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#![no_std]
extern crate alloc;
use alloc::vec::Vec;
use generational_arena::{Arena, Index};
pub type NodeIndex = Index;
pub struct LayoutStyle {
pub direction: Direction,
}
impl Default for LayoutStyle {
fn default() -> Self {
LayoutStyle {
direction: Direction::LeftRight,
}
}
}
pub enum Direction {
TopBottom,
LeftRight,
}
#[derive(Debug, PartialEq)]
pub struct Layout {
pub x: f64,
pub y: f64,
pub w: f64,
pub h: f64,
}
pub struct Node {
pub layout: Option<Layout>,
pub style: LayoutStyle,
pub children: Vec<NodeIndex>,
}
pub struct Shoji {
nodes: Arena<Node>,
}
pub struct LayoutSize {
width: Option<f64>,
height: Option<f64>,
}
impl LayoutSize {
pub fn new(w: f64, h: f64) -> LayoutSize {
LayoutSize {
width: Some(w),
height: Some(h),
}
}
}
impl Shoji {
pub fn new() -> Self {
Shoji {
nodes: Arena::new(),
}
}
pub fn new_node(
&mut self,
style: LayoutStyle,
children: Vec<NodeIndex>,
) -> Result<NodeIndex, &'static str> {
Ok(self.nodes.insert(Node {
layout: None,
style,
children,
}))
}
pub fn get_node(&mut self, node_index: NodeIndex) -> Result<&mut Node, &'static str> {
Ok(&mut self.nodes[node_index])
}
pub fn get_layout(&self, i: NodeIndex) -> Result<&Layout, &'static str> {
match &self.nodes[i].layout {
Some(l) => Ok(l),
None => Err("layout has not been calculated yet"),
}
}
pub fn compute_layout(
&mut self,
node_index: NodeIndex,
s: LayoutSize,
) -> Result<(), &'static str> {
let node = self.get_node(node_index)?;
node.layout = Some(Layout {
x: 0.0,
y: 0.0,
w: s.width.ok_or("cannot create width from undefined value")?,
h: s.height
.ok_or("cannot create height from undefined value")?,
});
let children = node.children.clone();
let num_children = children.len();
if num_children == 0 {
Ok(())
} else if num_children == 1 {
self.compute_layout(children[0], s)?;
let child_node = self.get_node(children[0])?;
match child_node.layout.as_mut() {
Some(l) => {
l.x = 0.0;
l.y = 0.0;
Ok(())
}
None => return Err("something went wrong"),
}
} else {
match node.style.direction {
Direction::LeftRight => {
let width = s.width;
let height = s.height;
match width {
Some(w) => {
let child_width = w / children.len() as f64;
for (i, c) in children.iter().enumerate() {
self.compute_layout(
*c,
LayoutSize {
width: Some(child_width),
height,
},
)?;
let child_node = self.get_node(*c)?;
match child_node.layout.as_mut() {
Some(l) => {
l.x = i as f64 * child_width;
l.y = 0.0;
}
None => return Err("something went wrong"),
}
}
Ok(())
}
None => Err("cannot compute layout of LeftRight without defined width"),
}
}
Direction::TopBottom => {
let width = s.width;
let height = s.height;
match height {
Some(h) => {
let child_height = h / children.len() as f64;
for (i, c) in children.iter().enumerate() {
self.compute_layout(
*c,
LayoutSize {
width,
height: Some(child_height),
},
)?;
let child_node = self.get_node(*c)?;
match child_node.layout.as_mut() {
Some(l) => {
l.x = 0.0;
l.y = i as f64 * child_height;
}
None => return Err("something went wrong"),
}
}
Ok(())
}
None => Err("cannot compute layout of TopBottom without defined width"),
}
}
}
}
}
}
#[cfg(test)]
mod shoji_test;