"use client";
import * as React from "react";
export interface ForceGraphNode {
id: string;
label: string;
/** Nodes in the same group share a colour (the first group uses the accent). */
group?: string;
}
export interface ForceGraphLink {
source: string;
target: string;
/** Optional weight; heavier links are drawn thicker. */
value?: number;
}
export interface ForceGraphData {
nodes: ForceGraphNode[];
links: ForceGraphLink[];
}
export type ForceGraphLabels = "auto" | "all" | "none";
export interface ForceGraphProps extends Omit<React.HTMLAttributes<HTMLDivElement>, "children"> {
data: ForceGraphData;
/** Height of the graph in px; the width follows the container. */
height?: number;
/** Resting length of the link springs, in px. */
linkDistance?: number;
/** Strength of the repulsion between nodes. */
charge?: number;
/** "auto" labels hubs and the highlighted neighbourhood; "all" or "none" are literal. */
labels?: ForceGraphLabels;
/** Colour of the first group and the highlight. */
accent?: string;
/** Accessible name of the graph. */
label?: string;
}
/* ----------------------------- Reduced motion ------------------------------ */
function subscribeReducedMotion(cb: () => void) {
const mq = window.matchMedia("(prefers-reduced-motion: reduce)");
mq.addEventListener("change", cb);
return () => mq.removeEventListener("change", cb);
}
function usePrefersReducedMotion() {
return React.useSyncExternalStore(
subscribeReducedMotion,
() => window.matchMedia("(prefers-reduced-motion: reduce)").matches,
() => false,
);
}
/* ---------------------------------- Graph ---------------------------------- */
const PALETTE = ["var(--fg-accent)", "#3d8bea", "#22b07d", "#f0b429", "#e87ba4", "#8b7cf0", "#4fb9c9", "#a3a3a3"];
const MAX_NODES = 150;
interface GNode {
id: string;
label: string;
group: string;
color: string;
degree: number;
radius: number;
hub: boolean;
neighbours: number[];
}
interface GLink {
source: number;
target: number;
value: number;
}
interface Graph {
nodes: GNode[];
links: GLink[];
}
/** Validates the data (unique ids, known endpoints, no self or duplicate links) and derives degree, size and colour. */
function buildGraph(data: ForceGraphData): Graph {
const index = new Map<string, number>();
const groups = new Map<string, number>();
const nodes: GNode[] = [];
for (const n of data.nodes) {
if (index.has(n.id) || nodes.length >= MAX_NODES) continue;
const group = n.group ?? "";
if (!groups.has(group)) groups.set(group, groups.size);
index.set(n.id, nodes.length);
nodes.push({ id: n.id, label: n.label, group, color: PALETTE[groups.get(group)! % PALETTE.length], degree: 0, radius: 4, hub: false, neighbours: [] });
}
const seen = new Set<string>();
const links: GLink[] = [];
for (const l of data.links) {
const s = index.get(l.source);
const t = index.get(l.target);
if (s === undefined || t === undefined || s === t) continue;
const key = s < t ? `${s}-${t}` : `${t}-${s}`;
if (seen.has(key)) continue;
seen.add(key);
links.push({ source: s, target: t, value: l.value ?? 1 });
nodes[s].neighbours.push(t);
nodes[t].neighbours.push(s);
}
const degrees = nodes.map((n) => (n.degree = n.neighbours.length)).sort((a, b) => b - a);
// Hubs: roughly the best-connected eighth, and never fewer than three links.
const hubAt = Math.max(3, degrees[Math.floor(nodes.length * 0.12)] ?? 3);
for (const n of nodes) {
n.radius = Math.min(13, 4 + Math.sqrt(n.degree) * 1.7);
n.hub = n.degree >= hubAt;
}
return { nodes, links };
}
/* -------------------------------- Simulation -------------------------------- */
interface Body {
x: number;
y: number;
vx: number;
vy: number;
/** Pinned position while dragged, else null. */
fx: number | null;
fy: number | null;
}
interface Sim {
graph: Graph;
bodies: Body[];
alpha: number;
alphaTarget: number;
distance: number;
charge: number;
}
const ALPHA_MIN = 0.001;
const ALPHA_DECAY = 1 - Math.pow(ALPHA_MIN, 1 / 300); // settles in ~300 steps (~5s)
const VELOCITY_KEEP = 0.6;
const PRESETTLE_ALPHA = 0.12;
const STEP_MS = 1000 / 60;
/**
* One simulation step (the d3-force recipe, inline): link springs, O(n²) many-body repulsion
* (fine up to 150 nodes), a gentle pull to the centre, collision, then velocity integration.
