feat(#15): Telemetry trace chart component

Implemented by claude via .agents/dev dispatch.
This commit is contained in:
2026-07-03 23:59:39 -04:00
parent 75ca5f4deb
commit eacd5f26e9
3 changed files with 413 additions and 0 deletions

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import { useMemo, useRef, useState } from 'react'
import '../../styles/telemetry-trace.css'
export interface TelemetryTraceSample {
speed: number
throttle: number
brake: number
}
export interface TelemetryTraceSeries {
label: string
color: string
samples: TelemetryTraceSample[]
}
export type TelemetryTraceChannel = 'speed' | 'throttle' | 'brake'
export interface TelemetryTraceChartProps {
series: TelemetryTraceSeries[]
channels?: TelemetryTraceChannel[]
/** Height of each channel panel in SVG units (viewBox space). */
height?: number
}
const VIEW_WIDTH = 800
const PANEL_GAP = 18
const PAD_TOP = 6
const PAD_BOTTOM = 6
const CHANNEL_LABELS: Record<TelemetryTraceChannel, string> = {
speed: 'Speed',
throttle: 'Throttle',
brake: 'Brake',
}
const clamp = (v: number, min: number, max: number) => Math.min(max, Math.max(min, v))
function channelValue(sample: TelemetryTraceSample, channel: TelemetryTraceChannel): number {
const raw = sample[channel]
// Throttle/brake are percentages; clamp so out-of-range API values can't
// draw outside the panel. Speed is clamped to >= 0.
if (channel === 'speed') return Math.max(0, raw)
return clamp(raw, 0, 100)
}
function formatValue(value: number, channel: TelemetryTraceChannel): string {
if (channel === 'speed') return `${Math.round(value)} km/h`
return `${Math.round(value)}%`
}
export function TelemetryTraceChart({
series,
channels = ['speed', 'throttle', 'brake'],
height = 110,
}: TelemetryTraceChartProps) {
const svgRef = useRef<SVGSVGElement | null>(null)
const [hoverIndex, setHoverIndex] = useState<number | null>(null)
// Series are index-aligned; mismatched lengths are clamped to the shortest
// series so every drawn x has a value for every driver.
const sampleCount = useMemo(
() => (series.length === 0 ? 0 : Math.min(...series.map((s) => s.samples.length))),
[series],
)
const speedMax = useMemo(() => {
let max = 0
for (const s of series) {
for (let i = 0; i < sampleCount; i++) {
max = Math.max(max, channelValue(s.samples[i], 'speed'))
}
}
return max > 0 ? max : 1
}, [series, sampleCount])
if (series.length === 0 || sampleCount === 0 || channels.length === 0) {
return <div className="telemetry-trace-empty">No telemetry data</div>
}
// Clamp a stale hover index in case the series prop shrank between renders.
const hover = hoverIndex === null ? null : Math.min(hoverIndex, sampleCount - 1)
const panelHeight = height
const totalHeight = channels.length * panelHeight + (channels.length - 1) * PANEL_GAP
const xAt = (i: number) => (i / Math.max(1, sampleCount - 1)) * VIEW_WIDTH
const channelMax = (channel: TelemetryTraceChannel) => (channel === 'speed' ? speedMax : 100)
const yAt = (value: number, channel: TelemetryTraceChannel, panelTop: number) => {
const usable = panelHeight - PAD_TOP - PAD_BOTTOM
const frac = channelValue({ speed: value, throttle: value, brake: value }, channel) / channelMax(channel)
return panelTop + PAD_TOP + (1 - frac) * usable
}
const handleMouseMove = (e: React.MouseEvent<SVGSVGElement>) => {
const rect = svgRef.current?.getBoundingClientRect()
if (!rect || rect.width === 0) {
setHoverIndex(0)
return
}
const frac = clamp((e.clientX - rect.left) / rect.width, 0, 1)
setHoverIndex(clamp(Math.round(frac * (sampleCount - 1)), 0, sampleCount - 1))
}
return (
<div className="telemetry-trace" data-testid="telemetry-trace">
<div className="telemetry-trace-legend">
{series.map((s) => (
<span key={s.label} className="telemetry-trace-legend-item">
<span className="telemetry-trace-swatch" style={{ background: s.color }} aria-hidden="true" />
{s.label}
</span>
))}
</div>
<svg
ref={svgRef}
className="telemetry-trace-svg"
viewBox={`0 0 ${VIEW_WIDTH} ${totalHeight}`}
role="img"
aria-label="Telemetry trace chart"
