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feat(frontend): range compare on every price chart, with click-anchor and a pinned result #389

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Merged
EraPartner merged 1 commit into from
Oct 30, 2026
Merged

feat(frontend): range compare on every price chart, with click-anchor and a pinned result #389

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174 changes: 74 additions & 100 deletions apps/frontend/src/components/charts/AreaChart.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -35,12 +35,12 @@ import {
} from "./CartesianChartFrame";
import { useChartSync } from "./ChartSyncContext";
import { useChartKeyboardNav } from "./keyboardNav";
import { formatScrubDelta, useChartScrub } from "./scrub";
import { ScrubBand, ScrubReadout } from "./ScrubOverlay";
import { scrubView, useChartScrub, type ScrubSeries } from "./scrub";
import { ChartTooltip, type ChartTooltipDatum } from "./ChartTooltip";
import { CHART_NEUTRAL, getChartColor } from "./palette";
import { ChartEntrance, ChartLayerSvg, ChartReveal } from "./chartEntrance";
import { durations } from "@/lib/motion";
import { cn } from "@/lib/utils";
import { useLanguage } from "@/stores/hydration/LanguageHydration";
import { useAppSettings } from "@/stores/hydration/AppSettingsHydration";
import { formatDateWithAppSettings } from "@/lib/dateUtils";
Expand Down Expand Up @@ -93,7 +93,7 @@ export interface AreaChartProps<Datum> {
readonly ariaLabel?: string | undefined;
/** Opt into synced crosshairs with sibling charts sharing this id (needs ChartSyncProvider). */
readonly syncId?: string | undefined;
/** Enable pointer-drag range compare (Δ + %) on the primary series. */
/** Enable range compare (Δ + % per series): drag across the chart, or click a point and move. */
readonly scrubbable?: boolean | undefined;
}

Expand Down Expand Up @@ -416,7 +416,7 @@ function AreaChartInner<Datum>({
if (datum === undefined) return;
setHoverIndex(idx);
publishHover(Number(stableXAccessor(datum)));
if (scrub.scrubbing) scrub.move(idx);
scrub.hover(idx);
},
[indexAtClientX, publishHover, stableXAccessor, data, scrub],
);
Expand All @@ -433,13 +433,14 @@ function AreaChartInner<Datum>({
if (!scrubbable) return;
const idx = indexAtClientX(event);
if (idx == null) return;
// Keep receiving moves while the button is held outside the plot.
event.currentTarget.setPointerCapture(event.pointerId);
scrub.begin(idx);
scrub.press(idx);
},
[scrubbable, indexAtClientX, scrub],
);

const handleUp = useCallback(() => scrub.end(), [scrub]);
const handleUp = useCallback(() => scrub.release(), [scrub]);

// Keyboard path (←/→, Home/End, Shift+←/→, Escape) — drives the same
// hover/scrub state as the pointer, so tooltip/crosshair render unchanged.
Expand Down Expand Up @@ -511,6 +512,27 @@ function AreaChartInner<Datum>({
: 0;
const tooltipTop = margin.top;

const titleOf = (datum: Datum) =>
tooltipTitle
? tooltipTitle(datum)
: formatHoverTitle(xAccessor(datum), appSettings.dateFormat);

const scrubSeries = useMemo<ScrubSeries<Datum>[]>(
() =>
series.map((s, i) => ({
key: s.key,
label: s.label,
color: s.color ?? getChartColor(i),
value: s.accessor,
})),
[series],
);
const scrubbed = scrubbable ? scrubView(scrub, data, scrubSeries) : null;
const formatScrubValue = (v: number, key: string) =>
tooltipValueFormat
? tooltipValueFormat(v, key)
: String(Math.round(v * 100) / 100);

// useId: deterministic per render position (stable snapshots), unique per
// chart instance — replaces the old Math.random() suffix.
const reactId = useId();
Expand Down Expand Up @@ -604,33 +626,34 @@ function AreaChartInner<Datum>({
})}

