bite-gp-engine 1.25.202

//! Font identity, metrics, and rendering parameter types shared by `gpui` and its platform backends.

use anyhow::Result;
use derive_more::{Add, FromStr, Sub};
use gpui_shared_string::SharedString;
use gpui_types::{
    Bounds, DevicePixels, Hsla, Pixels, Point, Size, StrikethroughStyle, UnderlineStyle, point, px,
    size,
};
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};
use smallvec::SmallVec;
use std::borrow::Cow;
use std::fmt::{Debug, Display, Formatter};
use std::hash::{Hash, Hasher};
use std::sync::Arc;

/// Number of subpixel glyph variants along the X axis.
pub const SUBPIXEL_VARIANTS_X: u8 = 4;

/// Number of subpixel glyph variants along the Y axis.
pub const SUBPIXEL_VARIANTS_Y: u8 = 1;

use crate::{FontFallbacks, FontFeatures, FontId, GlyphId, RenderGlyphParams};

/// An opaque identifier for a specific font family.
#[derive(Hash, PartialEq, Eq, Clone, Copy, Debug)]
pub struct FontFamilyId(pub usize);

/// The degree of blackness or stroke thickness of a font. This value ranges from 100.0 to 900.0,
/// with 400.0 as normal.
#[derive(Clone, Copy, Debug, PartialEq, PartialOrd, Serialize, Deserialize, Add, Sub, FromStr)]
#[serde(transparent)]
pub struct FontWeight(pub f32);

impl Display for FontWeight {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl From<f32> for FontWeight {
    fn from(weight: f32) -> Self {
        FontWeight(weight)
    }
}

impl Default for FontWeight {
    #[inline]
    fn default() -> FontWeight {
        FontWeight::NORMAL
    }
}

impl Hash for FontWeight {
    fn hash<H: Hasher>(&self, state: &mut H) {
        state.write_u32(u32::from_be_bytes(self.0.to_be_bytes()));
    }
}

impl Eq for FontWeight {}

impl FontWeight {
    /// Thin weight (100), the thinnest value.
    pub const THIN: FontWeight = FontWeight(100.0);
    /// Extra light weight (200).
    pub const EXTRA_LIGHT: FontWeight = FontWeight(200.0);
    /// Light weight (300).
    pub const LIGHT: FontWeight = FontWeight(300.0);
    /// Normal (400).
    pub const NORMAL: FontWeight = FontWeight(400.0);
    /// Medium weight (500, higher than normal).
    pub const MEDIUM: FontWeight = FontWeight(500.0);
    /// Semibold weight (600).
    pub const SEMIBOLD: FontWeight = FontWeight(600.0);
    /// Bold weight (700).
    pub const BOLD: FontWeight = FontWeight(700.0);
    /// Extra-bold weight (800).
    pub const EXTRA_BOLD: FontWeight = FontWeight(800.0);
    /// Black weight (900), the thickest value.
    pub const BLACK: FontWeight = FontWeight(900.0);

    /// All of the font weights, in order from thinnest to thickest.
    pub const ALL: [FontWeight; 9] = [
        Self::THIN,
        Self::EXTRA_LIGHT,
        Self::LIGHT,
        Self::NORMAL,
        Self::MEDIUM,
        Self::SEMIBOLD,
        Self::BOLD,
        Self::EXTRA_BOLD,
        Self::BLACK,
    ];
}

impl schemars::JsonSchema for FontWeight {
    fn schema_name() -> Cow<'static, str> {
        "FontWeight".into()
    }

    fn json_schema(_: &mut schemars::SchemaGenerator) -> schemars::Schema {
        use schemars::json_schema;
        json_schema!({
            "type": "number",
            "minimum": Self::THIN,
            "maximum": Self::BLACK,
            "default": Self::default(),
            "description": "Font weight value between 100 (thin) and 900 (black)"
        })
    }
}

/// Allows italic or oblique faces to be selected.
#[derive(Clone, Copy, Eq, PartialEq, Debug, Hash, Default, Serialize, Deserialize, JsonSchema)]
pub enum FontStyle {
    /// A face that is neither italic not obliqued.
    #[default]
    Normal,
    /// A form that is generally cursive in nature.
    Italic,
    /// A typically-sloped version of the regular face.
    Oblique,
}

impl Display for FontStyle {
    fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
        Debug::fmt(self, f)
    }
}