*/
function tick(sim: Sim) {
const { bodies, graph, alpha } = sim;
const n = bodies.length;
// Link springs, stiffer for nodes with few links (as in d3: 1 / min degree).
for (const l of graph.links) {
const s = bodies[l.source];
const t = bodies[l.target];
const ds = graph.nodes[l.source].degree;
const dt = graph.nodes[l.target].degree;
let dx = t.x + t.vx - s.x - s.vx || 1e-6;
let dy = t.y + t.vy - s.y - s.vy || 1e-6;
const len = Math.sqrt(dx * dx + dy * dy);
const k = ((len - sim.distance) / len) * alpha * (1 / Math.min(ds, dt));
dx *= k;
dy *= k;
const bias = ds / (ds + dt);
t.vx -= dx * bias;
t.vy -= dy * bias;
s.vx += dx * (1 - bias);
s.vy += dy * (1 - bias);
}
// Many-body repulsion and collision, pairwise.
for (let i = 0; i < n; i++) {
const a = bodies[i];
const ra = graph.nodes[i].radius;
for (let j = i + 1; j < n; j++) {
const b = bodies[j];
let dx = b.x - a.x;
let dy = b.y - a.y;
if (dx === 0 && dy === 0) {
// Deterministic nudge for coincident nodes.
dx = ((i * 7 + j * 13) % 11) / 1000 - 0.005 || 1e-3;
dy = ((i * 5 + j * 3) % 7) / 1000 - 0.003 || 1e-3;
}
const d2 = Math.max(1, dx * dx + dy * dy);
if (d2 < 640_000) {
const f = (sim.charge * alpha) / d2;
a.vx -= dx * f;
a.vy -= dy * f;
b.vx += dx * f;
b.vy += dy * f;
}
const reach = ra + graph.nodes[j].radius + 3;
if (d2 < reach * reach) {
const d = Math.sqrt(d2);
const push = ((reach - d) / d) * 0.35;
a.vx -= dx * push;
a.vy -= dy * push;
b.vx += dx * push;
b.vy += dy * push;
}
}
}
for (const body of bodies) {
// Weak pull toward the centre keeps disconnected pieces in view.
body.vx -= body.x * 0.035 * alpha;
body.vy -= body.y * 0.035 * alpha;
if (body.fx !== null && body.fy !== null) {
body.x = body.fx;
body.y = body.fy;
body.vx = 0;
body.vy = 0;
} else {
body.vx *= VELOCITY_KEEP;
body.vy *= VELOCITY_KEEP;
body.x += body.vx;
body.y += body.vy;
}
}
sim.alpha += (sim.alphaTarget - sim.alpha) * ALPHA_DECAY;
}
type Point = [number, number];
const r2 = (v: number) => Math.round(v * 100) / 100;
/**
* Deterministic start: nodes on a phyllotaxis spiral (no randomness), then simulated until
* mostly settled. Server and client compute the same layout, so the SSR markup hydrates as-is
* and the client only animates the last stretch of settling.
