Type: Kerning has an Optical option that spaces characters by their shapes

Squashed from #4825 onto main.

crates/doc/src/text/char_style.rs

@@ -25,9 +25,12 @@ pub struct CharStyle {
     /// Tracking in 1/1000 em.
     #[serde(default)]
     pub tracking: f64,
-    /// Kerning: None = Auto (metrics), Some(v) = manual in 1/1000 em.
+    /// Manual pair spacing in 1/1000 em; None uses the automatic mode.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub kerning: Option<f64>,
+    /// Use glyph shapes for automatic pair spacing; false uses font metrics.
+    #[serde(default, rename = "opticalKerning", skip_serializing_if = "crate::skip::is_default")]
+    pub optical_kerning: bool,
     #[serde(default)]
     pub baseline_shift: f64,
     #[serde(default = "hundred")]
@@ -266,6 +269,7 @@ impl Default for CharStyle {
             leading: None,
             tracking: 0.0,
             kerning: None,
+            optical_kerning: false,
             baseline_shift: 0.0,
             h_scale: 100.0,
             v_scale: 100.0,

crates/doc/src/text/tabs_lists.rs

@@ -223,6 +223,7 @@ impl ParaList {
             position: CharPosition::Normal,
             tracking: 0.0,
             kerning: None,
+            optical_kerning: first.optical_kerning,
             tate_chu_yoko: false,
             underline: false,
             strikethrough: false,