barcode-scanning

@capacitor-mlkit/barcode-scanning

Unofficial Capacitor plugin for ML Kit Barcode Scanning.¹²

Features

• 🧩 Optional ready-to-use interface without webview customizations
• 🏎️ Extremely fast
• 📷 Scan multiple barcodes at once
• ⏺️ Define detection area
• 🏞️ Reading barcodes from images
• 🔦 Torch and Autofocus support
• 🔋 Supports Android and iOS

For a complete list of supported barcodes, see BarcodeFormat.

Demo

A working example can be found here: https://github.com/robingenz/capacitor-mlkit-plugin-demo

Android

Guides

• How to build an Ionic Barcode Scanner with Capacitor

Installation

npm install @capacitor-mlkit/barcode-scanning
npx cap sync

Android

Permissions

This API requires the following permissions be added to your AndroidManifest.xml before the application tag:

<!-- To get access to the camera. -->
<uses-permission android:name="android.permission.CAMERA" />
<!-- To get access to the flashlight. -->
<uses-permission android:name="android.permission.FLASHLIGHT"/>

You also need to add the following meta data in the application tag in your AndroidManifest.xml:

<meta-data android:name="com.google.mlkit.vision.DEPENDENCIES" android:value="barcode_ui"/>
<!-- To use multiple models: android:value="face,model2,model3" -->

Data Binding

Enable the databinding library by setting the dataBinding and enabled build options to true in your module-level (app-level) Gradle file (usually android/app/build.gradle):

android {
    ...
+    buildFeatures {
+        dataBinding true
+    }
+    dataBinding {
+        enabled = true
+    }
}

Variables

This plugin will use the following project variables (defined in your app’s variables.gradle file):

• $androidxCameraCamera2Version version of com.google.mlkit:barcode-scanning (default: 1.1.0)
• $androidxCameraCoreVersion version of com.google.mlkit:barcode-scanning (default: 1.1.0)
• $androidxCameraLifecycleVersion version of com.google.mlkit:barcode-scanning (default: 1.1.0)
• $androidxCameraViewVersion version of com.google.mlkit:barcode-scanning (default: 1.1.0)
• $mlkitBarcodeScanningVersion version of com.google.mlkit:barcode-scanning (default: 17.1.0)
• $playServicesCodeScannerVersion version of com.google.mlkit:barcode-scanning (default: 16.0.0)

iOS

Add the NSCameraUsageDescription key to the ios/App/App/Info.plist file, which tells the user why the app needs to use the camera:

+ <key>NSCameraUsageDescription</key>
+ <string>The app enables the scanning of various barcodes.</string>

Configuration

No configuration required for this plugin.

Demo

A working example can be found here: robingenz/capacitor-mlkit-plugin-demo

Usage

import {
  BarcodeScanner,
  BarcodeFormat,
  LensFacing,
} from '@capacitor-mlkit/barcode-scanning';

const startScan = async () => {
  // The camera is visible behind the WebView, so that you can customize the UI in the WebView.
  // However, this means that you have to hide all elements that should not be visible.
  // You can find an example in our demo repository.
  // In this case we set a class `barcode-scanner-active`, which then contains certain CSS rules for our app.
  document.querySelector('body')?.classList.add('barcode-scanner-active');

  // Add the `barcodeScanned` listener
  const listener = await BarcodeScanner.addListener(
    'barcodeScanned',
    async result => {
      console.log(result.barcode);
    },
  );

  // Start the barcode scanner
  await BarcodeScanner.startScan();
};

const stopScan = async () => {
  // Make all elements in the WebView visible again
  document.querySelector('body')?.classList.remove('barcode-scanner-active');

  // Remove all listeners
  await BarcodeScanner.removeAllListeners();

