QR Mobile Vision

pub package

Reading QR codes and other barcodes using Firebase's Mobile Vision API.

UPDATE - Now using Firebase since apps using GoogleMobileVision have become unreleaseable on iOS.

This plugin uses Android & iOS native APIs for reading images from the device's camera. It then pipes these images both to the Firebase Mobile Vision API which detects barcodes/qrcodes etc, and outputs a preview image to be shown on a flutter texture.

The plugin includes a widget which performs all needed transformations on the camera output to show within the defined area.

If you are only targeting android and don't want to switch to Firebase Mobile Vision from Google Mobile Vision, use a 0.* version of the plugin.

If you target iOS as well but don't want to integrate Firebase (and like this plugin over other ones available on pub.dev) please head over to this issue and give it a +1, as that will tell the developer how much interest there is in it.

Setting up Firebase

If you're using firebase elsewhere in your app, you should be able to simply use this plugin. However, if you're not, you'll have to follow steps 1, 2, and 3 from Firebase's Flutter instructions, which include setting up projects in Firebase and

For android, that's all you need to do - the library doesn't seem to actually need initialization.

For iOS, you need to make sure that FirebaseApp.configure() is called somewhere before the plugin is used - for instance, in your app's AppDelegate. The example app does this.

Usage

See the example for how to use this plugin; it is the best resource available as it shows the plugin in use. However, these are the steps you need to take to use this plugin.

First, figure out the area that you want the camera preview to be shown in. This is important as the preview needs to have a constrained size or it won't be able to build. This is required due to the complex nature of the transforms needed to get the camera preview to show correctly on both iOS and Android, while still working with the screen rotated etc.

It may be possible to get the camera preview to work without putting it in a SizedBox or Container, but the recommended way is to put it in a SizedBox or Container.

You then need to include the package and instantiate the camera.

import 'package:qr_mobile_vision/qr_camera.dart';

...

new SizedBox(
  width: 300.0,
  height: 600.0,
  child: new QrCamera(
    qrCodeCallback: (code) {
      ...
    },
  ),
)

The QrCodeCallback can do anything you'd like, and wil keep receiving QR codes until the camera is stopped.

There are also optional parameters to QrCamera.

fit

Takes as parameter the flutter BoxFit. Setting this to different values should get the preview image to fit in different ways, but only BoxFit = cover has been tested extensively.

notStartedBuilder

A callback that must return a widget if defined. This should build whatever you want to show up while the camera is loading (which can take from milliseconds to seconds depending on the device).

child

Widget that is shown on top of the QrCamera. If you give it a specific size it may cause weird issues so try not to.

key

Standard flutter key argument. Can be used to get QrCameraState with a GlobalKey.

offscreenBuilder

A callback that must return a widget if defined. This should build whatever you want to show up when the camera view is 'offscreen'. i.e. when the app is paused. May or may not show up in preview of app.

onError

Callback for if there's an error.

formats

A list of supported formats, all by default. If you use all, you shouldn't define any others.

These are the supported types:

  ALL_FORMATS,
  AZTEC,
  CODE_128,
  CODE_39,
  CODE_93,
  CODABAR,
  DATA_MATRIX,
  EAN_13,
  EAN_8,
  ITF,
  PDF417,
  QR_CODE,
  UPC_A,
  UPC_E

Push and Pop

If you push a new widget on top of a the current page using the navigator, the camera doesn't necessarily know about it.

Contributions

Anyone wanting to contribute to this project is very welcome to! I'll take a look at PR's as soon as I can, and any bug reports are appreciated. I've only a few devices on which to test this so feedback about other devices is appreciated as well.

This has been tested on:

  • Nexus 5x
  • Nexus 4
  • Pixel 3a
  • iPhone 6

Libraries

qr_camera
qr_mobile_vision