{/* Scrub range band */}
{scrub.range
? (() => {
const startDatum = data[scrub.range.startIndex];
const endDatum = data[scrub.range.endIndex];
if (
startDatum === undefined ||
endDatum === undefined
)
return null;
const xA =
xScale(stableXAccessor(startDatum));
const xB = xScale(stableXAccessor(endDatum));
return (
<rect
x={Math.min(xA, xB)}
y={0}
width={Math.abs(xB - xA)}
height={innerHeight}
fill={CHART_NEUTRAL.label}
fillOpacity={0.08}
stroke={CHART_NEUTRAL.label}
strokeOpacity={0.25}
pointerEvents="none"
/>
);
})()
: null}
{scrubbed ? (
<ScrubBand
xStart={xScale(stableXAccessor(scrubbed.startDatum))}
xEnd={xScale(stableXAccessor(scrubbed.endDatum))}
innerHeight={innerHeight}
rows={scrubbed.rows}
// Stacked bands sit on cumulative values; dots on
// the raw values would float off the marks.
startMarkers={
stacked
? undefined
: scrubbed.rows.map((r) => ({
key: r.key,
y: yScale(r.start),
color: r.color,
}))
}
endMarkers={
stacked
? undefined
: scrubbed.rows.map((r) => ({
key: r.key,
y: yScale(r.end),
color: r.color,
}))
}
/>
) : null}

{/* Crosshair */}
{hoverDatum != null ? (
Expand Down Expand Up @@ -702,82 +725,33 @@ function AreaChartInner<Datum>({
onPointerLeave={handleLeave}
onPointerDown={handleDown}
onPointerUp={handleUp}
onPointerCancel={handleUp}
onPointerCancel={handleLeave}
/>
</Group>
</CartesianChartFrame>

{scrub.range
? (() => {
const first = series[0];
const startDatum = data[scrub.range.startIndex];
const endDatum = data[scrub.range.endIndex];
if (
!first ||
startDatum === undefined ||
endDatum === undefined
)
return null;
const a = first.accessor(startDatum);
const b = first.accessor(endDatum);
if (
a == null ||
b == null ||
!Number.isFinite(a) ||
!Number.isFinite(b)
)
return null;
const fmt = (v: number) =>
tooltipValueFormat
? tooltipValueFormat(v, first.key)
: String(Math.round(v * 100) / 100);
const xA =
margin.left +
(xScale(stableXAccessor(startDatum)));
const xB =
margin.left +
(xScale(stableXAccessor(endDatum)));
const mid = (xA + xB) / 2;
const rising = b - a > 0;
return (
<div
className={cn(
"pointer-events-none absolute left-0 top-0 z-10 -translate-x-1/2 whitespace-nowrap rounded-full px-2.5 py-1 type-footnote font-medium tabular-nums",
fullEffects
? "glass-thick"
: "border border-border/60 bg-card shadow-elevation-1",
rising
? "text-gain"
: b - a < 0
? "text-loss"
: "text-foreground",
)}
// transform, not left/top: the pill follows the pointer, and
// a transform moves it without relayout per move.
style={{
transform: `translate(${mid}px, 2px)`,
}}
>
{formatScrubDelta(a, b, fmt, formatPercent)}
</div>
);
})()
: null}
{scrubbed?.isRange ? (
<ScrubReadout
xStart={
margin.left + xScale(stableXAccessor(scrubbed.startDatum))
}
xEnd={margin.left + xScale(stableXAccessor(scrubbed.endDatum))}
width={width}
top={2}
startTitle={titleOf(scrubbed.startDatum)}
endTitle={titleOf(scrubbed.endDatum)}
rows={scrubbed.rows}
formatValue={formatScrubValue}
formatPercent={formatPercent}
fullEffects={fullEffects}
/>
) : null}

<ChartTooltip
open={hoverDatum != null && !scrub.range}
left={tooltipLeft}
top={tooltipTop}
title={
hoverDatum != null && tooltipTitle
? tooltipTitle(hoverDatum)
: hoverDatum != null
? formatHoverTitle(
xAccessor(hoverDatum),
appSettings.dateFormat,
)
: undefined
}
title={hoverDatum != null ? titleOf(hoverDatum) : undefined}
items={tooltipItems}
/>
</div>
Expand Down
9 changes: 8 additions & 1 deletion apps/frontend/src/components/charts/CartesianChartFrame.tsx
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,8 @@ import {
useRef,
} from "react";

import { cn } from "@/lib/utils";

export interface CartesianChartMargin {
readonly top: number;
readonly right: number;
Expand Down Expand Up @@ -127,7 +129,12 @@ export function CartesianChartFrame({
}: CartesianChartFrameProps) {
return (
<svg
className={className}
// A click focuses the chart (it is a tab stop); only keyboard
// focus draws the ring, not the browser's default outline.
className={cn(
"[&:focus:not(:focus-visible)]:outline-none",
className,
)}
width={width}
height={height}
role="img"
Expand Down
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