flutter_ocr_native 0.1.0

A Flutter plugin for extracting text from images using native on-device OCR. Android uses ML Kit, iOS uses Apple Vision. Supports Aadhaar masking, handwriting detection, and English-only text extraction.

flutter_ocr_native

A Flutter plugin for extracting text from images using native on-device OCR engines — no third-party Dart OCR packages required.

• Android: Google ML Kit Text Recognition
• iOS: Apple Vision Framework
• macOS: Apple Vision Framework
• Windows: Windows.Media.Ocr (WinRT)
• Linux: Tesseract OCR

Features

• Read text from image file path, File, or raw bytes
• Structured results: blocks → lines → elements with bounding boxes & confidence scores
• English-only extraction — non-Latin scripts auto-filtered
• Aadhaar number masking (text + image) — configurable
• Aadhaar & PAN number validation (Verhoeff checksum, format check)
• Handwriting detection — rejects non-printed documents
• Document viewer with pinch-to-zoom
• Download with configurable watermark (Lead ID, Lat, Long, etc.)
• Watermark auto-scales to image resolution — always readable
• Configurable image compression (JPEG quality 1-100 or PNG lossless)
• Supports any input image format (JPEG, PNG, WEBP, BMP, GIF, HEIC, TIFF)
• Platform-specific download paths handled internally
• Fully on-device — no network calls, works offline

Getting Started

dependencies:
  flutter_ocr_native: ^0.1.0

Android

Minimum SDK 21. Add to android/app/build.gradle:

android {
    defaultConfig {
        minSdk 21
    }
}

iOS / macOS

iOS minimum 13.0, macOS minimum 10.15.

Windows

Requires Windows 10+. No additional setup.

Linux

Requires Tesseract:

sudo apt install libtesseract-dev tesseract-ocr-eng libleptonica-dev

Usage

Basic OCR

import 'package:flutter_ocr_native/flutter_ocr_native.dart';

final reader = OcrReader();
final result = await reader.readFromPath('/path/to/image.jpg');
print(result.text);

// From File
final result = await reader.readFromFile(File('image.png'));

// From bytes
final result = await reader.readFromBytes(imageBytes);

// Structured data
for (final block in result.blocks) {
  for (final line in block.lines) {
    print('${line.text} (confidence: ${line.confidence})');
  }
}

await reader.dispose();

Validation & Aadhaar Masking

final reader = OcrReader(
  validateDocument: true,  // reject empty & handwritten
  maskAadhaar: true,       // mask Aadhaar in text
);

try {
  final result = await reader.readFromPath('/path/to/aadhaar.jpg');

  // Masked text
  print(result.text); // "XXXX XXXX 2356"

  // Masked image (Aadhaar digits blacked out)
  if (result.hasAadhaar) {
    Image.memory(result.maskedImageBytes!);
  }
} on EmptyImageException {
  print('No text found');
} on HandwrittenTextException {
  print('Handwritten — not accepted');
}

Document Number Validation

final result = await reader.readFromPath(path);

// Aadhaar validation
if (result.isAadhaarValid) {
  print('Valid Aadhaar');
} else {
  print(result.aadhaarError); // "Aadhaar checksum invalid"
}

// PAN validation
if (result.isPanValid) {
  print('Valid PAN — ${result.panHolderType}'); // "Individual"
} else {
  print(result.panError); // "PAN 4th character is invalid holder type"
}

// Standalone validation
DocumentNumberValidator.isValidAadhaar('5399 8956 2356'); // true/false
DocumentNumberValidator.validateAadhaar('0000 0000 0000'); // "Aadhaar cannot start with 0"
DocumentNumberValidator.isValidPAN('ABCPD1234F'); // true/false
DocumentNumberValidator.validatePAN('ABCXD1234F'); // "PAN 4th character is invalid holder type"

Document Details Parsing

final details = AadhaarDetails.fromText(result.text);
print(details.name);          // "Ram Deva"
print(details.fatherName);    // "Shiv Kumar"
print(details.dob);           // "01/08/1994"
print(details.gender);        // "Male"
print(details.address);       // "123 Main St, Chennai 600001"
print(details.aadhaarNumber); // "5399 8956 2356"

