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

Pure JavaScript game engine. Fully featured and production ready.

import { Codec } from "./Codec.js";

export class CodecWithFallback extends Codec {
    /**
     *
     * @param {Codec} codecs
     */
    constructor(...codecs) {
        super();

        this.children = codecs.slice();

        if (this.children.length < 1) {
            throw new Error('At least one codec must be provided');
        }
    }

    async test(data) {
        const codecs = this.children;
        const codec_count = codecs.length;

        for (let i = 0; i < codec_count; i++) {
            const codec = codecs[i];

            const codec_supports_data = await codec.test(data);

            if (codec_supports_data) {
                return true;
            }
        }

        return false;
    }

    async decode(data) {

        const codecs = this.children;
        const codec_count = codecs.length;

        const errors = [];

        let result;

        for (let i = 0; i < codec_count; i++) {
            const codec = codecs[i];

            const codec_supports_data = await codec.test(data);

            if (!codec_supports_data) {
                errors.push({
                    index: i, error: "Codec doesn't support this data"
                });
                continue;
            }

            try {
                result = await codec.decode(data);
            } catch (e) {

                errors.push({
                    index: i, error: e
                });

                continue;
            }

            return result;
        }

        throw new Error(`All codecs failed, errors: ${errors.map(a => JSON.stringify(a)).join('\n')}`);

    }
}