canary-rs/src/text.rs

use super::{DrawCommand, MeshIndex, MeshVertex};

use allsorts::binary::read::ReadScope;
use allsorts::cff::CFF;
use allsorts::font::{GlyphTableFlags, MatchingPresentation};
use allsorts::font_data::{DynamicFontTableProvider, FontData as AllsortsFontData};
use allsorts::glyph_position::{GlyphLayout, TextDirection};
use allsorts::outline::OutlineBuilder;
use allsorts::pathfinder_geometry::{line_segment::LineSegment2F, vector::Vector2F};
use allsorts::tables::{glyf::GlyfTable, loca::LocaTable};
use allsorts::tables::{FontTableProvider, SfntVersion};
use allsorts::{tag, Font as AllsortsFont};
use canary_types::GlyphPosition;
use lyon::path::Path;
use ouroboros::self_referencing;
use parking_lot::{Mutex, RwLock};

const TEXT_SCALE: f32 = 0.075;

pub struct GlyphCache {
    units_per_em: f32,
    glyphs: RwLock<Vec<CachedGlyph>>,
}

impl GlyphCache {
    pub fn new(font: &AllsortsFont<DynamicFontTableProvider>) -> Self {
        let glyph_num = font.num_glyphs();
        let mut glyphs = Vec::with_capacity(glyph_num as usize);
        let units_per_em = font.head_table().unwrap().unwrap().units_per_em as f32;

        if font.glyph_table_flags.contains(GlyphTableFlags::CFF)
            && font.font_table_provider.sfnt_version() == tag::OTTO
        {
            let cff_data = font.font_table_provider.read_table_data(tag::CFF).unwrap();
            let mut cff = ReadScope::new(&cff_data).read::<CFF<'_>>().unwrap();
            for index in 0..glyph_num {
                glyphs.push(CachedGlyph::new(units_per_em, &mut cff, index));
            }
        } else if font.glyph_table_flags.contains(GlyphTableFlags::GLYF) {
            let loca_data = font.font_table_provider.read_table_data(tag::LOCA).unwrap();
            let loca = ReadScope::new(&loca_data)
                .read_dep::<LocaTable<'_>>((
                    usize::from(font.maxp_table.num_glyphs),
                    font.head_table().unwrap().unwrap().index_to_loc_format,
                ))
                .unwrap();
            let glyf_data = font.font_table_provider.read_table_data(tag::GLYF).unwrap();
            let mut glyf = ReadScope::new(&glyf_data)
                .read_dep::<GlyfTable<'_>>(&loca)
                .unwrap();

            for index in 0..glyph_num {
                glyphs.push(CachedGlyph::new(units_per_em, &mut glyf, index));
            }
        } else {
            panic!("no glyf or CFF table");
        }

        Self {
            units_per_em,
            glyphs: RwLock::new(glyphs),
        }
    }
}

pub struct CachedGlyph {
    path: Path,
    mesh: Option<GlyphMesh>,
}

impl CachedGlyph {
    pub fn new(units_per_em: f32, builder: &mut impl OutlineBuilder, index: u16) -> Self {
        let mut sink = OutlineSink::new(units_per_em);
        builder.visit(index, &mut sink).unwrap();
        let path = sink.builder.build();

        Self { path, mesh: None }
    }

    pub fn get_mesh(&mut self) -> &GlyphMesh {
        self.mesh.get_or_insert_with(|| {
            use lyon::tessellation::*;

            let mut geometry: VertexBuffers<MeshVertex, MeshIndex> = VertexBuffers::new();
            let fill_options = FillOptions::default().with_tolerance(0.0005);
            let mut tessellator = FillTessellator::new();
            tessellator
                .tessellate_path(
                    &self.path.clone(),
                    &fill_options,
                    &mut BuffersBuilder::new(&mut geometry, |vertex: FillVertex| {
                        let position = vertex.position() * TEXT_SCALE;
                        let position = canary_types::Vec2 {
                            x: position.x,
                            y: position.y,
                        };

                        MeshVertex {
                            position,
                            color: canary_types::Color::WHITE,
                        }
                    }),
                )
                .unwrap();

            GlyphMesh {
                vertices: geometry.vertices,
                indices: geometry.indices,
            }
        })
    }
}

pub struct GlyphMesh {
    vertices: Vec<MeshVertex>,
    indices: Vec<MeshIndex>,
}

pub struct Font {
    data: Mutex<FontData>,
    glyph_cache: GlyphCache,
}

impl Font {
    pub fn load(
        face_index: u16,
        script: u32,
        direction: TextDirection,
        vertical: bool,
        file_buffer: Vec<u8>,
    ) -> Self {
        let mut data = FontData::load(face_index, script, direction, vertical, file_buffer);
        let glyph_cache = data.with_inner_mut(|font| GlyphCache::new(font));
        let data = Mutex::new(data);
        Self { data, glyph_cache }
    }

    pub fn shape(&self, text: &str) -> Vec<GlyphPosition> {
        self.data.lock().shape(text)
    }

    pub fn draw(&self, mesh: &mut DummyText, positions: &[GlyphPosition], yoff: f32) {
        // TODO defer tessellation of missed glyph cache entries
        let mut glyphs = self.glyph_cache.glyphs.write();
        let units_per_em = self.glyph_cache.units_per_em;
        let mut xcur = 0;
        let mut ycur = 0;
        for position in positions.iter() {
            let glyph = glyphs.get_mut(position.index as usize).unwrap().get_mesh();

            let xpos = xcur + position.xoff;
            let ypos = ycur + position.yoff;
            xcur += position.hori_advance;
            ycur += position.vert_advance;

            let voff = mesh.vertices.len() as MeshIndex;
            let scale = TEXT_SCALE / units_per_em;
            let xpos = xpos as f32 * scale;
            let ypos = ypos as f32 * scale;

            for v in glyph.vertices.iter() {
                let x = v.position.x + xpos - 0.9;
                let y = v.position.y + ypos + yoff;
                mesh.vertices.push(MeshVertex {
                    position: canary_types::Vec2 { x, y },
                    color: v.color,
                });
            }

            for i in glyph.indices.iter() {
                mesh.indices.push(i + voff);
            }
        }
    }
}

#[self_referencing]
pub struct FontData {
    file_buffer: Vec<u8>,
    face_index: u16,
    script: u32,
    direction: TextDirection,
    vertical: bool,

    #[borrows(file_buffer)]
    #[covariant]
    read_scope: ReadScope<'this>,

    #[borrows(read_scope)]
    #[not_covariant]
    font_data: AllsortsFontData<'this>,

    #[borrows(font_data)]
    #[covariant]
    inner: AllsortsFont<DynamicFontTableProvider<'this>>,
}

impl FontData {
    pub fn load(
        face_index: u16,
        script: u32,
        direction: TextDirection,
        vertical: bool,
        file_buffer: Vec<u8>,
    ) -> Self {
        FontDataBuilder {
            file_buffer,
            face_index,
            script,
            direction,
            vertical,
            read_scope_builder: |buffer| ReadScope::new(buffer),
            font_data_builder: |scope| scope.read::<AllsortsFontData<'_>>().unwrap(),
            inner_builder: |font_data| {
                AllsortsFont::new(font_data.table_provider(0).unwrap())
                    .unwrap()
                    .unwrap()
            },
        }
        .build()
    }

    pub fn shape(&mut self, text: &str) -> Vec<GlyphPosition> {
        let face_index = *self.borrow_face_index() as u16;
        let presentation = MatchingPresentation::Required;
        let script = *self.borrow_script();
        let lang_tag = None;
        let features = allsorts::gsub::Features::default();
        let kerning = true;
        let direction = *self.borrow_direction();
        let vertical = *self.borrow_vertical();

        self.with_inner_mut(|font| {
            let mapped = font.map_glyphs(text, script, presentation);
            let infos = font
                .shape(mapped, script, lang_tag, &features, kerning)
                .unwrap();
            let mut layout = GlyphLayout::new(font, &infos, direction, vertical);
            let positions = layout.glyph_positions().unwrap();
            let mut glyphs = Vec::with_capacity(positions.len());
            for (glyph, position) in infos.iter().zip(&positions) {
                glyphs.push(GlyphPosition {
                    face: face_index,
                    index: glyph.glyph.glyph_index,
                    hori_advance: position.hori_advance,
                    vert_advance: position.vert_advance,
                    xoff: position.x_offset,
                    yoff: position.y_offset,
                });
            }

