Flutter Edge Detection

A Flutter plugin to detect edges of objects, scan paper, detect corners, and detect rectangles. It allows cropping of the detected object image and returns the path of the cropped image.

Features

• 📱 Cross-platform: Works on both Android and iOS
• 📷 Camera Integration: Live camera scanning with edge detection
• 🖼️ Gallery Support: Process images from device gallery
• ✂️ Smart Cropping: Automatic edge detection and cropping
• 🎨 Image Enhancement: Black and white filter options
• 🔧 Customizable UI: Customizable button titles and labels
• 🛡️ Error Handling: Comprehensive error handling with custom exceptions

Requirements

• Flutter: >=3.27.0
• Dart: >=3.0.0
• Android: API level 21+ (Android 5.0+)
• iOS: 13.0+

Installation

Add this to your package's pubspec.yaml file:

dependencies:
  flutter_edge_detection: ^1.0.0

Usage

Basic Usage

import 'package:flutter_edge_detection/flutter_edge_detection.dart';
import 'package:path_provider/path_provider.dart';
import 'package:path/path.dart';

// Scan with camera
Future<void> scanWithCamera() async {
  try {
    final directory = await getApplicationSupportDirectory();
    final imagePath = join(
      directory.path,
      'edge_detection_${DateTime.now().millisecondsSinceEpoch}.jpeg',
    );

    final success = await FlutterEdgeDetection.detectEdge(
      imagePath,
      canUseGallery: true,
      androidScanTitle: 'Scanning',
      androidCropTitle: 'Crop',
      androidCropBlackWhiteTitle: 'Black White',
      androidCropReset: 'Reset',
    );

    if (success) {
      print('Image saved to: $imagePath');
    } else {
      print('Scanning was cancelled');
    }
  } on EdgeDetectionException catch (e) {
    print('Error: ${e.message}');
  }
}

// Scan from gallery
Future<void> scanFromGallery() async {
  try {
    final directory = await getApplicationSupportDirectory();
    final imagePath = join(
      directory.path,
      'edge_detection_${DateTime.now().millisecondsSinceEpoch}.jpeg',
    );

    final success = await FlutterEdgeDetection.detectEdgeFromGallery(
      imagePath,
      androidCropTitle: 'Crop',
      androidCropBlackWhiteTitle: 'Black White',
      androidCropReset: 'Reset',
    );

    if (success) {
      print('Image saved to: $imagePath');
    } else {
      print('Processing was cancelled');
    }
  } on EdgeDetectionException catch (e) {
    print('Error: ${e.message}');
  }
}

Error Handling

The plugin provides custom exceptions for better error handling:

try {
  await FlutterEdgeDetection.detectEdge(imagePath);
} on EdgeDetectionException catch (e) {
  print('Error Code: ${e.code}');
  print('Error Message: ${e.message}');
  print('Error Details: ${e.details}');
} catch (e) {
  print('Unexpected error: $e');
}

API Reference

FlutterEdgeDetection.detectEdge()

Scans an object using the camera with edge detection.

Parameters:

• saveTo (String): The file path where the cropped image will be saved
• canUseGallery (bool, optional): Whether to allow switching to gallery mode (default: true)
• androidScanTitle (String, optional): Title for the scan screen on Android (default: "Scanning")
• androidCropTitle (String, optional): Title for the crop button on Android (default: "Crop")
• androidCropBlackWhiteTitle (String, optional): Title for the black/white filter button on Android (default: "Black White")
• androidCropReset (String, optional): Title for the reset button on Android (default: "Reset")

Returns: Future<bool> - true if successful, false if cancelled

FlutterEdgeDetection.detectEdgeFromGallery()

Processes an image from the gallery with edge detection.

Parameters:

• saveTo (String): The file path where the cropped image will be saved
• androidCropTitle (String, optional): Title for the crop button on Android (default: "Crop")
• androidCropBlackWhiteTitle (String, optional): Title for the black/white filter button on Android (default: "Black White")
• androidCropReset (String, optional): Title for the reset button on Android (default: "Reset")

Returns: Future<bool> - true if successful, false if cancelled

EdgeDetectionException

Custom exception thrown when edge detection operations fail.

Properties:

• code (String): The error code
• message (String): The error message
• details (dynamic): Additional error details

Permissions

Android

Add the following permissions to your android/app/src/main/AndroidManifest.xml:

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

iOS

Add the following keys to your ios/Runner/Info.plist:

<key>NSCameraUsageDescription</key>
<string>This app needs camera access to scan documents</string>
<key>NSPhotoLibraryUsageDescription</key>
<string>This app needs photo library access to select images for scanning</string>

Example

See the example/ directory for a complete working example.

Contributing

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

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

Changelog

See CHANGELOG.md for a list of changes.

Support

If you encounter any issues or have questions, please file an issue on the GitHub repository.