Testing gifwrap

gif_to_png_test.js

const fs = require('fs');
const { GifCodec, BitmapImage } = require('./');
const Jimp = require('jimp');

let gif = fs.readFileSync('test/fixtures/rnaples-offsets-public.gif');

const codec = new GifCodec();
codec.decodeGif(gif).then((sourceGif) => {
  const w = sourceGif.width;
  const h = sourceGif.height;
  const num_frames = sourceGif.frames.length;
  let composite_jimp = new Jimp(w * num_frames, h, 0xFF00FFff);
  const composite_bitmap = new BitmapImage(1, 1, 0);
  composite_bitmap.bitmap = composite_jimp.bitmap;
  const frame_jimp = new Jimp(1, 1, 0);

  sourceGif.frames.forEach((frame, idx) => {
    frame_jimp.bitmap = frame.bitmap;
    if (idx !== 0) {
      // composite_jimp.blit(composite_jimp, idx * w, 0, (idx - 1) * w, 0, w, h);
      composite_bitmap.blit(composite_bitmap, idx * w, 0, (idx - 1) * w, 0, w, h); // faster
    }
    composite_jimp.composite(frame_jimp, idx * w + frame.xOffset, frame.yOffset);
  });

  composite_jimp.getBuffer('image/png', function (err, data) {
    if (err) {
      throw err;
    }
    fs.writeFileSync('out.png', data);
  });
});

Expected results:

Actual results: