patina/examples/render_layout_tree.rs

use std::collections::HashMap;

#[derive(serde::Deserialize)]
struct Margin {
    top: isize,
    bottom: isize,
    left: isize,
    right: isize,
}

#[derive(serde::Deserialize)]
struct Node {
    id: usize,
    behaviour: String,
    child_arrangement: String,
    width_policy: [usize; 3],
    height_policy: [usize; 3],
    halign: String,
    valign: String,
    margin: Margin,
    table_cell: Option<[usize; 2]>,
    render_area: Option<[[usize; 2]; 2]>,

    children: Vec<Node>,
}

fn main() {
    let mut args = std::env::args();
    let execname = args.next().unwrap();
    if args.len() != 1 {
        println!("usage: {} path-to-json", execname);
        return;
    }

    let fname = args.next().unwrap();
    let indata = std::fs::read(fname).expect("couldn't open file");

    let nodetree: Node = serde_json::from_slice(&indata).expect("couldn't parse file");

    let mut x_pos: HashMap<usize, usize> = HashMap::new();
    let mut y_pos: HashMap<usize, usize> = HashMap::new();

    let mut parents: HashMap<usize, usize> = HashMap::new();
    let mut siblings: HashMap<usize, usize> = HashMap::new();

    let mut dfs = vec![&nodetree];
    let mut max_x = 0;
    while let Some(node) = dfs.pop() {
        println!("visiting node {}", node.id);

        // X coordinate:
        // case 1: no sibling, so same x as parent
        // case 2: sibling, so use max_x + 1
        // Y coordinate:
        // always use parent's y pos + 1

        let x = match siblings.get(&node.id) {
            None => parents
                .get(&node.id)
                .and_then(|p| x_pos.get(p))
                .cloned()
                .unwrap_or(0),
            Some(_sib) => max_x + 1,
        };
        let y = parents
            .get(&node.id)
            .and_then(|p| y_pos.get(p))
            .map(|v| v + 1)
            .unwrap_or(0);

        max_x = max_x.max(x);

        x_pos.insert(node.id, x);
        y_pos.insert(node.id, y);

        let mut sibling: Option<usize> = None;
        for ch in node.children.iter() {
            parents.insert(ch.id, node.id);
            if let Some(sibling) = sibling {
                siblings.insert(ch.id, sibling);
            }
            sibling = Some(ch.id);
            dfs.push(ch);
        }
    }

    let mut yvalues = y_pos.values().collect::<Vec<_>>();
    yvalues.sort();
    yvalues.dedup();
    for y in yvalues {
        let mut line = y_pos
            .iter()
            .filter(|(_, v)| *v == y)
            .map(|(k, _)| (x_pos.get(k).unwrap(), k))
            .collect::<Vec<_>>();
        line.sort();
        println!("{line:?}");
    }
}