bite-gp-engine-default 1.25.202

//! Conversion from the engine's layout style to `taffy`.
//!
//! The engine enums and `taffy`'s enums are both foreign to this crate, so the
//! enum conversions are free functions rather than `From` impls. Everything
//! else is expressed through the private [`ToTaffy`] trait, whose impls are
//! allowed because the trait is local.

use gpui_engine::{
    AlignContent, AlignItems, Display, EngineLayoutStyle, FlexDirection, FlexWrap, GridTemplate,
    GridTemplateMinSize, Overflow, Position,
};
use gpui_types::{
    AbsoluteLength, DefiniteLength, Edges, GridPlacement, Length, Pixels, Size,
    round_stroke_to_device_pixel, round_to_device_pixel,
};
use std::{fmt::Debug, ops::Range};
use taffy::{
    geometry::{Rect as TaffyRect, Size as TaffySize},
    prelude::{max_content, min_content},
};

fn to_taffy_align_items(value: AlignItems) -> taffy::style::AlignItems {
    match value {
        AlignItems::Start => taffy::style::AlignItems::START,
        AlignItems::End => taffy::style::AlignItems::END,
        AlignItems::FlexStart => taffy::style::AlignItems::FLEX_START,
        AlignItems::FlexEnd => taffy::style::AlignItems::FLEX_END,
        AlignItems::Center => taffy::style::AlignItems::CENTER,
        AlignItems::Baseline => taffy::style::AlignItems::BASELINE,
        AlignItems::Stretch => taffy::style::AlignItems::STRETCH,
    }
}

fn to_taffy_align_content(value: AlignContent) -> taffy::style::AlignContent {
    match value {
        AlignContent::Start => taffy::style::AlignContent::START,
        AlignContent::End => taffy::style::AlignContent::END,
        AlignContent::FlexStart => taffy::style::AlignContent::FLEX_START,
        AlignContent::FlexEnd => taffy::style::AlignContent::FLEX_END,
        AlignContent::Center => taffy::style::AlignContent::CENTER,
        AlignContent::Stretch => taffy::style::AlignContent::STRETCH,
        AlignContent::SpaceBetween => taffy::style::AlignContent::SPACE_BETWEEN,
        AlignContent::SpaceEvenly => taffy::style::AlignContent::SPACE_EVENLY,
        AlignContent::SpaceAround => taffy::style::AlignContent::SPACE_AROUND,
    }
}

fn to_taffy_display(value: Display) -> taffy::style::Display {
    match value {
        Display::Block => taffy::style::Display::Block,
        Display::Flex => taffy::style::Display::Flex,
        Display::Grid => taffy::style::Display::Grid,
        Display::None => taffy::style::Display::None,
    }
}

fn to_taffy_flex_wrap(value: FlexWrap) -> taffy::style::FlexWrap {
    match value {
        FlexWrap::NoWrap => taffy::style::FlexWrap::NoWrap,
        FlexWrap::Wrap => taffy::style::FlexWrap::Wrap,
        FlexWrap::WrapReverse => taffy::style::FlexWrap::WrapReverse,
    }
}

fn to_taffy_flex_direction(value: FlexDirection) -> taffy::style::FlexDirection {
    match value {
        FlexDirection::Row => taffy::style::FlexDirection::Row,
        FlexDirection::Column => taffy::style::FlexDirection::Column,
        FlexDirection::RowReverse => taffy::style::FlexDirection::RowReverse,
        FlexDirection::ColumnReverse => taffy::style::FlexDirection::ColumnReverse,
    }
}

fn to_taffy_overflow(value: Overflow) -> taffy::style::Overflow {
    match value {
        Overflow::Visible => taffy::style::Overflow::Visible,
        Overflow::Clip => taffy::style::Overflow::Clip,
        Overflow::Hidden => taffy::style::Overflow::Hidden,
        Overflow::Scroll => taffy::style::Overflow::Scroll,
    }
}

fn to_taffy_position(value: Position) -> taffy::style::Position {
    match value {
        Position::Relative => taffy::style::Position::Relative,
        Position::Absolute => taffy::style::Position::Absolute,
    }
}