*/
function presimulate(graph: Graph, distance: number, charge: number) {
const bodies: Body[] = graph.nodes.map((_, i) => {
const r = 10 * Math.sqrt(0.5 + i);
const a = i * Math.PI * (3 - Math.sqrt(5));
return { x: r * Math.cos(a), y: r * Math.sin(a), vx: 0, vy: 0, fx: null, fy: null };
});
const sim: Sim = { graph, bodies, alpha: 1, alphaTarget: 0, distance, charge };
while (sim.alpha > PRESETTLE_ALPHA) tick(sim);
return { graph, positions: bodies.map((b): Point => [r2(b.x), r2(b.y)]), alpha: sim.alpha };
}
/* ---------------------------------- View ----------------------------------- */
interface View {
k: number;
/** Pan offset of the graph's origin from the centre of the box, px. */
px: number;
py: number;
}
const MIN_K = 0.25;
const MAX_K = 4;
/** Zoom and offset that fit every node in the box with some padding (never zooming in past 1.4×). */
function fitView(points: Point[], w: number, h: number): View {
if (!points.length) return { k: 1, px: 0, py: 0 };
let x0 = Infinity;
let y0 = Infinity;
let x1 = -Infinity;
let y1 = -Infinity;
for (const [x, y] of points) {
x0 = Math.min(x0, x);
y0 = Math.min(y0, y);
x1 = Math.max(x1, x);
y1 = Math.max(y1, y);
}
const pad = Math.min(56, Math.min(w, h) * 0.12);
const k = Math.min(1.4, Math.max(MIN_K, Math.min((w - pad * 2) / Math.max(1, x1 - x0), (h - pad * 2) / Math.max(1, y1 - y0))));
return { k: Math.round(k * 1000) / 1000, px: r2(-((x0 + x1) / 2) * k), py: r2(-((y0 + y1) / 2) * k) };
}
const viewTransform = (v: View, w: number, h: number) => `translate(${r2(w / 2 + v.px)},${r2(h / 2 + v.py)}) scale(${Math.round(v.k * 1000) / 1000})`;
/* -------------------------------- Component -------------------------------- */
/**
* A force-directed network graph in SVG with an inline simulation (springs, O(n²) repulsion,
* centring, collision) that runs on fixed 60Hz steps and stops once settled. Drag nodes (they
* pin while held), pan the background, zoom with the buttons, keys or Ctrl/⌘ + wheel or pinch.
* Hover or focus highlights a node's neighbours. Every node is a tab stop and arrow keys move
* to the nearest node in that direction, preferring connected ones. Up to 150 nodes.
*/
export function ForceGraph({
data,
height = 440,
linkDistance = 48,
charge = 120,
labels = "auto",
accent = "#FF7448",
label = "Network graph",
className = "",
style,
...props
}: ForceGraphProps) {
const reduceMotion = usePrefersReducedMotion();
const uid = React.useId().replace(/[^a-zA-Z0-9_-]/g, "");
const hintId = `${uid}-hint`;
const boxRef = React.useRef<HTMLDivElement>(null);
const svgRef = React.useRef<SVGSVGElement>(null);
const viewportRef = React.useRef<SVGGElement>(null);
const simRef = React.useRef<Sim | null>(null);
const viewRef = React.useRef<View>({ k: 1, px: 0, py: 0 });
const controlsRef = React.useRef<{ reheat: (alpha: number) => void } | null>(null);
const movedRef = React.useRef(false); // the user has panned or zoomed
const H = Math.max(160, height);
const [width, setWidth] = React.useState(720);
const W = Math.max(160, width);
const [seed, setSeed] = React.useState(() => presimulate(buildGraph(data), linkDistance, charge));
const [positions, setPositions] = React.useState<Point[]>(seed.positions);
const [view, setView] = React.useState<View>(() => fitView(seed.positions, 720, H));
const [prevData, setPrevData] = React.useState(data);
if (data !== prevData) {
// New data: a fresh deterministic layout, fitted to the box.
