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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use geom::{Point2D, Rect, Size2D};
use std::mem;
use std::string;
use std::rc::Rc;
use std::cell::RefCell;
use servo_util::cache::{Cache, HashCache};
use style::computed_values::{font_weight, font_style};
use sync::Arc;
use servo_util::geometry::Au;
use platform::font_context::FontContextHandle;
use platform::font::{FontHandle, FontTable};
use text::glyph::{GlyphStore, GlyphId};
use text::shaping::ShaperMethods;
use text::{Shaper, TextRun};
use font_template::FontTemplateDescriptor;
use platform::font_template::FontTemplateData;
// FontHandle encapsulates access to the platform's font API,
// e.g. quartz, FreeType. It provides access to metrics and tables
// needed by the text shaper as well as access to the underlying font
// resources needed by the graphics layer to draw glyphs.
pub trait FontHandleMethods {
fn new_from_template(fctx: &FontContextHandle, template: Arc<FontTemplateData>, pt_size: Option<f64>)
-> Result<Self,()>;
fn get_template(&self) -> Arc<FontTemplateData>;
fn family_name(&self) -> String;
fn face_name(&self) -> String;
fn is_italic(&self) -> bool;
fn boldness(&self) -> font_weight::T;
fn glyph_index(&self, codepoint: char) -> Option<GlyphId>;
fn glyph_h_advance(&self, GlyphId) -> Option<FractionalPixel>;
fn glyph_h_kerning(&self, GlyphId, GlyphId) -> FractionalPixel;
fn get_metrics(&self) -> FontMetrics;
fn get_table_for_tag(&self, FontTableTag) -> Option<FontTable>;
}
// Used to abstract over the shaper's choice of fixed int representation.
pub type FractionalPixel = f64;
pub type FontTableTag = u32;
pub trait FontTableTagConversions {
fn tag_to_str(&self) -> String;
}
impl FontTableTagConversions for FontTableTag {
fn tag_to_str(&self) -> String {
unsafe {
let reversed = string::raw::from_buf_len(mem::transmute(self), 4);
return String::from_chars([reversed.as_slice().char_at(3),
reversed.as_slice().char_at(2),
reversed.as_slice().char_at(1),
reversed.as_slice().char_at(0)]);
}
}
}
pub trait FontTableMethods {
fn with_buffer(&self, |*const u8, uint|);
}
#[deriving(Clone)]
pub struct FontMetrics {
pub underline_size: Au,
pub underline_offset: Au,
pub strikeout_size: Au,
pub strikeout_offset: Au,
pub leading: Au,
pub x_height: Au,
pub em_size: Au,
pub ascent: Au,
pub descent: Au,
pub max_advance: Au,
pub line_gap: Au,
}
// TODO(Issue #179): eventually this will be split into the specified
// and used font styles. specified contains uninterpreted CSS font
// property values, while 'used' is attached to gfx::Font to descript
// the instance's properties.
//
// For now, the cases are differentiated with a typedef
#[deriving(Clone, PartialEq)]
pub struct FontStyle {
pub pt_size: f64,
pub weight: font_weight::T,
pub style: font_style::T,
pub families: Vec<String>,
// TODO(Issue #198): font-stretch, text-decoration, font-variant, size-adjust
}
pub type SpecifiedFontStyle = FontStyle;
pub type UsedFontStyle = FontStyle;
pub struct Font {
pub handle: FontHandle,
pub metrics: FontMetrics,
pub descriptor: FontTemplateDescriptor,
pub pt_size: f64,
pub shaper: Option<Shaper>,
pub shape_cache: HashCache<String, Arc<GlyphStore>>,
pub glyph_advance_cache: HashCache<u32, FractionalPixel>,
}
impl Font {
pub fn shape_text(&mut self, text: String, is_whitespace: bool) -> Arc<GlyphStore> {
self.make_shaper();
let shaper = &self.shaper;
self.shape_cache.find_or_create(&text, |txt| {
let mut glyphs = GlyphStore::new(text.as_slice().char_len() as int, is_whitespace);
shaper.get_ref().shape_text(txt.as_slice(), &mut glyphs);
Arc::new(glyphs)
})
}
fn make_shaper<'a>(&'a mut self) -> &'a Shaper {
// fast path: already created a shaper
match self.shaper {
Some(ref shaper) => {
let s: &'a Shaper = shaper;
return s;
},
None => {}
}
let shaper = Shaper::new(self);
self.shaper = Some(shaper);
self.shaper.get_ref()
}
pub fn get_table_for_tag(&self, tag: FontTableTag) -> Option<FontTable> {
let result = self.handle.get_table_for_tag(tag);
let status = if result.is_some() { "Found" } else { "Didn't find" };
debug!("{:s} font table[{:s}] with family={}, face={}",
status, tag.tag_to_str(),
self.handle.family_name(), self.handle.face_name());
return result;
}
pub fn glyph_index(&self, codepoint: char) -> Option<GlyphId> {
self.handle.glyph_index(codepoint)
}
pub fn glyph_h_kerning(&mut self, first_glyph: GlyphId, second_glyph: GlyphId) -> FractionalPixel {
self.handle.glyph_h_kerning(first_glyph, second_glyph)
}
pub fn glyph_h_advance(&mut self, glyph: GlyphId) -> FractionalPixel {
let handle = &self.handle;
self.glyph_advance_cache.find_or_create(&glyph, |glyph| {
match handle.glyph_h_advance(*glyph) {
Some(adv) => adv,
None => 10f64 as FractionalPixel // FIXME: Need fallback strategy
}
})
}
}
pub struct FontGroup {
pub fonts: Vec<Rc<RefCell<Font>>>,
}
impl FontGroup {
pub fn new(fonts: Vec<Rc<RefCell<Font>>>) -> FontGroup {
FontGroup {
fonts: fonts
}
}
pub fn create_textrun(&self, text: String) -> TextRun {
assert!(self.fonts.len() > 0);
// TODO(Issue #177): Actually fall back through the FontGroup when a font is unsuitable.
TextRun::new(&mut *self.fonts[0].borrow_mut(), text.clone())
}
}
pub struct RunMetrics {
// may be negative due to negative width (i.e., kerning of '.' in 'P.T.')
pub advance_width: Au,
pub ascent: Au, // nonzero
pub descent: Au, // nonzero
// this bounding box is relative to the left origin baseline.
// so, bounding_box.position.y = -ascent
pub bounding_box: Rect<Au>
}
impl RunMetrics {
pub fn new(advance: Au, ascent: Au, descent: Au) -> RunMetrics {
let bounds = Rect(Point2D(Au(0), -ascent),
Size2D(advance, ascent + descent));
// TODO(Issue #125): support loose and tight bounding boxes; using the
// ascent+descent and advance is sometimes too generous and
// looking at actual glyph extents can yield a tighter box.
RunMetrics {
advance_width: advance,
bounding_box: bounds,
ascent: ascent,
descent: descent,
}
}
}
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