/// The configuration details for identifying a specific font.
#[derive(Clone, Debug, Eq, PartialEq, Hash)]
pub struct Font {
    /// The font family name.
    ///
    /// The special name ".SystemUIFont" is used to identify the system UI font, which varies based on platform.
    pub family: SharedString,

    /// The font features to use.
    pub features: FontFeatures,

    /// The fallbacks fonts to use.
    pub fallbacks: Option<FontFallbacks>,

    /// The font weight.
    pub weight: FontWeight,

    /// The font style.
    pub style: FontStyle,
}

impl Default for Font {
    fn default() -> Self {
        font(".SystemUIFont")
    }
}

/// Get a [`Font`] for a given name.
pub fn font(family: impl Into<SharedString>) -> Font {
    Font {
        family: family.into(),
        features: FontFeatures::default(),
        weight: FontWeight::default(),
        style: FontStyle::default(),
        fallbacks: None,
    }
}

impl Font {
    /// Set this Font to be bold
    pub fn bold(mut self) -> Self {
        self.weight = FontWeight::BOLD;
        self
    }

    /// Set this Font to be italic
    pub fn italic(mut self) -> Self {
        self.style = FontStyle::Italic;
        self
    }
}

/// A struct for storing font metrics.
/// It is used to define the measurements of a typeface.
#[derive(Clone, Copy, Debug)]
pub struct FontMetrics {
    /// The number of font units that make up the "em square",
    /// a scalable grid for determining the size of a typeface.
    pub units_per_em: u32,

    /// The vertical distance from the baseline of the font to the top of the glyph covers.
    pub ascent: f32,

    /// The vertical distance from the baseline of the font to the bottom of the glyph covers.
    pub descent: f32,

    /// The recommended additional space to add between lines of type.
    pub line_gap: f32,

    /// The suggested position of the underline.
    pub underline_position: f32,

    /// The suggested thickness of the underline.
    pub underline_thickness: f32,

    /// The height of a capital letter measured from the baseline of the font.
    pub cap_height: f32,

    /// The height of a lowercase x.
    pub x_height: f32,

    /// The outer limits of the area that the font covers.
    /// Corresponds to the xMin / xMax / yMin / yMax values in the OpenType `head` table
    pub bounding_box: Bounds<f32>,
}

impl FontMetrics {
    /// Returns the vertical distance from the baseline of the font to the top of the glyph covers in pixels.
    pub fn ascent(&self, font_size: Pixels) -> Pixels {
        Pixels((self.ascent / self.units_per_em as f32) * font_size.0)
    }

    /// Returns the vertical distance from the baseline of the font to the bottom of the glyph covers in pixels.
    pub fn descent(&self, font_size: Pixels) -> Pixels {
        Pixels((self.descent / self.units_per_em as f32) * font_size.0)
    }

    /// Returns the recommended additional space to add between lines of type in pixels.
    pub fn line_gap(&self, font_size: Pixels) -> Pixels {
        Pixels((self.line_gap / self.units_per_em as f32) * font_size.0)
    }

    /// Returns the suggested position of the underline in pixels.
    pub fn underline_position(&self, font_size: Pixels) -> Pixels {
        Pixels((self.underline_position / self.units_per_em as f32) * font_size.0)
    }

    /// Returns the suggested thickness of the underline in pixels.
    pub fn underline_thickness(&self, font_size: Pixels) -> Pixels {
        Pixels((self.underline_thickness / self.units_per_em as f32) * font_size.0)
    }

    /// Returns the height of a capital letter measured from the baseline of the font in pixels.
    pub fn cap_height(&self, font_size: Pixels) -> Pixels {
        Pixels((self.cap_height / self.units_per_em as f32) * font_size.0)
    }

    /// Returns the height of a lowercase x in pixels.
    pub fn x_height(&self, font_size: Pixels) -> Pixels {
        Pixels((self.x_height / self.units_per_em as f32) * font_size.0)
    }

    /// Returns the outer limits of the area that the font covers in pixels.
    pub fn bounding_box(&self, font_size: Pixels) -> Bounds<Pixels> {
        (self.bounding_box / self.units_per_em as f32 * font_size.0).map(px)
    }
}

