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dist/contact-sheet.js
31 KB · Oct 5, 2026 · 18:37 UTC
import { createHash, randomBytes } from "node:crypto";
import { constants } from "node:fs";
import { lstat, mkdir, open, realpath, rename, rm, stat } from "node:fs/promises";
import path from "node:path";
import { PNG } from "pngjs";
import { assertSafePlatformPath, isPathWithinRoot } from "./platform.js";
export const GAME_BOY_FRAME_WIDTH = 160;
export const GAME_BOY_FRAME_HEIGHT = 144;
export const MAX_CONTACT_SHEET_FRAMES = 64;
export const MAX_CONTACT_SHEET_MAGNIFICATION = 6;
export const MAX_CONTACT_SHEET_FRAME_BYTES = 2 * 1024 * 1024;
export const MAX_CONTACT_SHEET_LABEL_LENGTH = 160;
export const MAX_CONTACT_SHEET_PNG_BYTES = 8 * 1024 * 1024;
const MAX_CANVAS_DIMENSION = 8_192;
const MAX_CANVAS_PIXELS = 32_000_000;
const GUTTER = 12;
const PADDING = 8;
const FONT_WIDTH = 5;
const FONT_HEIGHT = 7;
const PNG_SIGNATURE = Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]);
const CANVAS_COLOR = [13, 17, 23, 255];
const CARD_COLOR = [22, 27, 34, 255];
const BORDER_COLOR = [48, 54, 61, 255];
const PRIMARY_TEXT = [230, 237, 243, 255];
const SECONDARY_TEXT = [139, 148, 158, 255];
const FRAME_ACCENT = [88, 166, 255, 255];
const CHANGE_ACCENT = [255, 184, 76, 255];
/** Compact, dependency-free 5-by-7 glyphs stored as seven five-bit rows. */
const GLYPHS = {
" ": [0, 0, 0, 0, 0, 0, 0],
"!": [4, 4, 4, 4, 4, 0, 4],
'"': [10, 10, 10, 0, 0, 0, 0],
"#": [10, 10, 31, 10, 31, 10, 10],
"$": [4, 15, 20, 14, 5, 30, 4],
"%": [24, 25, 2, 4, 8, 19, 3],
"&": [12, 18, 20, 8, 21, 18, 13],
"'": [4, 4, 8, 0, 0, 0, 0],
"(": [2, 4, 8, 8, 8, 4, 2],
")": [8, 4, 2, 2, 2, 4, 8],
"*": [0, 4, 21, 14, 21, 4, 0],
"+": [0, 4, 4, 31, 4, 4, 0],
",": [0, 0, 0, 0, 4, 4, 8],
"-": [0, 0, 0, 31, 0, 0, 0],
".": [0, 0, 0, 0, 0, 12, 12],
"/": [1, 2, 4, 8, 16, 0, 0],
"0": [14, 17, 19, 21, 25, 17, 14],
"1": [4, 12, 4, 4, 4, 4, 14],
"2": [14, 17, 1, 2, 4, 8, 31],
"3": [30, 1, 1, 14, 1, 1, 30],
"4": [2, 6, 10, 18, 31, 2, 2],
"5": [31, 16, 30, 1, 1, 17, 14],
"6": [6, 8, 16, 30, 17, 17, 14],
"7": [31, 1, 2, 4, 8, 8, 8],
"8": [14, 17, 17, 14, 17, 17, 14],
"9": [14, 17, 17, 15, 1, 2, 12],
":": [0, 12, 12, 0, 12, 12, 0],
";": [0, 12, 12, 0, 12, 12, 8],
"<": [2, 4, 8, 16, 8, 4, 2],
"=": [0, 0, 31, 0, 31, 0, 0],
">": [8, 4, 2, 1, 2, 4, 8],
"?": [14, 17, 1, 2, 4, 0, 4],
"@": [14, 17, 23, 21, 23, 16, 14],
A: [14, 17, 17, 31, 17, 17, 17],
B: [30, 17, 17, 30, 17, 17, 30],
C: [14, 17, 16, 16, 16, 17, 14],
D: [30, 17, 17, 17, 17, 17, 30],
E: [31, 16, 16, 30, 16, 16, 31],
F: [31, 16, 16, 30, 16, 16, 16],
G: [14, 17, 16, 23, 17, 17, 15],
H: [17, 17, 17, 31, 17, 17, 17],
I: [14, 4, 4, 4, 4, 4, 14],
J: [7, 2, 2, 2, 2, 18, 12],
K: [17, 18, 20, 24, 20, 18, 17],
L: [16, 16, 16, 16, 16, 16, 31],
M: [17, 27, 21, 21, 17, 17, 17],
N: [17, 25, 21, 19, 17, 17, 17],
O: [14, 17, 17, 17, 17, 17, 14],
P: [30, 17, 17, 30, 16, 16, 16],
Q: [14, 17, 17, 17, 21, 18, 13],
R: [30, 17, 17, 30, 20, 18, 17],
S: [15, 16, 16, 14, 1, 1, 30],
T: [31, 4, 4, 4, 4, 4, 4],
U: [17, 17, 17, 17, 17, 17, 14],
V: [17, 17, 17, 17, 17, 10, 4],
W: [17, 17, 17, 21, 21, 21, 10],
X: [17, 17, 10, 4, 10, 17, 17],
Y: [17, 17, 10, 4, 4, 4, 4],
