--- title: Spren Vision Android SDK slug: spren-vision/spren-vision-android-sdk description: Learn about the Android SDK in Alpha and its device support, including compatible and incompatible devices. Follow instructions for preparation and installation and discover code examples for using the Spren UI Finger Camera. Configure the SprenUI library docTags: createdAt: 2022-12-23T19:28:59.000Z --- The Android SDK is in Alpha. We're working quickly to expand our support in the heterogeneity of Android devices. ### Device Support and Recommendations ### Compatible Devices (Tested) :::BlockQuote There may be other compatible, but untested Android devices that are not contained in this list. ::: - Google Pixel 3XL, 4, 4a, 5, 6\*, 6 Pro\*, 7\*, 7 Pro\* - Xiaomi Redmi 9, Note 10 Pro - Huawei Mate 20 - Samsung Galaxy Note 9, A51, S9, S10, S10+, S20 FE, S21 Ultra, S22, S22+, S22 Ultra - Motorola Moto G 5G Plus (2020 model) - LG Velvet - OnePlus 7 Pro, 9 5G \*Devices with an asterisk are ones that use the wide angle camera for readings. All other devices use the default camera. ### Incompatible Devices (Tested) - Huawei P20 Lite - Redmi Note 11 - Google Pixel 6a ### Recommendations ### Flash Currently, we allow users to only perform readings with flash on. ### Hardware 1. We recommend using an Android device that is not a low RAM device, has at least 8 cores, and has 192MB or more RAM available to your app. ```kotlin val activityManager = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager val isHighPerformingDevice = !activityManager.isLowRamDevice && Runtime.getRuntime().availableProcessors() >= 8 && activityManager.memoryClass >= 192 ``` 2. 30FPS is acceptable, but for best accuracy and UX, we recommend devices that support 60FPS in CameraX. Note that 60FPS or better may be listed in manufacturer's device specifications, thus, be supported in the native camera app, but be unavailable to CameraX. ### End User 1. Rub fingertips and hands to warm up 2. Ensure adequate room lighting 3. Wait a few seconds for reading to initialize ### Installation 1. Visit the [Spren Vision Android SDK Maven Repository](https://search.maven.org/search?q=com.spren) to install the SDK via the Gradle build tool. We encourage using the latest remote binary available. For more information, see the Android docs for [Add build dependencies](https://developer.android.com/studio/build/dependencies). 2. Add a camera usage permission to your app's Manifest. For more information, [Request app permissions](https://developer.android.com/training/permissions/requesting). The open source code is available in the [Spren Vision Android SDK GitHub Repository](https://github.com/Elite-HRV/spren-vision-android). ### Spren UI ### Finger Camera Example ```kotlin // MainActivity.kt import com.spren.sprenui.SprenUI class MainActivity : AppCompatActivity() { private lateinit var binding: ActivityMainBinding private lateinit var hardwareAlert: HardwareAlert override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) // optionally set custom theme // theme inherits from "Theme.MaterialComponents.DayNight.NoActionBar" // see themes.xml example below setTheme(R.style.Theme_SprenUI) binding = ActivityMainBinding.inflate(layoutInflater) setContentView(binding.root) // optionally check if hardware is compatible hardwareAlert = HardwareAlert(this) if (!HardwareCheck.isHighPerformingDevice(this)) { hardwareAlert.show() } // set user ID SprenUI.Config.userId = ... // optionally set user biological sex SprenUI.Config.userGender = ... // optionally set user birthdate SprenUI.Config.userBirthdate = ... // after dismissing results screen SprenUI.Config.onFinish = { results, _ -> // handle completion of reading UI flow } // user presses X SprenUI.Config.onCancel = { // handle user exit of UI flow without completing a reading } // optionally override default intro screen graphics // provide drawable ids for image sets in project // *all are required for each project if overriding SprenUI.Config.graphics = mapOf( SprenUI.Graphic.GREETING_1 to , // greeting screen 1 SprenUI.Graphic.GREETING_2 to , // greeting screen 2 SprenUI.Graphic.FINGER_ON_CAMERA to , // finger on camera instruction screen SprenUI.Graphic.NO_CAMERA to , // camera access authorization denied screen SprenUI.Graphic.SERVER_ERROR to // server or calculation error ) } } ``` ### Body Composition Example ```kotlin // MainActivity.kt import com.spren.sprenui.SprenUI class MainActivity : AppCompatActivity() { private lateinit var binding: ActivityMainBinding private lateinit var hardwareAlert: HardwareAlert