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413 lines
12 KiB
Rust
413 lines
12 KiB
Rust
use std::cell::RefCell;
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use std::cmp::{max, min};
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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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#[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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Length(u16),
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Max(u16),
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Min(u16),
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}
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#[derive(Debug, Clone, Copy, PartialEq)]
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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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// TODO: enforce constraints size once const generics has landed
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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: u16,
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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: 0,
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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 fn margin(mut self, margin: u16) -> Layout {
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self.margin = margin;
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self
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}
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pub 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 tui::layout::{Rect, Constraint, Direction, Layout};
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///
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/// # fn main() {
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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{x: 2, y: 2, width: 10, height: 10});
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/// assert_eq!(chunks, vec![Rect{x:2, y: 2, width: 10, height: 5},
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/// Rect{x: 2, y: 7, width: 10, height: 5}])
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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.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::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::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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/// A simple rectangle used in the computation of the layout and to give widgets an hint about the
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/// area they are supposed to render to.
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#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
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pub struct Rect {
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pub x: u16,
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pub y: u16,
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pub width: u16,
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pub height: u16,
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}
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impl Default for Rect {
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fn default() -> Rect {
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Rect {
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x: 0,
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y: 0,
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width: 0,
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height: 0,
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}
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}
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}
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impl Rect {
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/// Creates a new rect, with width and height limited to keep the area under max u16.
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/// If clipped, aspect ratio will be preserved.
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pub fn new(x: u16, y: u16, width: u16, height: u16) -> Rect {
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let max_area = u16::max_value();
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let (clipped_width, clipped_height) =
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if u32::from(width) * u32::from(height) > u32::from(max_area) {
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let aspect_ratio = f64::from(width) / f64::from(height);
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let max_area_f = f64::from(max_area);
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let height_f = (max_area_f / aspect_ratio).sqrt();
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let width_f = height_f * aspect_ratio;
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(width_f as u16, height_f as u16)
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} else {
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(width, height)
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};
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Rect {
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x,
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y,
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width: clipped_width,
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height: clipped_height,
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}
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}
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pub fn area(self) -> u16 {
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self.width * self.height
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}
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pub fn left(self) -> u16 {
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self.x
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}
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pub fn right(self) -> u16 {
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self.x + self.width
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}
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pub fn top(self) -> u16 {
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self.y
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}
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pub fn bottom(self) -> u16 {
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self.y + self.height
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}
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pub fn inner(self, margin: u16) -> Rect {
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if self.width < 2 * margin || self.height < 2 * margin {
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Rect::default()
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} else {
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Rect {
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x: self.x + margin,
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y: self.y + margin,
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width: self.width - 2 * margin,
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height: self.height - 2 * margin,
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}
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}
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}
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pub fn union(self, other: Rect) -> Rect {
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let x1 = min(self.x, other.x);
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let y1 = min(self.y, other.y);
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let x2 = max(self.x + self.width, other.x + other.width);
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let y2 = max(self.y + self.height, other.y + other.height);
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Rect {
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x: x1,
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y: y1,
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width: x2 - x1,
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height: y2 - y1,
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}
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}
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pub fn intersection(self, other: Rect) -> Rect {
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let x1 = max(self.x, other.x);
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let y1 = max(self.y, other.y);
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let x2 = min(self.x + self.width, other.x + other.width);
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let y2 = min(self.y + self.height, other.y + other.height);
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Rect {
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x: x1,
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y: y1,
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width: x2 - x1,
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height: y2 - y1,
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}
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}
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pub fn intersects(self, other: Rect) -> bool {
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self.x < other.x + other.width
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&& self.x + self.width > other.x
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&& self.y < other.y + other.height
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&& self.y + self.height > other.y
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}
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}
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#[test]
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fn test_rect_size_truncation() {
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for width in 256u16..300u16 {
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for height in 256u16..300u16 {
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let rect = Rect::new(0, 0, width, height);
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rect.area(); // Should not panic.
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assert!(rect.width < width || rect.height < height);
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// The target dimensions are rounded down so the math will not be too precise
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// but let's make sure the ratios don't diverge crazily.
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assert!(
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(f64::from(rect.width) / f64::from(rect.height)
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- f64::from(width) / f64::from(height))
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.abs()
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< 1.0
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)
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}
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}
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// One dimension below 255, one above. Area above max u16.
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let width = 900;
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let height = 100;
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let rect = Rect::new(0, 0, width, height);
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assert_ne!(rect.width, 900);
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assert_ne!(rect.height, 100);
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assert!(rect.width < width || rect.height < height);
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}
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#[test]
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fn test_rect_size_preservation() {
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for width in 0..256u16 {
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for height in 0..256u16 {
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let rect = Rect::new(0, 0, width, height);
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rect.area(); // Should not panic.
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assert_eq!(rect.width, width);
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assert_eq!(rect.height, height);
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}
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}
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// One dimension below 255, one above. Area below max u16.
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let rect = Rect::new(0, 0, 300, 100);
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assert_eq!(rect.width, 300);
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assert_eq!(rect.height, 100);
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}
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