Z: [31, 1, 2, 4, 8, 16, 31],
"[": [14, 8, 8, 8, 8, 8, 14],
"\\": [16, 8, 4, 2, 1, 0, 0],
"]": [14, 2, 2, 2, 2, 2, 14],
"^": [4, 10, 17, 0, 0, 0, 0],
_: [0, 0, 0, 0, 0, 0, 31],
"`": [8, 4, 0, 0, 0, 0, 0],
"{": [2, 4, 4, 8, 4, 4, 2],
"|": [4, 4, 4, 4, 4, 4, 4],
"}": [8, 4, 4, 2, 4, 4, 8],
"~": [0, 0, 9, 22, 0, 0, 0],
};
export class ContactSheetError extends Error {
constructor(message, options) {
super(message, options);
this.name = "ContactSheetError";
}
}
function pathsMatch(left, right, platform) {
if (platform !== "win32")
return left === right;
return path.win32.normalize(left).toLowerCase() === path.win32.normalize(right).toLowerCase();
}
function ensureInsideRoot(root, candidate, platform) {
if (!isPathWithinRoot(root, candidate, platform)) {
throw new ContactSheetError(`The contact-sheet path must remain inside the project root: ${candidate}`);
}
}
function assertSafeContactSheetPath(value, platform, label, rejectNetworkPath = false) {
if (platform !== "win32")
return;
try {
if (rejectNetworkPath && /^[\\/]{2}/u.test(value)) {
throw new TypeError("Untrusted UNC contact-sheet paths are not permitted.");
}
assertSafePlatformPath(value, platform);
}
catch (error) {
throw new ContactSheetError(`The contact-sheet ${label} contains an unsafe Windows path: ${value}`, {
cause: error,
});
}
}
async function verifyWindowsPath(root, candidate, platform, expectedLeaf) {
if (platform !== "win32")
return;
assertSafeContactSheetPath(candidate, platform, expectedLeaf);
ensureInsideRoot(root, candidate, platform);
const relative = path.relative(root, candidate);
const components = relative.length === 0 ? [] : relative.split(path.sep);
let current = root;
for (let index = -1; index < components.length; index += 1) {
if (index >= 0)
current = path.join(current, components[index]);
const metadata = await lstat(current);
const leaf = index === components.length - 1;
if (metadata.isSymbolicLink() ||
(leaf && expectedLeaf === "file" ? !metadata.isFile() : !metadata.isDirectory()) ||
!pathsMatch(await realpath(current), current, platform) ||
!isPathWithinRoot(root, current, platform)) {
throw new ContactSheetError(`Refusing an unsafe contact-sheet reparse point or path: ${current}`);
}
}
}
function validateLabel(value, field) {
if (typeof value !== "string" ||
value.length > MAX_CONTACT_SHEET_LABEL_LENGTH ||
/[\u0000-\u001f\u007f]/u.test(value)) {
throw new ContactSheetError(`The contact-sheet ${field} must be a string of at most ${MAX_CONTACT_SHEET_LABEL_LENGTH} printable characters`);
}
}
function validateFrame(frame, index) {
if (typeof frame !== "object" || frame === null || Array.isArray(frame)) {
throw new ContactSheetError(`Contact-sheet frame ${index + 1} must be an object`);
}
if (typeof frame.path !== "string" || frame.path.trim().length === 0) {
throw new ContactSheetError(`Contact-sheet frame ${index + 1} requires a non-empty PNG path`);
}
if (frame.frame !== undefined && (!Number.isSafeInteger(frame.frame) || frame.frame < 0)) {
throw new ContactSheetError(`Contact-sheet frame ${index + 1} has an invalid frame number`);
}
if (frame.sha256 !== undefined && !/^[a-f\d]{64}$/u.test(frame.sha256)) {
throw new ContactSheetError(`Contact-sheet frame ${index + 1} has an invalid SHA-256 digest`);
