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font.rs
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font.rs
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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,
}
}