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Implement downloadable fonts on Windows
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@vvuk
vvuk committed Jan 18, 2017
1 parent 68fa988 commit a9611c3
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7 changes: 7 additions & 0 deletions Cargo.lock
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3 changes: 2 additions & 1 deletion components/gfx/Cargo.toml
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Expand Up @@ -60,4 +60,5 @@ servo-fontconfig = "0.2.1"
simd = {git = "https://github.com/huonw/simd"}

[target.'cfg(target_os = "windows")'.dependencies]
dwrote = "0.1.1"
dwrote = "0.1.5"
truetype = "0.24"
1 change: 1 addition & 0 deletions components/gfx/lib.rs
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Expand Up @@ -29,6 +29,7 @@ extern crate bitflags;

// Windows-specific library dependencies
#[cfg(target_os = "windows")] extern crate dwrote;
#[cfg(target_os = "windows")] extern crate truetype;

extern crate euclid;
extern crate fnv;
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282 changes: 231 additions & 51 deletions components/gfx/platform/windows/font.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,8 @@
// renderer moves to a sandboxed process.

use app_units::Au;
use dwrote::{Font, FontFace};
use dwrote;
use dwrote::{Font, FontFace, FontFile};
use dwrote::{FontWeight, FontStretch, FontStyle};
use font::{FontHandleMethods, FontMetrics, FontTableMethods};
use font::{FontTableTag, FractionalPixel};
Expand All @@ -17,6 +18,7 @@ use platform::windows::font_list::font_from_atom;
use std::sync::Arc;
use style::computed_values::{font_stretch, font_weight};
use text::glyph::GlyphId;
use truetype;

// 1em = 12pt = 16px, assuming 72 points per inch and 96 px per inch
fn pt_to_px(pt: f64) -> f64 { pt / 72. * 96. }
Expand All @@ -40,11 +42,205 @@ impl FontTableMethods for FontTable {
}
}

fn make_tag(tag_bytes: &[u8]) -> FontTableTag {
assert_eq!(tag_bytes.len(), 4);
unsafe { *(tag_bytes.as_ptr() as *const FontTableTag) }
}

macro_rules! try_lossy(($result:expr) => (try!($result.map_err(|_| (())))));

// Given a set of records, figure out the string indices for the family and face
// names. We want name_id 1 and 2, and we need to use platform_id == 1 and
// language_id == 0 to avoid limitations in the truetype crate. We *could* just
// do our own parsing here, and use the offset/length data and pull the values out
// ourselves.
fn get_family_face_indices(records: &[truetype::naming_table::Record]) -> Option<(usize, usize)> {
let mut family_name_index = None;
let mut face_name_index = None;

for i in 0..records.len() {
// the truetype crate can only decode mac platform format names
if records[i].platform_id != 1 {
continue;
}

if records[i].language_id != 0 {
continue;
}

if records[i].name_id == 1 {
family_name_index = Some(i);
} else if records[i].name_id == 2 {
face_name_index = Some(i);
}
}

if family_name_index.is_some() && face_name_index.is_some() {
Some((family_name_index.unwrap(), face_name_index.unwrap()))
} else {
None
}
}

// We need the font (DWriteFont) in order to be able to query things like
// the family name, face name, weight, etc. On Windows 10, the
// DWriteFontFace3 interface provides this on the FontFace, but that's only
// available on Win10+.
//
// Instead, we do the parsing work using the truetype crate for raw fonts.
// We're just extracting basic info, so this is sufficient for now.

#[derive(Debug)]
struct FontInfo {
family_name: String,
face_name: String,
weight: font_weight::T,
stretch: font_stretch::T,
style: FontStyle,
}

impl FontInfo {
fn new_from_face(face: &FontFace) -> Result<FontInfo, ()> {
use std::cmp::{min, max};
use std::io::Cursor;
use truetype::{NamingTable, Value, WindowsMetrics};

let name_table_bytes = face.get_font_table(make_tag(b"name"));
let os2_table_bytes = face.get_font_table(make_tag(b"OS/2"));
if name_table_bytes.is_none() || os2_table_bytes.is_none() {
return Err(());
}

