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macOS use system font fallback

This commit is contained in:
Martin Algesten 2017-05-31 12:53:12 +02:00 committed by Joe Wilm
parent 1e064fb3e7
commit 40de8402a7

View file

@ -23,14 +23,13 @@ use ::{Slant, Weight, Style};
use core_foundation::base::TCFType;
use core_foundation::string::{CFString, CFStringRef};
use core_foundation::array::CFIndex;
use core_foundation_sys::string::UniChar;
use core_foundation::array::{CFIndex, CFArray};
use core_graphics::base::kCGImageAlphaPremultipliedFirst;
use core_graphics::color_space::CGColorSpace;
use core_graphics::context::{CGContext};
use core_graphics::font::{CGFont, CGGlyph};
use core_graphics::geometry::{CGPoint, CGRect, CGSize};
use core_text::font::{CTFont, new_from_descriptor as ct_new_from_descriptor};
use core_text::font::{CTFont, new_from_descriptor as ct_new_from_descriptor, cascade_list_for_languages as ct_cascade_list_for_languages};
use core_text::font_collection::create_for_family;
use core_text::font_collection::get_family_names as ct_get_family_names;
use core_text::font_descriptor::kCTFontDefaultOrientation;
@ -65,6 +64,19 @@ pub struct Descriptor {
ct_descriptor: CTFontDescriptor
}
impl Descriptor {
fn new(desc:CTFontDescriptor) -> Descriptor {
Descriptor {
family_name: desc.family_name(),
font_name: desc.font_name(),
style_name: desc.style_name(),
display_name: desc.display_name(),
font_path: desc.font_path().unwrap_or_else(||{"".to_owned()}),
ct_descriptor: desc,
}
}
}
/// Rasterizer, the main type exported by this package
///
/// Given a fontdesc, can rasterize fonts.
@ -142,7 +154,22 @@ impl ::Rasterize for Rasterizer {
.get(&(desc.to_owned(), size))
.map(|k| Ok(*k))
.unwrap_or_else(|| {
let font = self.get_font(desc, size)?;
let mut font = self.get_font(desc, size)?;
// TODO, we can't use apple's proposed
// .Apple Symbol Fallback (filtered out below),
// but not having these makes us not able to render
// many chars. We add the symbols back in.
// Investigate if we can actually use the .-prefixed
// fallbacks somehow.
{
let symbols = {
let d = FontDesc::new("Apple Symbols".to_owned(), desc.style.clone());
self.get_font(&d, size)?
};
font.fallbacks.push(symbols);
}
let key = FontKey::next();
self.fonts.insert(key, font);
@ -154,12 +181,25 @@ impl ::Rasterize for Rasterizer {
/// Get rasterized glyph for given glyph key
fn get_glyph(&mut self, glyph: &GlyphKey) -> Result<RasterizedGlyph, Error> {
let scaled_size = self.device_pixel_ratio * glyph.size.as_f32_pts();
self.fonts
// get loaded font
let font = self.fonts
.get(&glyph.font_key)
.ok_or(Error::FontNotLoaded)?
.get_glyph(glyph.c, scaled_size as _, self.use_thin_strokes)
.ok_or(Error::FontNotLoaded)?;
// first try the font itself as a direct hit
self.maybe_get_glyph(glyph, font)
.unwrap_or_else(|| {
// then try fallbacks
for fallback in &font.fallbacks {
if let Some(result) = self.maybe_get_glyph(glyph, &fallback) {
// found a fallback
return result;
}
}
// no fallback, give up.
Err(Error::MissingGlyph(glyph.c))
})
}
}
@ -175,7 +215,7 @@ impl Rasterizer {
if descriptor.style_name == style {
// Found the font we want
let scaled_size = size.as_f32_pts() as f64 * self.device_pixel_ratio as f64;
let font = descriptor.to_font(scaled_size);
let font = descriptor.to_font(scaled_size, true);
return Ok(font);
}
}
@ -202,7 +242,7 @@ impl Rasterizer {
let descriptors = descriptors_for_family(&desc.name[..]);
for descriptor in descriptors {
let font = descriptor.to_font(scaled_size);
let font = descriptor.to_font(scaled_size, true);
if font.is_bold() == bold && font.is_italic() == italic {
// Found the font we want
return Ok(font);
@ -220,6 +260,22 @@ impl Rasterizer {
},
}
}
