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use std::borrow::{Borrow, Cow};
use std::collections::HashMap;
use std::i32;
use std::io::Read;
use std::sync::{Arc, RwLock};
use lazy_static::lazy_static;
use rusttype::{point, Error, Font, FontCollection, Scale, SharedBytes};
use font_kit::family_name::FamilyName;
use font_kit::handle::Handle;
use font_kit::properties::{Properties, Style, Weight};
use font_kit::source::SystemSource;
use super::{FontData, FontFamily, FontStyle, LayoutBox};
type FontResult<T> = Result<T, FontError>;
#[derive(Debug, Clone)]
pub enum FontError {
LockError,
NoSuchFont(String, String),
FontLoadError(Arc<Error>),
}
impl std::fmt::Display for FontError {
fn fmt(&self, fmt: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
match self {
FontError::LockError => write!(fmt, "Could not lock mutex"),
FontError::NoSuchFont(family, style) => {
write!(fmt, "No such font: {} {}", family, style)
}
FontError::FontLoadError(e) => write!(fmt, "Font loading error: {}", e),
}
}
}
impl std::error::Error for FontError {}
lazy_static! {
static ref CACHE: RwLock<HashMap<String, FontResult<Font<'static>>>> =
RwLock::new(HashMap::new());
}
thread_local! {
static FONT_SOURCE: SystemSource = SystemSource::new();
}
#[allow(dead_code)]
/// Lazily load font data. Font type doesn't own actual data, which
/// lives in the cache.
fn load_font_data(face: FontFamily, style: FontStyle) -> FontResult<Font<'static>> {
let key = match style {
FontStyle::Normal => Cow::Borrowed(face.as_str()),
_ => Cow::Owned(format!("{}, {}", face.as_str(), style.as_str())),
};
let cache = CACHE.read().unwrap();
if let Some(cached) = cache.get(Borrow::<str>::borrow(&key)) {
return cached.clone();
}
drop(cache);
let mut properties = Properties::new();
match style {
FontStyle::Normal => properties.style(Style::Normal),
FontStyle::Italic => properties.style(Style::Italic),
FontStyle::Oblique => properties.style(Style::Oblique),
FontStyle::Bold => properties.weight(Weight::BOLD),
};
let family = match face {
FontFamily::Serif => FamilyName::Serif,
FontFamily::SansSerif => FamilyName::SansSerif,
FontFamily::Monospace => FamilyName::Monospace,
FontFamily::Name(name) => FamilyName::Title(name.to_owned()),
};
let make_not_found_error =
|| FontError::NoSuchFont(face.as_str().to_owned(), style.as_str().to_owned());
if let Ok(handle) = FONT_SOURCE
.with(|source| source.select_best_match(&[family, FamilyName::SansSerif], &properties))
{
let (data, id) = match handle {
Handle::Path {
path,
font_index: idx,
} => {
let mut buf = vec![];
std::fs::File::open(path)
.map_err(|_| make_not_found_error())?
.read_to_end(&mut buf)
.map_err(|_| make_not_found_error())?;
(buf, idx)
}
Handle::Memory {
bytes,
font_index: idx,
} => (bytes[..].to_owned(), idx),
};
// TODO: font-kit actually have rasterizer, so consider remove dependency for rusttype as
// well
let result = FontCollection::from_bytes(Into::<SharedBytes>::into(data))
.map_err(|err| FontError::FontLoadError(Arc::new(err)))?
.font_at(id.max(0) as usize)
.map_err(|err| FontError::FontLoadError(Arc::new(err)));
CACHE
.write()
.map_err(|_| FontError::LockError)?
.insert(key.into_owned(), result.clone());
return result;
}
Err(make_not_found_error())
}
/// Remove all cached fonts data.
#[allow(dead_code)]
pub fn clear_font_cache() -> FontResult<()> {
let mut cache = CACHE.write().map_err(|_| FontError::LockError)?;
cache.clear();
Ok(())
}
#[derive(Clone)]
pub struct FontDataInternal(Font<'static>);
impl FontData for FontDataInternal {
type ErrorType = FontError;
fn new(family: FontFamily, style: FontStyle) -> Result<Self, FontError> {
Ok(FontDataInternal(load_font_data(family, style)?))
}
fn estimate_layout(&self, size: f64, text: &str) -> Result<LayoutBox, Self::ErrorType> {
let scale = Scale::uniform(size as f32);
let (mut min_x, mut min_y) = (i32::MAX, i32::MAX);
let (mut max_x, mut max_y) = (0, 0);
let font = &self.0;
for g in font.layout(text, scale, point(0.0, 0.0)) {
if let Some(rect) = g.pixel_bounding_box() {
min_x = min_x.min(rect.min.x);
min_y = min_y.min(rect.min.y);
max_x = max_x.max(rect.max.x);
max_y = max_y.max(rect.max.y);
}
}
if min_x == i32::MAX || min_y == i32::MAX {
return Ok(((0, 0), (0, 0)));
}
Ok(((min_x, min_y), (max_x, max_y)))
}
fn draw<E, DrawFunc: FnMut(i32, i32, f32) -> Result<(), E>>(
&self,
(base_x, base_y): (i32, i32),
size: f64,
text: &str,
mut draw: DrawFunc,
) -> Result<Result<(), E>, Self::ErrorType> {
let scale = Scale::uniform(size as f32);
let mut result = Ok(());
let font = &self.0;
for g in font.layout(text, scale, point(0.0, 0.0)) {
if let Some(rect) = g.pixel_bounding_box() {
let (x0, y0) = (rect.min.x, rect.min.y);
g.draw(|x, y, v| {
let (x, y) = (x as i32 + x0, y as i32 + y0);
result = draw(x + base_x, y + base_y, v);
});
if result.is_err() {
break;
}
}
}
Ok(result)
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_font_cache() -> FontResult<()> {
clear_font_cache()?;
// We cannot only check the size of font cache, because
// the test case may be run in parallel. Thus the font cache
// may contains other fonts.
let _a = load_font_data(FontFamily::Serif, FontStyle::Normal)?;
assert!(CACHE.read().unwrap().contains_key("serif"));
let _b = load_font_data(FontFamily::Serif, FontStyle::Normal)?;
assert!(CACHE.read().unwrap().contains_key("serif"));
// TODO: Check they are the same
return Ok(());
}
}
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