ab_glyph/
variable.rs

1#[cfg(not(feature = "std"))]
2use alloc::string::String;
3#[cfg(not(feature = "std"))]
4use alloc::vec::Vec;
5
6/// Logic for variable fonts.
7///
8/// Requires feature `variable-fonts` (enabled by default).
9pub trait VariableFont {
10    /// Sets a variation axis coordinate value by it's tag.
11    ///
12    /// Returns false if there is no such axis tag.
13    ///
14    /// # Example
15    /// ```
16    /// use ab_glyph::{FontRef, VariableFont};
17    ///
18    /// # fn main() -> Result<(), ab_glyph::InvalidFont> {
19    /// let mut font = FontRef::try_from_slice(include_bytes!("../../dev/fonts/Cantarell-VF.otf"))?;
20    ///
21    /// // set weight to 600
22    /// assert!(font.set_variation(b"wght", 600.0));
23    ///
24    /// // no such variation tag "foob" so return false
25    /// assert!(!font.set_variation(b"foob", 200.0));
26    /// # Ok(()) }
27    /// ```
28    fn set_variation(&mut self, tag: &[u8; 4], value: f32) -> bool;
29
30    /// Returns variation axes.
31    ///
32    /// # Example
33    /// ```
34    /// use ab_glyph::{FontRef, VariableFont};
35    ///
36    /// # fn main() -> Result<(), ab_glyph::InvalidFont> {
37    /// let font = FontRef::try_from_slice(include_bytes!("../../dev/fonts/Cantarell-VF.otf"))?;
38    /// let var = &font.variations()[0];
39    /// # eprintln!("{var:#?}");
40    ///
41    /// assert_eq!(var.tag, *b"wght");
42    /// assert_eq!(var.name.as_deref(), Some("Weight"));
43    /// assert!((var.min_value - 100.0).abs() < f32::EPSILON);
44    /// assert!((var.default_value - 400.0).abs() < f32::EPSILON);
45    /// assert!((var.max_value - 800.0).abs() < f32::EPSILON);
46    /// assert!(!var.hidden);
47    /// # Ok(()) }
48    /// ```
49    fn variations(&self) -> Vec<VariationAxis>;
50}
51
52#[non_exhaustive]
53#[derive(Debug, Clone)]
54pub struct VariationAxis {
55    /// Tag identifying the design variation for the axis.
56    pub tag: [u8; 4],
57    /// Unicode name.
58    pub name: Option<String>,
59    /// The minimum coordinate value for the axis.
60    pub min_value: f32,
61    /// The default coordinate value for the axis.
62    pub default_value: f32,
63    /// The maximum coordinate value for the axis.
64    pub max_value: f32,
65    /// Whether the axis should be exposed directly in user interfaces.
66    pub hidden: bool,
67}
ab_glyph/variable.rs

ab_glyph/
variable.rs