const next = presimulate(buildGraph(data), linkDistance, charge);
setPrevData(data);
setSeed(next);
setPositions(next.positions);
setView(fitView(next.positions, W, H));
}
const graph = seed.graph;
const [hoverId, setHoverId] = React.useState<number | null>(null);
const [focusId, setFocusId] = React.useState<number | null>(null);
const active = hoverId ?? focusId;
const lit = active === null ? null : new Set([active, ...graph.nodes[active].neighbours]);
React.useEffect(() => {
viewRef.current = view;
}, [view]);
/* ------------------------- simulation + gestures ------------------------- */
const tuning = React.useEffectEvent(() => ({ distance: linkDistance, charge, reduce: reduceMotion }));
const commitView = React.useEffectEvent((v: View) => setView({ ...v }));
const commitPositions = React.useEffectEvent((sim: Sim) => setPositions(sim.bodies.map((b): Point => [r2(b.x), r2(b.y)])));
const tapNode = React.useEffectEvent((i: number) => setHoverId((h) => (h === i ? null : i)));
const clearTap = React.useEffectEvent(() => setHoverId(null));
React.useEffect(() => {
const svg = svgRef.current;
const viewport = viewportRef.current;
if (!svg || !viewport) return;
const { distance, charge: strength } = tuning();
const sim: Sim = {
graph: seed.graph,
bodies: seed.positions.map(([x, y]) => ({ x, y, vx: 0, vy: 0, fx: null, fy: null })),
alpha: seed.alpha,
alphaTarget: 0,
distance,
charge: strength,
};
simRef.current = sim;
const nodeEls = new Map<number, SVGGElement>();
svg.querySelectorAll<SVGGElement>("[data-fg-node]").forEach((el) => nodeEls.set(Number(el.dataset.fgNode), el));
const linkEls = new Map<number, SVGLineElement>();
svg.querySelectorAll<SVGLineElement>("[data-fg-link]").forEach((el) => linkEls.set(Number(el.dataset.fgLink), el));
/** Writes positions straight to the DOM; React state is only updated once things settle. */
const paint = () => {
sim.bodies.forEach((b, i) => nodeEls.get(i)?.setAttribute("transform", `translate(${r2(b.x)},${r2(b.y)})`));
sim.graph.links.forEach((l, i) => {
const el = linkEls.get(i);
if (!el) return;
const s = sim.bodies[l.source];
const t = sim.bodies[l.target];
el.setAttribute("x1", String(r2(s.x)));
el.setAttribute("y1", String(r2(s.y)));
el.setAttribute("x2", String(r2(t.x)));
el.setAttribute("y2", String(r2(t.y)));
});
};
let raf = 0;
let last = 0;
let pending = 0;
let running = false;
let inView = true;
const frame = (now: number) => {
raf = 0;
const dt = Math.min(64, last ? now - last : STEP_MS);
last = now;
// Fixed 60Hz steps: the same settling on 60, 120 or 144Hz displays. A short frame may run
// no step at all; alpha only changes inside a step, so such a frame can never count as settled.
pending = Math.min(pending + dt, STEP_MS * 4);
let stepped = false;
while (pending >= STEP_MS) {
tick(sim);
pending -= STEP_MS;
stepped = true;
}
if (stepped) paint();
if (stepped && sim.alpha < ALPHA_MIN && sim.alphaTarget === 0) {
running = false;
last = 0;
pending = 0;
commitPositions(sim);
return;
}
schedule();
};
const schedule = () => {
if (running && !raf && inView && !document.hidden) raf = requestAnimationFrame(frame);
};
const stop = () => {
cancelAnimationFrame(raf);
raf = 0;
last = 0;
};
/** Restarts the simulation; with reduced motion it runs to rest synchronously, unseen. */
const reheat = (to: number) => {
sim.alpha = Math.max(sim.alpha, to);
if (tuning().reduce) {
while (sim.alpha >= ALPHA_MIN) tick(sim);
paint();
commitPositions(sim);
return;
}
running = true;
schedule();
};
controlsRef.current = {
reheat: (to) => {
const t = tuning();
sim.distance = t.distance;
sim.charge = t.charge;
reheat(to);
},
};
// Finish the last stretch of settling (instantly with reduced motion).
reheat(0);
/* -------------------------------- gestures ------------------------------- */
const pointers = new Map<number, { x: number; y: number }>();
let drag: { index: number; id: number; startX: number; startY: number; moved: boolean } | null = null;
let pan: { id: number; x: number; y: number } | null = null;
let pinch: { dist: number; k: number } | null = null;
let commitTimer = 0;
const applyView = () => viewport.setAttribute("transform", viewTransform(viewRef.current, svg.clientWidth, svg.clientHeight));
const local = (e: PointerEvent | WheelEvent) => {
const rect = svg.getBoundingClientRect();
return { x: e.clientX - rect.left, y: e.clientY - rect.top };
};
const toSim = (x: number, y: number) => {
const v = viewRef.current;
return { x: (x - svg.clientWidth / 2 - v.px) / v.k, y: (y - svg.clientHeight / 2 - v.py) / v.k };
};
/** Zooms by `factor` keeping the point (x, y) of the box fixed. */
const zoomAt = (factor: number, x: number, y: number) => {
const v = viewRef.current;
const k = Math.min(MAX_K, Math.max(MIN_K, v.k * factor));
const cx = x - svg.clientWidth / 2;
const cy = y - svg.clientHeight / 2;
viewRef.current = { k, px: cx - ((cx - v.px) * k) / v.k, py: cy - ((cy - v.py) * k) / v.k };
movedRef.current = true;
applyView();
};
const onPointerDown = (e: PointerEvent) => {
if (e.button !== 0) return;
const p = local(e);
pointers.set(e.pointerId, p);
svg.setPointerCapture(e.pointerId);
if (pointers.size === 2) {
// Second finger: switch to pinch zoom.
