IsolateImageCompress

IsolateImageCompress is a package to compress and resize the images in isolate (IsolateFlutter).

Supported formats: JPEG, PNG, GIF and TGA.

Requirements

Flutter >=3.35.0, Dart ^3.9.0. Verified against Flutter 3.44.

Installation

dependencies:
  isolate_image_compress: ^3.0.0

import 'package:isolate_image_compress/isolate_image_compress.dart';

*** The image package (4.x) declares its own ImageFormat, which collides with the one exported here. If you import both libraries, hide one of them, or use a prefix:

import 'package:image/image.dart' hide ImageFormat;

Usage

Compress

• Compress with file path

Future<void> compressImage(String path) async {
    final _image = IsolateImage.path(path);
    print('isolate_image_compress begin - : ${_image.data?.length}');
    final _data = await _image.compress(maxSize: 1 * 1024 * 1024); // 1 MB
    print('isolate_image_compress end - : ${_data?.length}');
}

• Compress with file data (Uint8List or List<int>)

Future<void> compressImage(Uint8List fileData) async {
    print('isolate_image_compress begin - : ${fileData.length}');
    final _data = await fileData.compress(maxSize: 1 * 1024 * 1024); // 1 MB
    print('isolate_image_compress end - : ${_data?.length}');
}

Both return null if the isolate could not be created, the data unchanged if it is already under maxSize (or if maxSize is omitted), and an empty Uint8List if the image could not be brought under maxSize.

Options

Option	Description
maxSize	Compressed file size limit, in bytes. Without it nothing is compressed.
maxResolution / resolution	Largest resolution to keep. Defaults to ImageResolution.uhd.
format	Force a decoder instead of detecting it from the data.

*** The resolution argument is named maxResolution on IsolateImage but resolution on the Uint8List and List<int> extensions.

final _data = await fileData.compress(
    maxSize: 1 * 1024 * 1024,
    resolution: ImageResolution.fhd,
    format: ImageFormat.jpeg);

JPEG is compressed by lowering quality, PNG by raising the compression level. If the image still does not fit, the resolution steps down (uhd → qhd → fhd → hd → sd) and it tries again.

Resize

void resizeImage(String path) {
    final _image = IsolateImage.path(path);
    final _resized = _image.resizeWithResolution(ImageResolution.fhd);
    print('isolate_image_compress resized - : ${_resized?.width}');
}

Resizing keeps the aspect ratio and never scales an image up: an image that already fits inside the resolution is returned unchanged.

ImageResolution

sd (640x480), hd (1280x720), fhd (1920x1080), qhd (2560x1440), uhd (3840x2160), fuhd (7680x4320). Use prev() and next() to walk the ladder, or build your own with ImageResolution(width, height).

Author

IsolateImageCompress is developed by Thong Dang. You can contact me at thongdn.it@gmail.com

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Thank you! ❤️