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//! #7 — braille history graph.
//!
//! Finishes what `GraphMeterMode_draw` leaves as "an honest stub"
//! (`src/ported/meter.rs:353`), as an extension-side renderer. A [`Scalar`]
//! ring of one metric renders to a multi-row braille bitmap via the shared
//! [`crate::extensions::braille::Canvas`]. Newest sample at the right, bars grow up.
use std::collections::VecDeque;
/// Bounded ring of one scalar metric over time.
pub struct Scalar {
cap: usize,
buf: VecDeque<f64>,
}
impl Scalar {
pub fn new(cap: usize) -> Self {
Scalar {
cap: cap.max(1),
buf: VecDeque::with_capacity(cap),
}
}
pub fn push(&mut self, v: f64) {
if self.buf.len() == self.cap {
self.buf.pop_front();
}
self.buf.push_back(v);
}
pub fn len(&self) -> usize {
self.buf.len()
}
pub fn is_empty(&self) -> bool {
self.buf.is_empty()
}
/// Render the last `width_cells*2` samples as `height_cells` braille rows,
/// scaling values to `max`, newest at the right edge. Delegates to the
/// shared [`crate::extensions::braille::graph_rows`] so the graph and the
/// per-PID sparklines render identically.
pub fn render(&self, width_cells: usize, height_cells: usize, max: f64) -> Vec<String> {
let values: Vec<f64> = self.buf.iter().copied().collect();
crate::extensions::braille::graph_rows(&values, width_cells, height_cells, max)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn bounded_by_capacity() {
let mut s = Scalar::new(4);
for i in 0..10 {
s.push(i as f64);
}
assert_eq!(s.len(), 4);
}
#[test]
fn render_dimensions() {
let mut s = Scalar::new(64);
for i in 0..20 {
s.push(i as f64);
}
let rows = s.render(10, 3, 20.0);
assert_eq!(rows.len(), 3); // height_cells rows
assert_eq!(rows[0].chars().count(), 10); // width_cells cols
}
#[test]
fn full_value_lights_bottom_row() {
let mut s = Scalar::new(8);
s.push(100.0);
let rows = s.render(1, 2, 100.0);
// bottom cell must be non-blank; top may or may not be full
assert_ne!(rows[1], "\u{2800}");
}
#[test]
fn zero_max_is_blank() {
let mut s = Scalar::new(8);
s.push(50.0);
let rows = s.render(2, 2, 0.0);
assert!(rows.iter().all(|r| r.chars().all(|c| c == '\u{2800}')));
}
}