  // Stop the barcode scanner
  await BarcodeScanner.stopScan();
};

const scanSingleBarcode = async () => {
  return new Promise(async resolve => {
    document.querySelector('body')?.classList.add('barcode-scanner-active');

    const listener = await BarcodeScanner.addListener(
      'barcodeScanned',
      async result => {
        await listener.remove();
        document
          .querySelector('body')
          ?.classList.remove('barcode-scanner-active');
        await BarcodeScanner.stopScan();
        resolve(result.barcode);
      },
    );

    await BarcodeScanner.startScan();
  });
};

const scan = async () => {
  const { barcodes } = await BarcodeScanner.scan({
    formats: [BarcodeFormat.QrCode],
  });
  return barcodes;
};

const isSupported = async () => {
  const { supported } = await BarcodeScanner.isSupported();
  return supported;
};

const enableTorch = async () => {
  await BarcodeScanner.enableTorch();
};

const disableTorch = async () => {
  await BarcodeScanner.disableTorch();
};

const toggleTorch = async () => {
  await BarcodeScanner.toggleTorch();
};

const isTorchEnabled = async () => {
  const { enabled } = await BarcodeScanner.isTorchEnabled();
  return enabled;
};

const isTorchAvailable = async () => {
  const { available } = await BarcodeScanner.isTorchAvailable();
  return available;
};

const setZoomRatio = async () => {
  await BarcodeScanner.setZoomRatio({ zoomRatio: 0.5 });
};

const getZoomRatio = async () => {
  const { zoomRatio } = await BarcodeScanner.getZoomRatio();
  return zoomRatio;
};

const getMinZoomRatio = async () => {
  const { zoomRatio } = await BarcodeScanner.getMinZoomRatio();
  return zoomRatio;
};

const getMaxZoomRatio = async () => {
  const { zoomRatio } = await BarcodeScanner.getMaxZoomRatio();
  return zoomRatio;
};

const openSettings = async () => {
  await BarcodeScanner.openSettings();
};

const isGoogleBarcodeScannerModuleAvailable = async () => {
  const { available } =
    await BarcodeScanner.isGoogleBarcodeScannerModuleAvailable();
  return available;
};

const installGoogleBarcodeScannerModule = async () => {
  await BarcodeScanner.installGoogleBarcodeScannerModule();
};

const checkPermissions = async () => {
  const { camera } = await BarcodeScanner.checkPermissions();
  return camera;
};

const requestPermissions = async () => {
  const { camera } = await BarcodeScanner.requestPermissions();
  return camera;
};

An example of the CSS class barcode-scanner-active with Ionic Framework could be:

// Hide all elements
body.barcode-scanner-active {
  visibility: hidden;
  --background: transparent;
  --ion-background-color: transparent;
}

// Show only the barcode scanner modal
.barcode-scanner-modal {
  visibility: visible;
}

@media (prefers-color-scheme: dark) {
  .barcode-scanner-modal {
    --background: transparent;
    --ion-background-color: transparent;
  }
}

An example of the CSS class barcode-scanner-active without Ionic Framework could be:

// Hide all elements
body.barcode-scanner-active {
  visibility: hidden;
}

// Show only the barcode scanner modal
.barcode-scanner-modal {
  visibility: visible;
}

If you can't see the camera view, make sure all elements in the DOM are not visible or have a transparent background to debug the issue.

API

• startScan(...)
• stopScan()
• readBarcodesFromImage(...)
• scan(...)
• isSupported()
• enableTorch()
• disableTorch()
• toggleTorch()
• isTorchEnabled()
• isTorchAvailable()
• setZoomRatio(...)
• getZoomRatio()
• getMinZoomRatio()
• getMaxZoomRatio()
• openSettings()
• isGoogleBarcodeScannerModuleAvailable()
• installGoogleBarcodeScannerModule()
• checkPermissions()
• requestPermissions()
• addListener('barcodeScanned', ...)
• addListener('scanError', ...)
• addListener('googleBarcodeScannerModuleInstallProgress', ...)
• removeAllListeners()
• Interfaces
• Type Aliases
• Enums

startScan(...)

startScan(options?: StartScanOptions | undefined) => Promise<void>

Start scanning for barcodes.

Only available on Android and iOS.

Param	Type
options	StartScanOptions

Since: 0.0.1

---

stopScan()

stopScan() => Promise<void>

Stop scanning for barcodes.

Only available on Android and iOS.

Since: 0.0.1

---

readBarcodesFromImage(...)

readBarcodesFromImage(options: ReadBarcodesFromImageOptions) => Promise<ReadBarcodesFromImageResult>

Read barcodes from an image.