// Helper to try and get a glyph for a given font. Used for font fallback.
fn maybe_get_glyph(
&self,
glyph: &GlyphKey,
font: &Font,
) -> Option<Result<RasterizedGlyph, Error>> {
let scaled_size = self.device_pixel_ratio * glyph.size.as_f32_pts();
font.get_glyph(glyph.c, scaled_size as _, self.use_thin_strokes)
.map(|r| Some(Ok(r)))
.unwrap_or_else(|e| match e {
Error::MissingGlyph(_) => None,
_ => Some(Err(e)),
})
}
}
/// Specifies the intended rendering orientation of the font for obtaining glyph metrics
@ -241,6 +297,7 @@ impl Default for FontOrientation {
pub struct Font {
ct_font: CTFont,
cg_font: CGFont,
fallbacks: Vec<Font>,
}
unsafe impl Send for Font {}
@ -259,6 +316,36 @@ pub fn get_family_names() -> Vec<String> {
owned_names
}
/// Return fallback descriptors for font/language list
fn cascade_list_for_languages(
ct_font: &CTFont,
languages: &Vec<String>
) -> Vec<Descriptor> {
// convert language type &Vec<String> -> CFArray
let langarr:CFArray = {
let tmp:Vec<CFString> = languages.iter()
.map(|language| CFString::new(&language))
.collect();
CFArray::from_CFTypes(&tmp)
};
// CFArray of CTFontDescriptorRef (again)
let list = ct_cascade_list_for_languages(ct_font, &langarr);
// convert CFArray to Vec<Descriptor>
list.into_iter()
.map(|fontdesc| {
let desc: CTFontDescriptor = unsafe {
TCFType::wrap_under_get_rule(fontdesc as CTFontDescriptorRef)
};
Descriptor::new(desc)
})
.collect()
}
/// Get descriptors for family name
pub fn descriptors_for_family(family: &str) -> Vec<Descriptor> {
let mut out = Vec::new();
@ -274,14 +361,7 @@ pub fn descriptors_for_family(family: &str) -> Vec<Descriptor> {
let desc: CTFontDescriptor = unsafe {
TCFType::wrap_under_get_rule(descriptor as CTFontDescriptorRef)
};
out.push(Descriptor {
family_name: desc.family_name(),
font_name: desc.font_name(),
style_name: desc.style_name(),
display_name: desc.display_name(),
font_path: desc.font_path().unwrap_or_else(||{"".to_owned()}),
ct_descriptor: desc,
});
out.push(Descriptor::new(desc));
}
out
@ -289,12 +369,31 @@ pub fn descriptors_for_family(family: &str) -> Vec<Descriptor> {
impl Descriptor {
/// Create a Font from this descriptor
pub fn to_font(&self, size: f64) -> Font {
pub fn to_font(&self, size: f64, load_fallbacks:bool) -> Font {
let ct_font = ct_new_from_descriptor(&self.ct_descriptor, size);
let cg_font = ct_font.copy_to_CGFont();
let fallbacks = if load_fallbacks {
// TODO fixme, hardcoded en for english
cascade_list_for_languages(&ct_font, &vec!["en".to_owned()])
.into_iter()
// the system lists contains (at least) two strange fonts:
// .Apple Symbol Fallback
// .Noto Sans Universal
// both have a .-prefix (to indicate they are internal?)
// neither work very well. the latter even breaks things because
// it defines code points with just [?] glyphs.
.filter(|desc| desc.font_path != "")
.map(|desc| desc.to_font(size, false))
.collect()
} else {
vec![]
};
Font {
ct_font: ct_font,
cg_font: cg_font,
fallbacks: fallbacks,
}
}
}
@ -438,13 +537,23 @@ impl Font {
}
fn glyph_index(&self, character: char) -> Option<u32> {
let chars = [character as UniChar];
let mut glyphs = [0 as CGGlyph];
// encode this char as utf-16
let mut buf = [0; 2];
let encoded:&[u16] = character.encode_utf16(&mut buf);
// and use the utf-16 buffer to get the index
self.glyph_index_utf16(encoded)
}
fn glyph_index_utf16(&self, encoded: &[u16]) -> Option<u32> {
// output buffer for the glyph. for non-BMP glyphs, like
// emojis, this will be filled with two chars the second
// always being a 0.
let mut glyphs:[CGGlyph; 2] = [0; 2];
let res = self.ct_font.get_glyphs_for_characters(
&chars[0],
&mut glyphs[0],
1 as CFIndex
encoded.as_ptr(),
glyphs.as_mut_ptr(),
encoded.len() as CFIndex
);
if res {