369 lines
11 KiB
Rust
369 lines
11 KiB
Rust
use std::cell::RefCell;
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use std::collections::HashMap;
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use cassowary::strength::{REQUIRED, WEAK};
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use cassowary::WeightedRelation::*;
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use cassowary::{Constraint as CassowaryConstraint, Expression, Solver, Variable};
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use helix_view::graphics::{Margin, Rect};
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#[derive(Debug, Hash, Clone, Copy, PartialEq, Eq)]
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pub enum Corner {
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TopLeft,
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TopRight,
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BottomRight,
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BottomLeft,
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}
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#[derive(Debug, Hash, Clone, PartialEq, Eq)]
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pub enum Direction {
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Horizontal,
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Vertical,
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
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pub enum Constraint {
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// TODO: enforce range 0 - 100
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Percentage(u16),
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Ratio(u32, u32),
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Length(u16),
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Max(u16),
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Min(u16),
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}
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impl Constraint {
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pub fn apply(&self, length: u16) -> u16 {
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match *self {
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Constraint::Percentage(p) => length * p / 100,
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Constraint::Ratio(num, den) => {
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let r = num * u32::from(length) / den;
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r as u16
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}
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Constraint::Length(l) => length.min(l),
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Constraint::Max(m) => length.min(m),
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Constraint::Min(m) => length.max(m),
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}
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}
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub enum Alignment {
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Left,
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Center,
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Right,
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}
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#[derive(Debug, Clone, PartialEq, Eq, Hash)]
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pub struct Layout {
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direction: Direction,
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margin: Margin,
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constraints: Vec<Constraint>,
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}
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thread_local! {
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static LAYOUT_CACHE: RefCell<HashMap<(Rect, Layout), Vec<Rect>>> = RefCell::new(HashMap::new());
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}
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impl Default for Layout {
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fn default() -> Layout {
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Layout {
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direction: Direction::Vertical,
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margin: Margin::none(),
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constraints: Vec::new(),
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}
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}
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}
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impl Layout {
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pub fn constraints<C>(mut self, constraints: C) -> Layout
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where
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C: Into<Vec<Constraint>>,
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{
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self.constraints = constraints.into();
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self
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}
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pub const fn margin(mut self, margin: u16) -> Layout {
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self.margin = Margin::all(margin);
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self
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}
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pub const fn horizontal_margin(mut self, horizontal: u16) -> Layout {
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self.margin.horizontal = horizontal;
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self
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}
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pub const fn vertical_margin(mut self, vertical: u16) -> Layout {
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self.margin.vertical = vertical;
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self
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}
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pub const fn direction(mut self, direction: Direction) -> Layout {
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self.direction = direction;
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self
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}
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/// Wrapper function around the cassowary-rs solver to be able to split a given
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/// area into smaller ones based on the preferred widths or heights and the direction.
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///
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/// # Examples
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/// ```
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/// # use helix_tui::layout::{Constraint, Direction, Layout};
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/// # use helix_view::graphics::Rect;
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/// let chunks = Layout::default()
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/// .direction(Direction::Vertical)
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/// .constraints([Constraint::Length(5), Constraint::Min(0)].as_ref())
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/// .split(Rect {
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/// x: 2,
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/// y: 2,
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/// width: 10,
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/// height: 10,
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/// });
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/// assert_eq!(
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/// chunks,
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/// vec![
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/// Rect {
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/// x: 2,
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/// y: 2,
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/// width: 10,
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/// height: 5
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/// },
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/// Rect {
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/// x: 2,
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/// y: 7,
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/// width: 10,
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/// height: 5
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/// }
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/// ]
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/// );
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///
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/// let chunks = Layout::default()
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/// .direction(Direction::Horizontal)
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/// .constraints([Constraint::Ratio(1, 3), Constraint::Ratio(2, 3)].as_ref())
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/// .split(Rect {
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/// x: 0,
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/// y: 0,
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/// width: 9,
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/// height: 2,
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/// });
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/// assert_eq!(
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/// chunks,
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/// vec![
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/// Rect {
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/// x: 0,
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/// y: 0,
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/// width: 3,
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/// height: 2
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/// },
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/// Rect {
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/// x: 3,
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/// y: 0,
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/// width: 6,
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/// height: 2
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/// }
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/// ]
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/// );
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/// ```
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pub fn split(&self, area: Rect) -> Vec<Rect> {
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// TODO: Maybe use a fixed size cache ?