}
if (frame.caption !== undefined)
validateLabel(frame.caption, "caption");
if (typeof frame.input === "string") {
validateLabel(frame.input, "input");
}
else if (Array.isArray(frame.input)) {
if (frame.input.length > 8) {
throw new ContactSheetError("A contact-sheet frame may contain at most eight input labels");
}
for (const input of frame.input)
validateLabel(input, "input");
}
else if (frame.input !== undefined) {
throw new ContactSheetError("A contact-sheet input label must be a string or an array of strings");
}
}
async function existingAncestor(candidate) {
let ancestor = candidate;
while (true) {
try {
await lstat(ancestor);
return ancestor;
}
catch (error) {
if (!(error instanceof Error) || !("code" in error) || error.code !== "ENOENT")
throw error;
const parent = path.dirname(ancestor);
if (parent === ancestor) {
throw new ContactSheetError(`The contact-sheet output has no accessible parent: ${candidate}`);
}
ancestor = parent;
}
}
}
async function resolveOutput(root, requestedRoot, outputPath, platform) {
if (typeof outputPath !== "string" || outputPath.trim().length === 0) {
throw new ContactSheetError("The contact-sheet output path must be a non-empty string");
}
assertSafeContactSheetPath(outputPath, platform, "output", true);
if (path.extname(outputPath).toLowerCase() !== ".png") {
throw new ContactSheetError("The contact-sheet output path must use the .png extension");
}
const candidate = path.resolve(requestedRoot, outputPath);
assertSafeContactSheetPath(candidate, platform, "output");
if (!isPathWithinRoot(requestedRoot, candidate, platform) && !isPathWithinRoot(root, candidate, platform)) {
ensureInsideRoot(root, candidate, platform);
}
const parent = path.dirname(candidate);
const ancestor = await existingAncestor(parent);
const canonicalAncestor = await realpath(ancestor);
ensureInsideRoot(root, canonicalAncestor, platform);
await verifyWindowsPath(root, canonicalAncestor, platform, "directory");
if (platform === "win32" && !pathsMatch(canonicalAncestor, ancestor, platform)) {
throw new ContactSheetError(`Refusing an unsafe contact-sheet reparse point or path: ${ancestor}`);
}
await mkdir(parent, { recursive: true });
const canonicalParent = await realpath(parent);
ensureInsideRoot(root, canonicalParent, platform);
await verifyWindowsPath(root, canonicalParent, platform, "directory");
if (platform === "win32" && !pathsMatch(canonicalParent, parent, platform)) {
throw new ContactSheetError(`Refusing an unsafe contact-sheet reparse point or path: ${parent}`);
}
const destination = path.join(canonicalParent, path.basename(candidate));
assertSafeContactSheetPath(destination, platform, "output");
try {
const info = await lstat(destination);
if (info.isSymbolicLink() || !info.isFile()) {
throw new ContactSheetError(`Refusing to overwrite an unsafe contact-sheet output: ${destination}`);
}
if (platform === "win32" && !pathsMatch(await realpath(destination), destination, platform)) {
throw new ContactSheetError(`Refusing to overwrite an unsafe contact-sheet output: ${destination}`);
}
}
catch (error) {
if (!(error instanceof Error) || !("code" in error) || error.code !== "ENOENT")
throw error;
}
return destination;
}
