@woosh/meep-engine/src/engine/asset/loaders/image/codec/ThreadedImageDecoder.js

Pure JavaScript game engine. Fully featured and production ready.

import { assert } from "../../../../../core/assert.js";
import { OnDemandWorkerManager } from "../../../../../core/process/worker/OnDemandWorkerManager.js";
import WorkerBuilder from "../../../../../core/process/worker/WorkerBuilder.js";
import { PNG_HEADER_BYTES } from "../png/PNG_HEADER_BYTES.js";
import { Codec } from "./Codec.js";

export class ThreadedImageDecoder extends Codec {
    /**
     *
     * @param {string} [worker_path]
     */
    constructor({
                    worker_path = 'bundle-worker-image-decoder.js'
                } = {}) {

        super();

        const workerBuilder = new WorkerBuilder();

        workerBuilder.importScript(worker_path);

        workerBuilder.addMethod('decode', function (data, type) {
            return Lib.decode(data, type);
        });

        /**
         *
         * @type {OnDemandWorkerManager}
         */
        this.worker = new OnDemandWorkerManager(workerBuilder.build());

        // shut down worker if it's not used for a while
        this.worker.setTimeout(1200);
    }

    async test(data) {
        assert.defined(data, 'data');
        assert.notNull(data, 'data');
        assert.isInstanceOf(data, Uint8Array, 'data', 'Uint8Array');

        for (let i = 0; i < PNG_HEADER_BYTES.length; i++) {
            if (data[i] !== PNG_HEADER_BYTES[i]) {
                // only supports PNG
                return false;
            }
        }

        return true;
    }

    decode(data) {
        return this.worker.request('decode', [data.buffer]);
    }
}