override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) // optionally set custom theme // theme inherits from "Theme.MaterialComponents.DayNight.NoActionBar" // see themes.xml example below setTheme(R.style.Theme_SprenUI) binding = ActivityMainBinding.inflate(layoutInflater) setContentView(binding.root) // optionally check if hardware is compatible hardwareAlert = HardwareAlert(this) if (!HardwareCheck.isHighPerformingDevice(this)) { hardwareAlert.show() } // set user ID SprenUI.Config.userId = ... // optionally set user biological sex SprenUI.Config.userGender = ... // optionally set user birthdate SprenUI.Config.userBirthdate = ... // after dismissing results screen SprenUI.Config.onFinish = { _, results -> // user completed a scan! print(results) // dismiss SprenUI } SprenUI.Config.onCancel = { // handle user exit of UI flow without completing a scan } // optionally override default intro screen graphics // provide drawable ids for image sets in project // *all are required for each project if overriding SprenUI.Config.graphics = mapOf( SprenUI.Graphic.GREETINGS to , SprenUI.Graphic.PRIVACY to , SprenUI.Graphic.CAMERA_ACCESS_DENIED , SprenUI.Graphic.PHOTOS_ACCESS_DENIED to , SprenUI.Graphic.SETUP_GUIDE to , SprenUI.Graphic.SERVER_ERROR to , SprenUI.Graphic.INCORRECT_BODY_POSITION to ) } } ``` ### Layout and Theme ```xml ``` ```xml ``` ### SprenCapture and SprenCore ### Implementation Example Here is an example of how to implement the Spren Vision Android SDK in your own app. Refer to the comments throughout the file to see what functions get called at what point. ```kotlin import com.spren.sprencapture.SprenCapture import com.spren.sprencore.* import com.spren.sprencore.finger.compliance.ComplianceCheck import com.spren.sprencore.event.SprenEvent import com.spren.sprencore.event.SprenEventManager /* SprenCapture */ // configure camera and set up camera preview sprenCapture = SprenCapture(activity, previewView.surfaceProvider) sprenCapture?.start() /* SprenCore */ // handle state transitions private fun stateListener(values: HashMap) { when (values["state"]) { SprenState.STARTED -> // handle reading started UI update startState() SprenState.FINISHED -> // successful reading! // make POST request to the Spren API // with readingData to get insights! finishState() SprenState.CANCELLED -> // handle user cancelled UI update cancelState() SprenState.ERROR -> // handle error UI update errorState() // call sprenCapture reset when the app is ready to start a new reading } } // Subscribe to state events SprenEventManager.subscribe(SprenEvent.STATE, ::stateListener) // Unsubscribe when leaving the flow SprenEventManager.unsubscribe(SprenEvent.STATE, ::stateListener) // handle prereading compliance checks private fun complianceListener(values: HashMap) { val name = values["name"] as ComplianceCheck.Name val compliant = values["isCompliant"] as Boolean when (name) { ComplianceCheck.Name.LENS_COVERAGE -> // optionally update UI to reflect lens coverage compliance handleLensCoverageCompliance( name, compliant, ) ComplianceCheck.Name.EXPOSURE -> // optionally update UI to reflect exposure compliance handleExposureCompliance( name, compliant, ) } } // Subscribe to compliance events SprenEventManager.subscribe(SprenEvent.COMPLIANCE, ::complianceListener) // Unsubscribe when leaving the flow SprenEventManager.unsubscribe(SprenEvent.COMPLIANCE, ::complianceListener) // handle progress changes private fun progressListener(values: HashMap){ // handle progress UI update val progress = values["progress"] as Int updateProgress(progress) } // Subscribe to progress events SprenEventManager.subscribe(SprenEvent.PROGRESS, ::progressListener) // Unsubscribe when leaving the flow SprenEventManager.unsubscribe(SprenEvent.PROGRESS, ::progressListener) ``` ### Breaking changes in 2.x ### `SprenCapture` `var autoStart = true` (Replace with `SprenCapture reset` method) Enable or disable reading autostart. Autostart occurs after 3 seconds of conditions checks compliance. ### `Spren` `fun setTorchMode(torch: Boolean): Boolean` (Replace with `fun turnFlashOn()`) Attempts to toggle the torch (flashlight) on as appropriate. Returns the resulting torch mode. Setting the flash off has been disabled. `fun dropComplexity(): Boolean` (no need to handle anymore) This function has been deprecated and will be removed in the next releases. `fun handleOverExposure()` (no need to handle anymore) Attempts to reduce the exposure of the image by lowering the sensor exposure time. This may be called if exposure is non-compliant, i.e, at least 