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

Powered by a [custom fork](https://github.com/RReverser/libgphoto2) of [libgphoto2](https://github.com/gphoto/libgphoto2), the [WebUSB](https://github.com/WICG/webusb) backend of [libusb](https://github.com/libusb/libusb), and WebAssembly via [Emscripten](https://emscripten.org/).

# NPM
## Installation
```bash
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.

```ts
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:
```ts
// 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](https://stackoverflow.com/questions/64650119/react-error-sharedarraybuffer-is-not-defined-in-firefox)

### 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:
```ts
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](https://web.dev/porting-libusb-to-webusb/) running gPhoto2 on the Web:
![A picture of DSLR camera connected via a USB cable to a laptop. The laptop is running the Web demo mentioned in the article, which mirrors a live video feed from the camera as well as allows to tweak its settings via form controls.](https://web-dev.imgix.net/image/9oK23mr86lhFOwKaoYZ4EySNFp02/MR4YGRvl0Z9AWT6vv3sQ.jpg?auto=format&w=1600)

For the detailed technical write-up, see [the official blog post](https://web.dev/porting-libusb-to-webusb/). To see the demo in action, visit the hosted version [here](https://web-gphoto2.rreverser.com/) (but make sure to read the [cross-platform compatibility notes](https://web.dev/porting-libusb-to-webusb/#important-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:

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

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

## See also

[RReverser/eos-remote-web](https://github.com/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](https://github.com/GoogleChromeLabs/web-gphoto2/blob/main/LICENSE).