            glyphs
        })
    }
}

pub struct FontStore {
    source: Box<dyn font_kit::source::Source>,
}

impl FontStore {
    pub fn new() -> Self {
        let source = font_kit::source::SystemSource::new();
        let source = Box::new(source);
        Self { source }
    }

    pub fn load_font(&self, title: &str) -> Font {
        use font_kit::family_name::FamilyName;
        use font_kit::handle::Handle;
        use font_kit::properties::Properties;

        println!("loading font family {}", title);

        let font_handle = self
            .source
            .select_best_match(&[FamilyName::Title(title.to_string())], &Properties::new())
            .unwrap();

        println!("loading font file: {:?}", font_handle);

        let font_data = if let Handle::Path {
            path,
            font_index: _,
        } = font_handle
        {
            std::fs::read(path).unwrap()
        } else {
            panic!("font is not a file for some reason");
        };

        let script = tag::LATN;
        let face_index = 0;
        let direction = TextDirection::LeftToRight;
        let vertical = false;
        Font::load(face_index, script, direction, vertical, font_data.clone())
    }
}

pub struct DummyText {
    vertices: Vec<MeshVertex>,
    indices: Vec<MeshIndex>,
}

impl Default for DummyText {
    fn default() -> Self {
        let store = FontStore::new();
        let text = "toki o! nimi mi li jan [_mun_alasa_sona]. toki+pona li pona.";
        let font_families = ["mononoki", "Liberation Sans", "Ubuntu"];

        let mut mesh = Self {
            vertices: Vec::new(),
            indices: Vec::new(),
        };

        let line_height = -0.1;
        let mut line_offset = 0.9;
        for family in font_families.iter() {
            let font = store.load_font(family);
            let glyphs = font.shape(text);
            font.draw(&mut mesh, &glyphs, line_offset);
            line_offset += line_height;
        }

        mesh
    }
}

impl DummyText {
    pub fn draw(&self, cmds: &mut Vec<DrawCommand>) {
        cmds.push(DrawCommand::Mesh {
            vertices: self.vertices.clone(),
            indices: self.indices.clone(),
        });
    }
}

pub struct OutlineSink {
    units_per_em: f32,
    builder: lyon::path::path::Builder,
}

impl OutlineSink {
    pub fn new(units_per_em: f32) -> Self {
        Self {
            units_per_em,
            builder: lyon::path::Path::builder(),
        }
    }

    fn pf_line_to_lyon(
        &self,
        line: &LineSegment2F,
    ) -> (lyon::geom::Point<f32>, lyon::geom::Point<f32>) {
        (
            self.pf_vector_to_lyon(&line.from()),
            self.pf_vector_to_lyon(&line.to()),
        )
    }

    fn pf_vector_to_lyon(&self, v: &Vector2F) -> lyon::geom::Point<f32> {
        lyon::geom::Point::<f32>::new(v.x(), v.y()) / self.units_per_em
    }
}

impl allsorts::outline::OutlineSink for OutlineSink {
    fn move_to(&mut self, to: Vector2F) {
        let to = self.pf_vector_to_lyon(&to);
        self.builder.begin(to);
    }

    fn line_to(&mut self, to: Vector2F) {
        let to = self.pf_vector_to_lyon(&to);
        self.builder.line_to(to);
    }

    fn quadratic_curve_to(&mut self, control: Vector2F, to: Vector2F) {
        let control = self.pf_vector_to_lyon(&control);
        let to = self.pf_vector_to_lyon(&to);
        self.builder.quadratic_bezier_to(control, to);
    }

    fn cubic_curve_to(&mut self, control: LineSegment2F, to: Vector2F) {
        let (ctrl1, ctrl2) = self.pf_line_to_lyon(&control);
        let to = self.pf_vector_to_lyon(&to);
        self.builder.cubic_bezier_to(ctrl1, ctrl2, to);
    }

    fn close(&mut self) {
        self.builder.close();
    }
}