Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 | 4x 104x 115x 476x 69x 211x 114x 114x 1x 113x 113x 114x 114x 114x 114x 114x 114x 114x 114x 114x 114x 114x 114x 114x 114x 114x 179x 39x 39x 1x 1x 146x 50x 50x 1x 1x 114x 180x 180x 39x 39x 39x 3x 3x 39x 180x 180x 121x 121x 121x 121x 121x 121x 408x 3x 405x 88x 87x 87x 87x 87x 87x 87x 87x 87x 87x 423x 418x 96x 95x 95x 93x 93x 92x 92x 92x 92x 92x 233x 232x 232x 231x 231x 1x 230x 230x 230x 230x 85x 83x 83x 82x 82x 6x 6x 6x 83x 83x 3x 2x 2x 1x 104x 104x 28x 11x 11x 32x 31x 29x 28x 28x 11x 11x 28x 51x 50x 27x 24x 24x 24x 2x 1x 1x 1x 114x 112x 112x 112x 112x 112x 112x 38x 38x 38x 38x 38x 38x 38x 2x 2x 114x 114x 114x 114x 114x 1x 2x 1x 113x 113x 113x 75x 76x 29x 27x 12x 9x 9x 9x 9x 9x 22x 21x 21x 20x 14x 14x 6x 6x 20x 20x 11x 10x 10x 8x 6x 6x 2x 2x 8x 8x 63x 26x 25x 2x 23x 1x 22x 22x 1x 1x 22x 22x 23x 21x 21x 53x 51x 21x 20x 20x 22x 22x 22x 22x 8x 12x 8x 7x 24x 5x 3x 3x 3x 2x 2x 36x 35x 35x 35x 35x 36x 36x 36x 36x 36x 39x 39x 30x 33x 33x 29x 31x 31x 29x 319x 113x | /**
* The headless signature engine — pointer pipeline, canvas management
* (DPR backing store, ResizeObserver, `touch-action`), stroke building,
* incremental rendering, stroke-level history, and edge-only change
* notification. Framework-free and SSR-safe: nothing in this module
* touches `window`/`document`/canvas at import time; all environment
* access happens inside {@link createSignatureEngine} or later.
*/
import {
resolveOptions,
toFinite,
DEFAULT_PEN_COLOR,
type PNGExportOptions,
type SignatureData,
type SignatureOptions,
type SignaturePoint,
type SignaturePointerType,
type SignatureStroke,
type SVGExportOptions,
} from "../types";
import { passesMinDistance } from "../ink/filterPoints";
import {
createStrokeWalker,
type StrokeWalker,
type StrokeWalkerParams,
} from "../ink/strokeWalker";
import type { FlatStep } from "../ink/bezier";
import { isSafeCssColor, strokesToSVG } from "../ink/svg";
import { clearAndFill, drawSteps, replayStrokes } from "./render";
import { exportPNG } from "./png";
/** Maximum device-pixel-ratio used for backing-store sizing (SPEC §3.4). */
export const MAX_DPR = 2;
/** Options accepted by {@link createSignatureEngine}. */
export interface SignatureEngineOptions extends SignatureOptions {
/**
* Start with input detached (read-only display). Rendering, history,
* and restore (`fromJSON`) still work; pointer events and `ingest`
* are ignored.
* @default false
*/
readOnly?: boolean;
/**
* On-canvas underlay hook — invoked on every FULL redraw
* (construction, resize, undo/redo/clear/fromJSON replays) after the
* background fill and BEFORE the strokes, in CSS-px coordinates. This
* is the seam the React layer uses to draw the "sign here" guideline
* beneath the ink. **Excluded from PNG/SVG exports by construction** —
* the exporters replay strokes only, never this hook. The context is
* save/restore-wrapped and a throwing hook is isolated (logged).