let mut name_table_cursor = Cursor::new(name_table_bytes.as_ref().unwrap());
let names = try_lossy!(NamingTable::read(&mut name_table_cursor));
let (family, face) = match names {
NamingTable::Format0(ref table) => {
if let Some((family_index, face_index)) = get_family_face_indices(&table.records) {
let strings = table.strings().unwrap();
let family = strings[family_index].clone();
let face = strings[face_index].clone();
((family, face))
} else {
return Err(());
}
},
NamingTable::Format1(ref table) => {
if let Some((family_index, face_index)) = get_family_face_indices(&table.records) {
let strings = table.strings().unwrap();
let family = strings[family_index].clone();
let face = strings[face_index].clone();
((family, face))
} else {
return Err(());
}
}
};

let mut os2_table_cursor = Cursor::new(os2_table_bytes.as_ref().unwrap());
let metrics = try_lossy!(WindowsMetrics::read(&mut os2_table_cursor));
let (weight_val, width_val, italic_bool) = match metrics {
WindowsMetrics::Version0(ref m) => {
(m.weight_class, m.width_class, m.selection_flags.0 & 1 == 1)
},
WindowsMetrics::Version1(ref m) => {
(m.weight_class, m.width_class, m.selection_flags.0 & 1 == 1)
},
WindowsMetrics::Version2(ref m) |
WindowsMetrics::Version3(ref m) |
WindowsMetrics::Version4(ref m) => {
(m.weight_class, m.width_class, m.selection_flags.0 & 1 == 1)
},
WindowsMetrics::Version5(ref m) => {
(m.weight_class, m.width_class, m.selection_flags.0 & 1 == 1)
},
};

let weight = match min(9, max(1, weight_val / 100)) {
1 => font_weight::T::Weight100,
2 => font_weight::T::Weight200,
3 => font_weight::T::Weight300,
4 => font_weight::T::Weight400,
5 => font_weight::T::Weight500,
6 => font_weight::T::Weight600,
7 => font_weight::T::Weight700,
8 => font_weight::T::Weight800,
9 => font_weight::T::Weight900,
_ => return Err(()),
};

let stretch = match min(9, max(1, width_val)) {
1 => font_stretch::T::ultra_condensed,
2 => font_stretch::T::extra_condensed,
3 => font_stretch::T::condensed,
4 => font_stretch::T::semi_condensed,
5 => font_stretch::T::normal,
6 => font_stretch::T::semi_expanded,
7 => font_stretch::T::expanded,
8 => font_stretch::T::extra_expanded,
9 => font_stretch::T::ultra_expanded,
_ => return Err(()),
};

let style = if italic_bool {
FontStyle::Italic
} else {
FontStyle::Normal
};

Ok(FontInfo {
family_name: family,
face_name: face,
weight: weight,
stretch: stretch,
style: style,
})
}

fn new_from_font(font: &Font) -> Result<FontInfo, ()> {
let style = font.style();
let weight = match font.weight() {
FontWeight::Thin => font_weight::T::Weight100,
FontWeight::ExtraLight => font_weight::T::Weight200,
FontWeight::Light => font_weight::T::Weight300,
// slightly grayer gray
FontWeight::SemiLight => font_weight::T::Weight300,
FontWeight::Regular => font_weight::T::Weight400,
FontWeight::Medium => font_weight::T::Weight500,
FontWeight::SemiBold => font_weight::T::Weight600,
FontWeight::Bold => font_weight::T::Weight700,
FontWeight::ExtraBold => font_weight::T::Weight800,
FontWeight::Black => font_weight::T::Weight900,
// slightly blacker black
FontWeight::ExtraBlack => font_weight::T::Weight900,
};
let stretch = match font.stretch() {
FontStretch::Undefined => font_stretch::T::normal,
FontStretch::UltraCondensed => font_stretch::T::ultra_condensed,
FontStretch::ExtraCondensed => font_stretch::T::extra_condensed,
FontStretch::Condensed => font_stretch::T::condensed,
FontStretch::SemiCondensed => font_stretch::T::semi_condensed,
FontStretch::Normal => font_stretch::T::normal,
FontStretch::SemiExpanded => font_stretch::T::semi_expanded,
FontStretch::Expanded => font_stretch::T::expanded,
FontStretch::ExtraExpanded => font_stretch::T::extra_expanded,
FontStretch::UltraExpanded => font_stretch::T::ultra_expanded,
};

Ok(FontInfo {
family_name: font.family_name(),
face_name: font.face_name(),
style: style,
weight: weight,
stretch: stretch,
})
}
}