async function loadFrame(root, requestedRoot, frame, platform) {
assertSafeContactSheetPath(frame.path, platform, "frame", true);
const candidate = path.resolve(requestedRoot, frame.path);
assertSafeContactSheetPath(candidate, platform, "frame");
if (!isPathWithinRoot(requestedRoot, candidate, platform) && !isPathWithinRoot(root, candidate, platform)) {
ensureInsideRoot(root, candidate, platform);
}
let canonical;
try {
canonical = await realpath(candidate);
}
catch (error) {
throw new ContactSheetError(`The contact-sheet frame does not exist: ${frame.path}`, { cause: error });
}
ensureInsideRoot(root, canonical, platform);
if (platform === "win32" && !pathsMatch(canonical, candidate, platform)) {
throw new ContactSheetError(`Refusing an unsafe contact-sheet reparse point or path: ${frame.path}`);
}
await verifyWindowsPath(root, canonical, platform, "file");
if (path.extname(canonical).toLowerCase() !== ".png") {
throw new ContactSheetError(`Contact-sheet frames must be PNG files: ${frame.path}`);
}
let bytes;
try {
const noFollow = platform === "win32" ? 0 : (constants.O_NOFOLLOW ?? 0);
const handle = await open(canonical, constants.O_RDONLY | noFollow);
try {
const info = await handle.stat();
const openedPath = await realpath(canonical);
const named = await lstat(openedPath);
if (!pathsMatch(openedPath, canonical, platform) ||
!isPathWithinRoot(root, openedPath, platform) ||
named.isSymbolicLink() ||
!named.isFile() ||
info.dev !== named.dev ||
info.ino !== named.ino) {
throw new ContactSheetError(`The contact-sheet frame could not be safely read: ${frame.path}`);
}
if (!info.isFile()) {
throw new ContactSheetError(`The contact-sheet frame is not a regular file: ${frame.path}`);
}
if (info.size > MAX_CONTACT_SHEET_FRAME_BYTES) {
throw new ContactSheetError(`The contact-sheet frame exceeds the ${MAX_CONTACT_SHEET_FRAME_BYTES}-byte safety limit: ${frame.path}`);
}
bytes = await handle.readFile();
}
finally {
await handle.close();
}
}
catch (error) {
if (error instanceof ContactSheetError)
throw error;
throw new ContactSheetError(`The contact-sheet frame could not be safely read: ${frame.path}`, { cause: error });
}
if (bytes.length > MAX_CONTACT_SHEET_FRAME_BYTES) {
throw new ContactSheetError(`The contact-sheet frame exceeds the ${MAX_CONTACT_SHEET_FRAME_BYTES}-byte safety limit`);
}
if (bytes.length < 33 || !bytes.subarray(0, PNG_SIGNATURE.length).equals(PNG_SIGNATURE)) {
throw new ContactSheetError(`The contact-sheet frame is not a valid PNG: ${frame.path}`);
}
if (bytes.readUInt32BE(8) !== 13 ||
bytes.toString("ascii", 12, 16) !== "IHDR" ||
bytes.readUInt32BE(16) !== GAME_BOY_FRAME_WIDTH ||
bytes.readUInt32BE(20) !== GAME_BOY_FRAME_HEIGHT) {
throw new ContactSheetError(`Contact-sheet frames must be genuine ${GAME_BOY_FRAME_WIDTH}x${GAME_BOY_FRAME_HEIGHT} Game Boy PNG captures: ${frame.path}`);
}
let image;
try {
image = PNG.sync.read(bytes, { checkCRC: true });
}
catch (error) {
throw new ContactSheetError(`The contact-sheet frame is not a valid PNG: ${frame.path}`, { cause: error });
}
const sha256 = createHash("sha256").update(bytes).digest("hex");
if (frame.sha256 !== undefined && frame.sha256 !== sha256) {