const [a, b] = [...pointers.values()];
pinch = { dist: Math.hypot(a.x - b.x, a.y - b.y) || 1, k: viewRef.current.k };
if (drag) sim.bodies[drag.index].fx = sim.bodies[drag.index].fy = null;
drag = null;
pan = null;
return;
}
const nodeEl = (e.target as Element).closest<SVGGElement>("[data-fg-node]");
if (nodeEl) {
const index = Number(nodeEl.dataset.fgNode);
drag = { index, id: e.pointerId, startX: p.x, startY: p.y, moved: false };
sim.bodies[index].fx = sim.bodies[index].x;
sim.bodies[index].fy = sim.bodies[index].y;
} else {
pan = { id: e.pointerId, x: p.x, y: p.y };
if (e.pointerType !== "mouse") clearTap(); // touching the background clears a tapped highlight
}
};
const onPointerMove = (e: PointerEvent) => {
if (!pointers.has(e.pointerId)) return;
const p = local(e);
pointers.set(e.pointerId, p);
if (pinch && pointers.size >= 2) {
const [a, b] = [...pointers.values()];
const dist = Math.hypot(a.x - b.x, a.y - b.y) || 1;
zoomAt((pinch.k * (dist / pinch.dist)) / viewRef.current.k, (a.x + b.x) / 2, (a.y + b.y) / 2);
return;
}
if (drag && drag.id === e.pointerId) {
if (!drag.moved && Math.hypot(p.x - drag.startX, p.y - drag.startY) < 4) return;
drag.moved = true;
const at = toSim(p.x, p.y);
const body = sim.bodies[drag.index];
// The dragged node is pinned to the pointer; the rest of the graph reacts to it.
body.fx = at.x;
body.fy = at.y;
if (tuning().reduce) {
body.x = at.x;
body.y = at.y;
paint();
} else {
sim.alphaTarget = 0.3;
reheat(0.3);
}
} else if (pan && pan.id === e.pointerId) {
const v = viewRef.current;
viewRef.current = { ...v, px: v.px + p.x - pan.x, py: v.py + p.y - pan.y };
pan.x = p.x;
pan.y = p.y;
movedRef.current = true;
applyView();
}
};
const onPointerUp = (e: PointerEvent) => {
if (!pointers.has(e.pointerId)) return;
pointers.delete(e.pointerId);
if (pinch) {
if (pointers.size < 2) {
pinch = null;
commitView(viewRef.current);
}
return;
}
if (drag && drag.id === e.pointerId) {
const body = sim.bodies[drag.index];
body.fx = null;
body.fy = null;
sim.alphaTarget = 0;
if (!drag.moved && e.pointerType !== "mouse") tapNode(drag.index); // touch: tap shows the neighbourhood
else if (drag.moved) clearTap(); // pointer capture hides the leave event, so drop the hover here
if (drag.moved && tuning().reduce) commitPositions(sim);
drag = null;
} else if (pan && pan.id === e.pointerId) {
pan = null;
commitView(viewRef.current);
}
};
// Ctrl/⌘ + wheel (and trackpad pinch, which arrives as Ctrl + wheel) zooms; a plain wheel
// keeps scrolling the page.
