servo/components/gfx/tests/font_context.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 https://mozilla.org/MPL/2.0/. */

use std::cell::Cell;
use std::collections::HashMap;
use std::fs::File;
use std::io::prelude::*;
use std::path::PathBuf;
use std::rc::Rc;

use app_units::Au;
use gfx::font::{
    fallback_font_families, FontDescriptor, FontFamilyDescriptor, FontFamilyName, FontSearchScope,
};
use gfx::font_cache_thread::{CSSFontFaceDescriptors, FontIdentifier, FontTemplates};
use gfx::font_context::{FontContext, FontSource};
use gfx::font_template::{FontTemplate, FontTemplateRef};
use servo_arc::Arc;
use servo_atoms::Atom;
use servo_url::ServoUrl;
use style::properties::longhands::font_variant_caps::computed_value::T as FontVariantCaps;
use style::properties::style_structs::Font as FontStyleStruct;
use style::values::computed::font::{
    FamilyName, FontFamily, FontFamilyList, FontFamilyNameSyntax, FontSize, FontStretch, FontStyle,
    FontWeight, SingleFontFamily,
};
use style::values::computed::{FontLanguageOverride, XLang};
use style::values::generics::font::LineHeight;
use webrender_api::{FontInstanceFlags, FontInstanceKey, IdNamespace};

struct TestFontSource {
    families: HashMap<String, FontTemplates>,
    find_font_count: Rc<Cell<isize>>,
}

impl TestFontSource {
    fn new() -> TestFontSource {
        let mut csstest_ascii = FontTemplates::default();
        Self::add_face(&mut csstest_ascii, "csstest-ascii");

        let mut csstest_basic = FontTemplates::default();
        Self::add_face(&mut csstest_basic, "csstest-basic-regular");

        let mut fallback = FontTemplates::default();
        Self::add_face(&mut fallback, "csstest-basic-regular");

        let mut families = HashMap::new();
        families.insert("CSSTest ASCII".to_owned(), csstest_ascii);
        families.insert("CSSTest Basic".to_owned(), csstest_basic);
        families.insert(fallback_font_families(None)[0].to_owned(), fallback);

        TestFontSource {
            families,
            find_font_count: Rc::new(Cell::new(0)),
        }
    }

    fn identifier_for_font_name(name: &str) -> FontIdentifier {
        FontIdentifier::Web(Self::url_for_font_name(name))
    }

    fn url_for_font_name(name: &str) -> ServoUrl {
        let mut path: PathBuf = [env!("CARGO_MANIFEST_DIR"), "tests", "support", "CSSTest"]
            .iter()
            .collect();
        path.push(format!("{}.ttf", name));
        ServoUrl::from_file_path(path).unwrap()
    }

    fn add_face(family: &mut FontTemplates, name: &str) {
        let mut path: PathBuf = [env!("CARGO_MANIFEST_DIR"), "tests", "support", "CSSTest"]
            .iter()
            .collect();
        path.push(format!("{}.ttf", name));

        let file = File::open(path).unwrap();
        let data: Vec<u8> = file.bytes().map(|b| b.unwrap()).collect();
        family.add_template(
            FontTemplate::new_web_font(
                Self::url_for_font_name(name),
                std::sync::Arc::new(data),
                CSSFontFaceDescriptors::new(name),
            )
            .unwrap(),
        );
    }
}

impl FontSource for TestFontSource {
    fn get_font_instance(
        &mut self,
        _font_identifier: FontIdentifier,
        _size: Au,
        _flags: FontInstanceFlags,
    ) -> FontInstanceKey {
        FontInstanceKey(IdNamespace(0), 0)
    }

    fn find_matching_font_templates(
        &mut self,
        descriptor_to_match: &FontDescriptor,
        family_descriptor: FontFamilyDescriptor,
    ) -> Vec<FontTemplateRef> {
        self.find_font_count.set(self.find_font_count.get() + 1);
        self.families
            .get_mut(family_descriptor.name())
            .map(|family| family.find_for_descriptor(descriptor_to_match))
            .unwrap_or_default()
    }
}

fn style() -> FontStyleStruct {
    let mut style = FontStyleStruct {
        font_family: FontFamily::serif(),
        font_style: FontStyle::NORMAL,
        font_variant_caps: FontVariantCaps::Normal,
        font_weight: FontWeight::normal(),
        font_size: FontSize::medium(),
        font_stretch: FontStretch::hundred(),
        hash: 0,
        font_language_override: FontLanguageOverride::normal(),
        line_height: LineHeight::Normal,
        _x_lang: XLang::get_initial_value(),
    };
    style.compute_font_hash();
    style
}

fn font_family(names: Vec<&str>) -> FontFamily {
    let names: Vec<SingleFontFamily> = names
        .into_iter()
        .map(|name| {
            SingleFontFamily::FamilyName(FamilyName {
                name: Atom::from(name),
                syntax: FontFamilyNameSyntax::Quoted,
            })
        })
        .collect();