// Or use the ready-made widget
OcrDetailsCard(result: result, maskAadhaar: true)

Document Viewer

OcrDocumentViewer.show(
  context,
  result: result,
  originalFile: imageFile,
  title: 'My Document',
  watermark: OcrWatermark(lines: {
    'Lead ID': 'LD-20250101-001',
    'Lat': '12.9716',
    'Long': '77.5946',
  }),
  onSave: (bytes) async {
    await OcrDocumentSaver.downloadBytes(imageBytes: bytes);
  },
);

Download with Watermark

final watermark = OcrWatermark(
  lines: {
    'Lead ID': 'LD-20250101-001',
    'Lat': '12.9716',
    'Long': '77.5946',
    'Agent': 'Ram Kumar',
    'Date': '2025-01-15 10:30',
  },
);

// Auto downloads to platform-specific folder
final file = await OcrDocumentSaver.downloadFromPath(
  result: result,
  originalImagePath: imagePath,
  watermark: watermark,
);

// Download without watermark — just omit it
final file = await OcrDocumentSaver.downloadFromPath(
  result: result,
  originalImagePath: imagePath,
);

Image Compression

// JPEG with quality (default 90)
final file = await OcrDocumentSaver.downloadFromPath(
  result: result,
  originalImagePath: imagePath,
  imageQuality: 70,                    // JPEG 70%
);

// PNG lossless
final file = await OcrDocumentSaver.downloadFromPath(
  result: result,
  originalImagePath: imagePath,
  format: OcrImageFormat.png,
);

// Standalone compress any image
final compressed = await OcrDocumentSaver.compressImage(
  anyImageBytes,
  quality: 60,
);

Custom Validator

final reader = OcrReader(
  validateDocument: true,
  validator: OcrValidator(minTextLength: 20),
);

Toggle at Runtime

reader.validateDocument = false;
reader.maskAadhaar = false;

Architecture

lib/
├── flutter_ocr_native.dart               # Public barrel export
└── src/
    ├── models/
    │   ├── aadhaar_details.dart            # AadhaarDetails parser
    │   ├── ocr_exception.dart             # EmptyImageException, HandwrittenTextException
    │   ├── ocr_result.dart                # OcrResult, TextBlock, TextLine, TextElement
    │   └── ocr_watermark.dart             # OcrWatermark config
    ├── utils/
    │   └── ocr_document_saver.dart        # Download & save with watermark
    ├── validators/
    │   ├── document_number_validator.dart  # Aadhaar & PAN validation
    │   └── ocr_validator.dart             # Document validation
    ├── widgets/
    │   ├── ocr_details_card.dart          # Structured details card widget
    │   └── ocr_document_viewer.dart       # Full-screen viewer widget
    ├── ocr_platform_interface.dart         # Abstract platform contract
    ├── ocr_method_channel.dart             # MethodChannel implementation
    └── ocr_reader.dart                    # Public API class

android/src/main/kotlin/com/flutter_ocr_native/
    └── OcrPlugin.kt                       # ML Kit OCR + Aadhaar masking + watermark

ios/Classes/
    └── OcrPlugin.swift                    # Vision OCR + Aadhaar masking + watermark

macos/Classes/
    └── OcrPlugin.swift                    # Vision OCR (macOS)

windows/
    └── ocr_plugin.cpp                     # WinRT OCR + GDI+

linux/
    └── ocr_plugin.cc                      # Tesseract OCR + Leptonica

Supported Platforms

Platform	Min Version	OCR Engine
Android	SDK 21	Google ML Kit Text Recognition
iOS	13.0	Apple Vision Framework
macOS	10.15	Apple Vision Framework
Windows	10	Windows.Media.Ocr (WinRT)
Linux	Any	Tesseract OCR

Flutter Compatibility

Requires Flutter 3.19.0+ (Dart SDK >=3.2.4 <4.0.0)