5 frames are over-exposed. ### SprenCapture Library SprenCapture is where you can initialize a camera preview and first configure the camera. This will start a camera preview and image analysis, allow you to add the camera preview to your UI, and handle various other camera controls. Check out the function definitions below! ### `SprenCapture` `fun start(): Boolean` Attempts to create a Preview and ImageAnalysis use cases. Returns false when the camera does not support at least 30 FPS. For more information, see the Android docs for [CameraX overview](https://developer.android.com/training/camerax). `fun stop()` Stops the Preview and ImageAnalysis use cases `fun reset()` Starts or restarts a reading. Reading will start after 3 seconds of conditions checks compliance. This function needs to be called after `fun start(): Boolean` method and after subscribing to Spren Events `fun turnFlashOn()` Attempts to toggle the torch (flashlight) on. ### `RGBAnalyzer` RGBAnalyzer is an `ImageAnalysis.Analyzer` and handles providing frames to **SprenCore**. ### SprenCore Library The SprenCore library provides internal control over readings and allows you to gain information on what's going on internally in the SDK so your UI can be updated accordingly. Here you'll be able to set reading durations, handle progress updates, start and stop readings, and more. Use this library in conjunction with **SprenCapture** to utilize the full capabilities of Spren SDK. ### `SprenEventManager` subscribe `SprenEventManager.subscribe(SprenEvent.STATE, ::stateListener)` Subscribes to events when state changes occur, i.e., *started*, *finished*, *cancelled*, and *error*. ::::BlockQuote `fun stateListener(values: HashMap)` :::BlockQuote HashMap **key**: value - **state**: SprenState ::: :::: `SprenEventManager.subscribe(SprenEvent.COMPLIANCE, ::complianceListener)` Subscribes to events when a compliance check is performed. Compliance checks for lens coverage, and exposure are performed once per second. ::::BlockQuote `fun complianceListener(values: HashMap)` :::BlockQuote HashMap **key**: value - **name**: ComplianceCheck.Name - **isCompliant**: Boolean ::: :::: `SprenEventManager.subscribe(SprenEvent.PROGRESS, ::progressListener)` Subscribes to events when progress updates. Progress ranges from 0 to 99 in integer increments. State change to finished occurs in lieu of progress update at 100. ::::BlockQuote `fun progressListener(values: HashMap)` :::BlockQuote HashMap **key**: value - **progress**: Int ::: :::: ### `SprenEventManager` unsubscribe Unsubscribing events before leaving the flow ```text SprenEventManager.unsubscribe(SprenEvent.STATE, ::stateListener) SprenEventManager.unsubscribe(SprenEvent.COMPLIANCE, ::complianceListener) SprenEventManager.unsubscribe(SprenEvent.PROGRESS, ::progressListener) ``` ### `Spren` `fun Spren.Companion.startReading()` Manually start the reading. `fun Spren.Companion.cancelReading()` Manually stop the reading. `fun getReadingData(context: Context): String?` After Spren transitions to finished, reading data may be retrieved to hit the Spren API for results. See the **[User and SDK data](https://docs.spren.com/user-and-sdk-data)** **POST** endpoint for more information. `var readingDurationSeconds = 90` Reading duration ≥ 90 seconds or ≤ 240 seconds. `fun Spren.Companion.setReadingDuration(duration: Int)` Set the reading duration. A duration in the range ≥ 90 seconds or ≤ 240 seconds must be provided or the call returns. ### If not using SprenCapture If you'd like to use your own library or code to handle camera configurations and initialization, make sure to reference this section and the **RGBAnalyzer** section to get more context and see what functions need to be implemented. Reference `RGBAnalyzer` `fun process(frame: Bitmap, timestamp: Long)` Provide a frame for processing. `Bitmap` Created from ImageProxy e.g.: `val bitmap = imageProxy.image!!.toBitmap()` The ImageProxy format will be PixelFormat.RGBA\_8888, which has only one image plane (R, G, B, A pixel by pixel). For more information, [Image Analysis](https://developer.android.com/training/camerax/analyze). ### Compliance Checks ### `ComplianceCheck` Compliance checks are run at 1 second intervals as frames are provided, i.e., if internally to SprenCore the time when the frame is received is >1 second later than the last check. For `ComplianceCheck.Name`: - `LENS_COVERAGE`: finger must cover lens with light pressure. - `EXPOSURE`: less than 30 frames must have overexposure. A frame is over-exposed when it appears brighter than it should.