font_kit/
source.rs

1// font-kit/src/source.rs
2//
3// Copyright © 2018 The Pathfinder Project Developers.
4//
5// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8// option. This file may not be copied, modified, or distributed
9// except according to those terms.
10
11//! A database of installed fonts that can be queried.
12
13use crate::error::SelectionError;
14use crate::family::Family;
15use crate::family_handle::FamilyHandle;
16use crate::family_name::FamilyName;
17use crate::font::Font;
18use crate::handle::Handle;
19use crate::matching;
20use crate::properties::Properties;
21use std::any::Any;
22
23#[cfg(all(
24    any(target_os = "macos", target_os = "ios"),
25    not(feature = "loader-freetype-default")
26))]
27pub use crate::sources::core_text::CoreTextSource as SystemSource;
28#[cfg(all(target_family = "windows", not(feature = "source-fontconfig-default")))]
29pub use crate::sources::directwrite::DirectWriteSource as SystemSource;
30#[cfg(all(
31    any(
32        not(any(
33            target_os = "android",
34            target_os = "macos",
35            target_os = "ios",
36            target_family = "windows",
37            target_arch = "wasm32",
38        )),
39        feature = "source-fontconfig-default"
40    ),
41    not(target_env = "ohos")
42))]
43pub use crate::sources::fontconfig::FontconfigSource as SystemSource;
44#[cfg(all(target_os = "android", not(feature = "source-fontconfig-default")))]
45pub use crate::sources::fs::FsSource as SystemSource;
46
47#[cfg(target_env = "ohos")]
48pub use crate::sources::fs::FsSource as SystemSource;
49
50// FIXME(pcwalton): These could expand to multiple fonts, and they could be language-specific.
51#[cfg(any(target_family = "windows", target_os = "macos", target_os = "ios"))]
52const DEFAULT_FONT_FAMILY_SERIF: &'static str = "Times New Roman";
53#[cfg(any(target_family = "windows", target_os = "macos", target_os = "ios"))]
54const DEFAULT_FONT_FAMILY_SANS_SERIF: &'static str = "Arial";
55#[cfg(target_env = "ohos")]
56const DEFAULT_FONT_FAMILY_SANS_SERIF: &str = "HarmonyOS Sans";
57#[cfg(any(target_family = "windows", target_os = "macos", target_os = "ios"))]
58const DEFAULT_FONT_FAMILY_MONOSPACE: &'static str = "Courier New";
59#[cfg(target_env = "ohos")]
60const DEFAULT_FONT_FAMILY_MONOSPACE: &str = "HarmonyOS Sans";
61#[cfg(any(target_family = "windows", target_os = "macos", target_os = "ios"))]
62const DEFAULT_FONT_FAMILY_CURSIVE: &'static str = "Comic Sans MS";
63#[cfg(target_family = "windows")]
64const DEFAULT_FONT_FAMILY_FANTASY: &'static str = "Impact";
65#[cfg(any(target_os = "macos", target_os = "ios"))]
66const DEFAULT_FONT_FAMILY_FANTASY: &'static str = "Papyrus";
67
68#[cfg(not(any(target_family = "windows", target_os = "macos", target_os = "ios")))]
69const DEFAULT_FONT_FAMILY_SERIF: &str = "serif";
70#[cfg(not(any(
71    target_family = "windows",
72    target_os = "macos",
73    target_os = "ios",
74    target_env = "ohos"
75)))]
76const DEFAULT_FONT_FAMILY_SANS_SERIF: &str = "sans-serif";
77#[cfg(not(any(
78    target_family = "windows",
79    target_os = "macos",
80    target_os = "ios",
81    target_env = "ohos"
82)))]
83const DEFAULT_FONT_FAMILY_MONOSPACE: &str = "monospace";
84#[cfg(not(any(target_family = "windows", target_os = "macos", target_os = "ios")))]
85const DEFAULT_FONT_FAMILY_CURSIVE: &str = "cursive";
86#[cfg(not(any(target_family = "windows", target_os = "macos", target_os = "ios")))]
87const DEFAULT_FONT_FAMILY_FANTASY: &str = "fantasy";
88
89/// A database of installed fonts that can be queried.
