
        assert_eq!(
            base.scrollbar.motion(),
            scrollbar_motion(theme.scrollbar_mode)
        );
        assert_eq!(base.resizable.handle, Some(theme.border));
        assert_eq!(base.resizable.active_handle, Some(theme.drag_border));
    }

    #[gpui::test]
    fn default_component_palettes_match_base_light_and_dark_tokens(cx: &mut gpui::TestAppContext) {
        fn assert_close(left: ColorTokens, right: ColorTokens) {
            macro_rules! color {
                ($field:ident) => {
                    assert!(
                        (left.$field.h - right.$field.h).abs() < 1e-6
                            && (left.$field.s - right.$field.s).abs() < 1e-6
                            && (left.$field.l - right.$field.l).abs() < 1e-6
                            && (left.$field.a - right.$field.a).abs() < 1e-6,
                        "{} differs: {:?} != {:?}",
                        stringify!($field),
                        left.$field,
                        right.$field
                    );
                };
            }
            color!(background);
            color!(foreground);
            color!(surface);
            color!(surface_foreground);
            color!(primary);
            color!(primary_foreground);
            color!(secondary);
            color!(secondary_foreground);
            color!(muted);
            color!(muted_foreground);
            color!(accent);
            color!(accent_foreground);
            color!(destructive);
            color!(destructive_foreground);
            color!(border);
            color!(input);
            color!(ring);
            color!(selection);
        }

        cx.update(crate::init);
        cx.update(|cx| {
            assert_close(Theme::global(cx).color_tokens(), ColorTokens::light());
        });

        cx.update(|cx| Theme::change(ThemeMode::Dark, None, cx));
        cx.update(|cx| {
            assert_close(Theme::global(cx).color_tokens(), ColorTokens::dark());
        });
    }
}