feat: add Calculator & Grapher tool

Adds a full-featured mathematical calculator and interactive function
grapher at /calculate. Powered by Math.js v15 with a HiDPI Canvas
renderer for the graph.

- Evaluates arbitrary math expressions (trig, log, complex, matrices,
  factorials, combinatorics, and more) with named variable scope
- Persists history (50 entries) and variables via localStorage
- 32 quick-insert buttons for constants and functions
- Interactive graph: pan (drag), zoom (scroll), crosshair tooltip
  showing cursor coords and f₁(x)…f₈(x) values simultaneously
- Up to 8 color-coded functions with inline color pickers and
  visibility toggles
- Discontinuity detection for functions like tan(x)
- Adaptive grid labels that rescale with zoom
- Responsive layout: 2/5–3/5 split on desktop, tabbed on mobile

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
2026-02-28 20:44:53 +01:00
parent aa890a0d55
commit 9efa783ca3
11 changed files with 1249 additions and 1 deletions

View File

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'use client';
import { useRef, useEffect, useCallback, useState } from 'react';
import type { GraphFunction } from '@/lib/calculate/store';
import { sampleFunction, evaluateAt } from '@/lib/calculate/math-engine';
interface ViewState {
xMin: number;
xMax: number;
yMin: number;
yMax: number;
}
interface Props {
functions: GraphFunction[];
variables: Record<string, string>;
}
const DEFAULT_VIEW: ViewState = { xMin: -10, xMax: 10, yMin: -6, yMax: 6 };
function niceStep(range: number): number {
if (range <= 0) return 1;
const rawStep = range / 8;
const mag = Math.pow(10, Math.floor(Math.log10(rawStep)));
const n = rawStep / mag;
const nice = n <= 1 ? 1 : n <= 2 ? 2 : n <= 5 ? 5 : 10;
return nice * mag;
}
function fmtLabel(v: number): string {
if (Math.abs(v) < 1e-10) return '0';
const abs = Math.abs(v);
if (abs >= 1e5 || (abs < 0.01 && abs > 0)) return v.toExponential(1);
return parseFloat(v.toPrecision(4)).toString();
}
export default function GraphCanvas({ functions, variables }: Props) {
const canvasRef = useRef<HTMLCanvasElement>(null);
const viewRef = useRef<ViewState>(DEFAULT_VIEW);
const [, tick] = useState(0);
const redraw = useCallback(() => tick((n) => n + 1), []);
const [cursor, setCursor] = useState<{ x: number; y: number } | null>(null);
const cursorRef = useRef<{ x: number; y: number } | null>(null);
const functionsRef = useRef(functions);
const variablesRef = useRef(variables);
const dragRef = useRef<{ startX: number; startY: number; startView: ViewState } | null>(null);
const rafRef = useRef(0);
useEffect(() => { functionsRef.current = functions; }, [functions]);
useEffect(() => { variablesRef.current = variables; }, [variables]);
useEffect(() => { cursorRef.current = cursor; }, [cursor]);
const draw = useCallback(() => {
const canvas = canvasRef.current;
if (!canvas) return;
const ctx = canvas.getContext('2d');
if (!ctx) return;
const dpr = window.devicePixelRatio || 1;
const rect = canvas.getBoundingClientRect();
const W = rect.width;
const H = rect.height;
if (!W || !H) return;
if (canvas.width !== Math.round(W * dpr) || canvas.height !== Math.round(H * dpr)) {
