use std::fmt::{self, Display, Formatter}; use gpui::{App, BoxShadow, Hsla, hsla, point, px};use theme::{ActiveTheme, Appearance}; /// Today, elevation is primarily used to add shadows to elements, and set the correct background for elements like buttons.////// Elevation can be thought of as the physical closeness of an element to the/// user. Elements with lower elevations are physically further away on the/// z-axis and appear to be underneath elements with higher elevations.////// In the future, a more complete approach to elevation may be added.#[derive(Debug, Clone, Copy, PartialEq, Eq)]pub enum ElevationIndex {    /// On the layer of the app background. This is under panels, panes, and    /// other surfaces.    Background,    /// The primary surface – Contains panels, panes, containers, etc.    Surface,    /// The same elevation as the primary surface, but used for the editable areas, like buffers    EditorSurface,    /// A surface that is elevated above the primary surface. but below washes, models, and dragged elements.    ElevatedSurface,    /// A surface above the [ElevationIndex::ElevatedSurface] that is used for dialogs, alerts, modals, etc.    ModalSurface,} impl Display for ElevationIndex {    fn fmt(&self, f: &mut Formatter) -> fmt::Result {        match self {            ElevationIndex::Background => write!(f, "Background"),            ElevationIndex::Surface => write!(f, "Surface"),            ElevationIndex::EditorSurface => write!(f, "Editor Surface"),            ElevationIndex::ElevatedSurface => write!(f, "Elevated Surface"),            ElevationIndex::ModalSurface => write!(f, "Modal Surface"),        }    }} impl ElevationIndex {    /// Returns an appropriate shadow for the given elevation index.    pub fn shadow(self, cx: &App) -> Vec<BoxShadow> {        let is_light = cx.theme().appearance() == Appearance::Light;         match self {            ElevationIndex::Surface => vec![],            ElevationIndex::EditorSurface => vec![],             ElevationIndex::ElevatedSurface => vec![                BoxShadow {                    color: hsla(0., 0., 0., 0.12),                    offset: point(px(0.), px(2.)),                    blur_radius: px(3.),                    spread_radius: px(0.),                },                BoxShadow {                    color: hsla(0., 0., 0., if is_light { 0.03 } else { 0.06 }),                    offset: point(px(1.), px(1.)),                    blur_radius: px(0.),                    spread_radius: px(0.),                },            ],             ElevationIndex::ModalSurface => vec![                BoxShadow {                    color: hsla(0., 0., 0., if is_light { 0.06 } else { 0.12 }),                    offset: point(px(0.), px(2.)),                    blur_radius: px(3.),                    spread_radius: px(0.),                },                BoxShadow {                    color: hsla(0., 0., 0., if is_light { 0.06 } else { 0.08 }),                    offset: point(px(0.), px(3.)),                    blur_radius: px(6.),                    spread_radius: px(0.),                },                BoxShadow {                    color: hsla(0., 0., 0., 0.04),                    offset: point(px(0.), px(6.)),                    blur_radius: px(12.),                    spread_radius: px(0.),                },                BoxShadow {                    color: hsla(0., 0., 0., if is_light { 0.04 } else { 0.12 }),                    offset: point(px(1.), px(1.)),                    blur_radius: px(0.),                    spread_radius: px(0.),                },            ],             _ => vec![],        }    }     /// Returns the background color for the given elevation index.    pub fn bg(&self, cx: &mut App) -> Hsla {        match self {            ElevationIndex::Background => cx.theme().colors().background,            ElevationIndex::Surface => cx.theme().colors().surface_background,            ElevationIndex::EditorSurface => cx.theme().colors().editor_background,            ElevationIndex::ElevatedSurface => cx.theme().colors().elevated_surface_background,            ElevationIndex::ModalSurface => cx.theme().colors().elevated_surface_background,        }    }     /// Returns a color that is appropriate a filled element on this elevation    pub fn on_elevation_bg(&self, cx: &App) -> Hsla {        match self {            ElevationIndex::Background => cx.theme().colors().surface_background,            ElevationIndex::Surface => cx.theme().colors().background,            ElevationIndex::EditorSurface => cx.theme().colors().surface_background,            ElevationIndex::ElevatedSurface => cx.theme().colors().background,            ElevationIndex::ModalSurface => cx.theme().colors().background,        }    }     /// Attempts to return a darker background color than the current elevation index's background.    ///    /// If the current background color is already dark, it will return a lighter color instead.    pub fn darker_bg(&self, cx: &App) -> Hsla {        match self {            ElevationIndex::Background => cx.theme().colors().surface_background,            ElevationIndex::Surface => cx.theme().colors().editor_background,            ElevationIndex::EditorSurface => cx.theme().colors().surface_background,            ElevationIndex::ElevatedSurface => cx.theme().colors().editor_background,            ElevationIndex::ModalSurface => cx.theme().colors().editor_background,        }    }}