# @jsquash/avif

An easy experience for encoding and decoding AVIF images in the browser. Powered by WebAssembly ⚡️.

Uses the [libavif](https://github.com/AOMediaCodec/libavif) library.

A [jSquash](https://github.com/jamsinclair/jSquash) package. Codecs and supporting code derived from the [Squoosh](https://github.com/GoogleChromeLabs/squoosh) app.

## Installation

```shell
npm install --save @jsquash/avif
# Or your favourite package manager alternative
```

## Usage

Note: You will need to either manually include the wasm files from the codec directory or use a bundler like WebPack or Rollup to include them in your app/server.

### decode(data: ArrayBuffer): Promise<ImageData>

Decodes AVIF binary ArrayBuffer to raw RGB image data.

#### data
Type: `ArrayBuffer`

#### Example
```js
import { decode } from '@jsquash/avif';

const formEl = document.querySelector('form');
const formData = new FormData(formEl);
// Assuming user selected an input avif file
const imageData = await decode(await formData.get('image').arrayBuffer());
```

### encode(data: ImageData, options?: EncodeOptions): Promise<ArrayBuffer>

Encodes raw RGB image data to AVIF format and resolves to an ArrayBuffer of binary data.

#### data
Type: `ImageData`

#### options
Type: `Partial<EncodeOptions>`

The AVIF encoder options for the output image. [See default values](./meta.ts).

#### Example
```js
import { encode } from '@jsquash/avif';

async function loadImage(src) {
  const img = document.createElement('img');
  img.src = src;
  await new Promise(resolve => img.onload = resolve);
  const canvas = document.createElement('canvas');
  [canvas.width, canvas.height] = [img.width, img.height];
  const ctx = canvas.getContext('2d');
  ctx.drawImage(img, 0, 0);
  return ctx.getImageData(0, 0, img.width, img.height);
}

const rawImageData = await loadImage('/example.png');
const avifBuffer = await encode(rawImageData);
```

## Manual WASM initialisation (not recommended)

In most situations there is no need to manually initialise the provided WebAssembly modules.
The generated glue code takes care of this and supports most web bundlers.

One exception is CloudFlare workers. The environment at this time (this could change in the future) does not allow code to be dynamically imported. It needs to be bundled at runtime. WASM modules are set as global variables. [See the Cloudflare workers example](examples/cloudflare-worker).

The `encode` and `decode` modules both export an `init` function that can be used to manually load the wasm module.

```js
import decode, { init as initAvifDecode } from '@jsquash/avif/decode';

const WASM_MODULE = // A WebAssembly.Module object of the compiled wasm binary
initAvifDecode(WASM_MODULE);
const image = await fetch('./image.avif').then(res => res.arrayBuffer()).then(decode);
```