alexobviously/blurhash-dart

A pure dart implementation of blurhash

BlurHash Dart

A pure dart implementation of BlurHash. Supports both encoding and decoding. Runs on every supported Dart platform. See the BlurHash website or GitHub repository for more information.

The encoder of this dart implementation produces slightly different hashes than the TypeScript implementation but matches the official C and Python implementation. In practice this should not be relevant.

Basic usage

Decoding a BlurHash

import 'package:blurhash_dart/blurhash_dart.dart';
import 'package:image/image.dart' as img;

const hash = 'LEHV6nWB2yk8pyo0adR*.7kCMdnj';
BlurHash blurHash = BlurHash.decode(hash);
img.Image image = blurHash.toImage(35, 20);

// Display image...

Note: Usage with Flutter

Flutter does not expect raw bytes for its Image.memory widget, but fully encoded images with their corresponding headers (e.g. bitmap, jpg, png). The easiest way to accomplish this, is to use, for example, encodeJpg from package:image:

Widget build(BuildContext context) {
  final image = BlurHash.decode('LEHV6nWB2yk8pyo0adR*.7kCMdnj').toImage(35, 20);
  return Image.memory(Uint8List.fromList(encodeJpg(image)));
}

It is recommended to cache the resulting image in a stateful widget, such that it does not need to be recomputed on every build call.

Encoding an Image

import 'dart:io';

import 'package:blurhash_dart/blurhash_dart.dart';
import 'package:image/image.dart' as img;

final data = File('path/to/image.png').readAsBytesSync();
final image = img.decodeImage(data.toList());
final blurHash = BlurHash.encode(image!, numCompX: 4, numCompY: 3);

print(blurHash.hash);

Extension Methods

Additional extension methods to compute, for example color averages, are available when importing package:blurhash_dart/blurhash_extensions.dart. See example for basic usage.