Move all crates into a crates directory (#1940)

crates/epaint/src/text/font.rs

@@ -0,0 +1,407 @@
+use crate::{
+    mutex::{Mutex, RwLock},
+    TextureAtlas,
+};
+use emath::{vec2, Vec2};
+use std::collections::BTreeSet;
+use std::sync::Arc;
+
+// ----------------------------------------------------------------------------
+
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct UvRect {
+    /// X/Y offset for nice rendering (unit: points).
+    pub offset: Vec2,
+
+    /// Screen size (in points) of this glyph.
+    /// Note that the height is different from the font height.
+    pub size: Vec2,
+
+    /// Top left corner UV in texture.
+    pub min: [u16; 2],
+
+    /// Bottom right corner (exclusive).
+    pub max: [u16; 2],
+}
+
+impl UvRect {
+    pub fn is_nothing(&self) -> bool {
+        self.min == self.max
+    }
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct GlyphInfo {
+    pub(crate) id: ab_glyph::GlyphId,
+
+    /// Unit: points.
+    pub advance_width: f32,
+
+    /// Texture coordinates. None for space.
+    pub uv_rect: UvRect,
+}
+
+impl Default for GlyphInfo {
+    fn default() -> Self {
+        Self {
+            id: ab_glyph::GlyphId(0),
+            advance_width: 0.0,
+            uv_rect: Default::default(),
+        }
+    }
+}
+
+// ----------------------------------------------------------------------------
+
+/// A specific font with a size.
+/// The interface uses points as the unit for everything.
+pub struct FontImpl {
+    name: String,
+    ab_glyph_font: ab_glyph::FontArc,
+    /// Maximum character height
+    scale_in_pixels: u32,
+    height_in_points: f32,
+    // move each character by this much (hack)
+    y_offset: f32,
+    pixels_per_point: f32,
+    glyph_info_cache: RwLock<ahash::HashMap<char, GlyphInfo>>, // TODO(emilk): standard Mutex
+    atlas: Arc<Mutex<TextureAtlas>>,
+}
+
+impl FontImpl {
+    pub fn new(
+        atlas: Arc<Mutex<TextureAtlas>>,
+        pixels_per_point: f32,
+        name: String,
+        ab_glyph_font: ab_glyph::FontArc,
+        scale_in_pixels: u32,
+        y_offset_points: f32,
+    ) -> FontImpl {
+        assert!(scale_in_pixels > 0);
+        assert!(pixels_per_point > 0.0);
+
+        let height_in_points = scale_in_pixels as f32 / pixels_per_point;
+
+        // TODO(emilk): use these font metrics?
+        // use ab_glyph::ScaleFont as _;
+        // let scaled = ab_glyph_font.as_scaled(scale_in_pixels as f32);
+        // dbg!(scaled.ascent());
+        // dbg!(scaled.descent());
+        // dbg!(scaled.line_gap());
+
+        // Round to closest pixel:
+        let y_offset = (y_offset_points * pixels_per_point).round() / pixels_per_point;
+
+        Self {
+            name,
+            ab_glyph_font,
+            scale_in_pixels,
+            height_in_points,
+            y_offset,
+            pixels_per_point,
+            glyph_info_cache: Default::default(),
+            atlas,
+        }
+    }
+
+    fn ignore_character(&self, chr: char) -> bool {
+        if self.name == "emoji-icon-font" {
+            // HACK: https://github.com/emilk/egui/issues/1284 https://github.com/jslegers/emoji-icon-font/issues/18
+            // Don't show the wrong fullwidth capital letters:
+            if 'Ｓ' <= chr && chr <= 'Ｙ' {
+                return true;
+            }
+        }
+
+        matches!(
+            chr,
+            // Strip out a religious symbol with secondary nefarious interpretation:
+            '\u{534d}' | '\u{5350}' |
+
+            // Ignore ubuntu-specific stuff in `Ubuntu-Light.ttf`:
+            '\u{E0FF}' | '\u{EFFD}' | '\u{F0FF}' | '\u{F200}'
+        )
+    }
+
+    /// An un-ordered iterator over all supported characters.