canvas.width = Math.round(W * dpr);
canvas.height = Math.round(H * dpr);
}
ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
const v = viewRef.current;
const xRange = v.xMax - v.xMin;
const yRange = v.yMax - v.yMin;
const fns = functionsRef.current;
const vars = variablesRef.current;
const cur = cursorRef.current;
const toP = (mx: number, my: number): [number, number] => [
(mx - v.xMin) / xRange * W,
H - (my - v.yMin) / yRange * H,
];
// ── Background ──────────────────────────────────────────────
ctx.fillStyle = '#08080f';
ctx.fillRect(0, 0, W, H);
const radGrad = ctx.createRadialGradient(W * 0.5, H * 0.5, 0, W * 0.5, H * 0.5, Math.max(W, H) * 0.7);
radGrad.addColorStop(0, 'rgba(139, 92, 246, 0.05)');
radGrad.addColorStop(1, 'rgba(0, 0, 0, 0)');
ctx.fillStyle = radGrad;
ctx.fillRect(0, 0, W, H);
// ── Grid ─────────────────────────────────────────────────────
const xStep = niceStep(xRange);
const yStep = niceStep(yRange);
ctx.lineWidth = 1;
for (let x = Math.ceil(v.xMin / xStep) * xStep; x <= v.xMax + xStep * 0.01; x += xStep) {
const [px] = toP(x, 0);
ctx.strokeStyle =
Math.abs(x) < xStep * 0.01 ? 'rgba(255,255,255,0.18)' : 'rgba(255,255,255,0.055)';
ctx.beginPath(); ctx.moveTo(px, 0); ctx.lineTo(px, H); ctx.stroke();
}
for (let y = Math.ceil(v.yMin / yStep) * yStep; y <= v.yMax + yStep * 0.01; y += yStep) {
const [, py] = toP(0, y);
ctx.strokeStyle =
Math.abs(y) < yStep * 0.01 ? 'rgba(255,255,255,0.18)' : 'rgba(255,255,255,0.055)';
ctx.beginPath(); ctx.moveTo(0, py); ctx.lineTo(W, py); ctx.stroke();
}
// ── Axes ──────────────────────────────────────────────────────
const [ax, ay] = toP(0, 0);
ctx.lineWidth = 1.5;
ctx.strokeStyle = 'rgba(255,255,255,0.25)';
if (ay >= 0 && ay <= H) {
ctx.beginPath(); ctx.moveTo(0, ay); ctx.lineTo(W, ay); ctx.stroke();
}
if (ax >= 0 && ax <= W) {
ctx.beginPath(); ctx.moveTo(ax, 0); ctx.lineTo(ax, H); ctx.stroke();
}
// ── Axis arrow tips ───────────────────────────────────────────
const arrowSize = 5;
ctx.fillStyle = 'rgba(255,255,255,0.25)';
if (ax >= 0 && ax <= W) {
// Y-axis arrow (pointing up)
ctx.beginPath();
ctx.moveTo(ax, 4);
ctx.lineTo(ax - arrowSize, 4 + arrowSize * 1.8);
ctx.lineTo(ax + arrowSize, 4 + arrowSize * 1.8);
ctx.closePath(); ctx.fill();
}
if (ay >= 0 && ay <= H) {
// X-axis arrow (pointing right)
ctx.beginPath();
ctx.moveTo(W - 4, ay);
ctx.lineTo(W - 4 - arrowSize * 1.8, ay - arrowSize);
ctx.lineTo(W - 4 - arrowSize * 1.8, ay + arrowSize);
ctx.closePath(); ctx.fill();
}
// ── Axis labels ───────────────────────────────────────────────
ctx.font = '10px monospace';
ctx.fillStyle = 'rgba(161,161,170,0.6)';
const labelAY = Math.min(Math.max(ay + 5, 2), H - 14);
const labelAX = Math.min(Math.max(ax + 5, 2), W - 46);
ctx.textAlign = 'center'; ctx.textBaseline = 'top';
for (let x = Math.ceil(v.xMin / xStep) * xStep; x <= v.xMax; x += xStep) {
if (Math.abs(x) < xStep * 0.01) continue;
const [px] = toP(x, 0);
if (px < 8 || px > W - 8) continue;
ctx.fillText(fmtLabel(x), px, labelAY);
}
ctx.textAlign = 'left'; ctx.textBaseline = 'middle';
for (let y = Math.ceil(v.yMin / yStep) * yStep; y <= v.yMax; y += yStep) {
if (Math.abs(y) < yStep * 0.01) continue;
