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extern crate font_loader;
use self::font_loader::system_fonts;
extern crate rusttype;
use self::rusttype::{point, Codepoint, FontCollection, Scale};
use super::{FontDesc, FontKey, GlyphKey, Metrics, RasterizedGlyph, Size, Slant, Style, Weight};
pub struct RustTypeRasterizer {
fonts: Vec<rusttype::Font<'static>>,
dpi_ratio: f32,
}
impl crate::Rasterize for RustTypeRasterizer {
type Err = Error;
fn new(device_pixel_ratio: f32, _: bool) -> Result<RustTypeRasterizer, Error> {
Ok(RustTypeRasterizer {
fonts: Vec::new(),
dpi_ratio: device_pixel_ratio,
})
}
fn metrics(&self, key: FontKey, size: Size) -> Result<Metrics, Error> {
let scale = Scale::uniform(size.as_f32_pts() * self.dpi_ratio * 96. / 72.);
let vmetrics = self.fonts[key.token as usize].v_metrics(scale);
let hmetrics = self.fonts[key.token as usize]
.glyph(
// If the font is monospaced all glyphs *should* have the same width
// 33 '!' is the first displaying character
Codepoint(33),
)
.ok_or(Error::MissingGlyph)?
.scaled(scale)
.h_metrics();
let line_height = f64::from(vmetrics.ascent - vmetrics.descent + vmetrics.line_gap);
let average_advance = f64::from(hmetrics.advance_width);
let descent = vmetrics.descent;
// Strikeout and underline metrics.
// RustType doesn't support these, so we make up our own.
let thickness = (descent / 5.).round();
let underline_position = descent / 2.;
let strikeout_position = line_height as f32 / 2. - descent;
Ok(Metrics {
descent,
average_advance,
line_height,
underline_position,
underline_thickness: thickness,
strikeout_position,
strikeout_thickness: thickness,
})
}
fn load_font(&mut self, desc: &FontDesc, _size: Size) -> Result<FontKey, Error> {
let fp = system_fonts::FontPropertyBuilder::new()
.family(&desc.name)
.monospace();
let fp = match desc.style {
Style::Specific(_) => unimplemented!(""),
Style::Description { slant, weight } => {
let fp = match slant {
Slant::Normal => fp,
Slant::Italic => fp.italic(),
// This style is not supported by rust-font-loader
Slant::Oblique => return Err(Error::UnsupportedStyle),
};
match weight {
Weight::Bold => fp.bold(),
Weight::Normal => fp,
}
}
};
self.fonts.push(FontCollection::from_bytes(
system_fonts::get(&fp.build())
.ok_or_else(|| Error::MissingFont(desc.clone()))?
.0,
).into_font()
.ok_or(Error::UnsupportedFont)?);
Ok(FontKey {
token: (self.fonts.len() - 1) as u16,
})
}
fn get_glyph(&mut self, glyph_key: GlyphKey) -> Result<RasterizedGlyph, Error> {
match glyph_key.c {
super::UNDERLINE_CURSOR_CHAR => {
let metrics = self.metrics(glyph_key.font_key, glyph_key.size)?;
return super::get_underline_cursor_glyph(metrics.descent as i32, metrics.average_advance as i32);
}
super::BEAM_CURSOR_CHAR => {
let metrics = self.metrics(glyph_key.font_key, glyph_key.size)?;
return super::get_beam_cursor_glyph(
(metrics.line_height + f64::from(metrics.descent)).round() as i32,
metrics.line_height.round() as i32,
metrics.average_advance.round() as i32
);
}
super::BOX_CURSOR_CHAR => {
let metrics = self.metrics(glyph_key.font_key, glyph_key.size)?;
return super::get_box_cursor_glyph(
(metrics.line_height + f64::from(metrics.descent)).round() as i32,
metrics.line_height.round() as i32,
metrics.average_advance.round() as i32
);
}
_ => ()
}
let scaled_glyph = self.fonts[glyph_key.font_key.token as usize]
.glyph(glyph_key.c)
.ok_or(Error::MissingGlyph)?
.scaled(Scale::uniform(
glyph_key.size.as_f32_pts() * self.dpi_ratio * 96. / 72.,
));
let glyph = scaled_glyph.positioned(point(0.0, 0.0));
// Pixel bounding box
let bb = match glyph.pixel_bounding_box() {
Some(bb) => bb,
// Bounding box calculation fails for spaces so we provide a placeholder bounding box
None => rusttype::Rect {
min: point(0, 0),
max: point(0, 0),
},
};
let mut buf = Vec::with_capacity((bb.width() * bb.height()) as usize);
glyph.draw(|_x, _y, v| {
buf.push((v * 255.0) as u8);
buf.push((v * 255.0) as u8);
buf.push((v * 255.0) as u8);
});
Ok(RasterizedGlyph {
c: glyph_key.c,
width: bb.width(),
height: bb.height(),
top: -bb.min.y,
left: bb.min.x,
buf,
})
}
fn update_dpr(&mut self, device_pixel_ratio: f32) {
self.dpi_ratio = device_pixel_ratio;
}
}
#[derive(Debug)]
pub enum Error {
MissingFont(FontDesc),
UnsupportedFont,
UnsupportedStyle,
// NOTE: This error is different from how the FreeType code handles it
MissingGlyph,
}
impl ::std::error::Error for Error {
fn description(&self) -> &str {
match *self {
Error::MissingFont(ref _desc) => "Couldn't find the requested font",
Error::UnsupportedFont => "Only TrueType fonts are supported",
Error::UnsupportedStyle => "The selected style is not supported by rusttype",
Error::MissingGlyph => "The selected font does not have the requested glyph",
}
}
}
impl ::std::fmt::Display for Error {
fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
match *self {
Error::MissingFont(ref desc) => write!(
f,
"Couldn't find a font with {}\
\n\tPlease check the font config in your alacritty.yml.",
desc
),
Error::UnsupportedFont => write!(
f,
"Rusttype only supports TrueType fonts.\n\tPlease select a TrueType font instead."
),
Error::UnsupportedStyle => {
write!(f, "The selected font style is not supported by rusttype.")
}
Error::MissingGlyph => write!(f, "The selected font did not have the requested glyph."),
}
}
}
|