+    fn characters(&self) -> impl Iterator<Item = char> + '_ {
+        use ab_glyph::Font as _;
+        self.ab_glyph_font
+            .codepoint_ids()
+            .map(|(_, chr)| chr)
+            .filter(|&chr| !self.ignore_character(chr))
+    }
+
+    /// `\n` will result in `None`
+    fn glyph_info(&self, c: char) -> Option<GlyphInfo> {
+        {
+            if let Some(glyph_info) = self.glyph_info_cache.read().get(&c) {
+                return Some(*glyph_info);
+            }
+        }
+
+        if self.ignore_character(c) {
+            return None;
+        }
+
+        if c == '\t' {
+            if let Some(space) = self.glyph_info(' ') {
+                let glyph_info = GlyphInfo {
+                    advance_width: crate::text::TAB_SIZE as f32 * space.advance_width,
+                    ..GlyphInfo::default()
+                };
+                self.glyph_info_cache.write().insert(c, glyph_info);
+                return Some(glyph_info);
+            }
+        }
+
+        // Add new character:
+        use ab_glyph::Font as _;
+        let glyph_id = self.ab_glyph_font.glyph_id(c);
+
+        if glyph_id.0 == 0 {
+            if invisible_char(c) {
+                // hack
+                let glyph_info = GlyphInfo::default();
+                self.glyph_info_cache.write().insert(c, glyph_info);
+                Some(glyph_info)
+            } else {
+                None // unsupported character
+            }
+        } else {
+            let glyph_info = allocate_glyph(
+                &mut self.atlas.lock(),
+                &self.ab_glyph_font,
+                glyph_id,
+                self.scale_in_pixels as f32,
+                self.y_offset,
+                self.pixels_per_point,
+            );
+
+            self.glyph_info_cache.write().insert(c, glyph_info);
+            Some(glyph_info)
+        }
+    }
+
+    #[inline]
+    pub fn pair_kerning(
+        &self,
+        last_glyph_id: ab_glyph::GlyphId,
+        glyph_id: ab_glyph::GlyphId,
+    ) -> f32 {
+        use ab_glyph::{Font as _, ScaleFont};
+        self.ab_glyph_font
+            .as_scaled(self.scale_in_pixels as f32)
+            .kern(last_glyph_id, glyph_id)
+            / self.pixels_per_point
+    }
+
+    /// Height of one row of text. In points
+    #[inline(always)]
+    pub fn row_height(&self) -> f32 {
+        self.height_in_points
+    }
+
+    #[inline(always)]
+    pub fn pixels_per_point(&self) -> f32 {
+        self.pixels_per_point
+    }
+}
+
+type FontIndex = usize;
+
+// TODO(emilk): rename?
+/// Wrapper over multiple [`FontImpl`] (e.g. a primary + fallbacks for emojis)
+pub struct Font {
+    fonts: Vec<Arc<FontImpl>>,
+    /// Lazily calculated.
+    characters: Option<BTreeSet<char>>,
+    replacement_glyph: (FontIndex, GlyphInfo),
+    pixels_per_point: f32,
+    row_height: f32,
+    glyph_info_cache: ahash::HashMap<char, (FontIndex, GlyphInfo)>,
+}
+
+impl Font {
+    pub fn new(fonts: Vec<Arc<FontImpl>>) -> Self {
+        if fonts.is_empty() {
+            return Self {
+                fonts,
+                characters: None,
+                replacement_glyph: Default::default(),
+                pixels_per_point: 1.0,
+                row_height: 0.0,
+                glyph_info_cache: Default::default(),
+            };
+        }
+
+        let pixels_per_point = fonts[0].pixels_per_point();
+        let row_height = fonts[0].row_height();
+
+        let mut slf = Self {
+            fonts,
+            characters: None,
+            replacement_glyph: Default::default(),
+            pixels_per_point,
+            row_height,
+            glyph_info_cache: Default::default(),
+        };
+
+        const PRIMARY_REPLACEMENT_CHAR: char = '◻'; // white medium square
+        const FALLBACK_REPLACEMENT_CHAR: char = '?'; // fallback for the fallback
+
+        let replacement_glyph = slf
+            .glyph_info_no_cache_or_fallback(PRIMARY_REPLACEMENT_CHAR)
+            .or_else(|| slf.glyph_info_no_cache_or_fallback(FALLBACK_REPLACEMENT_CHAR))
+            .unwrap_or_else(|| {
+                panic!(
+                    "Failed to find replacement characters {:?} or {:?}",
+                    PRIMARY_REPLACEMENT_CHAR, FALLBACK_REPLACEMENT_CHAR
+                )
+            });
+        slf.replacement_glyph = replacement_glyph;
+
+        slf
+    }
+
+    pub fn preload_common_characters(&mut self) {
+        // Preload the printable ASCII characters [32, 126] (which excludes control codes):
+        const FIRST_ASCII: usize = 32; // 32 == space
+        const LAST_ASCII: usize = 126;
+        for c in (FIRST_ASCII..=LAST_ASCII).map(|c| c as u8 as char) {
+            self.glyph_info(c);
+        }
+        self.glyph_info('°');
+        self.glyph_info(crate::text::PASSWORD_REPLACEMENT_CHAR);
+    }
+
+    /// All supported characters
+    pub fn characters(&mut self) -> &BTreeSet<char> {
+        self.characters.get_or_insert_with(|| {
+            let mut characters = BTreeSet::new();
+            for font in &self.fonts {
+                characters.extend(font.characters());
+            }
+            characters
+        })
+    }
+
+    #[inline(always)]
+    pub fn round_to_pixel(&self, point: f32) -> f32 {
+        (point * self.pixels_per_point).round() / self.pixels_per_point
+    }
+
+    /// Height of one row of text. In points
+    #[inline(always)]
+    pub fn row_height(&self) -> f32 {
+        self.row_height
+    }
+
+    pub fn uv_rect(&self, c: char) -> UvRect {
+        self.glyph_info_cache
+            .get(&c)
+            .map(|gi| gi.1.uv_rect)
+            .unwrap_or_default()
+    }
+
+    /// Width of this character in points.