Only available on Android and iOS.

Param	Type
options	ReadBarcodesFromImageOptions

Returns: Promise<ReadBarcodesFromImageResult>

Since: 0.0.1

---

scan(...)

scan(options?: ScanOptions | undefined) => Promise<ScanResult>

Scan a barcode with a ready-to-use interface without WebView customization.

On Android, this method is only available on devices with Google Play Services installed. Therefore, no camera permission is required.

Attention: Before using this method on Android, first check if the Google Barcode Scanner module is available by using isGoogleBarcodeScannerModuleAvailable().

Only available on Android and iOS.

Param	Type
options	ScanOptions

Returns: Promise<ScanResult>

Since: 0.0.1

---

isSupported()

isSupported() => Promise<IsSupportedResult>

Returns whether or not the barcode scanner is supported.

Available on Android and iOS.

Returns: Promise<IsSupportedResult>

Since: 0.0.1

---

enableTorch()

enableTorch() => Promise<void>

Enable camera's torch (flash) during a scan session.

Only available on Android and iOS.

Since: 0.0.1

---

disableTorch()

disableTorch() => Promise<void>

Disable camera's torch (flash) during a scan session.

Only available on Android and iOS.

Since: 0.0.1

---

toggleTorch()

toggleTorch() => Promise<void>

Toggle camera's torch (flash) during a scan session.

Only available on Android and iOS.

Since: 0.0.1

---

isTorchEnabled()

isTorchEnabled() => Promise<IsTorchEnabledResult>

Returns whether or not the camera's torch (flash) is enabled.

Only available on Android and iOS.

Returns: Promise<IsTorchEnabledResult>

Since: 0.0.1

---

isTorchAvailable()

isTorchAvailable() => Promise<IsTorchAvailableResult>

Returns whether or not the camera's torch (flash) is available.

Only available on Android and iOS.

Returns: Promise<IsTorchAvailableResult>

Since: 0.0.1

---

setZoomRatio(...)

setZoomRatio(options: SetZoomRatioOptions) => Promise<void>

Set the zoom ratio of the camera.

Only available on Android and iOS.

Param	Type
options	SetZoomRatioOptions

Since: 5.4.0

---

getZoomRatio()

getZoomRatio() => Promise<GetZoomRatioResult>

Get the zoom ratio of the camera.

Only available on Android and iOS.

Returns: Promise<GetZoomRatioResult>

Since: 5.4.0

---

getMinZoomRatio()

getMinZoomRatio() => Promise<GetMinZoomRatioResult>

Get the minimum zoom ratio of the camera.

Only available on Android and iOS.

Returns: Promise<GetMinZoomRatioResult>

Since: 5.4.0

---

getMaxZoomRatio()

getMaxZoomRatio() => Promise<GetMaxZoomRatioResult>

Get the maximum zoom ratio of the camera.

Only available on Android and iOS.

Returns: Promise<GetMaxZoomRatioResult>

Since: 5.4.0

---

openSettings()

openSettings() => Promise<void>

Open the settings of the app so that the user can grant the camera permission.

Only available on Android and iOS.

Since: 0.0.1

---

isGoogleBarcodeScannerModuleAvailable()

isGoogleBarcodeScannerModuleAvailable() => Promise<IsGoogleBarcodeScannerModuleAvailableResult>

Check if the Google Barcode Scanner module is available.

If the Google Barcode Scanner module is not available, you can install it by using installGoogleBarcodeScannerModule().

Only available on Android.

Returns: Promise<IsGoogleBarcodeScannerModuleAvailableResult>

Since: 5.1.0

---

installGoogleBarcodeScannerModule()

installGoogleBarcodeScannerModule() => Promise<void>

Install the Google Barcode Scanner module.

Attention: This only starts the installation. The googleBarcodeScannerModuleInstallProgress event listener will notify you when the installation is complete.

Only available on Android.

Since: 5.1.0

---

checkPermissions()

checkPermissions() => Promise<PermissionStatus>

Check camera permission.

Only available on Android and iOS.

