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use typst_library::diag::SourceResult;
use typst_library::foundations::{Content, Packed, Resolve, StyleChain, SymbolElem};
use typst_library::layout::{Em, Frame, FrameItem, Point, Size};
use typst_library::math::{BinomElem, FracElem};
use typst_library::text::TextElem;
use typst_library::visualize::{FixedStroke, Geometry};
use typst_syntax::Span;
use super::{
style_for_denominator, style_for_numerator, FrameFragment, GlyphFragment,
MathContext, DELIM_SHORT_FALL,
};
const FRAC_AROUND: Em = Em::new(0.1);
/// Lays out a [`FracElem`].
#[typst_macros::time(name = "math.frac", span = elem.span())]
pub fn layout_frac(
elem: &Packed<FracElem>,
ctx: &mut MathContext,
styles: StyleChain,
) -> SourceResult<()> {
layout_frac_like(
ctx,
styles,
&elem.num,
std::slice::from_ref(&elem.denom),
false,
elem.span(),
)
}
/// Lays out a [`BinomElem`].
#[typst_macros::time(name = "math.binom", span = elem.span())]
pub fn layout_binom(
elem: &Packed<BinomElem>,
ctx: &mut MathContext,
styles: StyleChain,
) -> SourceResult<()> {
layout_frac_like(ctx, styles, &elem.upper, &elem.lower, true, elem.span())
}
/// Layout a fraction or binomial.
fn layout_frac_like(
ctx: &mut MathContext,
styles: StyleChain,
num: &Content,
denom: &[Content],
binom: bool,
span: Span,
) -> SourceResult<()> {
let short_fall = DELIM_SHORT_FALL.resolve(styles);
let axis = scaled!(ctx, styles, axis_height);
let thickness = scaled!(ctx, styles, fraction_rule_thickness);
let shift_up = scaled!(
ctx, styles,
text: fraction_numerator_shift_up,
display: fraction_numerator_display_style_shift_up,
);
let shift_down = scaled!(
ctx, styles,
text: fraction_denominator_shift_down,
display: fraction_denominator_display_style_shift_down,
);
let num_min = scaled!(
ctx, styles,
text: fraction_numerator_gap_min,
display: fraction_num_display_style_gap_min,
);
let denom_min = scaled!(
ctx, styles,
text: fraction_denominator_gap_min,
display: fraction_denom_display_style_gap_min,
);
let num_style = style_for_numerator(styles);
let num = ctx.layout_into_frame(num, styles.chain(&num_style))?;
let denom_style = style_for_denominator(styles);
let denom = ctx.layout_into_frame(
&Content::sequence(
// Add a comma between each element.
denom
.iter()
.flat_map(|a| [SymbolElem::packed(','), a.clone()])
.skip(1),
),
styles.chain(&denom_style),
)?;
let around = FRAC_AROUND.resolve(styles);
let num_gap = (shift_up - (axis + thickness / 2.0) - num.descent()).max(num_min);
let denom_gap =
(shift_down + (axis - thickness / 2.0) - denom.ascent()).max(denom_min);
let line_width = num.width().max(denom.width());
let width = line_width + 2.0 * around;
let height = num.height() + num_gap + thickness + denom_gap + denom.height();
let size = Size::new(width, height);
let num_pos = Point::with_x((width - num.width()) / 2.0);
let line_pos =
Point::new((width - line_width) / 2.0, num.height() + num_gap + thickness / 2.0);
let denom_pos = Point::new((width - denom.width()) / 2.0, height - denom.height());
let baseline = line_pos.y + axis;
let mut frame = Frame::soft(size);
frame.set_baseline(baseline);
frame.push_frame(num_pos, num);
frame.push_frame(denom_pos, denom);
if binom {
let mut left = GlyphFragment::new_char(ctx.font, styles, '(', span)?;
left.stretch_vertical(ctx, height - short_fall);
left.center_on_axis();
ctx.push(left);
ctx.push(FrameFragment::new(styles, frame));
let mut right = GlyphFragment::new_char(ctx.font, styles, ')', span)?;
right.stretch_vertical(ctx, height - short_fall);
right.center_on_axis();
ctx.push(right);
} else {
frame.push(
line_pos,
FrameItem::Shape(
Geometry::Line(Point::with_x(line_width)).stroked(
FixedStroke::from_pair(
styles.get_ref(TextElem::fill).as_decoration(),
thickness,
),
),
span,
),
);
ctx.push(FrameFragment::new(styles, frame));
}
Ok(())
}
|