throw new ContactSheetError(`The contact-sheet frame SHA-256 does not match its genuine PNG bytes: ${frame.path}`);
}
return {
metadata: {
path: canonical,
sha256,
...(frame.frame === undefined ? {} : { frame: frame.frame }),
...(frame.input === undefined ? {} : { input: Array.isArray(frame.input) ? [...frame.input] : frame.input }),
...(frame.caption === undefined ? {} : { caption: frame.caption }),
},
image,
};
}
function fillRectangle(image, x, y, width, height, color) {
for (let row = y; row < y + height; row += 1) {
for (let column = x; column < x + width; column += 1) {
const offset = (image.width * row + column) * 4;
image.data[offset] = color[0];
image.data[offset + 1] = color[1];
image.data[offset + 2] = color[2];
image.data[offset + 3] = color[3];
}
}
}
function drawText(image, x, y, text, maxWidth, color, scale) {
const advance = (FONT_WIDTH + 1) * scale;
const maxCharacters = Math.max(0, Math.floor((maxWidth + scale) / advance));
const normalized = text.toUpperCase().normalize("NFKD").replace(/[\u0300-\u036f]/gu, "");
const clipped = normalized.length > maxCharacters && maxCharacters > 3
? `${normalized.slice(0, maxCharacters - 3)}...`
: normalized.slice(0, maxCharacters);
for (let index = 0; index < clipped.length; index += 1) {
const glyph = GLYPHS[clipped[index] ?? "?"] ?? GLYPHS["?"];
for (let row = 0; row < FONT_HEIGHT; row += 1) {
const bits = glyph[row] ?? 0;
for (let column = 0; column < FONT_WIDTH; column += 1) {
if ((bits & (1 << (FONT_WIDTH - column - 1))) !== 0) {
fillRectangle(image, x + index * advance + column * scale, y + row * scale, scale, scale, color);
}
}
}
}
return normalized.length > maxCharacters;
}
function compositeFrame(canvas, source, previous, left, top, magnification, highlightChanges) {
let changedPixels = 0;
for (let sourceY = 0; sourceY < source.height; sourceY += 1) {
for (let sourceX = 0; sourceX < source.width; sourceX += 1) {
const offset = (source.width * sourceY + sourceX) * 4;
const changed = previous !== undefined && (source.data[offset] !== previous.data[offset] ||
source.data[offset + 1] !== previous.data[offset + 1] ||
source.data[offset + 2] !== previous.data[offset + 2] ||
source.data[offset + 3] !== previous.data[offset + 3]);
if (changed)
changedPixels += 1;
const alpha = (source.data[offset + 3] ?? 255) / 255;
const red = Math.round((source.data[offset] ?? 0) * alpha + CARD_COLOR[0] * (1 - alpha));
const green = Math.round((source.data[offset + 1] ?? 0) * alpha + CARD_COLOR[1] * (1 - alpha));
const blue = Math.round((source.data[offset + 2] ?? 0) * alpha + CARD_COLOR[2] * (1 - alpha));
const color = changed && highlightChanges
? [Math.round(red * 0.45 + CHANGE_ACCENT[0] * 0.55), Math.round(green * 0.45 + CHANGE_ACCENT[1] * 0.55), Math.round(blue * 0.45 + CHANGE_ACCENT[2] * 0.55), 255]
: [red, green, blue, 255];
fillRectangle(canvas, left + sourceX * magnification, top + sourceY * magnification, magnification, magnification, color);
}
}
return changedPixels;
}
/**
* Compose existing PNG bytes only: no filesystem access, capture, worker call,
* sampling, or provenance inference. Callers retain their original metadata.
* Variable dimensions support authored scene projections without rescaling or
* cropping them to a fabricated Game Boy framebuffer.