Returns: Promise<PermissionStatus>

Since: 0.0.1

---

requestPermissions()

requestPermissions() => Promise<PermissionStatus>

Request camera permission.

Only available on Android and iOS.

Returns: Promise<PermissionStatus>

Since: 0.0.1

---

addListener('barcodeScanned', ...)

addListener(eventName: 'barcodeScanned', listenerFunc: (event: BarcodeScannedEvent) => void) => Promise<PluginListenerHandle>

Called when a barcode is scanned.

Available on Android and iOS.

Param	Type
eventName	'barcodeScanned'
listenerFunc	(event: BarcodeScannedEvent) => void

Returns: Promise<PluginListenerHandle>

Since: 0.0.1

---

addListener('scanError', ...)

addListener(eventName: 'scanError', listenerFunc: (event: ScanErrorEvent) => void) => Promise<PluginListenerHandle>

Called when an error occurs during the scan.

Available on Android and iOS.

Param	Type
eventName	'scanError'
listenerFunc	(event: ScanErrorEvent) => void

Returns: Promise<PluginListenerHandle>

Since: 0.0.1

---

addListener('googleBarcodeScannerModuleInstallProgress', ...)

addListener(eventName: 'googleBarcodeScannerModuleInstallProgress', listenerFunc: (event: GoogleBarcodeScannerModuleInstallProgressEvent) => void) => Promise<PluginListenerHandle>

Called when the Google Barcode Scanner module is installed.

Available on Android.

Param	Type
eventName	'googleBarcodeScannerModuleInstallProgress'
listenerFunc	(event: GoogleBarcodeScannerModuleInstallProgressEvent) => void

Returns: Promise<PluginListenerHandle>

Since: 5.1.0

---

removeAllListeners()

removeAllListeners() => Promise<void>

Remove all listeners for this plugin.

Since: 0.0.1

---

Interfaces

StartScanOptions

Prop	Type	Description	Since
formats	BarcodeFormat[]	Improve the speed of the barcode scanner by configuring the barcode formats to scan for.	0.0.1
lensFacing	LensFacing	Configure the camera (front or back) to use.	0.0.1

ReadBarcodesFromImageResult

Prop	Type	Description	Since
barcodes	Barcode[]	The detected barcodes.	0.0.1

Barcode

Prop	Type	Description	Since
bytes	number[]	Raw bytes as it was encoded in the barcode.	0.0.1
cornerPoints	[[number, number], [number, number], [number, number], [number, number]]	The four corner points of the barcode in clockwise order starting with top-left. This property is currently only supported by the startScan(...) method.	0.0.1
displayValue	string	The barcode value in a human readable format.	0.0.1
format	BarcodeFormat	The barcode format.	0.0.1
rawValue	string	The barcode value in a machine readable format.	0.0.1
valueType	BarcodeValueType	The barcode value type.	0.0.1

ReadBarcodesFromImageOptions

Prop	Type	Description	Since
formats	BarcodeFormat[]	Improve the speed of the barcode scanner by configuring the barcode formats to scan for.	0.0.1
path	string	The local path to the image file.	0.0.1

ScanResult

Prop	Type	Description	Since
barcodes	Barcode[]	The detected barcodes.	0.0.1

ScanOptions

Prop	Type	Description	Since
formats	BarcodeFormat[]	Improve the speed of the barcode scanner by configuring the barcode formats to scan for.	0.0.1

IsSupportedResult

Prop	Type	Description	Since
supported	boolean	Whether or not the barcode scanner is supported by checking if the device has a camera.	0.0.1

IsTorchEnabledResult

Prop	Type	Description	Since
enabled	boolean	Whether or not the torch is enabled.	0.0.1

IsTorchAvailableResult

Prop	Type	Description	Since
available	boolean	Whether or not the torch is available.	0.0.1

SetZoomRatioOptions

Prop	Type	Description	Since
zoomRatio	number	The zoom ratio to set.	5.4.0

GetZoomRatioResult

Prop	Type	Description	Since
zoomRatio	number	The zoom ratio.	5.4.0

GetMinZoomRatioResult

Prop	Type	Description	Since
zoomRatio	number	The minimum zoom ratio.	5.4.0

GetMaxZoomRatioResult

Prop	Type	Description	Since
zoomRatio	number	The maximum zoom ratio.	5.4.0

IsGoogleBarcodeScannerModuleAvailableResult

Prop	Type	Description	Since
available	boolean	Whether or not the Google Barcode Scanner module is available.	5.1.0

