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perf: minimize the performance impact of text decoration

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Boxed the decoration data to go from 40b to 8b.
The performance is almost unchanged for text without decoration.
This commit is contained in:
Hojjat 2026-02-24 14:52:04 -07:00 • committed by Jeremy Soller
parent 6ef1ccbeed
commit 78665aab3b
4 changed files with 78 additions and 53 deletions
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44
src/shape.rs
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@ -5,8 +5,8 @@
use crate::fallback::FontFallbackIter;
use crate::{
math, Align, Attrs, AttrsList, CacheKeyFlags, Color, DecorationMetrics, Ellipsize,
EllipsizeHeightLimit, Font, FontSystem, Hinting, LayoutGlyph, LayoutLine, Metrics,
TextDecoration, Wrap,
EllipsizeHeightLimit, Font, FontSystem, GlyphDecorationData, Hinting, LayoutGlyph, LayoutLine,
Metrics, Wrap,
};
#[cfg(not(feature = "std"))]
use alloc::{format, vec, vec::Vec};
@ -16,7 +16,6 @@ use core::cmp::{max, min};
use core::fmt;
use core::mem;
use core::ops::Range;
use skrifa::metrics::Decoration;
#[cfg(not(feature = "std"))]
use core_maths::CoreFloat;
@ -132,7 +131,6 @@ fn shape_fallback(
let font_scale = font.metrics().units_per_em as f32;
let ascent = font.metrics().ascent / font_scale;
let descent = -font.metrics().descent / font_scale;
let (underline_metrics, strikethrough_metrics) = decoration_metrics(font);
let mut buffer = scratch.harfrust_buffer.take().unwrap_or_default();
buffer.set_direction(if span_rtl {
@ -239,9 +237,16 @@ fn shape_fallback(
metadata: attrs.metadata,
cache_key_flags: override_fake_italic(attrs.cache_key_flags, font, &attrs),
metrics_opt: attrs.metrics_opt.map(Into::into),
text_decoration: attrs.text_decoration,
underline_metrics,
strikethrough_metrics,
decoration_data: if attrs.text_decoration.has_decoration() {
let (ul_metrics, st_metrics) = decoration_metrics(font);
Some(Box::new(GlyphDecorationData {
text_decoration: attrs.text_decoration,
underline_metrics: ul_metrics,
strikethrough_metrics: st_metrics,
}))
} else {
None
},
});
}
@ -509,7 +514,7 @@ fn shape_skip(
let metrics = swash_font.metrics(&[]);
let glyph_metrics = swash_font.glyph_metrics(&[]).scale(1.0);
let (underline_metrics, strikethrough_metrics) = decoration_metrics(font.as_ref());
let deco_metrics = decoration_metrics(font.as_ref());
let ascent = metrics.ascent / f32::from(metrics.units_per_em);
let descent = metrics.descent / f32::from(metrics.units_per_em);
@ -544,9 +549,15 @@ fn shape_skip(
&attrs,
),
metrics_opt: attrs.metrics_opt.map(Into::into),
text_decoration: attrs.text_decoration,
underline_metrics,
strikethrough_metrics,
decoration_data: if attrs.text_decoration.has_decoration() {
Some(Box::new(GlyphDecorationData {
text_decoration: attrs.text_decoration,
underline_metrics: deco_metrics.0,
strikethrough_metrics: deco_metrics.1,
}))
} else {
None
},
}
}),
);
@ -583,13 +594,12 @@ pub struct ShapeGlyph {
pub metadata: usize,
pub cache_key_flags: CacheKeyFlags,
pub metrics_opt: Option<Metrics>,
pub text_decoration: TextDecoration,
pub underline_metrics: DecorationMetrics,
pub strikethrough_metrics: DecorationMetrics,
/// Decoration data, only allocated when decorations are active
pub decoration_data: Option<Box<GlyphDecorationData>>,
}
impl ShapeGlyph {
const fn layout(
fn layout(
&self,
font_size: f32,
line_height_opt: Option<f32>,
@ -615,9 +625,7 @@ impl ShapeGlyph {
color_opt: self.color_opt,
metadata: self.metadata,
cache_key_flags: self.cache_key_flags,
text_decoration: self.text_decoration,
underline_metrics: self.underline_metrics,
strikethrough_metrics: self.strikethrough_metrics,
decoration_data: self.decoration_data.clone(),
}
}