*/
export function renderContactSheetPng(options) {
options.signal?.throwIfAborted();
if (!Array.isArray(options.images) || options.images.length < 1 || options.images.length > MAX_CONTACT_SHEET_FRAMES) {
throw new ContactSheetError(`Contact sheets require between 1 and ${MAX_CONTACT_SHEET_FRAMES} images`);
}
validateLabel(options.title, "title");
validateLabel(options.subtitle, "subtitle");
const magnification = options.magnification ?? 2;
const columns = options.columns ?? Math.min(3, options.images.length);
if (!Number.isSafeInteger(magnification) || magnification < 1 || magnification > MAX_CONTACT_SHEET_MAGNIFICATION) {
throw new ContactSheetError(`Contact-sheet magnification must be an integer between 1 and ${MAX_CONTACT_SHEET_MAGNIFICATION}`);
}
if (!Number.isSafeInteger(columns) || columns < 1 || columns > MAX_CONTACT_SHEET_FRAMES) {
throw new ContactSheetError(`Contact-sheet columns must be an integer between 1 and ${MAX_CONTACT_SHEET_FRAMES}`);
}
let totalPixels = 0;
const dimensions = Array.from(options.images, (entry) => {
options.signal?.throwIfAborted();
if (typeof entry !== "object" || entry === null)
throw new ContactSheetError("Each contact-sheet image must contain PNG bytes and labels");
validateLabel(entry.label, "label");
validateLabel(entry.caption, "caption");
const bytes = entry.png;
if (!Buffer.isBuffer(bytes) || bytes.length < 33 || bytes.length > MAX_CONTACT_SHEET_FRAME_BYTES ||
!bytes.subarray(0, PNG_SIGNATURE.length).equals(PNG_SIGNATURE) ||
bytes.readUInt32BE(8) !== 13 || bytes.toString("ascii", 12, 16) !== "IHDR") {
throw new ContactSheetError("Contact-sheet images must be bounded PNG bytes");
}
if (typeof entry.sha256 !== "string" || !/^[a-f\d]{64}$/u.test(entry.sha256) || createHash("sha256").update(bytes).digest("hex") !== entry.sha256) {
throw new ContactSheetError("The contact-sheet image SHA-256 does not match its PNG bytes");
}
const width = bytes.readUInt32BE(16);
const height = bytes.readUInt32BE(20);
totalPixels += width * height;
if (width < 1 || height < 1 || width > MAX_CANVAS_DIMENSION || height > MAX_CANVAS_DIMENSION ||
totalPixels > MAX_CANVAS_PIXELS) {
throw new ContactSheetError("The contact-sheet input dimensions exceed the safe pixel budget");
}
return { width, height };
});
const rows = Math.ceil(options.images.length / columns);
const fontScale = magnification >= 3 ? 2 : 1;
const lineHeight = (FONT_HEIGHT + 3) * fontScale;
const imageWidth = Math.max(GAME_BOY_FRAME_WIDTH, ...dimensions.map((entry) => entry.width)) * magnification;
const imageHeight = Math.max(...dimensions.map((entry) => entry.height)) * magnification;
const cardWidth = imageWidth + PADDING * 2;
const cardHeight = imageHeight + PADDING * 3 + lineHeight * 2;
const headerHeight = PADDING + lineHeight * 2;
const width = GUTTER + columns * (cardWidth + GUTTER);
const height = headerHeight + GUTTER + rows * (cardHeight + GUTTER);
if (width > MAX_CANVAS_DIMENSION || height > MAX_CANVAS_DIMENSION || width * height > MAX_CANVAS_PIXELS) {
throw new ContactSheetError("The contact-sheet dimensions exceed the maximum safe canvas size");
}
// All dimensions and aggregate allocation bounds are checked before decoding.