const onWheel = (e: WheelEvent) => {
if (!e.ctrlKey && !e.metaKey) return;
e.preventDefault();
const p = local(e);
zoomAt(Math.exp(-e.deltaY * (e.ctrlKey ? 0.01 : 0.002)), p.x, p.y);
window.clearTimeout(commitTimer);
commitTimer = window.setTimeout(() => commitView(viewRef.current), 160);
};
const onVisibility = () => (document.hidden ? stop() : schedule());
const io = new IntersectionObserver(([entry]) => {
inView = entry.isIntersecting;
if (inView) schedule();
else stop();
});
io.observe(svg);
svg.addEventListener("pointerdown", onPointerDown);
svg.addEventListener("pointermove", onPointerMove);
svg.addEventListener("pointerup", onPointerUp);
svg.addEventListener("pointercancel", onPointerUp);
svg.addEventListener("wheel", onWheel, { passive: false });
document.addEventListener("visibilitychange", onVisibility);
return () => {
stop();
io.disconnect();
window.clearTimeout(commitTimer);
svg.removeEventListener("pointerdown", onPointerDown);
svg.removeEventListener("pointermove", onPointerMove);
svg.removeEventListener("pointerup", onPointerUp);
svg.removeEventListener("pointercancel", onPointerUp);
svg.removeEventListener("wheel", onWheel);
document.removeEventListener("visibilitychange", onVisibility);
controlsRef.current = null;
simRef.current = null;
};
}, [seed]);
// Changing the forces reheats the running simulation instead of starting over. Turning on
// reduced motion (which may only be known after hydration) finishes any settling at once.
React.useEffect(() => {
const sim = simRef.current;
if (!sim) return;
if (sim.distance !== linkDistance || sim.charge !== charge) controlsRef.current?.reheat(0.6);
else if (reduceMotion) controlsRef.current?.reheat(0);
}, [linkDistance, charge, reduceMotion]);
const fitNow = React.useEffectEvent(() => {
const sim = simRef.current;
const points = sim ? sim.bodies.map((b): Point => [b.x, b.y]) : positions;
movedRef.current = false;
setView(fitView(points, W, H));
});
React.useEffect(() => {
const box = boxRef.current;
if (!box) return;
const ro = new ResizeObserver((entries) => setWidth(Math.max(1, Math.round(entries[0].contentRect.width))));
ro.observe(box);
return () => ro.disconnect();
}, []);
// Until the user pans or zooms, keep the graph fitted to the box as it resizes.
React.useEffect(() => {
if (!movedRef.current) fitNow();
}, [W, H]);
/* -------------------------------- keyboard ------------------------------- */
const focusNode = (i: number) => svgRef.current?.querySelector<SVGElement>(`[data-fg-focus="${i}"]`)?.focus();
/** The nearest node in a direction, scored by distance along it plus sideways drift; neighbours win ties. */
const nearestIn = (from: number, dx: number, dy: number) => {
const sim = simRef.current;
const pts = sim ? sim.bodies.map((b): Point => [b.x, b.y]) : positions;
const [fx, fy] = pts[from];
const pick = (candidates: number[]) => {
let best = -1;
let bestScore = Infinity;
for (const j of candidates) {
if (j === from) continue;
const tx = pts[j][0] - fx;
const ty = pts[j][1] - fy;
const along = tx * dx + ty * dy;
if (along <= 0.5) continue;
const score = along + Math.abs(tx * dy - ty * dx) * 2;
if (score < bestScore) {
bestScore = score;
best = j;
}
}
return best;
};
const viaLink = pick(graph.nodes[from].neighbours);
return viaLink >= 0 ? viaLink : pick(graph.nodes.map((_, j) => j));
};
const onNodeKeyDown = (event: React.KeyboardEvent, i: number) => {
const dirs: Record<string, Point> = { ArrowRight: [1, 0], ArrowLeft: [-1, 0], ArrowDown: [0, 1], ArrowUp: [0, -1] };
const dir = dirs[event.key];
if (!dir) return;
event.preventDefault();
const next = nearestIn(i, dir[0], dir[1]);
