@khoohaoyit/image-size/dist/formats/png.js

A stream based image size extractor in Node

"use strict";
var __await = (this && this.__await) || function (v) { return this instanceof __await ? (this.v = v, this) : new __await(v); }
var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
    if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
    var g = generator.apply(thisArg, _arguments || []), i, q = [];
    return i = {}, verb("next"), verb("throw"), verb("return"), i[Symbol.asyncIterator] = function () { return this; }, i;
    function verb(n) { if (g[n]) i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; }
    function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
    function step(r) { r.value instanceof __await ? Promise.resolve(r.value.v).then(fulfill, reject) : settle(q[0][2], r); }
    function fulfill(value) { resume("next", value); }
    function reject(value) { resume("throw", value); }
    function settle(f, v) { if (f(v), q.shift(), q.length) resume(q[0][0], q[0][1]); }
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.extractPngSize = void 0;
const pngSignature = 'PNG\r\n\x1a\n';
const pngImageHeaderChunkName = 'IHDR';
// Used to detect "fried" png's: http://www.jongware.com/pngdefry.html
const pngFriedChunkName = 'CgBI';
exports.extractPngSize = function (stream) {
    return __asyncGenerator(this, arguments, function* () {
        if ((yield __await(stream.read(1, 7))) + '' !== pngSignature)
            return yield __await(void 0);
        const imageHeaderOrFried = (yield __await(stream.read(12, 4))) + '';
        let options;
        if (imageHeaderOrFried === pngImageHeaderChunkName)
            options = [16, 8];
        if (imageHeaderOrFried === pngFriedChunkName)
            options = [32, 8];
        if (!options)
            return yield __await(void 0);
        const buf = yield __await(stream.read(...options));
        return yield __await(yield yield __await({
            width: buf.readUint32BE(),
            height: buf.readUint32BE(4),
        }));
    });
};