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Explain ShapedGlyph and Glyph (#2901)

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Leedehai 2023-12-13 05:56:43 -05:00 committed by GitHub
parent 5338b02f9f
commit 5eedff8667
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2 changed files with 35 additions and 15 deletions
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44
crates/typst/src/layout/inline/shaping.rs
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@ -240,24 +240,24 @@ impl<'a> ShapedText<'a> {
} }
let pos = Point::new(offset, top + shift - y_offset.at(self.size)); let pos = Point::new(offset, top + shift - y_offset.at(self.size));
let glyphs = group let glyphs: Vec<Glyph> = group
.iter() .iter()
.map(|glyph| { .map(|shaped: &ShapedGlyph| {
let adjustability_left = if justification_ratio < 0.0 { let adjustability_left = if justification_ratio < 0.0 {
glyph.shrinkability().0 shaped.shrinkability().0
} else { } else {
glyph.stretchability().0 shaped.stretchability().0
}; };
let adjustability_right = if justification_ratio < 0.0 { let adjustability_right = if justification_ratio < 0.0 {
glyph.shrinkability().1 shaped.shrinkability().1
} else { } else {
glyph.stretchability().1 shaped.stretchability().1
}; };
let justification_left = adjustability_left * justification_ratio; let justification_left = adjustability_left * justification_ratio;
let mut justification_right = let mut justification_right =
adjustability_right * justification_ratio; adjustability_right * justification_ratio;
if glyph.is_justifiable() { if shaped.is_justifiable() {
justification_right += justification_right +=
Em::from_length(extra_justification, self.size) Em::from_length(extra_justification, self.size)
} }
@ -265,15 +265,33 @@ impl<'a> ShapedText<'a> {
frame.size_mut().x += justification_left.at(self.size) frame.size_mut().x += justification_left.at(self.size)
+ justification_right.at(self.size); + justification_right.at(self.size);
// |<---- a Glyph ---->|
// -->|ShapedGlyph|<--
// +---+-----------+---+
// | | *********| |
// | | * | |
// | | * ****| |
// | | * *| |
// | | *********| |
// +---+--+--------+---+
// A B C D
// Note A, B, D could be positive, zero, or negative.
// A: justification_left
// B: ShapedGlyph's x_offset
// (though a small part of the glyph may go inside B)
// B+C: ShapedGlyph's x_advance
// D: justification_right
// A+B: Glyph's x_offset
// A+B+C+D: Glyph's x_advance
Glyph { Glyph {
id: glyph.glyph_id, id: shaped.glyph_id,
x_advance: glyph.x_advance x_advance: shaped.x_advance
+ justification_left + justification_left
+ justification_right, + justification_right,
x_offset: glyph.x_offset + justification_left, x_offset: shaped.x_offset + justification_left,
range: (glyph.range.start - range.start).saturating_as() range: (shaped.range.start - range.start).saturating_as()
..(glyph.range.end - range.start).saturating_as(), ..(shaped.range.end - range.start).saturating_as(),
span: glyph.span, span: shaped.span,
} }
}) })
.collect(); .collect();

6
crates/typst/src/text/item.rs
View File

@ -21,7 +21,8 @@ pub struct TextItem {
pub lang: Lang, pub lang: Lang,
/// The item's plain text. /// The item's plain text.
pub text: EcoString, pub text: EcoString,
/// The glyphs. /// The glyphs. The number of glyphs may be different from the number of
/// characters in the plain text due to e.g. ligatures.
pub glyphs: Vec<Glyph>, pub glyphs: Vec<Glyph>,
} }
@ -49,7 +50,8 @@ pub struct Glyph {
pub x_advance: Em, pub x_advance: Em,
/// The horizontal offset of the glyph. /// The horizontal offset of the glyph.
pub x_offset: Em, pub x_offset: Em,
/// The range of the glyph in its item's text. /// The range of the glyph in its item's text. The range's length may
/// be more than one due to multi-byte UTF-8 encoding or ligatures.
pub range: Range<u16>, pub range: Range<u16>,
/// The source code location of the text. /// The source code location of the text.
pub span: (Span, u16), pub span: (Span, u16),