*/
renderUnderlay?: (ctx: CanvasRenderingContext2D, width: number, height: number) => void;
}
/**
* One synthetic input sample for {@link SignatureEngine.ingest} — the
* jsdom-testable and replayable twin of a real pointer event. Real
* pointer events are normalized to exactly this shape and flow through
* the same internal path.
*/
export interface IngestSample {
type: "down" | "move" | "up" | "cancel";
/** CSS-pixel coords relative to the canvas box. */
x: number;
y: number;
/** ms timestamp (`performance.now()` domain). */
time: number;
/** Normalized pressure 0–1. @default 0 */
pressure?: number;
/** `"pen" | "touch" | "mouse"`; unknown values are treated as `"mouse"`. @default "mouse" */
pointerType?: string;
}
/**
* The headless signature engine (SPEC §4.3). Created by
* {@link createSignatureEngine}; owns all canvas plumbing.
*/
export interface SignatureEngine {
/** `true` while no committed strokes exist. Edge-notified via {@link onChange}. */
readonly isEmpty: boolean;
/** Number of committed strokes. */
readonly strokeCount: number;
/** Whether {@link undo} would do anything. */
readonly canUndo: boolean;
/** Whether {@link redo} would do anything. */
readonly canRedo: boolean;
/**
* Wipe all ink as a **single undoable action** — one {@link undo}
* restores every cleared stroke (SPEC §3.2). No-op on an empty pad.
*/
clear(): void;
/** Undo the last action (stroke add or clear). No-op when nothing to undo. */
undo(): void;
/** Redo the last undone action. Invalidated by any new stroke or clear. */
redo(): void;
/**
* Snapshot the signature as a versioned, replayable document (deep
* copy). **Committed strokes only** — an in-progress stroke is
* excluded until it commits (same semantics as {@link toPNG}/
* {@link toSVG}). Strokes are self-contained — each carries the width
* parameters captured at its start, so the document replays
* identically on any engine.
*/
toJSON(): SignatureData;
/**
* Replace the signature with `data`: drops any in-progress stroke,
* resets history, replays, and notifies. Tolerant of unknown extra
* fields and silently drops non-finite points; throws on a missing
* stroke array or an unsupported major version.
*
* `data.width`/`data.height` are **informational** (the capture-time
* canvas size): points replay at their stored CSS-px coordinates,
* anchored top-left, never scaled (SPEC resolved decision #5) —
* restoring into a smaller canvas clips the ink.
*/
fromJSON(data: SignatureData): void;
/**
* Export the **committed** strokes as a PNG `{ dataURL, blob }` —
* offscreen replay of the exact same geometry pipeline the canvas
* renders (an in-progress stroke is excluded: exporting mid-stroke is
* a race by definition). `trim` (default true) crops to the ink bbox
* + `padding` (default 8); `scale` defaults to the engine's
* devicePixelRatio; `background` defaults to the engine's option
* (transparent when unset). An empty pad resolves to a minimal 1×1
* transparent artifact — never rejects for emptiness.
*/
toPNG(opts?: PNGExportOptions): Promise<{ dataURL: string; blob: Blob }>;
/**
* Export the **committed** strokes as a standalone SVG string built
* from the same segment geometry as the canvas (see `strokesToSVG`).
* Same `trim`/`padding`/`background` semantics as {@link toPNG}.
*/
toSVG(opts?: SVGExportOptions): string;
/**
* Manually re-sync the backing store to the canvas's CSS size and
* redraw (the engine's own ResizeObserver covers the normal path).
* Strokes are preserved as-is: CSS-px coordinates, anchored top-left,
* never scaled (SPEC resolved decision #5).
*/
resize(): void;
/**
* Attach/detach the input pipeline. Detaching mid-stroke commits the
* in-progress stroke gracefully (like `pointercancel`). Everything
* except input keeps working while read-only.
*/
setReadOnly(readOnly: boolean): void;
/**
* Remove all listeners/observers and release subscriptions.