/// A run of text with a single font.
#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
#[expect(missing_docs)]
pub struct FontRun {
    pub len: usize,
    pub font_id: FontId,
}

/// The text rendering mode to use for drawing glyphs.
#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
pub enum TextRenderingMode {
    /// Use the platform's default text rendering mode.
    #[default]
    PlatformDefault,
    /// Use subpixel (ClearType-style) text rendering.
    Subpixel,
    /// Use grayscale text rendering.
    Grayscale,
}

/// A laid out and styled line of text
#[derive(Default, Debug)]
pub struct LineLayout {
    /// The font size for this line
    pub font_size: Pixels,
    /// The width of the line
    pub width: Pixels,
    /// The ascent of the line
    pub ascent: Pixels,
    /// The descent of the line
    pub descent: Pixels,
    /// The shaped runs that make up this line
    pub runs: Vec<ShapedRun>,
    /// The length of the line in utf-8 bytes
    pub len: usize,
}

/// A run of text that has been shaped .
#[derive(Debug, Clone)]
pub struct ShapedRun {
    /// The font id for this run
    pub font_id: FontId,
    /// The glyphs that make up this run
    pub glyphs: Vec<ShapedGlyph>,
}

/// A single glyph, ready to paint.
#[derive(Clone, Debug)]
pub struct ShapedGlyph {
    /// The ID for this glyph, as determined by the text system.
    pub id: GlyphId,

    /// The position of this glyph in its containing line.
    pub position: Point<Pixels>,

    /// The index of this glyph in the original text.
    pub index: usize,

    /// Whether this glyph is an emoji
    pub is_emoji: bool,
}

/// A line of text that has been wrapped to fit a given width.
#[derive(Default, Debug)]
pub struct WrappedLineLayout {
    /// The line layout, pre-wrapping.
    pub unwrapped_layout: Arc<LineLayout>,

    /// The boundaries at which the line was wrapped.
    pub wrap_boundaries: SmallVec<[WrapBoundary; 1]>,

    /// The width of the line, if it was wrapped.
    pub wrap_width: Option<Pixels>,
}

/// A boundary at which a line was wrapped.
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub struct WrapBoundary {
    /// The index in the run just before the line was wrapped.
    pub run_ix: usize,
    /// The index of the glyph just before the line was wrapped.
    pub glyph_ix: usize,
}

impl WrappedLineLayout {
    /// The length of the underlying text, in utf8 bytes.
    #[allow(clippy::len_without_is_empty)]
    pub fn len(&self) -> usize {
        self.unwrapped_layout.len
    }

    /// The width of this line, in pixels, whether or not it was wrapped.
    pub fn width(&self) -> Pixels {
        self.wrap_width
            .unwrap_or(Pixels::MAX)
            .min(self.unwrapped_layout.width)
    }

    /// The size of the whole wrapped text, for the given line_height.
    /// can span multiple lines if there are multiple wrap boundaries.
    pub fn size(&self, line_height: Pixels) -> Size<Pixels> {
        Size {
            width: self.width(),
            height: line_height * (self.wrap_boundaries.len() + 1),
        }
    }

    /// The ascent of a line in this layout
    pub fn ascent(&self) -> Pixels {
        self.unwrapped_layout.ascent
    }

    /// The descent of a line in this layout
    pub fn descent(&self) -> Pixels {
        self.unwrapped_layout.descent
    }

    /// The wrap boundaries in this layout
    pub fn wrap_boundaries(&self) -> &[WrapBoundary] {
        &self.wrap_boundaries
    }

    /// The font size of this layout
    pub fn font_size(&self) -> Pixels {
        self.unwrapped_layout.font_size
    }

    /// The runs in this layout, sans wrapping
    pub fn runs(&self) -> &[ShapedRun] {
        &self.unwrapped_layout.runs
    }

    /// The index corresponding to a given position in this layout for the given line height.
    ///
    /// See also [`Self::closest_index_for_position`].
    pub fn index_for_position(
        &self,
        position: Point<Pixels>,
        line_height: Pixels,
    ) -> Result<usize, usize> {
        self._index_for_position(position, line_height, false)
    }

