BlurHash test

blurhash.js

const blurhash = require('blurhash');
const { createCanvas, loadImage, Image } = require('canvas')

const getImageData = (image) => {
    const canvas = createCanvas(image.width, image.height)
    const context = canvas.getContext('2d')
    context.drawImage(image, 0, 0)
    return context.getImageData(0, 0, image.width, image.height)
}

const encodeImageToBlurhash = async image => {
    const imageData = getImageData(image);
    console.log(`${imageData.width} ${imageData.height}`);
    const hash= blurhash.encode(imageData.data, imageData.width, imageData.height, 4, 4);
    return hash;
};

async function decodeBlurhash(imagehash, width, height, filename) {
    const pixels = blurhash.decode(imagehash, width, height);
    const canvas = createCanvas(width, height);
    const context = canvas.getContext('2d')
    const imageData = context.createImageData(width, height);
    imageData.data.set(pixels);
    context.putImageData(imageData, 0, 0);

    var fs = require('fs')
        , out = fs.createWriteStream(__dirname + '/' + filename)
        , stream = canvas.pngStream();

    stream.on('data', function(chunk){
        out.write(chunk);
    });

    stream.on('end', function(){
        console.log('saved png');
    });

}

async function testImage(imageUrl) {
    const image = await loadImage(imageUrl);
    const imageHash=  await encodeImageToBlurhash(image);
    await decodeBlurhash(imageHash, image.width, image.height, 'test3.png');
}

testImage('https://www.echosdunet.net/sites/default/files/styles/article/public/test-ping.png?itok=dQ_Mhhq9');