* Idempotent; every further *mutating* call is a no-op (pure reads —
* the live flags, `toJSON`, `toSVG`, `toPNG` — keep working on the
* frozen state). The last-rendered pixels are left on the canvas
* (visible ink must not blink out during teardown).
*/
destroy(): void;
/**
* Edge-only change subscription — fires once per committed state
* change (stroke end / undo / redo / clear / fromJSON), never per
* point. Returns an unsubscribe function.
*/
onChange(listener: (engine: SignatureEngine) => void): () => void;
/** Fires when a stroke begins (pointer down accepted). */
onBegin(listener: () => void): () => void;
/** Fires when a stroke ends (before the corresponding onChange). */
onEnd(listener: () => void): () => void;
/**
* Synthetic-input seam — testing & deterministic replay. Samples flow
* through the exact same pipeline as real pointer events (filtering,
* smoothing, width, incremental render, history, notifications).
* Ignored while read-only or destroyed.
*/
ingest(sample: IngestSample): void;
}
/** In-progress stroke state. */
interface ActiveStroke {
walker: StrokeWalker;
color: string;
/** Width-determining parameters captured at stroke start. */
params: StrokeWalkerParams;
/** Steps drawn so far — replayed on resize so live ink survives it. */
steps: FlatStep[];
}
type UndoEntry = { type: "add" } | { type: "clear"; strokes: SignatureStroke[] };
type RedoEntry = { type: "add"; stroke: SignatureStroke } | { type: "clear" };
function now(): number {
return typeof performance !== "undefined" ? performance.now() : Date.now();
}
function normalizePointerType(raw: string | undefined): SignaturePointerType {
return raw === "pen" || raw === "touch" || raw === "mouse" ? raw : "mouse";
}
function clamp01(value: number): number {
return Math.min(1, Math.max(0, value));
}
function copyStroke(stroke: SignatureStroke): SignatureStroke {
return {
points: stroke.points.map((p) => ({ ...p })),
color: stroke.color,
minWidth: stroke.minWidth,
maxWidth: stroke.maxWidth,
velocityFilterWeight: stroke.velocityFilterWeight,
pressure: stroke.pressure,
pointerType: stroke.pointerType,
};
}
/**
* Create a {@link SignatureEngine} bound to `canvas`.
*
* The engine owns everything about its canvas (confetti precedent, SPEC
* resolved decision #4): DPR-aware backing-store sizing (capped at ×2,
* `dpr` override), its own `ResizeObserver` (resize preserves strokes —
* redrawn at their CSS-px coordinates, anchored top-left, never scaled),
* `touch-action: none` (drawing must not scroll the page), and its own
* pointer listeners with `setPointerCapture` and a single-active-pointer
* policy (basic palm rejection).
*
* Must be called in a browser-like environment (needs a canvas with a 2D
* context); importing the module itself is SSR-safe.
*
* @throws If `canvas.getContext("2d")` returns `null`.
*
* @example
* ```ts
* import { createSignatureEngine } from "@usefy/signature-pad/headless";
*
* const engine = createSignatureEngine(canvas, { penColor: "#0f172a" });
* const off = engine.onChange((e) => console.log("empty?", e.isEmpty));
* // ...user signs...
* engine.undo();
* const draft = engine.toJSON();
* off();
* engine.destroy();
* ```
*/
export function createSignatureEngine(
canvas: HTMLCanvasElement,
options: SignatureEngineOptions = {},
): SignatureEngine {
const ctx = canvas.getContext("2d");
if (!ctx) {
throw new Error("@usefy/signature-pad: canvas.getContext('2d') returned null");
}
const opts = resolveOptions(options);
// Sanitized ONCE here and used for the live canvas AND as the export
// default — an unsafe background means "transparent" everywhere, so the
// screen and the exports can never disagree. (On canvas, an invalid
// fillStyle assignment is silently ignored and fillRect would paint
// with the previous — near-black — fill: an invisible signature.)
