Server side image generator

[kpetrow]

Is there any way to make a server side png? I see chartjs-node but requires some funky installs of Cairo. I need to create backedn reports to email

[LeeLenaleee]

You can use quickChart

[kpetrow]

You can use quickChart

I have to run a chart server? That seems crazy. I just want something that will generate a png

[LeeLenaleee]

Yes quickchart does that for you, just provide the url with the chart config, otherwise there are some implmentations of chart.js available for SSR so you can google for that.

[kpetrow]

Seems like this might be a good addition to the library? Hitting external source is not feasible for corporate software. I dont see any popular SSR versions of chartjs, could you provide a link to working repo?

[kurkle]

I've used node-canvas before for this (based on cairo though).

npm install canvas chart.js

simple_test.js

const fs = require('fs');
const {createCanvas} = require('canvas');
const Chart = require('chart.js');
const canvas = createCanvas(512, 512);
const ctx = canvas.getContext('2d');
const chart = new Chart(ctx, {/* chart config*/});

function writePng(canvas, name) {
  return new Promise((resolve, reject) => {
    const file = fs.createWriteStream(path.join(__dirname, name));
    const stream = canvas.createPNGStream();
    stream.pipe(file);
    file.on('finish', () => {
      console.log(name + ' created.');
      resolve();
    });
  });
}

writePng(canvas, 'test.png').then(() => chart.destroy());

Instead of writing to file, you can use https://www.chartjs.org/docs/latest/developers/api.html#tobase64image-type-quality