    FontFamily {
        families: FontFamilyList {
            list: names.into_boxed_slice(),
        },
        is_system_font: false,
        is_initial: false,
    }
}

#[test]
fn test_font_group_is_cached_by_style() {
    let source = TestFontSource::new();
    let context = FontContext::new(source);

    let style1 = style();

    let mut style2 = style();
    style2.set_font_style(FontStyle::ITALIC);

    assert!(
        std::ptr::eq(
            &*context.font_group(Arc::new(style1.clone())).read(),
            &*context.font_group(Arc::new(style1.clone())).read()
        ),
        "the same font group should be returned for two styles with the same hash"
    );

    assert!(
        !std::ptr::eq(
            &*context.font_group(Arc::new(style1.clone())).read(),
            &*context.font_group(Arc::new(style2.clone())).read()
        ),
        "different font groups should be returned for two styles with different hashes"
    )
}

#[test]
fn test_font_group_find_by_codepoint() {
    let source = TestFontSource::new();
    let count = source.find_font_count.clone();
    let mut context = FontContext::new(source);

    let mut style = style();
    style.set_font_family(font_family(vec!["CSSTest ASCII", "CSSTest Basic"]));

    let group = context.font_group(Arc::new(style));

    let font = group.write().find_by_codepoint(&mut context, 'a').unwrap();
    assert_eq!(
        font.identifier(),
        TestFontSource::identifier_for_font_name("csstest-ascii")
    );
    assert_eq!(
        count.get(),
        1,
        "only the first font in the list should have been loaded"
    );

    let font = group.write().find_by_codepoint(&mut context, 'a').unwrap();
    assert_eq!(
        font.identifier(),
        TestFontSource::identifier_for_font_name("csstest-ascii")
    );
    assert_eq!(
        count.get(),
        1,
        "we shouldn't load the same font a second time"
    );

    let font = group.write().find_by_codepoint(&mut context, 'á').unwrap();
    assert_eq!(
        font.identifier(),
        TestFontSource::identifier_for_font_name("csstest-basic-regular")
    );
    assert_eq!(count.get(), 2, "both fonts should now have been loaded");
}

#[test]
fn test_font_fallback() {
    let source = TestFontSource::new();
    let mut context = FontContext::new(source);

    let mut style = style();
    style.set_font_family(font_family(vec!["CSSTest ASCII"]));

    let group = context.font_group(Arc::new(style));

    let font = group.write().find_by_codepoint(&mut context, 'a').unwrap();
    assert_eq!(
        font.identifier(),
        TestFontSource::identifier_for_font_name("csstest-ascii"),
        "a family in the group should be used if there is a matching glyph"
    );

    let font = group.write().find_by_codepoint(&mut context, 'á').unwrap();
    assert_eq!(
        font.identifier(),
        TestFontSource::identifier_for_font_name("csstest-basic-regular"),
        "a fallback font should be used if there is no matching glyph in the group"
    );
}

#[test]
fn test_font_template_is_cached() {
    let source = TestFontSource::new();
    let count = source.find_font_count.clone();
    let context = FontContext::new(source);

    let mut font_descriptor = FontDescriptor {
        weight: FontWeight::normal(),
        stretch: FontStretch::hundred(),
        style: FontStyle::normal(),
        variant: FontVariantCaps::Normal,
        pt_size: Au(10),
    };

    let family_descriptor =
        FontFamilyDescriptor::new(FontFamilyName::from("CSSTest Basic"), FontSearchScope::Any);

    let font_template = context.matching_templates(&font_descriptor, &family_descriptor)[0].clone();

    let font1 = context
        .font(font_template.clone(), &font_descriptor)
        .unwrap();

    font_descriptor.pt_size = Au(20);
    let font2 = context
        .font(font_template.clone(), &font_descriptor)
        .unwrap();

    assert_ne!(
        font1.descriptor.pt_size, font2.descriptor.pt_size,
        "the same font should not have been returned"
    );

    assert_eq!(
        count.get(),
        1,
        "we should only have fetched the template data from the cache thread once"
    );
}