Web-gPhoto2

A gPhoto2 implementation using WebAssembly to control DSLR cameras from the browser.

NPM

Installation

npm install web-gphoto2
// or
yarn add web-gphoto2

Usage

Note: This package ONLY runs in the browser context. It will not work in NodeJS. If you are using a build-tool make sure to dynamically import this package so it is only imported in the browser context.

let initModule: any;

if (typeof window !== 'undefined') {
    import('web-gphoto2').then((module) => {
        initModule = module.default;
    }).catch((error) => {
        console.error("Error loading web-gphoto2", error);
    });
} else {
    console.warn("web-gphoto2 is only available in the browser");
}

A short example on how to use this package to obtain the camera config:

// After importing the initModule from web-gphoto2
const ModulePromise = initModule();

export function rethrowIfCritical(err) {
    if (err.constructor !== Error) throw err;
}

export async function connect() {
    const Module = await ModulePromise;

    let context = await new Module.Context();
    let supportedOps = await context.supportedOps();

    let queue = Promise.resolve();

    function schedule(op) {
        let res = queue.then(() => op(context));
        queue = res.catch(rethrowIfCritical);
        return res;
    }

    return {
        supportedOps,
        schedule,
        disconnect() {
            context.delete();
        }
    };
}

// Select the camera, connect, and obtain the config. Error handling is omitted for brevity but should be included, check the example for details.
await navigator.usb.requestDevice({
    filters: [
        {
            classCode: 6, // PTP
            subclassCode: 1 // MTP
        }
    ]
});
let connection = await connect();
let config = await connection.schedule((context: any) => context.configToJS());
console.log('Obtained config: ', config);

More information can be found in the example included in the Github repository.

Common Issues

SharedArrayBuffer can not be found

SharedArrayBuffer has been disabled across all browsers due to the Spectre vulnerability. This package uses SharedArrayBuffer to communicate with the WebAssembly module. To work around this issue, you need to set two response headers for your document:

Cross-Origin-Opener-Policy: same-origin
Cross-Origin-Embedder-Policy: require-corp

Information from Stackoverflow

Error: Not found: /node_modules/.vite/deps/libapi.wasm

Vite tries to optimize the dependencies by default. This causes the WebAssembly module to be moved to a different location. To prevent this, you need to exclude the web-gphoto2 package from the optimization.

In vite, both of the above mentioned issues are solved by adding the following to your vite.config.js:

import { sveltekit } from '@sveltejs/kit/vite';
import { defineConfig } from 'vite';

/** @type {import('vite').Plugin} */
const viteServerConfig = {
	name: 'add headers',
	configureServer: (server) => {
		server.middlewares.use((req, res, next) => {
			res.setHeader("Cross-Origin-Opener-Policy", "same-origin");
			res.setHeader("Cross-Origin-Embedder-Policy", "require-corp");
			next();
		});
	}
};

export default defineConfig({
	plugins: [sveltekit(), viteServerConfig],
	optimizeDeps: {
		exclude: ['web-gphoto2']
	}
});

Demo

This repository also contains a demo app running gPhoto2 on the Web:

For the detailed technical write-up, see the official blog post. To see the demo in action, visit the hosted version here (but make sure to read the cross-platform compatibility notes first).

If you don't have a DSLR, you can check out a recording of the demo below:

https://user-images.githubusercontent.com/557590/152155035-a1664656-a7d9-411f-8cb3-5f04320f1391.mp4

Building

To build, you'll need Docker. Then:

./build.sh # runs build in Docker
npx serve ui # starts a local server with COOP/COEP

Then, navigate to http://localhost:5000/ in Chrome.

License

Like the dependencies, this demo is licensed under LGPL v2.1.

5.1 KiB Raw Blame History