servo/components/gfx/platform/macos/font.rs

/* 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/. */

/// Implementation of Quartz (CoreGraphics) fonts.

extern crate core_foundation;
extern crate core_graphics;
extern crate core_text;

use font::{FontHandleMethods, FontMetrics, FontTableMethods};
use font::FontTableTag;
use font::FractionalPixel;
use servo_util::geometry::{Au, px_to_pt};
use servo_util::geometry;
use platform::macos::font_context::FontContextHandle;
use text::glyph::GlyphId;
use style::computed_values::font_weight;
use platform::font_template::FontTemplateData;

use core_foundation::base::CFIndex;
use core_foundation::data::CFData;
use core_foundation::string::UniChar;
use core_graphics::font::CGGlyph;
use core_graphics::geometry::CGRect;
use core_text::font::CTFont;
use core_text::font_descriptor::{SymbolicTraitAccessors, TraitAccessors};
use core_text::font_descriptor::{kCTFontDefaultOrientation};

use std::ptr;
use sync::Arc;

pub struct FontTable {
    data: CFData,
}

// Noncopyable.
impl Drop for FontTable {
    fn drop(&mut self) {}
}

impl FontTable {
    pub fn wrap(data: CFData) -> FontTable {
        FontTable { data: data }
    }
}

impl FontTableMethods for FontTable {
    fn with_buffer(&self, blk: |*const u8, uint|) {
        blk(self.data.bytes().as_ptr(), self.data.len() as uint);
    }
}

pub struct FontHandle {
    pub font_data: Arc<FontTemplateData>,
    pub ctfont: CTFont,
}

impl FontHandleMethods for FontHandle {
    fn new_from_template(_fctx: &FontContextHandle,
                       template: Arc<FontTemplateData>,
                       pt_size: Option<f64>)
                        -> Result<FontHandle, ()> {
        let size = match pt_size {
            Some(s) => s,
            None => 0.0
        };
        match template.ctfont {
            Some(ref ctfont) => {
                Ok(FontHandle {
                    font_data: template.clone(),
                    ctfont: ctfont.clone_with_font_size(size),
                })
            }
            None => {
                Err(())
            }
        }
    }

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

    fn family_name(&self) -> String {
        self.ctfont.family_name()
    }

    fn face_name(&self) -> String {
        self.ctfont.face_name()
    }

    fn is_italic(&self) -> bool {
        self.ctfont.symbolic_traits().is_italic()
    }

    fn boldness(&self) -> font_weight::T {
        // -1.0 to 1.0
        let normalized = self.ctfont.all_traits().normalized_weight();
        // 0.0 to 9.0
        let normalized = (normalized + 1.0) / 2.0 * 9.0;
        if normalized < 1.0 { return font_weight::Weight100; }
        if normalized < 2.0 { return font_weight::Weight200; }
        if normalized < 3.0 { return font_weight::Weight300; }
        if normalized < 4.0 { return font_weight::Weight400; }
        if normalized < 5.0 { return font_weight::Weight500; }
        if normalized < 6.0 { return font_weight::Weight600; }
        if normalized < 7.0 { return font_weight::Weight700; }
        if normalized < 8.0 { return font_weight::Weight800; }
        return font_weight::Weight900;
    }

    fn glyph_index(&self, codepoint: char) -> Option<GlyphId> {
        let characters: [UniChar,  ..1] = [codepoint as UniChar];
        let mut glyphs: [CGGlyph, ..1] = [0 as CGGlyph];
        let count: CFIndex = 1;

        let result = self.ctfont.get_glyphs_for_characters(&characters[0],
                                                           &mut glyphs[0],
                                                           count);

        if !result {
            // No glyph for this character
            return None;
        }

        assert!(glyphs[0] != 0); // FIXME: error handling
        return Some(glyphs[0] as GlyphId);
    }

    fn glyph_h_kerning(&self, _first_glyph: GlyphId, _second_glyph: GlyphId)
                        -> FractionalPixel {
        // TODO: Implement on mac
        0.0
    }

    fn glyph_h_advance(&self, glyph: GlyphId) -> Option<FractionalPixel> {
        let glyphs = [glyph as CGGlyph];
        let advance = self.ctfont.get_advances_for_glyphs(kCTFontDefaultOrientation,
                                                          &glyphs[0],
                                                          ptr::mut_null(),
                                                          1);
        Some(advance as FractionalPixel)
    }

    fn get_metrics(&self) -> FontMetrics {
        let bounding_rect: CGRect = self.ctfont.bounding_box();
        let ascent = self.ctfont.ascent() as f64;
        let descent = self.ctfont.descent() as f64;
        let em_size = Au::from_frac_px(self.ctfont.pt_size() as f64);
        let leading = self.ctfont.leading() as f64;

        let scale = px_to_pt(self.ctfont.pt_size() as f64) / (ascent + descent);
        let line_gap = (ascent + descent + leading + 0.5).floor();

        let metrics =  FontMetrics {
            underline_size:   Au::from_pt(self.ctfont.underline_thickness() as f64),
            // TODO(Issue #201): underline metrics are not reliable. Have to pull out of font table
            // directly.
            //
            // see also: https://bugs.webkit.org/show_bug.cgi?id=16768
            // see also: https://bugreports.qt-project.org/browse/QTBUG-13364
            underline_offset: Au::from_pt(self.ctfont.underline_position() as f64),
            strikeout_size:   geometry::from_pt(0.0), // FIXME(Issue #942)
            strikeout_offset: geometry::from_pt(0.0), // FIXME(Issue #942)
            leading:          Au::from_pt(leading),
            x_height:         Au::from_pt(self.ctfont.x_height() as f64),
            em_size:          em_size,
            ascent:           Au::from_pt(ascent * scale),
            descent:          Au::from_pt(descent * scale),
            max_advance:      Au::from_pt(bounding_rect.size.width as f64),
            line_gap:         Au::from_frac_px(line_gap),
        };
        debug!("Font metrics (@{:f} pt): {:?}", self.ctfont.pt_size() as f64, metrics);
        return metrics;
    }

    fn get_table_for_tag(&self, tag: FontTableTag) -> Option<FontTable> {
        let result: Option<CFData> = self.ctfont.get_font_table(tag);
        result.and_then(|data| {
            Some(FontTable::wrap(data))
        })
    }
}