encode_node.js

import * as path from "path";
import { promisify } from "util";
import { writeFile } from "fs/promises";
import getPixelsCb from "get-pixels";
import { GIFEncoder, quantize, applyPalette } from "../src/index.js";

const getPixels = promisify(getPixelsCb);
const __dirname = import.meta.dirname;

encode();

async function encode() {
  // Load width/height + RGBA uint8 array data
  const { data, width, height } = await readImage(
    path.resolve(__dirname, "fixtures/baboon.png"),
  );

  // Choose a pixel format: rgba4444, rgb444, rgb565
  const format = "rgb444";

  // If necessary, quantize your colors to a reduced palette
  const palette = quantize(data, 256, { format });

  // Apply palette to RGBA data to get an indexed bitmap
  const index = applyPalette(data, palette, format);

  // Now let's encode it into a GIF
  const gif = GIFEncoder();

  // Write a single frame into the encoder
  gif.writeFrame(index, width, height, { palette });

  // Finish encoding (write end-of-file character)
  gif.finish();

  // Get a uint8array buffer with our bytes
  const bytes = gif.bytes();

  // Write the uint8 array data to file
  await writeFile(
    path.resolve(__dirname, "output/test.gif"),
    Buffer.from(bytes),
  );
}

async function readImage(file) {
  const { data, shape } = await getPixels(file);
  let width, height;
  if (shape.length === 3) {
    // PNG,JPG,etc...
    width = shape[0];
    height = shape[1];
  } else if (shape.length === 4) {
    // still GIFs might appear in frames, so [N,w,h]
    width = shape[1];
    height = shape[2];
  } else {
    throw new Error("Invalid shape " + shape.join(", "));
  }
  return { data, width, height };
}