/* 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/. */
//! Access to font metrics from the style system.
#![deny(missing_docs)]
use crate::values::computed::Length;
/// Represents the font metrics that style needs from a font to compute the
/// value of certain CSS units like `ex`.
#[derive(Clone, Debug, PartialEq)]
pub struct FontMetrics {
/// The x-height of the font.
pub x_height: Option<Length>,
/// The zero advance. This is usually writing mode dependent
pub zero_advance_measure: Option<Length>,
/// The cap-height of the font.
pub cap_height: Option<Length>,
/// The ideographic-width of the font.
pub ic_width: Option<Length>,
/// The ascent of the font (a value is always available for this).
pub ascent: Length,
/// Script scale down factor for math-depth 1.
///
https://w3c.github.io/mathml-core/#dfn-scriptpercentscaledown
pub script_percent_scale_down: Option<f32>,
/// Script scale down factor for math-depth 2.
///
https://w3c.github.io/mathml-core/#dfn-scriptscriptpercentscaledown
pub script_script_percent_scale_down: Option<f32>,
}
impl Default for FontMetrics {
fn default() -> Self {
FontMetrics {
x_height: None,
zero_advance_measure: None,
cap_height: None,
ic_width: None,
ascent: Length::new(0.0),
script_percent_scale_down: None,
script_script_percent_scale_down: None,
}
}
}
/// Type of font metrics to retrieve.
#[derive(Clone, Debug, PartialEq)]
pub enum FontMetricsOrientation {
/// Get metrics for horizontal or vertical according to the Context's
/// writing mode, using horizontal metrics for vertical/mixed
MatchContextPreferHorizontal,
/// Get metrics for horizontal or vertical according to the Context's
/// writing mode, using vertical metrics for vertical/mixed
MatchContextPreferVertical,
/// Force getting horizontal metrics.
Horizontal,
}
