HEIC to PNG / JPG / WebP Converter

A Flutter package to convert HEIC images to PNG, JPG, or WebP on mobile, web, and desktop.

Features

• Convert HEIC/HEIF images to JPG, PNG, or WebP
• Web, iOS, Android, macOS, Windows, Linux support
• Resize by maxWidth, maxHeight, or both (aspect-ratio-preserving contain mode)
• Adjustable JPG / WebP quality (0–100)
• isHeic() — fast magic-byte check, no decode required
• getImageInfo() — read dimensions without full conversion
• convertBatch() — convert multiple files concurrently
• convertFile() — file-path API (mobile / desktop)
• Custom exception types for fine-grained error handling
• Isolate-based processing keeps the UI thread free

Platform support

Feature	Android	iOS	Web	macOS	Windows	Linux
JPG / PNG	✅	✅	✅	✅*	✅*	✅*
WebP	✅*	✅*	✅	✅*	✅*	✅*
convertFile()	✅	✅	❌	✅	✅	✅

* Desktop and WebP on mobile use the Dart image package fallback (HEIC support may be limited; WebP output falls back to PNG on mobile).

Installation

dependencies:
  heic_to_png_jpg: ^0.1.0

flutter pub get

No changes to web/index.html are needed — the package loads libheif-js automatically.

Usage

Basic conversion

import 'package:heic_to_png_jpg/heic_to_png_jpg.dart';

final Uint8List heicData = ...; // from file, network, etc.

// Convert to JPG
final jpg = await HeicConverter.convertToJPG(heicData: heicData, quality: 85);

// Convert to PNG
final png = await HeicConverter.convertToPNG(heicData: heicData);

// Convert to WebP (web: native; mobile: falls back to PNG)
final webp = await HeicConverter.convertToWebP(heicData: heicData, quality: 85);

// Generic — choose format at runtime
final output = await HeicConverter.convertToImage(
  heicData: heicData,
  format: ImageFormat.jpg,
  quality: 85,
  maxWidth: 1280,
  maxHeight: 720, // NEW: contain-mode when both are set
);

Resize

// Scale to fit within 800 × 600, preserving aspect ratio
final resized = await HeicConverter.convertToJPG(
  heicData: heicData,
  maxWidth: 800,
  maxHeight: 600,
);

// Constrain only width
final byWidth = await HeicConverter.convertToPNG(
  heicData: heicData,
  maxWidth: 1024,
);

Check if a file is HEIC

// Fast — checks magic bytes only, no decoding
if (HeicConverter.isHeic(bytes)) {
  // safe to convert
}

Read image dimensions

final info = await HeicConverter.getImageInfo(heicData);
print('${info.width} × ${info.height}');

Batch conversion

final tasks = [
  HeicConversionTask(heicData: data1, format: ImageFormat.jpg, quality: 85),
  HeicConversionTask(heicData: data2, format: ImageFormat.png, maxWidth: 800),
];

final results = await HeicConverter.convertBatch(
  tasks: tasks,
  concurrency: 3, // max simultaneous conversions
);

File-path API (mobile / desktop only)

final outputPath = await HeicConverter.convertFile(
  inputPath: '/path/to/photo.heic',
  format: ImageFormat.jpg,
  quality: 85,
  maxWidth: 1280,
);

Error handling

import 'package:heic_to_png_jpg/heic_to_png_jpg.dart';

try {
  final jpg = await HeicConverter.convertToJPG(heicData: data);
} on InvalidHeicDataException catch (e) {
  // Bad input (wrong format, invalid quality value)
  print(e.message);
} on ConversionFailedException catch (e) {
  // Encoding / decoding error
  print('${e.message} — caused by: ${e.cause}');
} on PlatformNotSupportedException catch (e) {
  // Feature not available on this platform
  print(e.message);
} on HeicConversionException catch (e) {
  // Any other conversion error
  print(e.message);
}

Custom libheif-js URL (web)

final png = await HeicConverter.convertToPNG(
  heicData: heicData,
  libheifJsUrl: 'https://cdn.jsdelivr.net/npm/libheif-js@1.19.8/libheif-wasm/libheif-bundle.js',
);

Migration from 0.0.x

Before (0.0.x)	After (0.1.0)
ImageFormat.jpg / .png only	+ ImageFormat.webp
maxWidth only	+ maxHeight
Generic Exception thrown	Typed HeicConversionException subclasses
No way to check if file is HEIC	HeicConverter.isHeic(data)
No batch API	HeicConverter.convertBatch(tasks: [...])
Must read file manually	HeicConverter.convertFile(inputPath: ...)

The core API (convertToJPG, convertToPNG, convertToImage, maxWidth, quality, libheifJsUrl) is fully backward compatible.

Notes

• Mobile (iOS / Android): Uses heif_converter for native decoding, falls back to the Dart image package if it fails.
• Web: Uses libheif-js (WebAssembly); auto-loaded from jsDelivr CDN.
• Desktop: Uses the Dart image package fallback (HEIC support may be limited).
• WebP on mobile: The image package has no WebP encoder, so WebP output falls back to PNG. Web uses the browser's native canvas encoder.

Issues and Contributions

Please file issues, bugs, or feature requests on GitHub.

License

MIT — see LICENSE.

About the Author

• Top-rated Flutter freelancer (100% Job Success on Upwork)
• Built 20+ production apps with real-time & payment features
• Passionate about clean architecture, compliance, and UX

---

👥 Contributors

We appreciate all contributions to this project!