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LAYOUT_CACHE.with(|c| {
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c.borrow_mut()
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.entry((area, self.clone()))
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.or_insert_with(|| split(area, self))
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.clone()
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})
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}
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}
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fn split(area: Rect, layout: &Layout) -> Vec<Rect> {
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let mut solver = Solver::new();
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let mut vars: HashMap<Variable, (usize, usize)> = HashMap::new();
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let elements = layout
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.constraints
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.iter()
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.map(|_| Element::new())
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.collect::<Vec<Element>>();
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let mut results = layout
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.constraints
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.iter()
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.map(|_| Rect::default())
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.collect::<Vec<Rect>>();
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let dest_area = area.inner(layout.margin);
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for (i, e) in elements.iter().enumerate() {
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vars.insert(e.x, (i, 0));
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vars.insert(e.y, (i, 1));
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vars.insert(e.width, (i, 2));
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vars.insert(e.height, (i, 3));
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}
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let mut ccs: Vec<CassowaryConstraint> =
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Vec::with_capacity(elements.len() * 4 + layout.constraints.len() * 6);
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for elt in &elements {
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ccs.push(elt.width | GE(REQUIRED) | 0f64);
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ccs.push(elt.height | GE(REQUIRED) | 0f64);
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ccs.push(elt.left() | GE(REQUIRED) | f64::from(dest_area.left()));
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ccs.push(elt.top() | GE(REQUIRED) | f64::from(dest_area.top()));
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ccs.push(elt.right() | LE(REQUIRED) | f64::from(dest_area.right()));
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ccs.push(elt.bottom() | LE(REQUIRED) | f64::from(dest_area.bottom()));
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}
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if let Some(first) = elements.first() {
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ccs.push(match layout.direction {
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Direction::Horizontal => first.left() | EQ(REQUIRED) | f64::from(dest_area.left()),
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Direction::Vertical => first.top() | EQ(REQUIRED) | f64::from(dest_area.top()),
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});
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}
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if let Some(last) = elements.last() {
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ccs.push(match layout.direction {
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Direction::Horizontal => last.right() | EQ(REQUIRED) | f64::from(dest_area.right()),
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Direction::Vertical => last.bottom() | EQ(REQUIRED) | f64::from(dest_area.bottom()),
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});
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}
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match layout.direction {
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Direction::Horizontal => {
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for pair in elements.windows(2) {
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ccs.push((pair[0].x + pair[0].width) | EQ(REQUIRED) | pair[1].x);
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}
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for (i, size) in layout.constraints.iter().enumerate() {
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ccs.push(elements[i].y | EQ(REQUIRED) | f64::from(dest_area.y));
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ccs.push(elements[i].height | EQ(REQUIRED) | f64::from(dest_area.height));
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ccs.push(match *size {
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Constraint::Length(v) => elements[i].width | EQ(WEAK) | f64::from(v),
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Constraint::Percentage(v) => {
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elements[i].width | EQ(WEAK) | (f64::from(v * dest_area.width) / 100.0)
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}
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Constraint::Ratio(n, d) => {
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elements[i].width
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| EQ(WEAK)
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| (f64::from(dest_area.width) * f64::from(n) / f64::from(d))
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}
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Constraint::Min(v) => elements[i].width | GE(WEAK) | f64::from(v),
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Constraint::Max(v) => elements[i].width | LE(WEAK) | f64::from(v),
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});
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}
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}
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Direction::Vertical => {
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for pair in elements.windows(2) {
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ccs.push((pair[0].y + pair[0].height) | EQ(REQUIRED) | pair[1].y);
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}
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for (i, size) in layout.constraints.iter().enumerate() {
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ccs.push(elements[i].x | EQ(REQUIRED) | f64::from(dest_area.x));
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ccs.push(elements[i].width | EQ(REQUIRED) | f64::from(dest_area.width));
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ccs.push(match *size {
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Constraint::Length(v) => elements[i].height | EQ(WEAK) | f64::from(v),
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Constraint::Percentage(v) => {
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elements[i].height | EQ(WEAK) | (f64::from(v * dest_area.height) / 100.0)
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}
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Constraint::Ratio(n, d) => {
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elements[i].height
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| EQ(WEAK)
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| (f64::from(dest_area.height) * f64::from(n) / f64::from(d))
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}
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Constraint::Min(v) => elements[i].height | GE(WEAK) | f64::from(v),
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Constraint::Max(v) => elements[i].height | LE(WEAK) | f64::from(v),
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});
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}
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}
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}
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solver.add_constraints(&ccs).unwrap();
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for &(var, value) in solver.fetch_changes() {
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let (index, attr) = vars[&var];
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let value = if value.is_sign_negative() {
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0
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} else {
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value as u16
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};
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match attr {
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0 => {
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results[index].x = value;
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}
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1 => {
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results[index].y = value;
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}
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2 => {
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results[index].width = value;
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}
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3 => {
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results[index].height = value;
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}
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_ => {}
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}
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}
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// Fix imprecision by extending the last item a bit if necessary
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if let Some(last) = results.last_mut() {
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match layout.direction {
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Direction::Vertical => {
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last.height = dest_area.bottom() - last.y;
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}
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Direction::Horizontal => {
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last.width = dest_area.right() - last.x;
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}
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}
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}
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results
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}
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/// A container used by the solver inside split
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struct Element {
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x: Variable,
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y: Variable,
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width: Variable,
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height: Variable,
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}
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impl Element {
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fn new() -> Element {
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Element {
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x: Variable::new(),
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y: Variable::new(),
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width: Variable::new(),
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height: Variable::new(),
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}
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}
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fn left(&self) -> Variable {
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self.x
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}
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fn top(&self) -> Variable {
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self.y
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}
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fn right(&self) -> Expression {
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self.x + self.width
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}
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fn bottom(&self) -> Expression {
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self.y + self.height
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_vertical_split_by_height() {
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let target = Rect {
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x: 2,
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y: 2,
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width: 10,
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height: 10,
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};
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let chunks = Layout::default()
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.direction(Direction::Vertical)
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.constraints(
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[
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Constraint::Percentage(10),
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Constraint::Max(5),
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Constraint::Min(1),
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]
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.as_ref(),
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)
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.split(target);
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assert_eq!(target.height, chunks.iter().map(|r| r.height).sum::<u16>());
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chunks.windows(2).for_each(|w| assert!(w[0].y <= w[1].y));
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}
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}
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