Web-gPhoto2

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

Powered by a custom fork of libgphoto2, the WebUSB backend of libusb, and WebAssembly via Emscripten.

Installation

npm install web-gphoto2

Usage

A short example on how to use this package:

import { Camera } from "web-gphoto2";

let camera = new Camera();

// Triggers the browser's native USB picker listing all connected cameras.
await Camera.showPicker();

// Connects to the camera exposed in the previous step.
// In the future we might allow to connect to multiple cameras by passing a specific instance.
await camera.connect();

console.log("Operations supported by the camera:", await camera.getSupportedOps());

console.log("Current configuration tree:", await camera.getConfig());

// Update camera configuration by the setting's name.
await camera.setConfigValue("iso", "800");

// Capture a lower-quality preview frame, useful for high-FPS live view stream.
// Returns a Blob with image mime type and contents.
const blob = await camera.capturePreviewAsBlob();
// Use `URL.createObjectURL` to create an image URL from the blob or `createImageBitmap` to decode it directly.
const img = new Image();
img.src = URL.createObjectURL(blob);

// Capture a full-resolution image in format currently selected on the camera (JPEG or RAW).
// This can be used in the same way as Blob above, but also has extra information such as filename useful for download.
const file = await camera.captureImageAsFile();
const a = document.createElement("a");
a.href = URL.createObjectURL(file);
a.download = file.name;

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:

4MUKvJhKOPK2CSTkhnEC.1.mp4

Building

To build the WebAssembly part of the repo, you'll need Docker on Linux (WSL works too) or macOS machine. Then:

npm run build:wasm # runs build in Docker

If you are just updating the JS library (src/camera.ts), then it's enough to do

npm run build:ts

on any system as Wasm parts are committed to this repo.

To serve the demo, run:

npx serve examples/preact # starts a local server with COOP/COEP

Then, navigate to http://localhost:3000/ in Chrome.

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"],
  },
});

See also

RReverser/eos-remote-web - my other project for controlling Canon cameras over Web Bluetooth.

License

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