flutter_doc_scanner

A Flutter plugin for document scanning on Android and iOS using ML Kit Document Scanner API and VisionKit.

Example

Check out the example directory for a sample Flutter app using flutter_doc_scanner.

Document Scanner Demo

Screenshots

Features

• High-quality and consistent user interface for digitizing physical documents.
• Accurate document detection with precise corner and edge detection for optimal scanning results.
• Flexible functionality allows users to crop scanned documents, apply filters, remove fingers, remove stains and other blemishes.
• On-device processing helps preserve privacy.
• Support for sending digitized files in PDF and JPEG formats back to your app.
• Ability to set a scan page limit.
• Typed return models (ImageScanResult, PdfScanResult) for type-safe result handling.
• Custom exceptions (DocScanException) with error codes for proper error handling.
• Configurable image format (ImageFormat.jpeg or ImageFormat.png) on iOS.
• Configurable JPEG quality (0.0–1.0) for iOS image compression control.
• Camera permission checks on iOS before presenting the scanner.

Installation

To use this plugin, add flutter_doc_scanner as a dependency in your pubspec.yaml file.

dependencies:
  flutter:
    sdk: flutter
  flutter_doc_scanner: ^0.0.18

Usage

Scan documents (default behavior)

Returns PDF on Android, images (PNG) on iOS:

Future<void> scanDocument() async {
  try {
    final scannedDocuments = await FlutterDocScanner().getScanDocuments(page: 3);
    print(scannedDocuments.toString());
  } on DocScanException catch (e) {
    print('Scan failed: ${e.code} - ${e.message}');
  }
}

Scan as images (typed result)

Returns an ImageScanResult with a list of file paths/URIs:

Future<void> scanAsImages() async {
  try {
    final result = await FlutterDocScanner().getScannedDocumentAsImages(
      page: 4,
      imageFormat: ImageFormat.jpeg, // or ImageFormat.png
    );
    if (result == null) {
      print('User cancelled');
      return;
    }
    print('Scanned ${result.count} images');
    for (final path in result.images) {
      print('Image: $path');
    }
  } on DocScanException catch (e) {
    print('Scan failed: ${e.code} - ${e.message}');
  }
}

Scan as PDF (typed result)

Returns a PdfScanResult with the PDF file path/URI:

Future<void> scanAsPdf() async {
  try {
    final result = await FlutterDocScanner().getScannedDocumentAsPdf(page: 4);
    if (result == null) {
      print('User cancelled');
      return;
    }
    print('PDF: ${result.pdfUri} (${result.pageCount} pages)');
  } on DocScanException catch (e) {
    print('Scan failed: ${e.code} - ${e.message}');
  }
}

Scan document URIs (Android only)

Returns an ImageScanResult. Throws DocScanException on non-Android platforms:

Future<void> scanDocumentUri() async {
  try {
    final result = await FlutterDocScanner().getScanDocumentsUri(page: 4);
    if (result == null) {
      print('User cancelled');
      return;
    }
    print('URIs: ${result.images}');
  } on DocScanException catch (e) {
    print('Error: ${e.code} - ${e.message}');
  }
}

Error handling

All scan methods throw DocScanException on failure. Error codes include:

Code	Description
NO_ACTIVITY	No foreground activity available (Android)
SCAN_IN_PROGRESS	Another scan is already running
SCAN_FAILED	The scan operation failed
PDF_CREATION_ERROR	Failed to create PDF (iOS)
PERMISSION_DENIED	Camera permission was denied (iOS)
UNSUPPORTED_PLATFORM	Feature not supported on this platform

Methods return null when the user cancels the scan.

Image format

The getScannedDocumentAsImages method accepts an optional imageFormat parameter:

Platform	ImageFormat.jpeg	ImageFormat.png
Android	JPEG (always, ML Kit default)	JPEG (ML Kit always returns JPEG)
iOS	JPEG (configurable quality)	PNG (lossless)

Default is ImageFormat.jpeg. On Android, ML Kit always returns JPEG regardless of this setting. On iOS, this controls the actual output format.

JPEG quality (iOS only)

When using ImageFormat.jpeg, you can control the compression quality on iOS with the quality parameter (0.0 to 1.0):

final result = await FlutterDocScanner().getScannedDocumentAsImages(
 imageFormat: ImageFormat.jpeg,
 quality: 0.7, // lower = smaller file, more compression
);

Default is 0.9. This parameter is ignored on Android (ML Kit controls quality) and when using ImageFormat.png.

Project Setup

Follow the steps below to set up your Flutter project on Android and iOS.

Android

Minimum Version Configuration

Ensure you meet the minimum version requirements to run the application on Android devices. In the android/app/build.gradle file, verify that minSdkVersion is at least 21. This setting specifies the minimum Android API level required to run your app, ensuring compatibility with a wide range of Android devices.

android {
    ...
    defaultConfig {
        ...
        minSdkVersion 21
        ...
    }
    ...
}

Google Play Services Requirement

This plugin uses ML Kit Document Scanner, which requires Google Play Services to be installed on the device. It will not work on devices without Google Play (e.g. Huawei devices with HMS, Amazon Fire tablets, custom ROMs without GApps). If Google Play Services are unavailable, the scanner will fail with a SCAN_FAILED error.

iOS

Minimum Version Configuration

Ensure you meet the minimum version requirements to run the application on iOS devices. In the ios/Podfile file, make sure the iOS platform version is at least 13.0. This setting specifies the minimum iOS version required to run your app, ensuring compatibility with a wide range of iOS devices.

platform :ios, '13.0'

Permission Configuration

Add a String property to the app's Info.plist file with the key NSCameraUsageDescription and the value as the description for why your app needs camera access. This step is required by Apple to explain to users why the app needs access to the camera, and it's crucial for App Store approval.

  <key>NSCameraUsageDescription</key>
  <string>Camera Permission Description</string>

Web

Currently, we have removed web support for this library. For document scanning on the web, you can use the following library: flutter_doc_scanner_web.

Issues and Feedback

Please file issues to send feedback or report a bug. Thank you!

License

The MIT License (MIT) Copyright (c) 2024 Shirsh Shukla

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Libraries

flutter_doc_scanner

flutter_doc_scanner_exception

flutter_doc_scanner_method_channel

flutter_doc_scanner_models

flutter_doc_scanner_platform_interface