#[derive(Debug)]
pub struct FontHandle {
font_data: Arc<FontTemplateData>,
font: Font,
face: FontFace,
info: FontInfo,
em_size: f32,
du_per_em: f32,
du_to_px: f32,
Expand All @@ -58,84 +254,68 @@ impl FontHandleMethods for FontHandle {
fn new_from_template(_: &FontContextHandle, template: Arc<FontTemplateData>, pt_size: Option<Au>)
-> Result<Self, ()>
{
if let Some(_) = template.bytes {
// FIXME we should load from template.bytes
Err(())
let (info, face) = if let Some(ref raw_font) = template.bytes {
let font_file = FontFile::new_from_data(&raw_font);
if font_file.is_none() {
// failed to load raw font
return Err(());
}

let face = font_file.unwrap().create_face(0, dwrote::DWRITE_FONT_SIMULATIONS_NONE);
let info = try!(FontInfo::new_from_face(&face));
(info, face)
} else {
let font = font_from_atom(&template.identifier);
let face = font.create_font_face();
let info = try!(FontInfo::new_from_font(&font));
(info, face)
};

let pt_size = pt_size.unwrap_or(au_from_pt(12.));
let du_per_em = face.metrics().designUnitsPerEm as f32;
let pt_size = pt_size.unwrap_or(au_from_pt(12.));
let du_per_em = face.metrics().designUnitsPerEm as f32;

let em_size = pt_size.to_f32_px() / 16.;
let design_units_per_pixel = du_per_em / 16.;
let em_size = pt_size.to_f32_px() / 16.;
let design_units_per_pixel = du_per_em / 16.;

let design_units_to_pixels = 1. / design_units_per_pixel;
let scaled_design_units_to_pixels = em_size / design_units_per_pixel;
let design_units_to_pixels = 1. / design_units_per_pixel;
let scaled_design_units_to_pixels = em_size / design_units_per_pixel;

Ok(FontHandle {
font_data: template.clone(),
font: font,
face: face,
em_size: em_size,
du_per_em: du_per_em,
du_to_px: design_units_to_pixels,
scaled_du_to_px: scaled_design_units_to_pixels,
})
}
Ok(FontHandle {
font_data: template.clone(),
face: face,
info: info,
em_size: em_size,
du_per_em: du_per_em,
du_to_px: design_units_to_pixels,
scaled_du_to_px: scaled_design_units_to_pixels,
})
}

fn template(&self) -> Arc<FontTemplateData> {
self.font_data.clone()
}

fn family_name(&self) -> String {
self.font.family_name()
self.info.family_name.clone()
}

fn face_name(&self) -> String {
self.font.face_name()
self.info.face_name.clone()
}

fn is_italic(&self) -> bool {
match self.font.style() {
match self.info.style {
FontStyle::Normal => false,
FontStyle::Oblique | FontStyle::Italic => true,
}
}

fn boldness(&self) -> font_weight::T {
match self.font.weight() {
FontWeight::Thin => font_weight::T::Weight100,
FontWeight::ExtraLight => font_weight::T::Weight200,
FontWeight::Light => font_weight::T::Weight300,
// slightly lighter gray
FontWeight::SemiLight => font_weight::T::Weight300,
FontWeight::Regular => font_weight::T::Weight400,
FontWeight::Medium => font_weight::T::Weight500,
FontWeight::SemiBold => font_weight::T::Weight600,
FontWeight::Bold => font_weight::T::Weight700,
FontWeight::ExtraBold => font_weight::T::Weight800,
FontWeight::Black => font_weight::T::Weight900,
// slightly blacker black
FontWeight::ExtraBlack => font_weight::T::Weight900,
}
self.info.weight
}

fn stretchiness(&self) -> font_stretch::T {
match self.font.stretch() {
FontStretch::Undefined => font_stretch::T::normal,
FontStretch::UltraCondensed => font_stretch::T::ultra_condensed,
FontStretch::ExtraCondensed => font_stretch::T::extra_condensed,
FontStretch::Condensed => font_stretch::T::condensed,
FontStretch::SemiCondensed => font_stretch::T::semi_condensed,
FontStretch::Normal => font_stretch::T::normal,
FontStretch::SemiExpanded => font_stretch::T::semi_expanded,
FontStretch::Expanded => font_stretch::T::expanded,
FontStretch::ExtraExpanded => font_stretch::T::extra_expanded,
FontStretch::UltraExpanded => font_stretch::T::ultra_expanded,
}
self.info.stretch
}

fn glyph_index(&self, codepoint: char) -> Option<GlyphId> {
Expand Down
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