if (next >= 0) focusNode(next);
};
/** Keeps a keyboard-focused node inside the box, panning if it was out of view. */
const revealNode = (i: number) => {
const sim = simRef.current;
const [x, y] = sim ? [sim.bodies[i].x, sim.bodies[i].y] : positions[i];
const sx = W / 2 + view.px + x * view.k;
const sy = H / 2 + view.py + y * view.k;
const m = 32;
if (sx >= m && sx <= W - m && sy >= m && sy <= H - m) return;
movedRef.current = true;
setView({ ...view, px: r2(-x * view.k), py: r2(-y * view.k) });
};
const zoomBy = (factor: number) => {
movedRef.current = true;
const k = Math.min(MAX_K, Math.max(MIN_K, view.k * factor));
setView({ k: Math.round(k * 1000) / 1000, px: r2((view.px * k) / view.k), py: r2((view.py * k) / view.k) });
};
const onRootKeyDown = (event: React.KeyboardEvent) => {
if (event.altKey || event.ctrlKey || event.metaKey) return;
if (event.key === "+" || event.key === "=") zoomBy(1.25);
else if (event.key === "-" || event.key === "_") zoomBy(0.8);
else if (event.key === "0") fitNow();
else return;
event.preventDefault();
};
/* --------------------------------- render -------------------------------- */
const activeNode = active === null ? null : graph.nodes[active];
const showLabel = (i: number) =>
labels === "all" || i === active || (labels === "auto" && (graph.nodes[i].hub || (lit !== null && lit.has(i))));
const buttonClass =
"grid size-7 place-items-center rounded-md text-zinc-600 transition-colors hover:bg-zinc-900/[0.06] hover:text-zinc-950 outline-hidden focus-visible:outline-2 focus-visible:outline-solid focus-visible:outline-[var(--fg-accent)] dark:text-zinc-300 dark:hover:bg-white/10 dark:hover:text-white";
return (
<div
className={`flex w-full min-w-0 flex-col gap-2 text-zinc-950 dark:text-zinc-50 ${className}`}
style={{ ["--fg-accent" as string]: accent, ...style }}
onKeyDown={onRootKeyDown}
{...props}
>
<div
ref={boxRef}
className="relative w-full overflow-hidden rounded-xl border border-zinc-900/10 bg-zinc-900/[0.015] dark:border-white/10 dark:bg-white/[0.02]"
style={{ height: H }}
>
<svg
ref={svgRef}
width={W}
height={H}
role="group"
aria-label={label}
aria-roledescription="network graph"
aria-describedby={hintId}
className="block cursor-grab touch-none select-none active:cursor-grabbing"
onPointerLeave={(e) => e.pointerType === "mouse" && setHoverId(null)}
>
<g ref={viewportRef} transform={viewTransform(view, W, H)}>
<g aria-hidden="true" strokeLinecap="round">
{graph.links.map((l, i) => {
const on = lit !== null && (l.source === active || l.target === active);
const [x1, y1] = positions[l.source];
const [x2, y2] = positions[l.target];
return (
<line
key={`${l.source}-${l.target}`}
data-fg-link={i}
x1={x1}
y1={y1}
x2={x2}
y2={y2}
stroke={on ? "var(--fg-accent)" : "currentColor"}
strokeWidth={r2((on ? 1.6 : 1) * Math.min(4, 0.8 + Math.sqrt(l.value) * 0.4))}
vectorEffect="non-scaling-stroke"
className={`text-zinc-400 transition-[stroke-opacity] duration-200 motion-reduce:transition-none dark:text-zinc-500 ${
lit === null ? "[stroke-opacity:0.5]" : on ? "[stroke-opacity:0.95]" : "[stroke-opacity:0.12]"
}`}
/>
);
})}
</g>
<g role="list" aria-label={`${label} nodes`}>
{graph.nodes.map((n, i) => {
const [x, y] = positions[i];
const dim = lit !== null && !lit.has(i);
return (
<g
key={n.id}
data-fg-node={i}
transform={`translate(${x},${y})`}
className={`group cursor-pointer transition-opacity duration-200 motion-reduce:transition-none ${dim ? "opacity-25" : "opacity-100"}`}
>
{/* Focus ring, keyboard focus only. */}
<circle
aria-hidden="true"
r={n.radius + 4}
fill="none"
strokeWidth={2}
vectorEffect="non-scaling-stroke"
