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|
use crate::layout::AlignElem;
use super::*;
pub const TIGHT_LEADING: Em = Em::new(0.25);
#[derive(Debug, Default, Clone)]
pub struct MathRow(Vec<MathFragment>);
impl MathRow {
pub fn new(fragments: Vec<MathFragment>) -> Self {
let iter = fragments.into_iter().peekable();
let mut last: Option<usize> = None;
let mut space: Option<MathFragment> = None;
let mut resolved: Vec<MathFragment> = vec![];
for mut fragment in iter {
match fragment {
// Keep space only if supported by spaced fragments.
MathFragment::Space(_) => {
if last.is_some() {
space = Some(fragment);
}
continue;
}
// Explicit spacing disables automatic spacing.
MathFragment::Spacing(_) => {
last = None;
space = None;
resolved.push(fragment);
continue;
}
// Alignment points are resolved later.
MathFragment::Align => {
resolved.push(fragment);
continue;
}
// New line, new things.
MathFragment::Linebreak => {
resolved.push(fragment);
space = None;
last = None;
continue;
}
_ => {}
}
// Convert variable operators into binary operators if something
// precedes them and they are not preceded by a operator or comparator.
if fragment.class() == Some(MathClass::Vary)
&& matches!(
last.and_then(|i| resolved[i].class()),
Some(
MathClass::Normal
| MathClass::Alphabetic
| MathClass::Closing
| MathClass::Fence
)
)
{
fragment.set_class(MathClass::Binary);
}
// Insert spacing between the last and this item.
if let Some(i) = last {
if let Some(s) = spacing(&resolved[i], space.take(), &fragment) {
resolved.insert(i + 1, s);
}
}
last = Some(resolved.len());
resolved.push(fragment);
}
Self(resolved)
}
pub fn iter(&self) -> std::slice::Iter<'_, MathFragment> {
self.0.iter()
}
pub fn width(&self) -> Abs {
self.iter().map(MathFragment::width).sum()
}
pub fn height(&self) -> Abs {
self.ascent() + self.descent()
}
pub fn ascent(&self) -> Abs {
self.iter().map(MathFragment::ascent).max().unwrap_or_default()
}
pub fn descent(&self) -> Abs {
self.iter().map(MathFragment::descent).max().unwrap_or_default()
}
pub fn into_frame(self, ctx: &MathContext) -> Frame {
let styles = ctx.styles();
let align = AlignElem::alignment_in(styles).x.resolve(styles);
self.into_aligned_frame(ctx, &[], align)
}
pub fn into_fragment(self, ctx: &MathContext) -> MathFragment {
if self.0.len() == 1 {
self.0.into_iter().next().unwrap()
} else {
FrameFragment::new(ctx, self.into_frame(ctx)).into()
}
}
pub fn into_aligned_frame(
mut self,
ctx: &MathContext,
points: &[Abs],
align: Align,
) -> Frame {
if self.iter().any(|frag| matches!(frag, MathFragment::Linebreak)) {
let fragments: Vec<_> = std::mem::take(&mut self.0);
let leading = if ctx.style.size >= MathSize::Text {
ParElem::leading_in(ctx.styles())
} else {
TIGHT_LEADING.scaled(ctx)
};
let mut rows: Vec<_> = fragments
.split(|frag| matches!(frag, MathFragment::Linebreak))
.map(|slice| Self(slice.to_vec()))
.collect();
if matches!(rows.last(), Some(row) if row.0.is_empty()) {
rows.pop();
}
let width = rows.iter().map(|row| row.width()).max().unwrap_or_default();
let points = alignments(&rows);
let mut frame = Frame::new(Size::zero());
for (i, row) in rows.into_iter().enumerate() {
let sub = row.into_line_frame(&points, align);
let size = frame.size_mut();
if i > 0 {
size.y += leading;
}
let mut pos = Point::with_y(size.y);
if points.is_empty() {
pos.x = align.position(width - sub.width());
}
size.y += sub.height();
size.x.set_max(sub.width());
frame.push_frame(pos, sub);
}
frame
} else {
self.into_line_frame(points, align)
}
}
fn into_line_frame(self, points: &[Abs], align: Align) -> Frame {
let ascent = self.ascent();
let descent = self.descent();
let size = Size::new(Abs::zero(), ascent + descent);
let mut frame = Frame::new(size);
let mut x = Abs::zero();
frame.set_baseline(ascent);
if let (Some(&first), Align::Center) = (points.first(), align) {
let mut offset = first;
for fragment in self.iter() {
offset -= fragment.width();
if matches!(fragment, MathFragment::Align) {
x = offset;
break;
}
}
}
let fragments = self.0.into_iter().peekable();
let mut i = 0;
for fragment in fragments {
if matches!(fragment, MathFragment::Align) {
if let Some(&point) = points.get(i) {
x = point;
}
i += 1;
continue;
}
let y = ascent - fragment.ascent();
let pos = Point::new(x, y);
x += fragment.width();
frame.push_frame(pos, fragment.into_frame());
}
frame.size_mut().x = x;
frame
}
}
impl<T: Into<MathFragment>> From<T> for MathRow {
fn from(fragment: T) -> Self {
Self(vec![fragment.into()])
}
}
|
