flutter_image_conversion

A Flutter plugin that converts HEIC images to JPEG format across multiple platforms. Supports iOS, macOS, and Web with full conversion, plus Android and Windows with graceful fallback.

Platform Support

Platform	Status	Implementation	Conversion	Notes
iOS	✅ Full	Swift (UIImage)	HEIC → JPEG	Resize + compression
macOS	✅ Full	Swift (NSImage)	HEIC → JPEG	Resize + compression
Web	✅ Full	Dart + JS (heic2any)	HEIC → JPEG	WASM compatible
Android	⚠️ Stub	Kotlin	Returns original	Logs warning
Windows	⚠️ Stub	C++	Returns original	Logs warning

Features

• ✅ Convert .heic and .heif files to .jpeg
• ✅ Resize images before conversion (default max width: 1080px)
• ✅ Adjustable compression quality (default: 0.7)
• ✅ Multi-platform support (iOS, macOS, Web, Android, Windows)
• ✅ Graceful fallback on unsupported platforms
• ✅ WASM compatible (flutter build web --wasm)
• ✅ Comprehensive test coverage

Installation

Add the package to your pubspec.yaml:

dependencies:
  flutter_image_conversion:
    git:
      url: https://github.com/cyberprophet/flutter-image-conversion.git

Or from pub.dev (once published):

dependencies:
  flutter_image_conversion: ^2.2.0

Usage

Basic Usage

import 'package:flutter_image_conversion/flutter_image_conversion.dart';
import 'dart:io';

final converter = FlutterImageConversion();

// Convert HEIC to JPEG
File heicFile = File('/path/to/image.heic');
File jpegFile = await converter.convertHeicToJpeg(heicFile);

// Use the converted file
print('Converted file: ${jpegFile.path}');

Platform-Specific Behavior

// iOS/macOS: Returns converted JPEG file in temp directory
// Example: /tmp/converted_abc123.jpg

// Web: Returns File with blob URL
// Example: blob:http://localhost/converted-jpeg

// Android/Windows: Returns original file unchanged
// Logs warning: "HEIC conversion not supported on [Platform]"

Get Platform Version

String? version = await converter.getPlatformVersion();
print('Platform: $version');
// iOS: "iOS 17.0"
// macOS: "macOS 14.0"
// Web: "Web"
// Android: "Android 14"
// Windows: "Windows"

Platform Implementation Details

iOS & macOS

• Technology: Swift with native ImageIO framework
• Processing:
  1. Load HEIC image using UIImage (iOS) or NSImage (macOS)
  2. Resize if width > 1080px (maintains aspect ratio)
  3. Convert to JPEG with 0.7 compression quality
  4. Save to temp directory as converted_<UUID>.jpg
• Requirements: iOS 12.0+, macOS 10.14+

Web

• Technology: Dart + JavaScript interop with heic2any library
• Interop: Uses package:web + dart:js_interop (WASM compatible)
• Processing:
  1. Fetch image blob from URL
  2. Convert using heic2any (WASM-based)
  3. Create object URL for converted blob
  4. Return File with blob URL
• Browser Support: All modern browsers with WASM support
• Build: Supports both flutter build web and flutter build web --wasm
• Fallback: Returns original file if conversion fails

Android & Windows

• Technology: Kotlin (Android), C++ (Windows)
• Behavior:
  • Logs warning message
  • Returns original file unchanged
• Reason: HEIC is Apple-proprietary format, not natively supported

Requirements

• Dart: ^3.8.1
• Flutter: >=3.32.0
• iOS: 12.0+
• macOS: 10.14+
• Android: SDK 21+ (Android 5.0+)
• Web: Modern browser with WASM support
• Windows: Windows 10+

Example App

See the example directory for a complete working application that demonstrates:

• Image selection from device gallery
• HEIC to JPEG conversion
• Display of converted images
• Platform-specific behavior

Run the example:

cd example
flutter run

Testing

The package includes comprehensive test coverage:

# Run unit tests
flutter test

# Run integration tests
cd example
flutter test integration_test/

Test Results: ✅ 11/11 tests passing

API Reference

FlutterImageConversion

Main plugin class for image conversion.

Methods

getPlatformVersion()

Returns the platform version string.

Future<String?> getPlatformVersion()

Returns: Platform-specific version string (e.g., "iOS 17.0", "Web")

convertHeicToJpeg(File file)

Converts a HEIC image file to JPEG format.

Future<File> convertHeicToJpeg(File file)

Parameters:

• file: Input HEIC file to convert

Returns:

• iOS/macOS/Web: Converted JPEG file
• Android/Windows: Original file unchanged

Processing Details:

• Max width: 1080px (auto-resize if larger)
• Aspect ratio: Maintained
• Compression quality: 0.7 (70%)
• Output format: JPEG
• Output location: Temporary directory (iOS/macOS), blob URL (Web)

Technical Architecture

Plugin Structure

flutter_image_conversion/
├── lib/
│   ├── flutter_image_conversion.dart           # Public API
│   ├── flutter_image_conversion_platform_interface.dart  # Platform interface
│   ├── flutter_image_conversion_method_channel.dart      # Method channel
│   └── flutter_image_conversion_web.dart       # Web implementation
├── ios/                                        # iOS native code
├── macos/                                      # macOS native code
├── android/                                    # Android native code
├── windows/                                    # Windows native code
├── web/                                        # Web assets
└── test/                                       # Unit tests

Communication Flow

┌─────────────────────────────────────┐
│  Dart Layer (Public API)           │
│  FlutterImageConversion             │
└─────────────────┬───────────────────┘
                  │
┌─────────────────▼───────────────────┐
│  Platform Interface                 │
│  FlutterImageConversionPlatform     │
└─────────────────┬───────────────────┘
                  │
        ┌─────────┴─────────┐
        │                   │
┌───────▼────────┐  ┌──────▼──────┐
│ Method Channel │  │ Web Direct  │
│ (iOS/Android)  │  │ (Dart+JS)   │
│ (macOS/Windows)│  │             │
└───────┬────────┘  └──────┬──────┘
        │                   │
┌───────▼────────┐  ┌──────▼──────┐
│ Native Code    │  │ heic2any.js │
│ Swift/Kotlin/  │  │ (WASM)      │
│ C++            │  │             │
└────────────────┘  └─────────────┘

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Changelog

See CHANGELOG.md for a detailed list of changes.

Support

For issues, questions, or suggestions, please file an issue on the GitHub repository.