className="pointer-events-none stroke-zinc-950 opacity-0 group-has-[:focus-visible]:opacity-100 dark:stroke-white"
/>
<circle
data-fg-focus={i}
role="listitem"
tabIndex={0}
aria-label={`${n.label}${n.group ? `, ${n.group}` : ""}: ${n.degree} ${n.degree === 1 ? "connection" : "connections"}`}
r={n.radius}
fill={n.color}
strokeWidth={i === active ? 2.5 : 1.5}
vectorEffect="non-scaling-stroke"
className={`outline-none ${i === active ? "stroke-[var(--fg-accent)]" : "stroke-white dark:stroke-[#131619]"}`}
onPointerEnter={(e) => e.pointerType === "mouse" && setHoverId(i)}
onPointerLeave={(e) => e.pointerType === "mouse" && setHoverId(null)}
onFocus={(e) => {
setFocusId(i);
if (e.currentTarget.matches(":focus-visible")) revealNode(i);
}}
onBlur={() => setFocusId(null)}
onKeyDown={(e) => onNodeKeyDown(e, i)}
/>
{showLabel(i) && (
<text
aria-hidden="true"
x={n.radius + 5}
dy="0.35em"
className={`pointer-events-none fill-current text-[11px] tracking-[-0.01em] [paint-order:stroke] [stroke-linejoin:round] [stroke-width:3px] stroke-white/80 dark:stroke-black/60 ${
i === active ? "font-semibold" : "font-medium"
}`}
style={{ fontSize: r2(11 / Math.max(0.6, view.k)) }}
>
{n.label}
</text>
)}
</g>
);
})}
</g>
</g>
</svg>
<div
aria-hidden="true"
className="pointer-events-none absolute left-3 top-3 max-w-[60%] rounded-md border border-zinc-900/10 bg-white/85 px-2.5 py-1.5 backdrop-blur-sm dark:border-white/10 dark:bg-zinc-900/85"
>
{activeNode ? (
<>
<span className="block truncate text-[13px] font-semibold tracking-[-0.01em]">{activeNode.label}</span>
<span className="block font-mono text-[10px] uppercase tracking-[0.12em] text-zinc-500 dark:text-zinc-400">
{activeNode.group ? `${activeNode.group} · ` : ""}
{activeNode.degree} {activeNode.degree === 1 ? "link" : "links"}
</span>
</>
) : (
<span className="block font-mono text-[10px] uppercase tracking-[0.12em] text-zinc-500 dark:text-zinc-400">
{graph.nodes.length} nodes · {graph.links.length} links
</span>
)}
</div>
<div
role="group"
aria-label="Zoom"
className="absolute right-3 top-3 flex items-center gap-0.5 rounded-lg border border-zinc-900/10 bg-white/85 p-0.5 backdrop-blur-sm dark:border-white/10 dark:bg-zinc-900/85"
>
<button type="button" aria-label="Zoom out" className={buttonClass} onClick={() => zoomBy(0.8)}>
<svg viewBox="0 0 16 16" className="size-3.5" fill="none" stroke="currentColor" strokeWidth="1.5" aria-hidden="true">
<path d="M3.5 8h9" />
</svg>
</button>
<button type="button" aria-label="Zoom in" className={buttonClass} onClick={() => zoomBy(1.25)}>
<svg viewBox="0 0 16 16" className="size-3.5" fill="none" stroke="currentColor" strokeWidth="1.5" aria-hidden="true">
<path d="M3.5 8h9M8 3.5v9" />
</svg>
</button>
<button type="button" aria-label="Fit graph to view" className={buttonClass} onClick={() => fitNow()}>
<svg viewBox="0 0 16 16" className="size-3.5" fill="none" stroke="currentColor" strokeWidth="1.5" aria-hidden="true">
<path d="M2.5 6V2.5H6M10 2.5h3.5V6M13.5 10v3.5H10M6 13.5H2.5V10" />
</svg>
</button>
</div>
</div>
<p id={hintId} className="sr-only">
Tab moves through the nodes. Arrow keys jump to the nearest node in that direction, preferring connected ones. Plus and minus zoom, 0 fits the graph. With a pointer, drag nodes or the background, and zoom with Ctrl or Command and the wheel.
</p>
<div className="sr-only">
<p>{label}: adjacency list</p>
<ul>
{graph.nodes.map((n) => (
<li key={n.id}>
{n.label}
{n.group ? ` (${n.group})` : ""}:{" "}
{n.neighbours.length ? `connected to ${n.neighbours.map((j) => graph.nodes[j].label).join(", ")}` : "no connections"}
</li>
))}
</ul>
</div>
</div>
);
}