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Demo gif

React Native Document Scanner

Live document detection library. Returns either a URI or a base64 encoded string of the captured image, allowing you to easily store it or use it as you wish !

Features :

  • Live detection
  • Perspective correction and crop of the image
  • Live camera filters (brightness, saturation, contrast)
  • Flash
  • Easy to use base64 image

Can be easily plugged with react-native-perspective-image-cropper

Demo crop gif

Both Platform

Use version >=1.4.1 if you are using react-native 0.48+

$ yarn add https://github.com/Michaelvilleneuve/react-native-document-scanner

$ react-native link react-native-document-scanner

Edit the info.plist file in XCode and add the following permission : NSCameraUsageDescription

Remember, this library uses your device camera, you can't run it on a simulator.

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/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 } from "react";
import { View, Image } from "react-native";

import DocumentScanner from "react-native-document-scanner";

class YourComponent extends Component {
  render() {
    return (
      <View>
        <DocumentScanner
          useBase64
          saveInAppDocument={false}
          onPictureTaken={data =>
            this.setState({
              image: data.croppedImage,
              initialImage: data.initialImage,
              rectangleCoordinates: data.rectangleCoordinates
            })
          }
          overlayColor="rgba(255,130,0, 0.7)"
          enableTorch={false}
          brightness={0.3}
          saturation={1}
          contrast={1.1}
          quality={0.5}
          onRectangleDetect={({ stableCounter, lastDetectionType }) =>
            this.setState({ stableCounter, lastDetectionType })
          }
          detectionCountBeforeCapture={5}
          detectionRefreshRateInMS={50}
          onPermissionsDenied={() => console.log("Permissions Denied")}
        />
        <Image
          source={{ uri: `data:image/jpeg;base64,${this.state.image}` }}
          resizeMode="contain"
        />
      </View>
    );
  }
}

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
onPermissionsDenied android null func Function to call when the Android permissions are denied

Manual capture

  • First get component ref
<DocumentScanner ref={ref => (this.scanner = ref)} />
  • Then call :
this.scanner.capture();

Each rectangle detection (iOS only)

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

  1. Correctly formated rectangle
  2. Wrong perspective, bad angle
  3. 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: 'object of coordinates' }

Save in app document

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

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