This example uses CameraX's MlKitAnalyzer to perform QR Code scanning. For QR Codes that encode Urls, this app will prompt the user to open the Url in a broswer. This app can be adapted to handle other types of QR Code data.

The interesting part of the code is in MainActivity.kt in the startCamera() function. There, we set up BarcodeScannerOptions to match on QR Codes. Then we call cameraController.setImageAnalysisAnalyzer with an MlKitAnalyzer (available as of CameraX 1.2). We also pass in COORDINATE_SYSTEM_VIEW_REFERENCED so that CameraX will handle the cordinates coming off of the camera sensor, making it easy to draw a box around the QR Code. Finally, we create a QrCodeDrawable, which is a class defined in this sample, extending View, for displaying an overlay on the QR Code and handling tap events on the QR Code.

You can open this project in Android Studio to explore the code further, and to build and run the application on a test device.

To build the app directly from the command line, run:

./gradlew assembleDebug

Unit testing and instrumented device testing share the same code. To test the app using Robolectric, no device required, run:

./gradlew test

To run the same tests in an Android device connected via ADB, run:

./gradlew connectedAndroidTest

Alternatively, test running configurations can be added to Android Studio for convenience (and a nice UI). To do that:

1. Go to: Run > Edit Configurations > Add New Configuration.
2. For Robolectric select Android JUnit, for connected device select Android Instrumented Tests.
3. Select app module and com.android.example.cameraxbasic.MainInstrumentedTest class.
4. Optional: Give the run configuration a name, like test robolectric or test device