89 lines
2.5 KiB
TypeScript
89 lines
2.5 KiB
TypeScript
import { useCallback, useEffect, useRef, type DependencyList } from 'react';
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import type uPlot from 'uplot';
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export type BuildFn = (
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el: HTMLDivElement,
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w: number,
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h: number,
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legendRef: React.RefObject<HTMLDivElement | null>,
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) => uPlot | null;
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/** Converts a data index to the pixel x position uPlot expects for setCursor */
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function idxToPixel(plot: uPlot, idx: number): number {
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const x = plot.data[0]?.[idx];
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if (x == null) return -10;
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return plot.valToPos(x, 'x');
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}
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/**
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* Manages full uPlot lifecycle:
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* - builds/rebuilds on dep change or resize
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* - mounts legend into legendRef container
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* - pins cursor to last data point on init (legend shows latest values)
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* - restores last-point legend on mouseleave
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*/
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export function usePlot(
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build: BuildFn,
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deps: DependencyList,
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): {
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containerRef: React.RefObject<HTMLDivElement | null>;
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legendRef: React.RefObject<HTMLDivElement | null>;
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} {
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const containerRef = useRef<HTMLDivElement | null>(null);
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const legendRef = useRef<HTMLDivElement>(null);
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const plotRef = useRef<uPlot | null>(null);
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const lastIdxRef = useRef<number>(0);
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const rebuild = useCallback(() => {
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const el = containerRef.current;
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if (!el) return;
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const w = el.clientWidth,
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h = el.clientHeight;
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if (w < 10 || h < 10) return;
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plotRef.current?.destroy();
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if (legendRef.current) legendRef.current.innerHTML = '';
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const plot = build(el, w, h, legendRef);
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plotRef.current = plot;
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if (plot) {
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const lastIdx = Math.max(0, (plot.data[0]?.length ?? 1) - 1);
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lastIdxRef.current = lastIdx;
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// Pin legend to latest data point
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plot.setCursor({ left: idxToPixel(plot, lastIdx), top: -10 });
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// Defer mouseleave — prevents React hydration events firing before lastIdxRef set
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requestAnimationFrame(() => {
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plot.over.addEventListener('mouseleave', () => {
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const p = plotRef.current;
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if (!p) return;
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p.setCursor({ left: idxToPixel(p, lastIdxRef.current), top: -10 });
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});
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});
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}
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// deps is intentionally dynamic — passed by parent to allow external rebuild triggers
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// eslint-disable-next-line react-x/exhaustive-deps
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}, deps);
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useEffect(() => {
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rebuild();
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return () => {
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plotRef.current?.destroy();
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plotRef.current = null;
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};
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}, [rebuild]);
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useEffect(() => {
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const el = containerRef.current;
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if (!el) return;
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const ro = new ResizeObserver(rebuild);
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ro.observe(el);
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return () => ro.disconnect();
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}, [rebuild]);
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return { containerRef, legendRef };
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}
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