const images = options.images.map(({ png }) => {
options.signal?.throwIfAborted();
try {
return PNG.sync.read(png, { checkCRC: true });
}
catch (error) {
throw new ContactSheetError("The contact-sheet image is not a valid PNG", { cause: error });
}
});
const canvas = new PNG({ width, height });
fillRectangle(canvas, 0, 0, width, height, CANVAS_COLOR);
const headerClipped = [
drawText(canvas, GUTTER, PADDING, options.title, width - GUTTER * 2, PRIMARY_TEXT, fontScale),
drawText(canvas, GUTTER, PADDING + lineHeight, options.subtitle, width - GUTTER * 2, SECONDARY_TEXT, fontScale),
];
const tiles = images.map((image, index) => {
options.signal?.throwIfAborted();
const entry = options.images[index];
const cardX = GUTTER + (index % columns) * (cardWidth + GUTTER);
const cardY = headerHeight + GUTTER + Math.floor(index / columns) * (cardHeight + GUTTER);
const x = cardX + PADDING;
const y = cardY + PADDING;
fillRectangle(canvas, cardX, cardY, cardWidth, cardHeight, BORDER_COLOR);
fillRectangle(canvas, cardX + 1, cardY + 1, cardWidth - 2, cardHeight - 2, CARD_COLOR);
compositeFrame(canvas, image, undefined, x, y, magnification, false);
const labelY = y + imageHeight + PADDING;
const labelsClipped = [
drawText(canvas, x, labelY, entry.label, imageWidth, FRAME_ACCENT, fontScale),
drawText(canvas, x, labelY + lineHeight, entry.caption, imageWidth, PRIMARY_TEXT, fontScale),
];
return {
index, sha256: entry.sha256, sourceWidth: image.width, sourceHeight: image.height,
x, y, width: image.width * magnification, height: image.height * magnification,
label: entry.label, caption: entry.caption, labelsClipped,
};
});
const png = PNG.sync.write(canvas, { colorType: 6, inputColorType: 6, inputHasAlpha: true });
options.signal?.throwIfAborted();
if (png.length > MAX_CONTACT_SHEET_PNG_BYTES)
throw new ContactSheetError("The contact-sheet PNG exceeds its byte limit");
return {
png, sha256: createHash("sha256").update(png).digest("hex"), width, height, columns, rows, magnification,
imageCount: images.length, title: options.title, subtitle: options.subtitle, headerClipped, tiles,
};
}
async function writeAtomic(root, destination, bytes, platform) {
const temporary = path.join(path.dirname(destination), `.${path.basename(destination)}.${process.pid}.${randomBytes(8).toString("hex")}.tmp`);
let handle;
try {
assertSafeContactSheetPath(temporary, platform, "temporary output");
await verifyWindowsPath(root, path.dirname(destination), platform, "directory");
const noFollow = platform === "win32" ? 0 : (constants.O_NOFOLLOW ?? 0);
handle = await open(temporary, constants.O_WRONLY | constants.O_CREAT | constants.O_EXCL | noFollow, 0o600);
const opened = await handle.stat();
const named = await lstat(temporary);
const canonical = await realpath(temporary);
if (named.isSymbolicLink() ||
!named.isFile() ||
!opened.isFile() ||
!pathsMatch(canonical, temporary, platform) ||
!isPathWithinRoot(root, canonical, platform) ||
opened.dev !== named.dev ||
opened.ino !== named.ino) {
throw new ContactSheetError(`Refusing an unsafe contact-sheet temporary output: ${temporary}`);
}
await handle.writeFile(bytes);
await handle.close();
handle = undefined;
await verifyWindowsPath(root, path.dirname(destination), platform, "directory");
await rename(temporary, destination);
}
catch (error) {
if (handle !== undefined)
await handle.close();
await rm(temporary, { force: true });
throw new ContactSheetError(`The contact sheet could not be safely written: ${destination}`, { cause: error });
}
}
/** Compose authentic Game Boy emulator captures into a deterministic, labeled PNG. */
export async function createContactSheet(options, runtime = {}) {
const platform = runtime.platform ?? process.platform;
if (typeof options !== "object" || options === null) {
throw new ContactSheetError("Contact-sheet options must be an object");
}
if (typeof options.projectRoot !== "string" || options.projectRoot.trim().length === 0) {
throw new ContactSheetError("The contact-sheet project root must be a non-empty directory path");
}
assertSafeContactSheetPath(options.projectRoot, platform, "project root");
if (!Array.isArray(options.frames) || options.frames.length < 1 || options.frames.length > MAX_CONTACT_SHEET_FRAMES) {
throw new ContactSheetError(`Contact sheets require between 1 and ${MAX_CONTACT_SHEET_FRAMES} frames`);
}
