style/
font_metrics.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5//! Access to font metrics from the style system.
6
7#![deny(missing_docs)]
8
9use crate::values::computed::Length;
10
11/// Represents the font metrics that style needs from a font to compute the
12/// value of certain CSS units like `ex`.
13#[derive(Clone, Debug, PartialEq)]
14pub struct FontMetrics {
15    /// The x-height of the font.
16    pub x_height: Option<Length>,
17    /// The zero advance. This is usually writing mode dependent
18    pub zero_advance_measure: Option<Length>,
19    /// The cap-height of the font.
20    pub cap_height: Option<Length>,
21    /// The ideographic-width of the font.
22    pub ic_width: Option<Length>,
23    /// The ascent of the font (a value is always available for this).
24    pub ascent: Length,
25    /// Script scale down factor for math-depth 1.
26    /// https://w3c.github.io/mathml-core/#dfn-scriptpercentscaledown
27    pub script_percent_scale_down: Option<f32>,
28    /// Script scale down factor for math-depth 2.
29    /// https://w3c.github.io/mathml-core/#dfn-scriptscriptpercentscaledown
30    pub script_script_percent_scale_down: Option<f32>,
31}
32
33impl Default for FontMetrics {
34    fn default() -> Self {
35        FontMetrics {
36            x_height: None,
37            zero_advance_measure: None,
38            cap_height: None,
39            ic_width: None,
40            ascent: Length::new(0.0),
41            script_percent_scale_down: None,
42            script_script_percent_scale_down: None,
43        }
44    }
45}
46
47/// Type of font metrics to retrieve.
48#[derive(Clone, Debug, PartialEq)]
49pub enum FontMetricsOrientation {
50    /// Get metrics for horizontal or vertical according to the Context's
51    /// writing mode, using horizontal metrics for vertical/mixed
52    MatchContextPreferHorizontal,
53    /// Get metrics for horizontal or vertical according to the Context's
54    /// writing mode, using vertical metrics for vertical/mixed
55    MatchContextPreferVertical,
56    /// Force getting horizontal metrics.
57    Horizontal,
58}
style/font_metrics.rs

style/
font_metrics.rs
