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|
use super::*;
/// A node that stacks its children.
#[derive(Debug, Clone, PartialEq)]
pub struct StackNode {
/// The `main` and `cross` directions of this stack.
///
/// The children are stacked along the `main` direction. The `cross`
/// direction is required for aligning the children.
pub dirs: Gen<Dir>,
/// The nodes to be stacked.
pub children: Vec<StackChild>,
}
/// A child of a stack node.
#[derive(Debug, Clone, PartialEq)]
pub enum StackChild {
/// Spacing between other nodes.
Spacing(Length),
/// Any child node and how to align it in the stack.
Any(AnyNode, Gen<Align>),
}
impl Layout for StackNode {
fn layout(&self, ctx: &mut LayoutContext, areas: &Areas) -> Vec<Frame> {
let mut layouter = StackLayouter::new(self.dirs, areas.clone());
for child in &self.children {
match *child {
StackChild::Spacing(amount) => layouter.push_spacing(amount),
StackChild::Any(ref node, aligns) => {
let mut frames = node.layout(ctx, &layouter.areas).into_iter();
if let Some(frame) = frames.next() {
layouter.push_frame(frame, aligns);
}
for frame in frames {
layouter.finish_area();
layouter.push_frame(frame, aligns);
}
}
}
}
layouter.finish()
}
}
impl From<StackNode> for AnyNode {
fn from(stack: StackNode) -> Self {
Self::new(stack)
}
}
struct StackLayouter {
dirs: Gen<Dir>,
main: SpecAxis,
areas: Areas,
finished: Vec<Frame>,
frames: Vec<(Length, Frame, Gen<Align>)>,
size: Gen<Length>,
ruler: Align,
}
impl StackLayouter {
fn new(dirs: Gen<Dir>, areas: Areas) -> Self {
Self {
dirs,
main: dirs.main.axis(),
areas,
finished: vec![],
frames: vec![],
size: Gen::ZERO,
ruler: Align::Start,
}
}
fn push_spacing(&mut self, amount: Length) {
let main_rest = self.areas.current.get_mut(self.main);
let capped = amount.min(*main_rest);
*main_rest -= capped;
self.size.main += capped;
}
fn push_frame(&mut self, frame: Frame, aligns: Gen<Align>) {
if self.ruler > aligns.main {
self.finish_area();
}
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.main);
self.frames.push((self.size.main, frame, aligns));
self.ruler = aligns.main;
self.size.main += size.main;
self.size.cross = self.size.cross.max(size.cross);
*self.areas.current.get_mut(self.main) -= size.main;
}
fn finish_area(&mut self) {
let full_size = {
let Areas { current, full, expand, .. } = self.areas;
let used = self.size.switch(self.main).to_size();
let mut size = Size::new(
expand.horizontal.resolve(used.width, full.width),
expand.vertical.resolve(used.height, full.height),
);
if let Some(aspect) = self.areas.aspect {
let width = size
.width
.max(aspect * size.height)
.min(current.width)
.min((current.height + used.height) / aspect);
size = Size::new(width, width / aspect);
}
size
};
let mut output = Frame::new(full_size, full_size.height);
let mut first = true;
let full_size = full_size.switch(self.main);
for (before, frame, aligns) in std::mem::take(&mut self.frames) {
let child_size = frame.size.switch(self.main);
// Align along the main axis.
let main = aligns.main.resolve(
self.dirs.main,
if self.dirs.main.is_positive() {
before .. before + full_size.main - self.size.main
} else {
self.size.main - (before + child_size.main)
.. full_size.main - (before + child_size.main)
},
);
// Align along the cross axis.
let cross = aligns.cross.resolve(
self.dirs.cross,
Length::ZERO .. full_size.cross - child_size.cross,
);
let pos = Gen::new(main, cross).switch(self.main).to_point();
if first {
output.baseline = pos.y + frame.baseline;
first = false;
}
output.push_frame(pos, frame);
}
self.finished.push(output);
self.areas.next();
self.ruler = Align::Start;
self.size = Gen::ZERO;
}
fn finish(mut self) -> Vec<Frame> {
self.finish_area();
self.finished
}
}
|