const background =
opts.background !== undefined && isSafeCssColor(opts.background)
? opts.background
: undefined;
// toFinite: a NaN devicePixelRatio must never produce a 0×0 or NaN-sized
// backing store (SPEC resolved decision #8).
const envDpr = typeof window !== "undefined" ? toFinite(window.devicePixelRatio, 1) : 1;
const baseDpr = Math.min(Math.max(envDpr > 0 ? envDpr : 1, 0.1), MAX_DPR);
const dpr = opts.dpr !== null ? Math.min(Math.max(opts.dpr, 0.1), MAX_DPR) : baseDpr;
/** Canvas CSS-pixel viewport. */
let viewWidth = 0;
let viewHeight = 0;
const strokes: SignatureStroke[] = [];
const undoStack: UndoEntry[] = [];
const redoStack: RedoEntry[] = [];
let active: ActiveStroke | null = null;
let activePointerId: number | null = null;
let readOnly = false;
let destroyed = false;
const changeListeners = new Set<(engine: SignatureEngine) => void>();
const beginListeners = new Set<() => void>();
const endListeners = new Set<() => void>();
/**
* Dispatch to a listener set: copied before iteration (listeners may
* (un)subscribe re-entrantly) and per-listener try/catch — a throwing
* consumer must never break the stroke pipeline or its co-listeners
* (confetti onActiveChange semantics).
*/
function dispatch(listeners: Set<() => void>): void {
for (const listener of [...listeners]) {
try {
listener();
} catch (error) {
Eif (typeof console !== "undefined") {
console.error("@usefy/signature-pad: listener threw", error);
}
}
}
}
function notifyChange(): void {
for (const listener of [...changeListeners]) {
try {
listener(engine);
} catch (error) {
Eif (typeof console !== "undefined") {
console.error("@usefy/signature-pad: onChange listener threw", error);
}
}
}
}
const renderUnderlay =
typeof options.renderUnderlay === "function" ? options.renderUnderlay : null;
/**
* Full deterministic replay: background, underlay (guideline layer —
* never part of exports), committed strokes, live stroke.
*/
function replayAll(): void {
clearAndFill(ctx!, viewWidth, viewHeight, background);
if (renderUnderlay) {
ctx!.save();
try {
renderUnderlay(ctx!, viewWidth, viewHeight);
} catch (error) {
Eif (typeof console !== "undefined") {
console.error("@usefy/signature-pad: renderUnderlay threw", error);
}
} finally {
ctx!.restore();
}
}
replayStrokes(ctx!, strokes);
if (active) drawSteps(ctx!, active.color, active.steps);
}
function resizeAndRedraw(): void {
viewWidth = canvas.clientWidth;
viewHeight = canvas.clientHeight;
canvas.width = Math.max(0, Math.round(viewWidth * dpr));
canvas.height = Math.max(0, Math.round(viewHeight * dpr));
// Setting width/height resets the context state — re-apply the DPR
// transform so all drawing happens in CSS pixels.
ctx!.setTransform(dpr, 0, 0, dpr, 0, 0);
replayAll();
}
/** Sanitize an ingest sample into a point, or null when unusable. */
function sanePoint(sample: IngestSample): SignaturePoint | null {
if (
!Number.isFinite(sample.x) ||
!Number.isFinite(sample.y) ||
!Number.isFinite(sample.time)
) {
return null;
}
return {
x: sample.x,
y: sample.y,
time: sample.time,
pressure: clamp01(toFinite(sample.pressure, 0)),
};
}
function commitActive(): void {
if (!active) return;
const tail = active.walker.finish();
drawSteps(ctx!, active.color, tail);
active.steps.push(...tail);
strokes.push({
points: [...active.walker.points],
color: active.color,
minWidth: active.params.minWidth,
maxWidth: active.params.maxWidth,
velocityFilterWeight: active.params.velocityFilterWeight,
pressure: active.params.pressure,
pointerType: active.params.pointerType,
});
active = null;
undoStack.push({ type: "add" });
redoStack.length = 0;
dispatch(endListeners);
notifyChange();
}
/**
* The single input path — real pointer events are normalized into
* {@link IngestSample}s and funneled through here, identically to
* public `ingest()` calls. Returns `true` when a `down` began a stroke.
