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|
use super::*;
/// A node that stacks and align its children.
#[derive(Debug, Clone, PartialEq)]
pub struct Stack {
/// 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 flow: Flow,
/// How to align this stack in _its_ parent.
pub align: BoxAlign,
/// Whether to expand the axes to fill the area or to fit the content.
pub expansion: Gen<Expansion>,
/// The nodes to be stacked.
pub children: Vec<LayoutNode>,
}
impl Layout for Stack {
fn layout(&self, ctx: &mut LayoutContext, areas: &Areas) -> Layouted {
let mut layouter = StackLayouter::new(self, areas.clone());
for child in &self.children {
match child.layout(ctx, &layouter.areas) {
Layouted::Spacing(spacing) => layouter.push_spacing(spacing),
Layouted::Layout(layout, align) => layouter.push_layout(layout, align),
Layouted::Layouts(layouts, align) => {
for layout in layouts {
layouter.push_layout(layout, align);
}
}
}
}
Layouted::Layouts(layouter.finish(), self.align)
}
}
impl From<Stack> for LayoutNode {
fn from(stack: Stack) -> Self {
Self::dynamic(stack)
}
}
struct StackLayouter<'a> {
stack: &'a Stack,
main: SpecAxis,
flow: Flow,
areas: Areas,
finished: Vec<BoxLayout>,
layouts: Vec<(Length, BoxLayout, BoxAlign)>,
used: Gen<Length>,
ruler: Align,
}
impl<'a> StackLayouter<'a> {
fn new(stack: &'a Stack, areas: Areas) -> Self {
Self {
stack,
main: stack.flow.main.axis(),
flow: stack.flow,
areas,
finished: vec![],
layouts: vec![],
used: Gen::ZERO,
ruler: Align::Start,
}
}
fn push_spacing(&mut self, amount: Length) {
let main_rest = self.areas.current.rem.get_mut(self.main);
let capped = amount.min(*main_rest);
*main_rest -= capped;
self.used.main += capped;
}
fn push_layout(&mut self, layout: BoxLayout, align: BoxAlign) {
if self.ruler > align.main {
self.finish_area();
}
while !self.areas.current.rem.fits(layout.size) {
if self.areas.in_full_last() {
// TODO: Diagnose once the necessary spans exist.
let _ = warning!("cannot fit box into any area");
break;
} else {
self.finish_area();
}
}
let size = layout.size.switch(self.flow);
self.layouts.push((self.used.main, layout, align));
*self.areas.current.rem.get_mut(self.main) -= size.main;
self.used.main += size.main;
self.used.cross = self.used.cross.max(size.cross);
self.ruler = align.main;
}
fn finish_area(&mut self) {
let full_size = {
let full = self.areas.current.full.switch(self.flow);
Gen::new(
match self.stack.expansion.main {
Expansion::Fill => full.main,
Expansion::Fit => self.used.main.min(full.main),
},
match self.stack.expansion.cross {
Expansion::Fill => full.cross,
Expansion::Fit => self.used.cross.min(full.cross),
},
)
};
let mut output = BoxLayout::new(full_size.switch(self.flow).to_size());
for (before, layout, align) in std::mem::take(&mut self.layouts) {
let child_size = layout.size.switch(self.flow);
// Align along the main axis.
let main = align.main.resolve(if self.flow.main.is_positive() {
let after_with_self = self.used.main - before;
before .. full_size.main - after_with_self
} else {
let before_with_self = before + child_size.main;
let after = self.used.main - (before + child_size.main);
full_size.main - before_with_self .. after
});
// Align along the cross axis.
let cross = align.cross.resolve(if self.flow.cross.is_positive() {
Length::ZERO .. full_size.cross - child_size.cross
} else {
full_size.cross - child_size.cross .. Length::ZERO
});
let pos = Gen::new(main, cross).switch(self.flow).to_point();
output.push_layout(pos, layout);
}
self.finished.push(output);
self.areas.next();
self.used = Gen::ZERO;
self.ruler = Align::Start;
}
fn finish(mut self) -> Vec<BoxLayout> {
self.finish_area();
self.finished
}
}
|