+    pub fn glyph_width(&mut self, c: char) -> f32 {
+        self.glyph_info(c).1.advance_width
+    }
+
+    /// `\n` will (intentionally) show up as the replacement character.
+    fn glyph_info(&mut self, c: char) -> (FontIndex, GlyphInfo) {
+        if let Some(font_index_glyph_info) = self.glyph_info_cache.get(&c) {
+            return *font_index_glyph_info;
+        }
+
+        let font_index_glyph_info = self.glyph_info_no_cache_or_fallback(c);
+        let font_index_glyph_info = font_index_glyph_info.unwrap_or(self.replacement_glyph);
+        self.glyph_info_cache.insert(c, font_index_glyph_info);
+        font_index_glyph_info
+    }
+
+    #[inline]
+    pub(crate) fn glyph_info_and_font_impl(&mut self, c: char) -> (Option<&FontImpl>, GlyphInfo) {
+        if self.fonts.is_empty() {
+            return (None, self.replacement_glyph.1);
+        }
+        let (font_index, glyph_info) = self.glyph_info(c);
+        let font_impl = &self.fonts[font_index];
+        (Some(font_impl), glyph_info)
+    }
+
+    fn glyph_info_no_cache_or_fallback(&mut self, c: char) -> Option<(FontIndex, GlyphInfo)> {
+        for (font_index, font_impl) in self.fonts.iter().enumerate() {
+            if let Some(glyph_info) = font_impl.glyph_info(c) {
+                self.glyph_info_cache.insert(c, (font_index, glyph_info));
+                return Some((font_index, glyph_info));
+            }
+        }
+        None
+    }
+}
+
+#[inline]
+fn invisible_char(c: char) -> bool {
+    // See https://github.com/emilk/egui/issues/336
+
+    // From https://www.fileformat.info/info/unicode/category/Cf/list.htm
+    ('\u{200B}'..='\u{206F}').contains(&c) // TODO(emilk): heed bidi characters
+}
+
+fn allocate_glyph(
+    atlas: &mut TextureAtlas,
+    font: &ab_glyph::FontArc,
+    glyph_id: ab_glyph::GlyphId,
+    scale_in_pixels: f32,
+    y_offset: f32,
+    pixels_per_point: f32,
+) -> GlyphInfo {
+    assert!(glyph_id.0 != 0);
+    use ab_glyph::{Font as _, ScaleFont};
+
+    let glyph =
+        glyph_id.with_scale_and_position(scale_in_pixels, ab_glyph::Point { x: 0.0, y: 0.0 });
+
+    let uv_rect = font.outline_glyph(glyph).map(|glyph| {
+        let bb = glyph.px_bounds();
+        let glyph_width = bb.width() as usize;
+        let glyph_height = bb.height() as usize;
+        if glyph_width == 0 || glyph_height == 0 {
+            UvRect::default()
+        } else {
+            let (glyph_pos, image) = atlas.allocate((glyph_width, glyph_height));
+            glyph.draw(|x, y, v| {
+                if v > 0.0 {
+                    let px = glyph_pos.0 + x as usize;
+                    let py = glyph_pos.1 + y as usize;
+                    image[(px, py)] = v;
+                }
+            });
+
+            let offset_in_pixels = vec2(bb.min.x, scale_in_pixels + bb.min.y);
+            let offset = offset_in_pixels / pixels_per_point + y_offset * Vec2::Y;
+            UvRect {
+                offset,
+                size: vec2(glyph_width as f32, glyph_height as f32) / pixels_per_point,
+                min: [glyph_pos.0 as u16, glyph_pos.1 as u16],
+                max: [
+                    (glyph_pos.0 + glyph_width) as u16,
+                    (glyph_pos.1 + glyph_height) as u16,
+                ],
+            }
+        }
+    });
+    let uv_rect = uv_rect.unwrap_or_default();
+
+    let advance_width_in_points =
+        font.as_scaled(scale_in_pixels).h_advance(glyph_id) / pixels_per_point;
+
+    GlyphInfo {
+        id: glyph_id,
+        advance_width: advance_width_in_points,
+        uv_rect,
+    }
+}