/// Converts an engine layout style into the `taffy` style the layout tree owns.
pub(crate) fn to_taffy_style(
    style: &EngineLayoutStyle,
    rem_size: Pixels,
    scale_factor: f32,
) -> taffy::style::Style {
    style.to_taffy(rem_size, scale_factor)
}

fn border_widths_to_taffy(
    widths: &Edges<AbsoluteLength>,
    rem_size: Pixels,
    scale_factor: f32,
) -> TaffyRect<taffy::style::LengthPercentage> {
    let snap = |w: &AbsoluteLength| {
        taffy::style::LengthPercentage::length(round_stroke_to_device_pixel(
            w.to_pixels(rem_size).0,
            scale_factor,
        ))
    };
    TaffyRect {
        top: snap(&widths.top),
        right: snap(&widths.right),
        bottom: snap(&widths.bottom),
        left: snap(&widths.left),
    }
}

trait ToTaffy<Output> {
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> Output;
}

impl ToTaffy<taffy::style::Style> for EngineLayoutStyle {
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> taffy::style::Style {
        use taffy::style_helpers::{fr, length, minmax, repeat};

        fn to_grid_line(placement: &Range<GridPlacement>) -> taffy::Line<taffy::GridPlacement> {
            taffy::Line {
                start: placement.start.into(),
                end: placement.end.into(),
            }
        }

        fn to_grid_repeat<T: taffy::style::CheapCloneStr>(
            unit: &Option<GridTemplate>,
        ) -> Vec<taffy::GridTemplateComponent<T>> {
            unit.map(|template| {
                match template.min_size {
                    // grid-template-*: repeat(<number>, minmax(0, 1fr));
                    GridTemplateMinSize::Zero => {
                        vec![repeat(
                            template.repeat,
                            vec![minmax(length(0.0_f32), fr(1.0_f32))],
                        )]
                    }
                    // grid-template-*: repeat(<number>, minmax(min-content, 1fr));
                    GridTemplateMinSize::MinContent => {
                        vec![repeat(
                            template.repeat,
                            vec![minmax(min_content(), fr(1.0_f32))],
                        )]
                    }
                    // grid-template-*: repeat(<number>, minmax(0, max-content))
                    GridTemplateMinSize::MaxContent => {
                        vec![repeat(
                            template.repeat,
                            vec![minmax(length(0.0_f32), max_content())],
                        )]
                    }
                }
            })
            .unwrap_or_default()
        }

        taffy::style::Style {
            display: to_taffy_display(self.display),
            overflow: taffy::geometry::Point {
                x: to_taffy_overflow(self.overflow.x),
                y: to_taffy_overflow(self.overflow.y),
            },
            scrollbar_width: self.scrollbar_width.to_taffy(rem_size, scale_factor),
            position: to_taffy_position(self.position),
            inset: self.inset.to_taffy(rem_size, scale_factor),
            size: self.size.to_taffy(rem_size, scale_factor),
            min_size: self.min_size.to_taffy(rem_size, scale_factor),
            max_size: self.max_size.to_taffy(rem_size, scale_factor),
            aspect_ratio: self.aspect_ratio,
            margin: self.margin.to_taffy(rem_size, scale_factor),
            padding: self.padding.to_taffy(rem_size, scale_factor),
            border: border_widths_to_taffy(&self.border_widths, rem_size, scale_factor),
            align_items: self.align_items.map(to_taffy_align_items),
            align_self: self.align_self.map(to_taffy_align_items),
            align_content: self.align_content.map(to_taffy_align_content),
            justify_content: self.justify_content.map(to_taffy_align_content),
            gap: self.gap.to_taffy(rem_size, scale_factor),
            flex_direction: to_taffy_flex_direction(self.flex_direction),
            flex_wrap: to_taffy_flex_wrap(self.flex_wrap),
            flex_basis: self.flex_basis.to_taffy(rem_size, scale_factor),
            flex_grow: self.flex_grow,
            flex_shrink: self.flex_shrink,
            grid_template_rows: to_grid_repeat(&self.grid_rows),
            grid_template_columns: to_grid_repeat(&self.grid_cols),
            grid_row: self
                .grid_location
                .as_ref()
                .map(|location| to_grid_line(&location.row))
                .unwrap_or_default(),
            grid_column: self
                .grid_location
                .as_ref()
                .map(|location| to_grid_line(&location.column))
                .unwrap_or_default(),
            ..Default::default()
        }
    }
}

impl ToTaffy<f32> for AbsoluteLength {
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> f32 {
        round_to_device_pixel(self.to_pixels(rem_size).0, scale_factor)
    }
}