*/
function ingestCore(sample: IngestSample): boolean {
if (destroyed || readOnly) return false;
switch (sample.type) {
case "down": {
if (active) return false; // single-active-pointer policy
const pointerType = normalizePointerType(sample.pointerType);
if (!opts.acceptPointerTypes.includes(pointerType)) return false;
const point = sanePoint(sample);
if (!point) return false;
const params: StrokeWalkerParams = {
minWidth: opts.minWidth,
maxWidth: opts.maxWidth,
velocityFilterWeight: opts.velocityFilterWeight,
pressure: opts.pressure,
pointerType,
};
active = {
walker: createStrokeWalker(params),
color: opts.penColor,
params,
steps: [],
};
active.walker.add(point);
dispatch(beginListeners);
return true;
}
case "move": {
if (!active) return false;
const point = sanePoint(sample);
if (!point) return false;
const points = active.walker.points;
// Same predicate as the batch filterPoints — live and replayed
// geometry must agree.
if (!passesMinDistance(points[points.length - 1], point, opts.minDistance)) {
return false;
}
const steps = active.walker.add(point);
drawSteps(ctx!, active.color, steps);
active.steps.push(...steps);
return false;
}
case "up": {
if (!active) return false;
const point = sanePoint(sample);
if (point) {
const points = active.walker.points;
if (passesMinDistance(points[points.length - 1], point, opts.minDistance)) {
const steps = active.walker.add(point);
drawSteps(ctx!, active.color, steps);
active.steps.push(...steps);
}
}
commitActive();
return false;
}
case "cancel": {
// Graceful end: the stroke is KEPT (SPEC §3.1) — the cancel
// event's coordinates are untrusted and never added.
if (!active) return false;
commitActive();
return false;
}
}
return false;
}
// ── Real pointer pipeline ──────────────────────────────────────────
function toSample(e: PointerEvent, type: IngestSample["type"]): IngestSample {
const rect = canvas.getBoundingClientRect();
return {
type,
x: e.clientX - rect.left,
y: e.clientY - rect.top,
// The EVENT's timestamp (performance.now() domain in modern
// browsers), not handler-run time: when the main thread janks and a
// burst of queued pointermoves dispatches in one tick, handler-time
// deltas collapse to ~0 → velocity 0 → the ink would snap toward
// maxWidth exactly while moving fastest. toFinite guards exotic
// environments with degenerate timeStamps.
time: toFinite(e.timeStamp, now()),
pressure: e.pressure,
pointerType: e.pointerType,
};
}
function releaseCapture(pointerId: number): void {
if (typeof canvas.releasePointerCapture === "function") {
try {
canvas.releasePointerCapture(pointerId);
} catch {
/* capture may already be gone */
}
}
}
function handlePointerDown(e: PointerEvent): void {
// Single active pointer: while one real pointer draws, all other
// pointers (e.g. a resting palm) are ignored entirely.
if (activePointerId !== null) return;
// Mouse strokes require the primary button — a right/middle click
// must neither ink a dot nor swallow the context menu. Pen/touch
// contact always reports button 0, so they are unaffected. The
// `ingest` seam stays button-less by design.
