Output and Comparison topic

Pxl is a headless pixel manipulation library, and provides limited support for rendering, expecting the user to provide their own rendering solution (any Canvas-like API will do, or something that supports pixel buffers in one of the many formats Pxl provides).

To aid with testing and debugging, Pxl provides a few useful utilities.

Comparisons

Two buffers can be compared for differences using the compare method:

final diff = pixels1.compare(pixels2);
print(diff);

The compare method returns a Comparison object, which can be used to summarize, iterate, or visualize the differences between two buffers. Pxl itself uses this method in its test suite to compare expected and actual results for pixel operations.

final diff = pixels1.compare(pixels2);
if (diff.difference < 0.01) {
  print('The buffers are nearly identical.');
} else {
  print('The buffers differ by ${diff.difference}.');
}

Codecs

Converting pixel buffers to popular formats is best done with a full-featured library like image or dart:ui, but Pxl provides a few simple codecs for converting pixel buffers to pixel-based formats like PFM, PBM, and can even output as an uncompressed PNG with uncompressedPngEncoder:

import 'dart:io';

import 'package:pxl/pxl.dart';

void main() {
  final image = IntPixels(8, 8);
  image.fill(abgr8888.red);

  final bytes = uncompressedPngEncoder.convert(image);
  File('example.png').writeAsBytesSync(bytes);
}