    /// The closest index to a given position in this layout for the given line height.
    ///
    /// Closest means the character boundary closest to the given position.
    ///
    /// See also [`LineLayout::closest_index_for_x`].
    pub fn closest_index_for_position(
        &self,
        position: Point<Pixels>,
        line_height: Pixels,
    ) -> Result<usize, usize> {
        self._index_for_position(position, line_height, true)
    }

    fn _index_for_position(
        &self,
        position: Point<Pixels>,
        line_height: Pixels,
        closest: bool,
    ) -> Result<usize, usize> {
        let wrapped_line_ix = (position.y / line_height) as usize;

        let wrapped_line_start_index;
        let wrapped_line_start_x;
        if wrapped_line_ix > 0 {
            let Some(line_start_boundary) = self.wrap_boundaries.get(wrapped_line_ix - 1) else {
                return Err(0);
            };
            let run = &self.unwrapped_layout.runs[line_start_boundary.run_ix];
            let glyph = &run.glyphs[line_start_boundary.glyph_ix];
            wrapped_line_start_index = glyph.index;
            wrapped_line_start_x = glyph.position.x;
        } else {
            wrapped_line_start_index = 0;
            wrapped_line_start_x = Pixels::ZERO;
        };

        let wrapped_line_end_index;
        let wrapped_line_end_x;
        if wrapped_line_ix < self.wrap_boundaries.len() {
            let next_wrap_boundary_ix = wrapped_line_ix;
            let next_wrap_boundary = self.wrap_boundaries[next_wrap_boundary_ix];
            let run = &self.unwrapped_layout.runs[next_wrap_boundary.run_ix];
            let glyph = &run.glyphs[next_wrap_boundary.glyph_ix];
            wrapped_line_end_index = glyph.index;
            wrapped_line_end_x = glyph.position.x;
        } else {
            wrapped_line_end_index = self.unwrapped_layout.len;
            wrapped_line_end_x = self.unwrapped_layout.width;
        };

        let mut position_in_unwrapped_line = position;
        position_in_unwrapped_line.x += wrapped_line_start_x;
        if position_in_unwrapped_line.x < wrapped_line_start_x {
            Err(wrapped_line_start_index)
        } else if position_in_unwrapped_line.x >= wrapped_line_end_x {
            Err(wrapped_line_end_index)
        } else if closest {
            Ok(self
                .unwrapped_layout
                .closest_index_for_x(position_in_unwrapped_line.x))
        } else {
            // The shaper can place a trailing zero-width wrap boundary glyph slightly past
            // the line's width, so the row can extend past where `index_for_x` has glyphs.
            self.unwrapped_layout
                .index_for_x(position_in_unwrapped_line.x)
                .ok_or(wrapped_line_end_index)
        }
    }

    /// Returns the pixel position for the given byte index.
    pub fn position_for_index(&self, index: usize, line_height: Pixels) -> Option<Point<Pixels>> {
        let mut line_start_ix = 0;
        let line_end_indices = self
            .wrap_boundaries
            .iter()
            .map(|wrap_boundary| {
                let run = &self.unwrapped_layout.runs[wrap_boundary.run_ix];
                let glyph = &run.glyphs[wrap_boundary.glyph_ix];
                glyph.index
            })
            .chain([self.len()])
            .enumerate();
        for (ix, line_end_ix) in line_end_indices {
            let line_y = ix as f32 * line_height;
            if index < line_start_ix {
                break;
            } else if index > line_end_ix {
                line_start_ix = line_end_ix;
                continue;
            } else {
                let line_start_x = self.unwrapped_layout.x_for_index(line_start_ix);
                let x = self.unwrapped_layout.x_for_index(index) - line_start_x;
                return Some(point(x, line_y));
            }
        }

        None
    }
}

/// A saved position in a line-layout cache, used to reuse or truncate the
/// layouts produced during a frame.
#[derive(Clone, Default)]
pub struct LineLayoutIndex {
    /// The font generation the retained layouts were shaped against.
    pub font_generation: usize,
    /// The number of shaped lines retained at this position.
    pub lines_index: usize,
    /// The number of wrapped lines retained at this position.
    pub wrapped_lines_index: usize,
    /// The number of content-hashed shaped lines retained at this position.
    pub lines_by_hash_index: usize,
    /// The number of content-hashed wrapped lines retained at this position.
    pub wrapped_lines_by_hash_index: usize,
}

impl LineLayout {
    /// The index for the character at the given x coordinate
    pub fn index_for_x(&self, x: Pixels) -> Option<usize> {
        if x >= self.width {
            None
        } else {
            for run in self.runs.iter().rev() {
                for glyph in run.glyphs.iter().rev() {
                    if glyph.position.x <= x {
                        return Some(glyph.index);
                    }
                }
            }
            Some(0)
        }
    }

    /// closest_index_for_x returns the character boundary closest to the given x coordinate
    /// (e.g. to handle aligning up/down arrow keys)
    pub fn closest_index_for_x(&self, x: Pixels) -> usize {
        let mut prev_index = 0;
        let mut prev_x = px(0.);

        for run in self.runs.iter() {
            for glyph in run.glyphs.iter() {
                if glyph.position.x >= x {
                    if glyph.position.x - x < x - prev_x {
                        return glyph.index;
                    } else {
                        return prev_index;
                    }
                }
                prev_index = glyph.index;
                prev_x = glyph.position.x;
            }
        }

        if self.len == 1 {
            if x > self.width / 2. {
                return 1;
            } else {
                return 0;
            }
        }

        self.len
    }

    /// The x position of the character at the given index
    pub fn x_for_index(&self, index: usize) -> Pixels {
        for run in &self.runs {
            for glyph in &run.glyphs {
                if glyph.index >= index {
                    return glyph.position.x;
                }
            }
        }
        self.width
    }

    /// The corresponding Font at the given index
    pub fn font_id_for_index(&self, index: usize) -> Option<FontId> {
        for run in &self.runs {
            for glyph in &run.glyphs {
                if glyph.index >= index {
                    return Some(run.font_id);
                }
            }
        }
        None
    }

    /// Split this layout at a byte index, returning `(prefix, suffix)`.
    ///
    /// - `prefix` contains glyphs for bytes `[0, byte_index)` with original positions.
    ///   Its width equals the x-advance up to the split point.
    /// - `suffix` contains glyphs for bytes `[byte_index, len)` with positions
    ///   shifted left so the first glyph starts at x=0, and byte indices rebased to 0.
    /// - `font_size`, `ascent`, and `descent` are copied to both halves.
    pub fn split_at(&self, byte_index: usize) -> (LineLayout, LineLayout) {
        let x_offset = self.x_for_index(byte_index);

        // Partition glyph runs. A single run may contribute glyphs to both halves.
        let mut left_runs = Vec::new();
        let mut right_runs = Vec::new();

        for run in &self.runs {
            let split_pos = run.glyphs.partition_point(|g| g.index < byte_index);

            if split_pos > 0 {
                left_runs.push(ShapedRun {
                    font_id: run.font_id,
                    glyphs: run.glyphs[..split_pos].to_vec(),
                });
            }

            if split_pos < run.glyphs.len() {
                let right_glyphs = run.glyphs[split_pos..]
                    .iter()
                    .map(|g| ShapedGlyph {
                        id: g.id,
                        position: point(g.position.x - x_offset, g.position.y),
                        index: g.index - byte_index,
                        is_emoji: g.is_emoji,
                    })
                    .collect();
                right_runs.push(ShapedRun {
                    font_id: run.font_id,
                    glyphs: right_glyphs,
                });
            }
        }

        let left = LineLayout {
            font_size: self.font_size,
            width: x_offset,
            ascent: self.ascent,
            descent: self.descent,
            runs: left_runs,
            len: byte_index,
        };

        let right = LineLayout {
            font_size: self.font_size,
            width: self.width - x_offset,
            ascent: self.ascent,
            descent: self.descent,
            runs: right_runs,
            len: self.len - byte_index,
        };