const magnification = options.magnification ?? 2;
if (!Number.isSafeInteger(magnification) || magnification < 1 || magnification > MAX_CONTACT_SHEET_MAGNIFICATION) {
throw new ContactSheetError(`Contact-sheet magnification must be an integer between 1 and ${MAX_CONTACT_SHEET_MAGNIFICATION}`);
}
const columns = options.columns ?? Math.min(3, options.frames.length);
if (!Number.isSafeInteger(columns) || columns < 1 || columns > MAX_CONTACT_SHEET_FRAMES) {
throw new ContactSheetError(`Contact-sheet columns must be an integer between 1 and ${MAX_CONTACT_SHEET_FRAMES}`);
}
if (options.highlightChanges !== undefined && typeof options.highlightChanges !== "boolean") {
throw new ContactSheetError("The contact-sheet highlightChanges option must be a boolean");
}
for (let index = 0; index < options.frames.length; index += 1)
validateFrame(options.frames[index], index);
const requestedRoot = path.resolve(options.projectRoot);
let root;
try {
root = await realpath(requestedRoot);
if (!(await stat(root)).isDirectory())
throw new Error("not a directory");
if (platform === "win32") {
const requested = await lstat(requestedRoot);
if (requested.isSymbolicLink() || !pathsMatch(root, requestedRoot, platform)) {
throw new Error("the project root contains a symbolic link or reparse point");
}
await verifyWindowsPath(root, root, platform, "directory");
}
}
catch (error) {
throw new ContactSheetError(`The contact-sheet project root does not exist: ${options.projectRoot}`, { cause: error });
}
const rows = Math.ceil(options.frames.length / columns);
const fontScale = magnification >= 3 ? 2 : 1;
const lineHeight = (FONT_HEIGHT + 3) * fontScale;
const imageWidth = GAME_BOY_FRAME_WIDTH * magnification;
const imageHeight = GAME_BOY_FRAME_HEIGHT * magnification;
const cardWidth = imageWidth + PADDING * 2;
const cardHeight = imageHeight + PADDING * 3 + lineHeight * 2;
const width = GUTTER + columns * (cardWidth + GUTTER);
const height = GUTTER + rows * (cardHeight + GUTTER);
if (width > MAX_CANVAS_DIMENSION || height > MAX_CANVAS_DIMENSION || width * height > MAX_CANVAS_PIXELS) {
throw new ContactSheetError("The contact-sheet dimensions exceed the maximum safe canvas size");
}
const destination = await resolveOutput(root, requestedRoot, options.outputPath, platform);
const loaded = [];
for (const frame of options.frames)
loaded.push(await loadFrame(root, requestedRoot, frame, platform));
const canvas = new PNG({ width, height });
fillRectangle(canvas, 0, 0, width, height, CANVAS_COLOR);
const tiles = [];
for (let index = 0; index < loaded.length; index += 1) {
const loadedFrame = loaded[index];
const column = index % columns;
const row = Math.floor(index / columns);
const cardX = GUTTER + column * (cardWidth + GUTTER);
const cardY = GUTTER + row * (cardHeight + GUTTER);
const x = cardX + PADDING;
const y = cardY + PADDING;
fillRectangle(canvas, cardX, cardY, cardWidth, cardHeight, BORDER_COLOR);
fillRectangle(canvas, cardX + 1, cardY + 1, cardWidth - 2, cardHeight - 2, CARD_COLOR);
const changedPixels = compositeFrame(canvas, loadedFrame.image, index === 0 ? undefined : loaded[index - 1].image, x, y, magnification, options.highlightChanges === true);
const metadata = loadedFrame.metadata;
const input = Array.isArray(metadata.input) ? metadata.input.join(" + ") : metadata.input;
const frameLabel = metadata.frame === undefined ? `FRAME ${index + 1}` : `FRAME ${metadata.frame}`;
const summary = input === undefined || input.length === 0 ? frameLabel : `${frameLabel} / ${input}`;
const caption = metadata.caption?.trim() || path.basename(metadata.path, path.extname(metadata.path));
const labelY = y + imageHeight + PADDING;
drawText(canvas, x, labelY, summary, imageWidth, FRAME_ACCENT, fontScale);
drawText(canvas, x, labelY + lineHeight, caption, imageWidth, metadata.caption ? PRIMARY_TEXT : SECONDARY_TEXT, fontScale);
tiles.push({
...metadata,
x,
y,
width: imageWidth,
height: imageHeight,
...(options.highlightChanges === true ? { changedPixels } : {}),
});
}
const encoded = PNG.sync.write(canvas, { colorType: 6, inputColorType: 6, inputHasAlpha: true });
await writeAtomic(root, destination, encoded, platform);
return {
path: destination,
sha256: createHash("sha256").update(encoded).digest("hex"),
width,
height,
columns,
rows,
magnification,
frameCount: loaded.length,
tiles,
};
}
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