const [, py] = toP(0, y);
if (py < 8 || py > H - 8) continue;
ctx.fillText(fmtLabel(y), labelAX, py);
}
if (ax >= 0 && ax <= W && ay >= 0 && ay <= H) {
ctx.fillStyle = 'rgba(161,161,170,0.35)';
ctx.textAlign = 'left'; ctx.textBaseline = 'top';
ctx.fillText('0', labelAX, labelAY);
}
// ── Function curves ───────────────────────────────────────────
const numPts = Math.round(W * 1.5);
for (const fn of fns) {
if (!fn.visible || !fn.expression.trim()) continue;
const pts = sampleFunction(fn.expression, v.xMin, v.xMax, numPts, vars);
// Three render passes: wide glow → medium glow → crisp line
const passes = [
{ alpha: 0.08, width: 10 },
{ alpha: 0.28, width: 3.5 },
{ alpha: 1.0, width: 1.8 },
];
for (const { alpha, width } of passes) {
ctx.beginPath();
ctx.strokeStyle = fn.color;
ctx.globalAlpha = alpha;
ctx.lineWidth = width;
ctx.lineJoin = 'round';
ctx.lineCap = 'round';
let penDown = false;
for (const pt of pts) {
if (pt === null) {
if (penDown) { ctx.stroke(); ctx.beginPath(); }
penDown = false;
} else {
const [px, py] = toP(pt.x, pt.y);
if (!penDown) { ctx.moveTo(px, py); penDown = true; }
else ctx.lineTo(px, py);
}
}
if (penDown) ctx.stroke();
ctx.globalAlpha = 1;
}
}
// ── Cursor crosshair + tooltip ────────────────────────────────
if (cur) {
const [cx, cy] = toP(cur.x, cur.y);
ctx.setLineDash([3, 5]);
ctx.strokeStyle = 'rgba(255,255,255,0.28)';
ctx.lineWidth = 1;
ctx.beginPath(); ctx.moveTo(cx, 0); ctx.lineTo(cx, H); ctx.stroke();
ctx.beginPath(); ctx.moveTo(0, cy); ctx.lineTo(W, cy); ctx.stroke();
ctx.setLineDash([]);
// Crosshair dot
ctx.fillStyle = 'rgba(255,255,255,0.75)';
ctx.beginPath(); ctx.arc(cx, cy, 3, 0, Math.PI * 2); ctx.fill();
// Function values at cursor x
type FnVal = { color: string; y: number; label: string };
const fnVals: FnVal[] = fns
.filter((f) => f.visible && f.expression.trim())
.map((f, i) => {
const y = evaluateAt(f.expression, cur.x, vars);
return isNaN(y) ? null : { color: f.color, y, label: `f${i + 1}(x)` };
})
.filter((v): v is FnVal => v !== null);
const coordLine = `x = ${cur.x.toFixed(3)} y = ${cur.y.toFixed(3)}`;
const lines: { text: string; color: string }[] = [
{ text: coordLine, color: 'rgba(200,200,215,0.85)' },
...fnVals.map((f) => ({
text: `${f.label} = ${f.y.toFixed(4)}`,
color: f.color,
})),
];
const lh = 15;
const pad = 9;
ctx.font = '10px monospace';
const maxW = Math.max(...lines.map((l) => ctx.measureText(l.text).width));
const bw = maxW + pad * 2;
const bh = lines.length * lh + pad * 2;
let bx = cx + 14;
let by = cy - bh / 2;
if (bx + bw > W - 4) bx = cx - bw - 14;
if (by < 4) by = 4;
if (by + bh > H - 4) by = H - bh - 4;
ctx.fillStyle = 'rgba(6, 6, 16, 0.92)';
ctx.strokeStyle = 'rgba(255,255,255,0.07)';
ctx.lineWidth = 1;
ctx.beginPath();
ctx.roundRect(bx, by, bw, bh, 5);
ctx.fill(); ctx.stroke();
lines.forEach((line, i) => {
ctx.fillStyle = line.color;
ctx.textAlign = 'left'; ctx.textBaseline = 'top';
ctx.fillText(line.text, bx + pad, by + pad + i * lh);
});
}
}, []);
const scheduleDraw = useCallback(() => {
if (rafRef.current) cancelAnimationFrame(rafRef.current);
rafRef.current = requestAnimationFrame(draw);
}, [draw]);
// Resize observer
