@fesoares/react-native-document-scanner

Live document detection library. Returns either a URI of the captured image, allowing you to easily store it or use it as you wish!

• Live detection
• Perspective correction and crop of the image
• Flash

Getting started

Version >=2.0.0 is thinking to work with React Native >= 0.60

Use version 1.6.2 if you are using React Native 0.59

Install the library using either yarn:

yarn add @fesoares/react-native-document-scanner`

or npm:

npm install @fesoares/react-native-document-scanner --save

Remember, this library uses your device's camera, it cannot run on a simulator and you must request camera permission by your own.

iOS Only

CocoaPods on iOS needs this extra step:

cd ios && pod install && cd ..

Android Only

If you do not have it already in your project, you must link openCV in your settings.gradle file

include ':openCVLibrary310'
project(':openCVLibrary310').projectDir = new File(rootProject.projectDir,'../node_modules/@fesoares/react-native-document-scanner/android/openCVLibrary310')

In android/app/src/main/AndroidManifest.xml

Change manifest header to avoid "Manifest merger error". After you add xmlns:tools="http://schemas.android.com/tools" should look like this:

<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.<yourAppName>" xmlns:tools="http://schemas.android.com/tools">

Add tools:replace="android:allowBackup" in <application tag. It should look like this:

<application tools:replace="android:allowBackup" android:name=".MainApplication" android:label="@string/app_name" android:icon="@mipmap/ic_launcher" android:allowBackup="false" android:theme="@style/AppTheme">

Add Camera permissions request:

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

Usage

import React, { Component, useRef } from "react"
import { View, Image } from "react-native"

import DocumentScanner from "@fesoares/react-native-document-scanner"

function YourComponent(props) {
  return (
    <View>
      <DocumentScanner
        style={styles.scanner}
        onPictureTaken={handleOnPictureTaken}
        overlayColor="rgba(255,130,0, 0.7)"
        enableTorch={false}
        quality={0.5}
        detectionCountBeforeCapture={5}
        detectionRefreshRateInMS={50}
      />
    </View>
  )
}

Full example in example folder.

Properties

Prop	Platform	Default	Type	Description
overlayColor	Both	none	string	Color of the detected rectangle : rgba recommended
detectionCountBeforeCapture	Both	5	integer	Number of correct rectangle to detect before capture
detectionRefreshRateInMS	iOS	50	integer	Time between two rectangle detection attempt
enableTorch	Both	false	bool	Allows to active or deactivate flash during document detection
useFrontCam	iOS	false	bool	Allows you to switch between front and back camera
brightness	iOS	0	float	Increase or decrease camera brightness. Normal as default.
saturation	iOS	1	float	Increase or decrease camera saturation. Set 0 for black & white
contrast	iOS	1	float	Increase or decrease camera contrast. Normal as default
quality	iOS	0.8	float	Image compression. Reduces both image size and quality
useBase64	iOS	false	bool	If base64 representation should be passed instead of image uri's
saveInAppDocument	iOS	false	bool	If should save in app document in case of not using base 64
captureMultiple	iOS	false	bool	Keeps the scanner on after a successful capture
saveOnDevice	Android	false	bool	Save the image in the device storage (Need storage permissions)

Manual capture

• First create a mutable ref object:

const documentScannerElement = useRef(null)

• Pass a ref object to your component:

<DocumentScanner ref={documentScannerElement} />

• Then call:

documentScannerElement.current.capture()

Each rectangle detection (iOS only) -Non tested-

Props	Params	Type	Description
onRectangleDetect	{ stableCounter, lastDetectionType }	object	See below

The returned object includes the following keys :

• stableCounter

Number of correctly formated rectangle found (this number triggers capture once it goes above detectionCountBeforeCapture)

• lastDetectionType

Enum (0, 1 or 2) corresponding to the type of rectangle found

0. Correctly formated rectangle
1. Wrong perspective, bad angle
2. Too far

Returned image

Prop	Params	Type	Description
onPictureTaken	data	object	Returns the captured image in an object { croppedImage: ('URI or BASE64 string'), initialImage: 'URI or BASE64 string', rectangleCoordinates[only iOS]: 'object of coordinates' }

Save in app document -Non tested-

If you want to use saveInAppDocument options, then don't forget to add those raws in .plist :

<key>LSSupportsOpeningDocumentsInPlace</key>
<true/>

Contributors

Set up dev environment

Medium article