if (e.pointerType === "mouse" && e.button !== 0) return;
if (!ingestCore(toSample(e, "down"))) return;
activePointerId = e.pointerId;
if (typeof canvas.setPointerCapture === "function") {
try {
canvas.setPointerCapture(e.pointerId);
} catch {
/* jsdom / detached canvas — capture is best-effort */
}
}
Eif (typeof e.preventDefault === "function") e.preventDefault();
}
function handlePointerMove(e: PointerEvent): void {
if (activePointerId === null || e.pointerId !== activePointerId) return;
ingestCore(toSample(e, "move"));
}
function handlePointerUp(e: PointerEvent): void {
if (activePointerId === null || e.pointerId !== activePointerId) return;
activePointerId = null;
releaseCapture(e.pointerId);
ingestCore(toSample(e, "up"));
}
function handlePointerCancel(e: PointerEvent): void {
if (activePointerId === null || e.pointerId !== activePointerId) return;
activePointerId = null;
releaseCapture(e.pointerId);
ingestCore(toSample(e, "cancel"));
}
let inputAttached = false;
function attachInput(): void {
Iif (inputAttached) return;
canvas.addEventListener("pointerdown", handlePointerDown);
canvas.addEventListener("pointermove", handlePointerMove);
canvas.addEventListener("pointerup", handlePointerUp);
canvas.addEventListener("pointercancel", handlePointerCancel);
inputAttached = true;
}
function detachInput(): void {
Iif (!inputAttached) return;
canvas.removeEventListener("pointerdown", handlePointerDown);
canvas.removeEventListener("pointermove", handlePointerMove);
canvas.removeEventListener("pointerup", handlePointerUp);
canvas.removeEventListener("pointercancel", handlePointerCancel);
inputAttached = false;
// Release the physical pointer too: a mid-stroke setReadOnly/destroy/
// fromJSON must not leave the canvas holding pointer capture.
if (activePointerId !== null) {
releaseCapture(activePointerId);
activePointerId = null;
}
}
// ── Construction ───────────────────────────────────────────────────
// `|| ""` — jsdom may report an unset touch-action as undefined; the
// restore in destroy() must write a string either way.
const prevTouchAction = canvas.style.touchAction || "";
canvas.style.touchAction = "none";
resizeAndRedraw();
let resizeObserver: ResizeObserver | null = null;
if (typeof ResizeObserver !== "undefined") {
resizeObserver = new ResizeObserver(() => {
if (!destroyed) resizeAndRedraw();
});
resizeObserver.observe(canvas);
}
readOnly = options.readOnly === true;
if (!readOnly) attachInput();
const engine: SignatureEngine = {
get isEmpty(): boolean {
return strokes.length === 0;
},
get strokeCount(): number {
return strokes.length;
},
get canUndo(): boolean {
return undoStack.length > 0;
},
get canRedo(): boolean {
return redoStack.length > 0;
},
clear(): void {
if (destroyed || strokes.length === 0) return;
// A single undoable action — undo restores every stroke (SPEC §3.2).
undoStack.push({ type: "clear", strokes: strokes.slice() });
strokes.length = 0;
redoStack.length = 0;
replayAll();
notifyChange();
},
undo(): void {
if (destroyed) return;
const entry = undoStack.pop();
if (!entry) return;
if (entry.type === "add") {
const stroke = strokes.pop()!;
redoStack.push({ type: "add", stroke });
} else {
// Undoing a clear: all post-clear adds are necessarily already
// undone (stack order), so the pad is exactly as the clear left
// it — restore the removed strokes wholesale.
strokes.push(...entry.strokes);
redoStack.push({ type: "clear" });
}
replayAll();
notifyChange();
},
redo(): void {
if (destroyed) return;
const entry = redoStack.pop();
if (!entry) return;
if (entry.type === "add") {
strokes.push(entry.stroke);
undoStack.push({ type: "add" });
} else {
undoStack.push({ type: "clear", strokes: strokes.slice() });
strokes.length = 0;
}
replayAll();
notifyChange();
},
toJSON(): SignatureData {
return {
v: 1,
width: viewWidth,
height: viewHeight,
strokes: strokes.map(copyStroke),
};
},
fromJSON(data: SignatureData): void {
if (destroyed) return;
if (typeof data !== "object" || data === null || !Array.isArray(data.strokes)) {
throw new TypeError("@usefy/signature-pad: fromJSON: invalid SignatureData");
}
if (data.v !== 1) {
throw new Error(
`@usefy/signature-pad: fromJSON: unsupported version ${String((data as { v: unknown }).v)}`,
);
}
// Replaces the document wholesale: any in-progress stroke is
// dropped and history is reset (fromJSON itself is not undoable).