useEffect(() => {
const canvas = canvasRef.current;
if (!canvas) return;
const obs = new ResizeObserver(scheduleDraw);
obs.observe(canvas);
scheduleDraw();
return () => obs.disconnect();
}, [scheduleDraw]);
// Redraw whenever reactive state changes
useEffect(() => { scheduleDraw(); }, [functions, variables, cursor, tick, scheduleDraw]);
// Convert mouse event to math coords
const toMath = useCallback((e: React.MouseEvent<HTMLCanvasElement>): [number, number] => {
const rect = canvasRef.current!.getBoundingClientRect();
const px = (e.clientX - rect.left) / rect.width;
const py = (e.clientY - rect.top) / rect.height;
const v = viewRef.current;
return [v.xMin + px * (v.xMax - v.xMin), v.yMax - py * (v.yMax - v.yMin)];
}, []);
const handleMouseDown = useCallback((e: React.MouseEvent<HTMLCanvasElement>) => {
dragRef.current = { startX: e.clientX, startY: e.clientY, startView: { ...viewRef.current } };
}, []);
const handleMouseMove = useCallback((e: React.MouseEvent<HTMLCanvasElement>) => {
const [mx, my] = toMath(e);
setCursor({ x: mx, y: my });
if (dragRef.current) {
const { startX, startY, startView: sv } = dragRef.current;
const rect = canvasRef.current!.getBoundingClientRect();
const dx = (e.clientX - startX) / rect.width * (sv.xMax - sv.xMin);
const dy = (e.clientY - startY) / rect.height * (sv.yMax - sv.yMin);
viewRef.current = {
xMin: sv.xMin - dx, xMax: sv.xMax - dx,
yMin: sv.yMin + dy, yMax: sv.yMax + dy,
};
redraw();
}
}, [toMath, redraw]);
const handleMouseUp = useCallback(() => { dragRef.current = null; }, []);
const handleMouseLeave = useCallback(() => { dragRef.current = null; setCursor(null); }, []);
const handleWheel = useCallback((e: WheelEvent) => {
e.preventDefault();
const rect = canvasRef.current!.getBoundingClientRect();
const px = (e.clientX - rect.left) / rect.width;
const py = (e.clientY - rect.top) / rect.height;
const v = viewRef.current;
const mx = v.xMin + px * (v.xMax - v.xMin);
const my = v.yMax - py * (v.yMax - v.yMin);
const factor = e.deltaY > 0 ? 1.12 : 1 / 1.12;
viewRef.current = {
xMin: mx - (mx - v.xMin) * factor,
xMax: mx + (v.xMax - mx) * factor,
yMin: my - (my - v.yMin) * factor,
yMax: my + (v.yMax - my) * factor,
};
redraw();
scheduleDraw();
}, [redraw, scheduleDraw]);
useEffect(() => {
const canvas = canvasRef.current;
if (!canvas) return;
canvas.addEventListener('wheel', handleWheel, { passive: false });
return () => canvas.removeEventListener('wheel', handleWheel);
}, [handleWheel]);
const resetView = useCallback(() => {
viewRef.current = DEFAULT_VIEW;
redraw();
scheduleDraw();
}, [redraw, scheduleDraw]);
return (
<div className="relative w-full h-full group">
<canvas
ref={canvasRef}
className="w-full h-full"
style={{ display: 'block', cursor: dragRef.current ? 'grabbing' : 'crosshair' }}
onMouseDown={handleMouseDown}
onMouseMove={handleMouseMove}
onMouseUp={handleMouseUp}
onMouseLeave={handleMouseLeave}
/>
<button
onClick={resetView}
className="absolute bottom-3 right-3 px-2.5 py-1 text-xs font-mono text-muted-foreground glass rounded-md opacity-0 group-hover:opacity-100 hover:text-foreground transition-all duration-200"
>
reset view
</button>
</div>
);
}