UserAccelerometer

Streams linear acceleration readings.

If the device is still, or is moving along a straight line at constant speed, the reported acceleration is zero. If the device is moving e.g. towards north and its speed is increasing, the reported acceleration is towards north; if it is slowing down, the reported acceleration is towards south; if it is turning right, the reported acceleration is towards east. The data of this stream is obtained by filtering out the effect of gravity from AccelerometerReadingEvent.

Note

Supported platforms: Android, iOS, Web. Web ignores requested sampling intervals and iOS apps must declare NSMotionUsageDescription.

Inherits: Service

Properties

• cancel_on_error(bool) –

  Whether the stream subscription should cancel on the first sensor error.

• enabled(bool) –

  Whether the sensor should be sampled. Disable to stop streaming.

• interval(Duration | None) –

  Desired sampling interval provided as a Duration.

Events

• on_error(EventHandler[SensorErrorEvent] | None) –

  Fired when the platform reports a sensor error. event.message is the error

• on_reading(EventHandler[UserAccelerometerReadingEvent] | None) –

  Fires when a new reading is available.

Examples

import flet as ft


def main(page: ft.Page):
    intro = ft.Text(
        "Linear acceleration without gravity. "
        "Keep the app running on a device with motion sensors."
    )
    reading = ft.Text("Waiting for data...")

    def handle_reading(e: ft.UserAccelerometerReadingEvent):
        reading.value = f"x={e.x:.2f} m/s^2, y={e.y:.2f} m/s^2, z={e.z:.2f} m/s^2"
        page.update()

    def handle_error(e: ft.SensorErrorEvent):
        page.add(ft.Text(f"UserAccelerometer error: {e.message}"))

    page.session.store.set(
        "user_accelerometer_service",
        ft.UserAccelerometer(
            on_reading=handle_reading,
            on_error=handle_error,
            interval=ft.Duration(milliseconds=100),
        ),
    )

    page.add(intro, reading)


ft.run(main)

Properties

cancel_on_error class-attribute instance-attribute

cancel_on_error: bool = True

Whether the stream subscription should cancel on the first sensor error.

enabled class-attribute instance-attribute

enabled: bool = True

Whether the sensor should be sampled. Disable to stop streaming.

interval class-attribute instance-attribute

interval: Duration | None = None

Desired sampling interval provided as a Duration. Defaults to 200 ms.

Events

on_error class-attribute instance-attribute

on_error: EventHandler[SensorErrorEvent] | None = None

Fired when the platform reports a sensor error. event.message is the error description.

on_reading class-attribute instance-attribute

on_reading: (
    EventHandler[UserAccelerometerReadingEvent] | None
) = None

Fires when a new reading is available.

event contains x, y, z acceleration values and timestamp (microseconds since epoch).