1 files changed, 58 insertions, 0 deletions
diff --git a/servo/components/style/font_metrics.rs b/servo/components/style/font_metrics.rs
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+++ b/servo/components/style/font_metrics.rs
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+/* 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,
+}