        (left, right)
    }
}

#[expect(missing_docs)]
pub trait PlatformTextSystem: Send + Sync {
    fn add_fonts(&self, fonts: Vec<Cow<'static, [u8]>>) -> Result<()>;
    /// Installs a nonblocking sink for unresolved grapheme clusters.
    fn set_missing_glyph_sink(&self, _sink: Option<Arc<dyn MissingGlyphSink>>) {}
    /// Get all available font names.
    fn all_font_names(&self) -> Vec<String>;
    /// Get the font ID for a font descriptor.
    fn font_id(&self, descriptor: &Font) -> Result<FontId>;
    /// Prewarm any system font caches needed to shape text.
    fn prewarm_fonts(&self, _font_ids: &[FontId]) {}
    /// Get metrics for a font.
    fn font_metrics(&self, font_id: FontId) -> FontMetrics;
    /// Get typographic bounds for a glyph.
    fn typographic_bounds(&self, font_id: FontId, glyph_id: GlyphId) -> Result<Bounds<f32>>;
    /// Get the advance width for a glyph.
    fn advance(&self, font_id: FontId, glyph_id: GlyphId) -> Result<Size<f32>>;
    /// Get the glyph ID for a character.
    fn glyph_for_char(&self, font_id: FontId, ch: char) -> Option<GlyphId>;
    /// Get raster bounds for a glyph.
    fn glyph_raster_bounds(&self, params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>>;
    /// Rasterize a glyph.
    fn rasterize_glyph(
        &self,
        params: &RenderGlyphParams,
        raster_bounds: Bounds<DevicePixels>,
    ) -> Result<(Size<DevicePixels>, Vec<u8>)>;
    /// Layout a line of text with the given font runs.
    fn layout_line(&self, text: &str, font_size: Pixels, runs: &[FontRun]) -> LineLayout;
    /// Returns the recommended text rendering mode for the given font and size.
    fn recommended_rendering_mode(&self, _font_id: FontId, _font_size: Pixels)
    -> TextRenderingMode;
    /// Returns the dilation level to use for a glyph painted in the given color.
    fn glyph_dilation_for_color(&self, _color: Hsla) -> u8 {
        0
    }
}

/// The spacing behavior required of a fallback font.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum FallbackFontClass {
    /// A proportionally spaced fallback font.
    Proportional,
    /// A fixed-width fallback font.
    Monospace,
}

/// A grapheme cluster that could not be represented by any available font.
#[derive(Clone, Debug, Eq, Hash, PartialEq)]
pub struct MissingGlyph {
    grapheme: SharedString,
    font_class: FallbackFontClass,
}

impl MissingGlyph {
    /// Creates a missing-glyph report.
    pub fn new(grapheme: SharedString, font_class: FallbackFontClass) -> Self {
        Self {
            grapheme,
            font_class,
        }
    }

    /// Returns the unresolved grapheme cluster.
    pub fn grapheme(&self) -> &str {
        &self.grapheme
    }

    /// Returns the spacing behavior required of a fallback font.
    pub fn font_class(&self) -> FallbackFontClass {
        self.font_class
    }
}

/// Accepts missing glyphs detected by a platform text system.
pub trait MissingGlyphSink: Send + Sync {
    /// Reports grapheme clusters that exhausted font fallback.
    fn report(&self, missing_glyphs: Vec<MissingGlyph>);
}

#[expect(missing_docs)]
pub struct NoopTextSystem;

#[expect(missing_docs)]
impl NoopTextSystem {
    #[allow(dead_code)]
    pub fn new() -> Self {
        Self
    }
}

impl PlatformTextSystem for NoopTextSystem {
    fn add_fonts(&self, _fonts: Vec<Cow<'static, [u8]>>) -> Result<()> {
        Ok(())
    }

    fn all_font_names(&self) -> Vec<String> {
        Vec::new()
    }

    fn font_id(&self, _descriptor: &Font) -> Result<FontId> {
        Ok(FontId(1))
    }

    fn font_metrics(&self, _font_id: FontId) -> FontMetrics {
        FontMetrics {
            units_per_em: 1000,
            ascent: 1025.0,
            descent: -275.0,
            line_gap: 0.0,
            underline_position: -95.0,
            underline_thickness: 60.0,
            cap_height: 698.0,
            x_height: 516.0,
            bounding_box: Bounds {
                origin: Point {
                    x: -260.0,
                    y: -245.0,
                },
                size: Size {
                    width: 1501.0,
                    height: 1364.0,
                },
            },
        }
    }

    fn typographic_bounds(&self, _font_id: FontId, _glyph_id: GlyphId) -> Result<Bounds<f32>> {
        Ok(Bounds {
            origin: Point { x: 54.0, y: 0.0 },
            size: size(392.0, 528.0),
        })
    }