90///
91/// This trait is object-safe.
92pub trait Source: Any {
93    /// Returns paths of all fonts installed on the system.
94    fn all_fonts(&self) -> Result<Vec<Handle>, SelectionError>;
95
96    /// Returns the names of all families installed on the system.
97    fn all_families(&self) -> Result<Vec<String>, SelectionError>;
98
99    /// Looks up a font family by name and returns the handles of all the fonts in that family.
100    fn select_family_by_name(&self, family_name: &str) -> Result<FamilyHandle, SelectionError>;
101
102    /// Selects a font by PostScript name, which should be a unique identifier.
103    ///
104    /// The default implementation, which is used by the DirectWrite and the filesystem backends,
105    /// does a brute-force search of installed fonts to find the one that matches.
106    fn select_by_postscript_name(&self, postscript_name: &str) -> Result<Handle, SelectionError> {
107        // TODO(pcwalton): Optimize this by searching for families with similar names first.
108        for family_name in self.all_families()? {
109            if let Ok(family_handle) = self.select_family_by_name(&family_name) {
110                if let Ok(family) = Family::<Font>::from_handle(&family_handle) {
111                    for (handle, font) in family_handle.fonts().iter().zip(family.fonts().iter()) {
112                        if let Some(font_postscript_name) = font.postscript_name() {
113                            if font_postscript_name == postscript_name {
114                                return Ok((*handle).clone());
115                            }
116                        }
117                    }
118                }
119            }
120        }
121        Err(SelectionError::NotFound)
122    }
123
124    // FIXME(pcwalton): This only returns one family instead of multiple families for the generic
125    // family names.
126    #[doc(hidden)]
127    fn select_family_by_generic_name(
128        &self,
129        family_name: &FamilyName,
130    ) -> Result<FamilyHandle, SelectionError> {
131        match *family_name {
132            FamilyName::Title(ref title) => self.select_family_by_name(title),
133            FamilyName::Serif => self.select_family_by_name(DEFAULT_FONT_FAMILY_SERIF),
134            FamilyName::SansSerif => self.select_family_by_name(DEFAULT_FONT_FAMILY_SANS_SERIF),
135            FamilyName::Monospace => self.select_family_by_name(DEFAULT_FONT_FAMILY_MONOSPACE),
136            FamilyName::Cursive => self.select_family_by_name(DEFAULT_FONT_FAMILY_CURSIVE),
137            FamilyName::Fantasy => self.select_family_by_name(DEFAULT_FONT_FAMILY_FANTASY),
138        }
139    }
140
141    /// Performs font matching according to the CSS Fonts Level 3 specification and returns the
142    /// handle.
143    #[inline]
144    fn select_best_match(
145        &self,
146        family_names: &[FamilyName],
147        properties: &Properties,
148    ) -> Result<Handle, SelectionError> {
149        for family_name in family_names {
150            if let Ok(family_handle) = self.select_family_by_generic_name(family_name) {
151                let candidates = self.select_descriptions_in_family(&family_handle)?;
152                if let Ok(index) = matching::find_best_match(&candidates, properties) {
153                    return Ok(family_handle.fonts[index].clone());
154                }
155            }
156        }
157        Err(SelectionError::NotFound)
158    }
159
160    #[doc(hidden)]
161    fn select_descriptions_in_family(
162        &self,
163        family: &FamilyHandle,
164    ) -> Result<Vec<Properties>, SelectionError> {
165        let mut fields = vec![];
166        for font_handle in family.fonts() {
167            match Font::from_handle(font_handle) {
168                Ok(font) => fields.push(font.properties()),
169                Err(e) => log::warn!("Error loading font from handle: {:?}", e),
170            }
171        }
172        Ok(fields)
173    }
174
175    /// Accesses this `Source` as `Any`, which allows downcasting back to a concrete type from a
176    /// trait object.
177    fn as_any(&self) -> &dyn Any;
178
179    /// Accesses this `Source` as `Any`, which allows downcasting back to a concrete type from a
180    /// trait object.
181    fn as_mut_any(&mut self) -> &mut dyn Any;
182}
font_kit/source.rs

font_kit/
source.rs