active = null;
if (activePointerId !== null) {
releaseCapture(activePointerId);
activePointerId = null;
}
strokes.length = 0;
for (const raw of data.strokes) {
if (typeof raw !== "object" || raw === null || !Array.isArray(raw.points)) continue;
const points: SignaturePoint[] = [];
for (const p of raw.points) {
if (
typeof p === "object" &&
p !== null &&
Number.isFinite(p.x) &&
Number.isFinite(p.y) &&
Number.isFinite(p.time)
) {
points.push({
x: p.x,
y: p.y,
time: p.time,
pressure: clamp01(toFinite(p.pressure, 0)),
});
}
}
if (points.length === 0) continue;
const minWidth = Math.max(0, toFinite(raw.minWidth, opts.minWidth));
strokes.push({
points,
color: typeof raw.color === "string" ? raw.color : DEFAULT_PEN_COLOR,
minWidth,
maxWidth: Math.max(minWidth, toFinite(raw.maxWidth, opts.maxWidth)),
// Self-contained stroke params (SPEC §4.1): stored values drive
// replay; the engine's own options are only the fallback for
// documents missing/corrupting them.
velocityFilterWeight: clamp01(
toFinite(raw.velocityFilterWeight, opts.velocityFilterWeight),
),
pressure:
raw.pressure === "auto" || raw.pressure === "ignore" ? raw.pressure : opts.pressure,
pointerType: normalizePointerType(raw.pointerType),
});
}
undoStack.length = 0;
redoStack.length = 0;
replayAll();
notifyChange();
},
toPNG(exportOpts: PNGExportOptions = {}): Promise<{ dataURL: string; blob: Blob }> {
return exportPNG(
{
ownerDocument: canvas.ownerDocument,
strokes,
viewWidth,
viewHeight,
defaultBackground: background,
defaultScale: dpr,
},
exportOpts,
);
},
toSVG(exportOpts: SVGExportOptions = {}): string {
return strokesToSVG(
{ v: 1, width: viewWidth, height: viewHeight, strokes },
{
...exportOpts,
background:
exportOpts.background !== undefined ? exportOpts.background : background,
},
);
},
resize(): void {
if (destroyed) return;
resizeAndRedraw();
},
setReadOnly(next: boolean): void {
if (destroyed || next === readOnly) return;
if (next) {
// Commit any in-progress stroke gracefully (like pointercancel)
// BEFORE flipping the flag — commit notifications still fire.
commitActive();
readOnly = true;
detachInput();
} else {
readOnly = false;
attachInput();
}
},
destroy(): void {
if (destroyed) return;
destroyed = true;
// The in-progress stroke (if any) is dropped without notifications —
// nothing may fire after destroy. Last-rendered pixels stay visible.
active = null;
detachInput();
resizeObserver?.disconnect();
resizeObserver = null;
changeListeners.clear();
beginListeners.clear();
endListeners.clear();
canvas.style.touchAction = prevTouchAction;
},
onChange(listener: (engine: SignatureEngine) => void): () => void {
changeListeners.add(listener);
return () => {
changeListeners.delete(listener);
};
},
onBegin(listener: () => void): () => void {
beginListeners.add(listener);
return () => {
beginListeners.delete(listener);
};
},
onEnd(listener: () => void): () => void {
endListeners.add(listener);
return () => {
endListeners.delete(listener);
};
},
ingest(sample: IngestSample): void {
ingestCore(sample);
},
};
return engine;
}
|