onMouseMove={handleMouseMove}
onMouseLeave={() => setHoverIndex(null)}
>
{channels.map((channel, panelIdx) => {
const panelTop = panelIdx * (panelHeight + PANEL_GAP)
return (
<g key={channel} className="telemetry-trace-panel" data-channel={channel}>
<rect
className="telemetry-trace-panel-bg"
x={0}
y={panelTop}
width={VIEW_WIDTH}
height={panelHeight}
/>
<text className="telemetry-trace-panel-title" x={6} y={panelTop + 13}>
{CHANNEL_LABELS[channel]}
</text>
<text className="telemetry-trace-axis-max" x={VIEW_WIDTH - 6} y={panelTop + 13} textAnchor="end">
{channel === 'speed' ? `${Math.round(speedMax)} km/h` : '100%'}
</text>
{series.map((s) => {
const points = Array.from({ length: sampleCount }, (_, i) => {
const x = xAt(i)
const y = yAt(s.samples[i][channel], channel, panelTop)
return `${x.toFixed(2)},${y.toFixed(2)}`
}).join(' ')
return (
<polyline
key={s.label}
className="telemetry-trace-line"
data-channel={channel}
data-series={s.label}
points={points}
fill="none"
stroke={s.color}
strokeWidth={1.6}
strokeLinejoin="round"
strokeLinecap="round"
/>
)
})}
</g>
)
})}
{hover !== null && (
<line
className="telemetry-trace-crosshair"
data-testid="telemetry-trace-crosshair"
x1={xAt(hover)}
y1={0}
x2={xAt(hover)}
y2={totalHeight}
/>
)}
</svg>
{hover !== null && (
<div className="telemetry-trace-readout" data-testid="telemetry-trace-readout">
<span className="telemetry-trace-readout-index">Sample {hover}</span>
{series.map((s) => (
<span key={s.label} className="telemetry-trace-readout-driver">
<span className="telemetry-trace-swatch" style={{ background: s.color }} aria-hidden="true" />
<span className="telemetry-trace-readout-label">{s.label}</span>
{channels.map((channel) => (
<span key={channel} className="telemetry-trace-readout-value">
{formatValue(channelValue(s.samples[hover], channel), channel)}
</span>
))}
</span>
))}
</div>
)}
</div>
)
}

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.telemetry-trace {
display: flex;
flex-direction: column;
gap: 8px;
}
.telemetry-trace-empty {
padding: 24px;
text-align: center;
color: var(--text-3);
font-size: 13px;
background: var(--surface);
border: 1px solid var(--border);
border-radius: 8px;
}
.telemetry-trace-legend {
display: flex;
flex-wrap: wrap;
gap: 14px;
font-size: 12px;
color: var(--text-2);
}
.telemetry-trace-legend-item {
display: inline-flex;
align-items: center;
gap: 6px;
}
.telemetry-trace-swatch {
display: inline-block;
width: 10px;
height: 10px;
border-radius: 2px;
flex: none;
}
.telemetry-trace-svg {
display: block;
width: 100%;
height: auto;
}
.telemetry-trace-panel-bg {
fill: var(--surface);
stroke: var(--border);
stroke-width: 1;
rx: 4;
}
.telemetry-trace-panel-title {
fill: var(--text-2);
font-size: 11px;
text-transform: uppercase;
letter-spacing: 0.06em;
}
.telemetry-trace-axis-max {
fill: var(--text-3);
font-size: 10px;
}
.telemetry-trace-crosshair {
stroke: var(--text-2);
stroke-width: 1;
stroke-dasharray: 3 3;
pointer-events: none;
}
.telemetry-trace-readout {
display: flex;
flex-wrap: wrap;
align-items: center;
gap: 12px;
padding: 6px 10px;
font-size: 12px;
color: var(--text-2);
background: var(--surface-h);
border: 1px solid var(--border);
border-radius: 6px;
}
.telemetry-trace-readout-index {
color: var(--text-3);
}
.telemetry-trace-readout-driver {
display: inline-flex;
align-items: center;
gap: 6px;
}
.telemetry-trace-readout-label {
color: var(--text);
font-weight: 600;
}
.telemetry-trace-readout-value {
font-variant-numeric: tabular-nums;
}

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import { describe, expect, it } from 'vitest'
import { fireEvent, render, screen } from '@testing-library/react'
import {
TelemetryTraceChart,
type TelemetryTraceSeries,
} from '../components/charts/TelemetryTraceChart'
function makeSeries(label: string, color: string, speeds: number[]): TelemetryTraceSeries {
return {
label,
color,
samples: speeds.map((speed, i) => ({
speed,
throttle: (i * 25) % 101,
brake: i % 2 === 0 ? 100 : 0,
})),
}
}