impl ToTaffy<taffy::style::LengthPercentageAuto> for Length {
    fn to_taffy(
        &self,
        rem_size: Pixels,
        scale_factor: f32,
    ) -> taffy::prelude::LengthPercentageAuto {
        match self {
            Length::Definite(length) => length.to_taffy(rem_size, scale_factor),
            Length::Auto => taffy::prelude::LengthPercentageAuto::auto(),
        }
    }
}

impl ToTaffy<taffy::style::Dimension> for Length {
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> taffy::prelude::Dimension {
        match self {
            Length::Definite(length) => length.to_taffy(rem_size, scale_factor),
            Length::Auto => taffy::prelude::Dimension::auto(),
        }
    }
}

impl ToTaffy<taffy::style::LengthPercentage> for DefiniteLength {
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> taffy::style::LengthPercentage {
        match self {
            DefiniteLength::Absolute(length) => length.to_taffy(rem_size, scale_factor),
            DefiniteLength::Fraction(fraction) => {
                taffy::style::LengthPercentage::percent(*fraction)
            }
        }
    }
}

impl ToTaffy<taffy::style::LengthPercentageAuto> for DefiniteLength {
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> taffy::style::LengthPercentageAuto {
        match self {
            DefiniteLength::Absolute(length) => length.to_taffy(rem_size, scale_factor),
            DefiniteLength::Fraction(fraction) => {
                taffy::style::LengthPercentageAuto::percent(*fraction)
            }
        }
    }
}

impl ToTaffy<taffy::style::Dimension> for DefiniteLength {
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> taffy::style::Dimension {
        match self {
            DefiniteLength::Absolute(length) => length.to_taffy(rem_size, scale_factor),
            DefiniteLength::Fraction(fraction) => taffy::style::Dimension::percent(*fraction),
        }
    }
}

impl ToTaffy<taffy::style::LengthPercentage> for AbsoluteLength {
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> taffy::style::LengthPercentage {
        taffy::style::LengthPercentage::length(self.to_taffy(rem_size, scale_factor))
    }
}

impl ToTaffy<taffy::style::LengthPercentageAuto> for AbsoluteLength {
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> taffy::style::LengthPercentageAuto {
        taffy::style::LengthPercentageAuto::length(self.to_taffy(rem_size, scale_factor))
    }
}

impl ToTaffy<taffy::style::Dimension> for AbsoluteLength {
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> taffy::style::Dimension {
        taffy::style::Dimension::length(self.to_taffy(rem_size, scale_factor))
    }
}

impl<T, U> ToTaffy<TaffySize<U>> for Size<T>
where
    T: ToTaffy<U> + Clone + Debug + Default + PartialEq,
{
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> TaffySize<U> {
        TaffySize {
            width: self.width.to_taffy(rem_size, scale_factor),
            height: self.height.to_taffy(rem_size, scale_factor),
        }
    }
}

impl<T, U> ToTaffy<TaffyRect<U>> for Edges<T>
where
    T: ToTaffy<U> + Clone + Debug + Default + PartialEq,
{
    fn to_taffy(&self, rem_size: Pixels, scale_factor: f32) -> TaffyRect<U> {
        TaffyRect {
            top: self.top.to_taffy(rem_size, scale_factor),
            right: self.right.to_taffy(rem_size, scale_factor),
            bottom: self.bottom.to_taffy(rem_size, scale_factor),
            left: self.left.to_taffy(rem_size, scale_factor),
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn border_widths_to_taffy_use_stroke_snapping() {
        let border_widths = Edges {
            top: Pixels(0.0).into(),
            right: Pixels(0.4).into(),
            bottom: Pixels(0.5).into(),
            left: Pixels(1.6).into(),
        };
        let taffy_border = border_widths_to_taffy(&border_widths, Pixels(16.0), 1.0);

        assert_eq!(
            taffy_border.top,
            taffy::style::LengthPercentage::length(0.0)
        );
        assert_eq!(
            taffy_border.right,
            taffy::style::LengthPercentage::length(1.0)
        );
        assert_eq!(
            taffy_border.bottom,
            taffy::style::LengthPercentage::length(1.0)
        );
        assert_eq!(
            taffy_border.left,
            taffy::style::LengthPercentage::length(2.0)
        );
    }
}