Use a low light boost session
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Use a low light boost session to turn Google Low Light Boost on and off.

Kotlin

dependencies {
  val low_light_boost_version = "16.0.0-beta01"
  implementation("org.jetbrains.kotlinx:kotlinx-coroutines-play-services:1.10.2")
  implementation("com.google.android.gms:play-services-base:18.7.0")
  implementation("com.google.android.gms:play-services-camera-low-light-boost:${low_light_boost_version}")
  implementation("com.google.android.gms:play-services-tasks:18.3.0")
}

Groovy

dependencies {
  def low_light_boost_version = "16.0.0-beta01"
  implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-play-services:1.10.2'
  implementation 'com.google.android.gms:play-services-base:18.7.0'
  implementation 'com.google.android.gms:play-services-camera-low-light-boost:${low_light_boost_version}'
  implementation 'com.google.android.gms:play-services-tasks:18.3.0'
}

LowLightBoostSession is provided by the Google Play services com.google.android.gms.cameralowlight package. See the Google Play services documentation for information on accessing Google Play services APIs.

Create a callback object

When you create the low light boost session, you'll need to pass it an object that implements the LowLightBoostCallback interface. This object's functions are called when the session is disconnected or destroyed. The following code shows how to create a callback:

Kotlin

private fun createLowLightBoostCallback(): LowLightBoostCallback =
  object : LowLightBoostCallback() {
    override fun onSessionDestroyed() {
      Log.d(TAG, "onSessionDestroyed")
      lowLightBoostSession = null
    }

    override fun onSessionDisconnected(statusCode: Int) {
      Log.d(TAG, "onSessionDisconnected: error=$statusCode")
      lowLightBoostSession = null
    }
  }

Java

private LowLightBoostCallback createLowLightBoostCallback() {
  LowLightBoostCallback lowLightBoostCallback = new LowLightBoostCallback() {
    @Override
    public void onSessionDestroyed() {
      Log.d(TAG, "onSessionDestroyed");
      lowLightBoostSession = null;
    }

    @Override
    public void onSessionDisconnected(int statusCode) {
      Log.d(TAG, "onSessionCreationFailed: error=" + statusCode);
      lowLightBoostSession = null;
    }
  }
  return lowLightBoostCallback;
}

Key points about this code

This code defines a private method, createLowLightBoostCallback(), which creates the callback object. You'll call that method when you actually create the low light boost session, as described in Create a session.
The callback is called when the session is disconnected or destroyed. It is not called when the session is created. To check whether the session was successfully created, examine the Task object returned by LowLightBoostClient.createSession.

Create a session

To create a low light session, call the method LowLightBoostClient.createSession.

Kotlin

val options = LowLightBoostOptions(
  previewSurface,
  cameraId,
  previewWidth,
  previewHeight,
  enableLowLightBoost
)

launch {
  try {
    val lowLightBoostSession = lowLightBoostClient
      .createSession(options, createLowLightBoostCallback()).await()

    Log.d(TAG, "Session created successfully")

    // Get the surface from the LLB session;
    // give it to camera so camera can write frames to it
  } catch (e: CancellationException) {
    Log.w(TAG, "Session creation was canceled", e)
    lowLightBoostSession = null
  } catch (e: ApiException) {
    Log.e(TAG, "Session creation failed with ApiException:", e)
    lowLightBoostSession = null
  } catch (e: Exception) {
    Log.e(TAG, "Session creation failed with Exception", e)
    lowLightBoostSession = null
  }
}

Java

LowLightBoostOptions options = new LowLightBoostOptions(
  previewSurface,
  cameraId,
  previewWidth,
  previewHeight,
  enableLowLightBoost);

lowLightBoostClient
  .createSession(options, createLowLightBoostCallback())
  .addOnSuccessListener(
    lowLightBoostExecutor,
    (session) -> {
      Log.d(TAG, "Session created successfully");

      // Get the surface from the LLB session;
      // give it to camera so camera can write frames to it

    })
  .addOnFailureListener(
    lowLightBoostExecutor,
    (e) -> {
      ApiException apiException = (ApiException) e;
      Log.d(TAG, "Session creation failed: " + e);
      lowLightBoostSession = null;
    })
  .addOnCompleteListener(
    lowLightBoostExecutor,
    (task) -> Log.d(TAG, "Session creation complete"))
  .addOnCanceledListener(
    lowLightBoostExecutor,
    () -> {
      throw new RuntimeException("Session creation canceled");
    });

