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|
use super::*;
/// A node that arranges its children into a paragraph.
#[derive(Debug, Clone, PartialEq)]
pub struct NodePar {
/// The `main` and `cross` directions of this paragraph.
///
/// The children are placed in lines along the `cross` direction. The lines
/// are stacked along the `main` direction.
pub dirs: LayoutDirs,
/// Whether to expand the cross axis to fill the area or to fit the content.
pub cross_expansion: Expansion,
/// The spacing to insert after each line.
pub line_spacing: Length,
/// The nodes to be arranged in a paragraph.
pub children: Vec<Node>,
/// How to align this paragraph in _its_ parent.
pub align: ChildAlign,
}
impl Layout for NodePar {
fn layout(&self, ctx: &mut LayoutContext, areas: &Areas) -> Layouted {
let mut layouter = ParLayouter::new(self, areas.clone());
for child in &self.children {
match child.layout(ctx, &layouter.areas) {
Layouted::Spacing(spacing) => layouter.push_spacing(spacing),
Layouted::Frame(frame, align) => layouter.push_frame(frame, align.cross),
Layouted::Frames(frames, align) => {
for frame in frames {
layouter.push_frame(frame, align.cross);
}
}
}
}
Layouted::Frames(layouter.finish(), self.align)
}
}
impl From<NodePar> for NodeAny {
fn from(par: NodePar) -> Self {
Self::new(par)
}
}
struct ParLayouter<'a> {
par: &'a NodePar,
main: SpecAxis,
cross: SpecAxis,
dirs: LayoutDirs,
areas: Areas,
finished: Vec<Frame>,
lines: Vec<(Length, Frame, Align)>,
lines_size: Gen<Length>,
run: Vec<(Length, Frame, Align)>,
run_size: Gen<Length>,
run_ruler: Align,
}
impl<'a> ParLayouter<'a> {
fn new(par: &'a NodePar, areas: Areas) -> Self {
Self {
par,
main: par.dirs.main.axis(),
cross: par.dirs.cross.axis(),
dirs: par.dirs,
areas,
finished: vec![],
lines: vec![],
lines_size: Gen::ZERO,
run: vec![],
run_size: Gen::ZERO,
run_ruler: Align::Start,
}
}
fn push_spacing(&mut self, amount: Length) {
let cross_max = self.areas.current.get(self.cross);
self.run_size.cross = (self.run_size.cross + amount).min(cross_max);
}
fn push_frame(&mut self, frame: Frame, align: Align) {
if self.run_ruler > align {
self.finish_run();
}
let fits = {
let mut usable = self.areas.current;
*usable.get_mut(self.cross) -= self.run_size.cross;
usable.fits(frame.size)
};
if !fits {
self.finish_run();
while !self.areas.current.fits(frame.size) {
if self.areas.in_full_last() {
// TODO: Diagnose once the necessary spans exist.
break;
} else {
self.finish_area();
}
}
}
let size = frame.size.switch(self.dirs);
self.run.push((self.run_size.cross, frame, align));
self.run_size.cross += size.cross;
self.run_size.main = self.run_size.main.max(size.main);
self.run_ruler = align;
}
fn finish_run(&mut self) {
let full_size = {
let full = self.areas.full.switch(self.dirs);
Gen::new(
self.run_size.main,
self.par
.cross_expansion
.resolve(self.run_size.cross.min(full.cross), full.cross),
)
};
let mut output = Frame::new(full_size.switch(self.dirs).to_size());
for (before, frame, align) in std::mem::take(&mut self.run) {
let child_cross_size = frame.size.get(self.cross);
// Position along the cross axis.
let cross = align.resolve(if self.dirs.cross.is_positive() {
let after_with_self = self.run_size.cross - before;
before .. full_size.cross - after_with_self
} else {
let before_with_self = before + child_cross_size;
let after = self.run_size.cross - (before + child_cross_size);
full_size.cross - before_with_self .. after
});
let pos = Gen::new(Length::ZERO, cross).switch(self.dirs).to_point();
output.push_frame(pos, frame);
}
self.lines.push((self.lines_size.main, output, self.run_ruler));
let main_offset = full_size.main + self.par.line_spacing;
*self.areas.current.get_mut(self.main) -= main_offset;
self.lines_size.main += main_offset;
self.lines_size.cross = self.lines_size.cross.max(full_size.cross);
self.run_size = Gen::ZERO;
self.run_ruler = Align::Start;
}
fn finish_area(&mut self) {
let size = self.lines_size;
let mut output = Frame::new(size.switch(self.dirs).to_size());
for (before, run, cross_align) in std::mem::take(&mut self.lines) {
let child_size = run.size.switch(self.dirs);
// Position along the main axis.
let main = if self.dirs.main.is_positive() {
before
} else {
size.main - (before + child_size.main)
};
// Align along the cross axis.
let cross = cross_align.resolve(if self.dirs.cross.is_positive() {
Length::ZERO .. size.cross - child_size.cross
} else {
size.cross - child_size.cross .. Length::ZERO
});
let pos = Gen::new(main, cross).switch(self.dirs).to_point();
output.push_frame(pos, run);
}
self.finished.push(output);
self.areas.next();
self.lines_size = Gen::ZERO;
}
fn finish(mut self) -> Vec<Frame> {
self.finish_run();
self.finish_area();
self.finished
}
}
|