    fn advance(&self, _font_id: FontId, glyph_id: GlyphId) -> Result<Size<f32>> {
        Ok(size(600.0 * glyph_id.0 as f32, 0.0))
    }

    fn glyph_for_char(&self, _font_id: FontId, ch: char) -> Option<GlyphId> {
        Some(GlyphId(ch.len_utf16() as u32))
    }

    fn glyph_raster_bounds(&self, _params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>> {
        Ok(Default::default())
    }

    fn rasterize_glyph(
        &self,
        _params: &RenderGlyphParams,
        raster_bounds: Bounds<DevicePixels>,
    ) -> Result<(Size<DevicePixels>, Vec<u8>)> {
        Ok((raster_bounds.size, Vec::new()))
    }

    fn layout_line(&self, text: &str, font_size: Pixels, _runs: &[FontRun]) -> LineLayout {
        let mut position = px(0.);
        let metrics = self.font_metrics(FontId(0));
        let em_width = font_size
            * self
                .advance(FontId(0), self.glyph_for_char(FontId(0), 'm').unwrap())
                .unwrap()
                .width
            / metrics.units_per_em as f32;
        let mut glyphs = Vec::new();
        for (ix, c) in text.char_indices() {
            if let Some(glyph) = self.glyph_for_char(FontId(0), c) {
                glyphs.push(ShapedGlyph {
                    id: glyph,
                    position: point(position, px(0.)),
                    index: ix,
                    is_emoji: glyph.0 == 2,
                });
                if glyph.0 == 2 {
                    position += em_width * 2.0;
                } else {
                    position += em_width;
                }
            } else {
                position += em_width
            }
        }
        let mut runs = Vec::default();
        if !glyphs.is_empty() {
            runs.push(ShapedRun {
                font_id: FontId(0),
                glyphs,
            });
        } else {
            position = px(0.);
        }

        LineLayout {
            font_size,
            width: position,
            ascent: font_size * (metrics.ascent / metrics.units_per_em as f32),
            descent: font_size * (metrics.descent / metrics.units_per_em as f32),
            runs,
            len: text.len(),
        }
    }

    fn recommended_rendering_mode(
        &self,
        _font_id: FontId,
        _font_size: Pixels,
    ) -> TextRenderingMode {
        TextRenderingMode::Grayscale
    }
}

/// Maps well-known virtual font names to their concrete equivalents.
#[allow(unused)]
pub fn font_name_with_fallbacks<'a>(name: &'a str, system: &'a str) -> &'a str {
    // Note: the "Zed Plex" fonts were deprecated as we are not allowed to use "Plex"
    // in a derived font name. They are essentially indistinguishable from IBM Plex/Lilex,
    // and so retained here for backward compatibility.
    match name {
        ".SystemUIFont" => system,
        ".ZedSans" | "Zed Plex Sans" => "IBM Plex Sans",
        ".ZedMono" | "Zed Plex Mono" => "Lilex",
        _ => name,
    }
}

/// Like [`font_name_with_fallbacks`] but accepts and returns [`SharedString`] references.
#[allow(unused)]
pub fn font_name_with_fallbacks_shared<'a>(
    name: &'a SharedString,
    system: &'a SharedString,
) -> &'a SharedString {
    // Note: the "Zed Plex" fonts were deprecated as we are not allowed to use "Plex"
    // in a derived font name. They are essentially indistinguishable from IBM Plex/Lilex,
    // and so retained here for backward compatibility.
    match name.as_str() {
        ".SystemUIFont" => system,
        ".ZedSans" | "Zed Plex Sans" => const { &SharedString::new_static("IBM Plex Sans") },
        ".ZedMono" | "Zed Plex Mono" => const { &SharedString::new_static("Lilex") },
        _ => name,
    }
}

/// A styled run of text.
#[derive(Clone, Debug, PartialEq, Eq, Default)]
pub struct TextRun {
    /// A number of utf8 bytes
    pub len: usize,
    /// The font to use for this run.
    pub font: Font,
    /// The color
    pub color: Hsla,
    /// The background color (if any)
    pub background_color: Option<Hsla>,
    /// The underline style (if any)
    pub underline: Option<UnderlineStyle>,
    /// The strikethrough style (if any)
    pub strikethrough: Option<StrikethroughStyle>,
}