PermissionStatus

Prop	Type	Since
camera	CameraPermissionState	0.0.1

PluginListenerHandle

Prop	Type
remove	() => Promise<void>

BarcodeScannedEvent

Prop	Type	Description	Since
barcode	Barcode	A detected barcode.	0.0.1

ScanErrorEvent

Prop	Type	Description	Since
message	string	The error message.	0.0.1

GoogleBarcodeScannerModuleInstallProgressEvent

Prop	Type	Description	Since
state	GoogleBarcodeScannerModuleInstallState	The current state of the installation.	5.1.0
progress	number	The progress of the installation in percent between 0 and 100.	5.1.0

Type Aliases

CameraPermissionState

PermissionState | 'limited'

PermissionState

'prompt' | 'prompt-with-rationale' | 'granted' | 'denied'

Enums

BarcodeFormat

Members	Value	Description	Since
Aztec	'AZTEC'	Only available on Android and iOS.	0.0.1
Codabar	'CODABAR'	Only available on Android and iOS.	0.0.1
Code39	'CODE_39'	Only available on Android and iOS.	0.0.1
Code93	'CODE_93'	Only available on Android and iOS.	0.0.1
Code128	'CODE_128'	Only available on Android and iOS.	0.0.1
DataMatrix	'DATA_MATRIX'	Only available on Android and iOS.	0.0.1
Ean8	'EAN_8'	Only available on Android and iOS.	0.0.1
Ean13	'EAN_13'	Only available on Android and iOS.	0.0.1
Itf	'ITF'	Only available on Android and iOS.	0.0.1
Pdf417	'PDF_417'	Only available on Android and iOS.	0.0.1
QrCode	'QR_CODE'	Only available on Android and iOS.	0.0.1
UpcA	'UPC_A'	Only available on Android and iOS.	0.0.1
UpcE	'UPC_E'	Only available on Android and iOS.	0.0.1

LensFacing

Members	Value	Since
Front	'FRONT'	0.0.1
Back	'BACK'	0.0.1

BarcodeValueType

Members	Value	Since
CalendarEvent	'CALENDAR_EVENT'	0.0.1
ContactInfo	'CONTACT_INFO'	0.0.1
DriversLicense	'DRIVERS_LICENSE'	0.0.1
Email	'EMAIL'	0.0.1
Geo	'GEO'	0.0.1
Isbn	'ISBN'	0.0.1
Phone	'PHONE'	0.0.1
Product	'PRODUCT'	0.0.1
Sms	'SMS'	0.0.1
Text	'TEXT'	0.0.1
Url	'URL'	0.0.1
Wifi	'WIFI'	0.0.1
Unknown	'UNKNOWN'	0.0.1

GoogleBarcodeScannerModuleInstallState

Members	Value	Since
UNKNOWN	0	5.1.0
PENDING	1	5.1.0
DOWNLOADING	2	5.1.0
CANCELED	3	5.1.0
COMPLETED	4	5.1.0
FAILED	5	5.1.0
INSTALLING	6	5.1.0
DOWNLOAD_PAUSED	7	5.1.0

Common Issues

NullPointerException during startScan(...)

The following error may occur when calling the startScan(...) method: Attempt to invoke virtual method 'void androidx.camera.view.PreviewView.setScaleType(androidx.camera.view.PreviewView$ScaleType)' on a null object reference. In this case, make sure that the databinding library is enabled (see Data Binding).

Terms & Privacy

This plugin uses the Google ML Kit:

• Terms & Privacy
• Android Data Disclosure
• iOS Data Disclosure

Changelog

See CHANGELOG.md.

License

See LICENSE.

Footnotes

1. This project is not affiliated with, endorsed by, sponsored by, or approved by Google LLC or any of their affiliates or subsidiaries. ↩

2. QR Code is a registered trademark of DENSO WAVE INCORPORATED. ↩