Uno Support for Windows.Devices.Sensors

Accelerometer

The following APIs are implemented on Android, iOS and WASM:

  • ReadingChanged
  • Shaken
  • ReportInterval

Implementation notes

While iOS features a built-in shake gesture recognition, this is not available on Android and WASM. For these platforms we use a commonly used implementation which tries to approximate the shake motion to detect it. Both Android and WASM use the same implementation. In case this is not sufficient for your use case, you can implement Shake detection above the ReadingChanged event.

ReportInterval property on WASM is not supported directly and we use an approximation in the form of raising the ReadingChanged event only when enough time has passed since the last report. The event is actually raised a bit more often to make sure the gap caused by the filter is not too large, but this is in-line with the behavior of UWP Accelerometer.

On Android, when both ReadingChanged and Shaken events are attached and the user sets the ReportInterval to a high value, the ReadingChanged event may be raised more often than requested. This is because for multiple subscribers to the same sensor the system may raise the sensor events with the frequency of the one with lower requested report delay. This is, however, again in line with the behavior of UWP Accelerometer and you can filter the events as necessary for your use case.

Barometer

Implementation notes

Android

  • Only ReadingChanged event and ReportInterval is supported, system does not support retrieval of a single reading.

iOS

  • Only ReadingChanged event is supported, system does not support retrieval of a single reading. ReportInterval is not supported.

WASM

  • No barometer API is currently available in JS

Gyrometer

Implementation notes

ReportInterval property on WASM is currently not supported directly. Uno uses an approximation in the form of raising the ReadingChanged event, only when enough time has passed since the last report. The event is raised a bit more often to make sure the gap caused by the filter is not too large, but this is in-line with the behavior of Windows' Gyrometer.

Magnetometer

Implementation notes

ReportInterval property on WASM is currently not supported directly. Uno uses an approximation in the form of raising the ReadingChanged event only when enough time has passed since the last report. The event is raised a bit more often to make sure the gap caused by the filter is not too large, but this is in-line with the behavior of UWP Magnetometer.

DirectionalAccuracy is not reported on iOS, so it will always return Unknown.

Pedometer

Implementation notes

Android

On Android, the first reading returns the cumulative number of steps since the device was first booted up. The sensor may not correctly respect the requested reporting interval, so the implementation does this manually to make sure the ReadingChanged events are triggered only after the ReportInterval elapses.

Since Android 10, your application must declare the permission to use the step counter sensor by adding the following uses-feature declaration to the AndroidManifest.xml in your project:

<uses-permission android:name="android.permission.ACTIVITY_RECOGNITION" />

iOS

The first reading on iOS returns the cumulative number of steps from 24 hours back to current moment. Unfortunately, in case the tracking was not enabled before, this will likely return 0 steps. Once the tracking is enabled, ReadingChanged will be triggered and step count will be updated appropriately.

Make sure to add the following capability declaration to your Info.plist file, otherwise the API will crash at runtime.

<key>NSMotionUsageDescription</key>
<string>Some reason why your app wants to track motion.</string>