Key points about this code

You pass a LowLightBoostOptions object to createSession() to configure the session. This object specifies such things as the target surface, the ID of the camera to use, and the dimensions of the preview.
This code assumes you have already opened a connection to a Camera2 camera, and used that information to set the values of cameraId, previewWidth, previewHeight. For more information, see the Camera2 documentation.
enableLowLightBoost is a boolean value specifying whether low light boost should start on or off.
createLowLightBoostCallback is a method you write to create the callback object. This object is called when the session is disconnected or destroyed.
The method LowLightBoostClient.createSession() returns a Task object. You use this object to set up success and failure listeners. Capture the video inside the success listener.
You can specify an Executor to run the listeners. If you don't specify an Executor, the listeners run on the main thread. In this code, we assume lowLightBoostExecutor is a suitable Executor.

Start camera preview

Once you have created a low light session, you can start the camera preview stream. You should do this inside the onSuccess() callback you pass to the low light session, as described in Create a session. The following code shows how to capture video:

Kotlin

MainActivity.this.lowLightBoostSession =
  lowLightBoostSession
MainActivity.this.lowLightBoostSession
  .setSceneDetectorCallback(
    (lowLightBoostSession, boostStrength) -> {
      Log.d(TAG, "onSceneBrightnessChanged: " +
        "boostStrength=$boostStrength")
      // boostStrength > 0.5 indicates a low light scene.
      // Update UI accordingly.
    },
    lowLightBoostExecutor
  )
try {
  startCaptureSession(
    lowLightBoostSession.getCameraSurface())
    // Start a Camera2 session here. Pass the LLB surface
    // to the camera so the camera can write frames to it.
} catch (e: CameraAccessException) {
  Log.e(TAG, "Failed to start capture session", e)
  // Must try again or start the capture session without LLB.
}

Java

MainActivity.this.lowLightBoostSession =
  lowLightBoostSession;
MainActivity.this.lowLightBoostSession
  .setSceneDetectorCallback(
    (lowLightBoostSession, boostStrength) -> {
      Log.d(TAG, "onSceneBrightnessChanged: " +
        "boostStrength=" + boostStrength);
      // boostStrength > 0.5 indicates a low light scene.
      // Update UI accordingly.
    },
    lowLightBoostExecutor
  );
try {
  startCaptureSession(
    lowLightBoostSession.getCameraSurface());
    // Start a Camera2 session here. Pass the LLB surface
    // to the camera so the camera can write frames to it.
} catch (CameraAccessException e) {
  Log.e(TAG, "Failed to start capture session", e);
  // Must try again or start the capture session without LLB.
}

Key points about this code

lowLightBoostSession is the session you created in Create a session.
setSceneDetectorCallback() defines a callback object implementing the SceneDetectorCallback interface. The session calls that object's onSceneBrightnessChanged() method when the scene brightness changes. Your implementation should adjust the camera's UI appropriately.
You can specify an Executor to run the callback. If you don't specify an Executor, the callback runs on the main thread. In this code, we assume lowLightBoostExecutor is a suitable Executor.
lowLightBoostSession.getCameraSurface() returns the Surface with the captured video.

Release the session

When the camera is no longer active, release the low light boost session by calling LowLightBoostSession.release(). In particular, you should make sure to release the session when your activity is destroyed. You can do this by calling the method in your activity's onDestroy() method:

Kotlin

override protected void onDestroy() {
  super.onDestroy()
  if (lowLightBoostSession != null) {
    lowLightBoostSession.release()
    lowLightBoostSession = null
  }
}

Java

@Override
protected void onDestroy() {
  super.onDestroy();
  if (lowLightBoostSession != null) {
    lowLightBoostSession.release();
    lowLightBoostSession = null;
  }
}

Key points about this code

After the session is released, you shouldn't call any of its methods. You should clear any variables pointing to the session, as this code does.

Use a low light boost session Stay organized with collections Save and categorize content based on your preferences.

Kotlin

Groovy

Create a callback object

Kotlin

Java

Key points about this code

Create a session

Kotlin

Java

Key points about this code

Start camera preview

Kotlin

Java

Key points about this code

Release the session

Kotlin

Java

Key points about this code

Use a low light boost session
Stay organized with collections Save and categorize content based on your preferences.