jeri/build_npm/utils/exr-parser.worker.js

JavaScript Extended-Range Image viewer

/**
 * Web worker script that uses an emscripten-compiled version
 * of OpenEXR to parse EXR files. The webworker can be used like this:
 *
 *  const ExrParser = require('worker-loader!./utils/exr-parser-webworker.js');
 *  var worker = new ExrParser();
 *  # Send an ArrayBuffer to the webworker
 *  # Because it's basses as the second argument, the data won't be copied
 *  # but ownership will be transfered.
 *  worker.postMessage({ data }, [data]);
 *  worker.onmessage = (event: MessageEvent) => {
 *      if (event.data.success) {
 *          console.log(event.data.image);
 *      } else {
 *          console.error(event.data.message);
 *      }
 *  };
 */


const exrwrapPath = require('file-loader?name=exr-wrap.js!../exr-wrap/exr-wrap.js');
const exrwrapWasmPath = require('file-loader?name=exr-wrap.wasm!../exr-wrap/exr-wrap.wasm');

let openEXRLoaded = false;
let queuedJobs = [];
let OpenEXR;

importScripts(exrwrapPath);

EXR().then(function(Module) {
	OpenEXR = Module;
	openEXRLoaded = true;
	while (queuedJobs.length > 0) {
		const job = queuedJobs.shift();
		if (job) {
			handleJob(job);
		}
	}
});

self.addEventListener('message', (event) => {
    if (!openEXRLoaded) {
        queuedJobs.push(event.data);
    } else {
        handleJob(event.data);
    }
});

function handleJob(job) {
    const jobId = job.jobId;
    try {
        const image = parseExr(job.data);
        self.postMessage(
            {
                jobId,
                success: true,
                image
            },
            [image.data.buffer]
        );
    } catch (error) {
        console.log('Error: ', error);
        self.postMessage({
            jobId,
            success: false,
            message: error.toString()
        });
    }
}

function parseExr(data) {
    console.time('Decoding EXR'); // tslint:disable-line
    let exrImage = null; // tslint:disable-line:no-any
    try {
        exrImage = OpenEXR.loadEXRStr(data);
        const channels = exrImage.channels();
        const {
            width,
            height
        } = exrImage;
        let nChannels = channels.length;
        let exrData;
        if (nChannels === 1) {
            const z = exrImage.plane(exrImage.channels()[0]);
            exrData = new Float32Array(width * height);
            for (let i = 0; i < width * height; i++) {
                exrData[i] = z[i];
            }
        } else if (exrImage.channels().includes('R') &&
            exrImage.channels().includes('G') &&
            exrImage.channels().includes('B')) {
            const r = exrImage.plane('R');
            const g = exrImage.plane('G');
            const b = exrImage.plane('B');
            exrData = new Float32Array(width * height * 3);
            for (let i = 0; i < width * height; i++) {
                exrData[i * 3] = r[i];
                exrData[i * 3 + 1] = g[i];
                exrData[i * 3 + 2] = b[i];
            }
            nChannels = 3;
        } else {
            throw new Error('EXR image not supported');
        }
        return {
            height,
            width,
            nChannels,
            data: exrData,
            type: 'HdrImage',
        };
    } finally {
        if (exrImage) {
            exrImage.delete();
        }
        console.timeEnd('Decoding EXR'); // tslint:disable-line
    }
}