const VER = makeSeries('VER', '#2563eb', [280, 310, 190, 90, 240])
const LEC = makeSeries('LEC', '#dc2626', [275, 305, 200, 95, 235])
describe('TelemetryTraceChart', () => {
it('renders one polyline per series per channel', () => {
const { container } = render(<TelemetryTraceChart series={[VER, LEC]} />)
const lines = container.querySelectorAll('polyline.telemetry-trace-line')
expect(lines).toHaveLength(2 * 3)
for (const channel of ['speed', 'throttle', 'brake']) {
expect(
container.querySelectorAll(`polyline.telemetry-trace-line[data-channel="${channel}"]`),
).toHaveLength(2)
}
expect(
container.querySelectorAll('polyline.telemetry-trace-line[data-series="VER"]'),
).toHaveLength(3)
})
it('respects the channels prop', () => {
const { container } = render(<TelemetryTraceChart series={[VER]} channels={['speed']} />)
expect(container.querySelectorAll('polyline.telemetry-trace-line')).toHaveLength(1)
expect(container.querySelectorAll('.telemetry-trace-panel')).toHaveLength(1)
})
it('renders an empty state for no series', () => {
render(<TelemetryTraceChart series={[]} />)
expect(screen.getByText('No telemetry data')).toBeInTheDocument()
})
it('renders an empty state when a series has no samples', () => {
render(<TelemetryTraceChart series={[makeSeries('VER', '#2563eb', [])]} />)
expect(screen.getByText('No telemetry data')).toBeInTheDocument()
})
it('survives a single sample and mismatched series lengths', () => {
const short = makeSeries('VER', '#2563eb', [300])
const long = makeSeries('LEC', '#dc2626', [280, 290, 300])
const { container } = render(<TelemetryTraceChart series={[short, long]} />)
// Clamped to the shortest series: every polyline has exactly one point.
const lines = container.querySelectorAll('polyline.telemetry-trace-line')
expect(lines).toHaveLength(6)
for (const line of lines) {
expect(line.getAttribute('points')!.trim().split(' ')).toHaveLength(1)
}
})
it('clamps throttle values to 0-100 within the panel', () => {
const wild: TelemetryTraceSeries = {
label: 'VER',
color: '#2563eb',
samples: [
{ speed: 100, throttle: 150, brake: 0 },
{ speed: 100, throttle: -20, brake: 0 },
{ speed: 100, throttle: 50, brake: 0 },
],
}
const { container } = render(
<TelemetryTraceChart series={[wild]} channels={['throttle']} height={110} />,
)
const line = container.querySelector('polyline.telemetry-trace-line[data-channel="throttle"]')!
const ys = line
.getAttribute('points')!
.split(' ')
.map((p) => Number(p.split(',')[1]))
// Panel occupies y 0..110 with 6px padding; clamped values pin to the edges.
expect(ys[0]).toBeCloseTo(6, 1) // 150% -> 100% -> panel top
expect(ys[1]).toBeCloseTo(104, 1) // -20% -> 0% -> panel bottom
expect(ys[2]).toBeCloseTo(55, 1) // 50% -> middle
})
it('shows the speed axis max in km/h', () => {
render(<TelemetryTraceChart series={[VER]} channels={['speed']} />)
expect(screen.getByText('310 km/h')).toBeInTheDocument()
})
it('lists every series in the legend with a color swatch', () => {
const { container } = render(<TelemetryTraceChart series={[VER, LEC]} />)
const legend = container.querySelector('.telemetry-trace-legend')!
expect(legend.textContent).toContain('VER')
expect(legend.textContent).toContain('LEC')
expect(legend.querySelectorAll('.telemetry-trace-swatch')).toHaveLength(2)
})
it('shows a crosshair and per-driver readout on hover, hides on leave', () => {
const { container } = render(<TelemetryTraceChart series={[VER, LEC]} />)
const svg = container.querySelector('svg.telemetry-trace-svg')!
expect(screen.queryByTestId('telemetry-trace-crosshair')).not.toBeInTheDocument()
fireEvent.mouseMove(svg, { clientX: 0, clientY: 10 })
expect(screen.getByTestId('telemetry-trace-crosshair')).toBeInTheDocument()
const readout = screen.getByTestId('telemetry-trace-readout')
expect(readout.textContent).toContain('VER')
expect(readout.textContent).toContain('LEC')
expect(readout.textContent).toContain('km/h')
fireEvent.mouseLeave(svg)
expect(screen.queryByTestId('telemetry-trace-crosshair')).not.toBeInTheDocument()
})
})