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// Copyright 2016 Joe Wilm, The Alacritty Project Contributors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
//! Rasterization powered by FreeType and FontConfig
use std::collections::HashMap;
use freetype::{self, Library, Face};
mod list_fonts;
use self::list_fonts::{Family, get_font_families};
use super::{FontDesc, RasterizedGlyph, Metrics, Size, FontKey, GlyphKey};
/// Rasterizes glyphs for a single font face.
pub struct FreeTypeRasterizer {
faces: HashMap<FontKey, Face<'static>>,
library: Library,
system_fonts: HashMap<String, Family>,
keys: HashMap<FontDesc, FontKey>,
dpi_x: u32,
dpi_y: u32,
dpr: f32,
}
#[inline]
fn to_freetype_26_6(f: f32) -> isize {
((1i32 << 6) as f32 * f) as isize
}
impl ::Rasterize for FreeTypeRasterizer {
type Err = Error;
fn new(dpi_x: f32, dpi_y: f32, device_pixel_ratio: f32) -> Result<FreeTypeRasterizer, Error> {
let library = Library::init()?;
Ok(FreeTypeRasterizer {
system_fonts: get_font_families(),
faces: HashMap::new(),
keys: HashMap::new(),
library: library,
dpi_x: dpi_x as u32,
dpi_y: dpi_y as u32,
dpr: device_pixel_ratio,
})
}
fn metrics(&self, key: FontKey, size: Size) -> Result<Metrics, Error> {
let face = self.faces
.get(&key)
.ok_or(Error::FontNotLoaded)?;
let scale_size = self.dpr as f64 * size.as_f32_pts() as f64;
let em_size = face.em_size() as f64;
let w = face.max_advance_width() as f64;
let h = (face.ascender() - face.descender() + face.height()) as f64;
let w_scale = w * scale_size / em_size;
let h_scale = h * scale_size / em_size;
Ok(Metrics {
average_advance: w_scale,
line_height: h_scale,
})
}
fn load_font(&mut self, desc: &FontDesc, _size: Size) -> Result<FontKey, Error> {
self.keys
.get(&desc.to_owned())
.map(|k| Ok(*k))
.unwrap_or_else(|| {
let face = self.get_face(desc)?;
let key = FontKey::next();
self.faces.insert(key, face);
Ok(key)
})
}
fn get_glyph(&mut self, glyph_key: &GlyphKey) -> Result<RasterizedGlyph, Error> {
let face = self.faces
.get(&glyph_key.font_key)
.ok_or(Error::FontNotLoaded)?;
let size = glyph_key.size.as_f32_pts() * self.dpr;
let c = glyph_key.c;
face.set_char_size(to_freetype_26_6(size), 0, self.dpi_x, self.dpi_y)?;
face.load_char(c as usize, freetype::face::TARGET_LIGHT)?;
let glyph = face.glyph();
glyph.render_glyph(freetype::render_mode::RenderMode::Lcd)?;
unsafe {
let ft_lib = self.library.raw();
freetype::ffi::FT_Library_SetLcdFilter(
ft_lib,
freetype::ffi::FT_LCD_FILTER_DEFAULT
);
}
let bitmap = glyph.bitmap();
let buf = bitmap.buffer();
let pitch = bitmap.pitch() as usize;
let mut packed = Vec::with_capacity((bitmap.rows() * bitmap.width()) as usize);
for i in 0..bitmap.rows() {
let start = (i as usize) * pitch;
let stop = start + bitmap.width() as usize;
packed.extend_from_slice(&buf[start..stop]);
}
Ok(RasterizedGlyph {
c: c,
top: glyph.bitmap_top(),
left: glyph.bitmap_left(),
width: glyph.bitmap().width() / 3,
height: glyph.bitmap().rows(),
buf: packed,
})
}
}
impl FreeTypeRasterizer {
fn get_face(&mut self, desc: &FontDesc) -> Result<Face<'static>, Error> {
self.system_fonts
.get(&desc.name[..])
.and_then(|font| font.variants().get(&desc.style[..]))
.ok_or_else(|| Error::MissingFont(desc.to_owned()))
.and_then(|variant| Ok(self.library.new_face(variant.path(), variant.index())?))
}
}
/// Errors occurring when using the freetype rasterizer
#[derive(Debug)]
pub enum Error {
/// Error occurred within the FreeType library
FreeType(freetype::Error),
/// Couldn't find font matching description
MissingFont(FontDesc),
/// Requested an operation with a FontKey that isn't known to the rasterizer
FontNotLoaded,
}
impl ::std::error::Error for Error {
fn cause(&self) -> Option<&::std::error::Error> {
match *self {
Error::FreeType(ref err) => Some(err),
_ => None,
}
}
fn description(&self) -> &str {
match *self {
Error::FreeType(ref err) => err.description(),
Error::MissingFont(ref _desc) => "couldn't find the requested font",
Error::FontNotLoaded => "tried to operate on font that hasn't been loaded",
}
}
}
impl ::std::fmt::Display for Error {
fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
match *self {
Error::FreeType(ref err) => {
err.fmt(f)
},
Error::MissingFont(ref desc) => {
write!(f, "Couldn't find a font with {}", desc)
},
Error::FontNotLoaded => {
f.write_str("Tried to use a font that hasn't been loaded")
}
}
}
}
impl From<freetype::Error> for Error {
fn from(val: freetype::Error) -> Error {
Error::FreeType(val)
}
}
unsafe impl Send for FreeTypeRasterizer {}
#[cfg(test)]
mod tests {
use ::FontDesc;
fn font_desc() -> FontDesc {
FontDesc::new("Ubuntu Mono", "Regular")
}
}
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