@jsquash/png
v3.0.1
Published
Wasm png encoder and decoder supporting the browser. Repackaged from Squoosh App.
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@jsquash/png
An easy experience for encoding and decoding PNG images in the browser. Powered by WebAssembly ⚡️.
Uses the rust PNG crate.
A jSquash package. Codecs and supporting code derived from the Squoosh app.
Installation
npm install --save @jsquash/png
# 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
Decodes PNG binary ArrayBuffer to raw RGB image data.
data
Type: ArrayBuffer
Example
import { decode } from '@jsquash/png';
const formEl = document.querySelector('form');
const formData = new FormData(formEl);
const imageData = await decode(await formData.get('image').arrayBuffer());
encode(data: ImageData): Promise
Encodes raw RGB image data to PNG format and resolves to an ArrayBuffer of binary data.
data
Type: ImageData
Example
import { encode } from '@jsquash/png';
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.jpg');
const pngBuffer = 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 situation where this arises is when using the modules in Cloudflare Workers (See the README for more info).
The encode
and decode
modules both export an init
function that can be used to manually load the wasm module.
import decode, { init as initPngDecode } from '@jsquash/png/decode';
initPngDecode(WASM_MODULE); // The `WASM_MODULE` variable will need to be sourced by yourself and passed as an ArrayBuffer.
const image = await fetch('./image.png').then(res => res.arrayBuffer()).then(decode);