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Guard against font bug in math glyph assembly code (#5288)

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Max 2024-10-30 15:32:11 +00:00 committed by GitHub
parent f85faf957f
commit 902088a237
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2 changed files with 49 additions and 32 deletions
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4
crates/typst-layout/src/math/fragment.rs
View File

@ -429,7 +429,7 @@ impl GlyphFragment {
/// Try to stretch a glyph to a desired height.
pub fn stretch_vertical(
self,
ctx: &MathContext,
ctx: &mut MathContext,
height: Abs,
short_fall: Abs,
) -> VariantFragment {
@ -439,7 +439,7 @@ impl GlyphFragment {
/// Try to stretch a glyph to a desired width.
pub fn stretch_horizontal(
self,
ctx: &MathContext,
ctx: &mut MathContext,
width: Abs,
short_fall: Abs,
) -> VariantFragment {

77
crates/typst-layout/src/math/stretch.rs
View File

@ -1,6 +1,6 @@
use ttf_parser::math::{GlyphAssembly, GlyphConstruction, GlyphPart};
use ttf_parser::LazyArray16;
use typst_library::diag::SourceResult;
use typst_library::diag::{warning, SourceResult};
use typst_library::foundations::{Packed, Smart, StyleChain};
use typst_library::layout::{Abs, Axis, Frame, Length, Point, Rel, Size};
use typst_library::math::StretchElem;
@ -81,11 +81,45 @@ pub fn stretch_fragment(
*fragment = MathFragment::Variant(variant);
}
/// Return whether the glyph is stretchable and if it is, along which axis it
/// can be stretched.
fn stretch_axis(ctx: &mut MathContext, base: &GlyphFragment) -> Option<Axis> {
let base_id = base.id;
let vertical = ctx
.table
.variants
.and_then(|variants| variants.vertical_constructions.get(base_id))
.map(|_| Axis::Y);
let horizontal = ctx
.table
.variants
.and_then(|variants| variants.horizontal_constructions.get(base_id))
.map(|_| Axis::X);
match (vertical, horizontal) {
(vertical, None) => vertical,
(None, horizontal) => horizontal,
_ => {
// As far as we know, there aren't any glyphs that have both
// vertical and horizontal constructions. So for the time being, we
// will assume that a glyph cannot have both.
ctx.engine.sink.warn(warning!(
base.span,
"glyph has both vertical and horizontal constructions";
hint: "this is probably a font bug";
hint: "please file an issue at https://github.com/typst/typst/issues"
));
None
}
}
}
/// Try to stretch a glyph to a desired width or height.
///
/// The resulting frame may not have the exact desired width.
pub fn stretch_glyph(
ctx: &MathContext,
ctx: &mut MathContext,
mut base: GlyphFragment,
target: Abs,
short_fall: Abs,
@ -137,36 +171,9 @@ pub fn stretch_glyph(
assemble(ctx, base, assembly, min_overlap, target, axis)
}
/// Return whether the glyph is stretchable and if it is, along which axis it
/// can be stretched.
fn stretch_axis(ctx: &MathContext, base: &GlyphFragment) -> Option<Axis> {
let base_id = base.id;
let vertical = ctx
.table
.variants
.and_then(|variants| variants.vertical_constructions.get(base_id))
.map(|_| Axis::Y);
let horizontal = ctx
.table
.variants
.and_then(|variants| variants.horizontal_constructions.get(base_id))
.map(|_| Axis::X);
match (vertical, horizontal) {
(vertical, None) => vertical,
(None, horizontal) => horizontal,
_ => {
// As far as we know, there aren't any glyphs that have both
// vertical and horizontal constructions. So for the time being, we
// will assume that a glyph cannot have both.
panic!("glyph {:?} has both vertical and horizontal constructions", base.c);
}
}
}
/// Assemble a glyph from parts.
fn assemble(
ctx: &MathContext,
ctx: &mut MathContext,
base: GlyphFragment,
assembly: GlyphAssembly,
min_overlap: Abs,
@ -193,6 +200,16 @@ fn assemble(
.end_connector_length
.min(next.start_connector_length)
.scaled(ctx, base.font_size);
if max_overlap < min_overlap {
// This condition happening is indicative of a bug in the
// font.
ctx.engine.sink.warn(warning!(
base.span,
"glyph has assembly parts with overlap less than minConnectorOverlap";
hint: "its rendering may appear broken - this is probably a font bug";
hint: "please file an issue at https://github.com/typst/typst/issues"
));
}
advance -= max_overlap;
growable += max_overlap - min_overlap;