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Magnetometer

Streams magnetometer flet.MagnetometerReadingEvent reporting the ambient magnetic field (uT) per axis for compass-style use cases.

Note
  • Supported platforms: Android, iOS.
  • Magnetometer APIs are not available on web. or desktop, so always handle on_error to detect unsupported hardware.

Inherits: Service

Properties

  • cancel_on_error - Whether the stream subscription should cancel on the first sensor error.
  • enabled - Whether the sensor should be sampled.
  • interval - Desired sampling interval provided as a Duration.

Events

  • on_error - Fired when the platform reports a sensor error.
  • on_reading - Fires when a new reading is available.

Examples​

import flet as ft


def main(page: ft.Page):
    def handle_reading(e: ft.MagnetometerReadingEvent):
        reading.value = f"x={e.x:.2f} uT, y={e.y:.2f} uT, z={e.z:.2f} uT"

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

    page.services.append(
        ft.Magnetometer(
            on_reading=handle_reading,
            on_error=handle_error,
            interval=ft.Duration(milliseconds=200),
        )
    )

    page.add(
        ft.SafeArea(
            content=ft.Column(
                controls=[
                    ft.Text("Monitor the ambient magnetic field (uT)."),
                    reading := ft.Text("Waiting for data..."),
                ],
            ),
        )
    )


if __name__ == "__main__":
    ft.run(main)

Properties​

cancel_on_errorclass-attributeinstance-attribute​

cancel_on_error: bool = True

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

enabledclass-attributeinstance-attribute​

enabled: bool = True

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

intervalclass-attributeinstance-attribute​

interval: Optional[Duration] = None

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

Events​

on_errorclass-attributeinstance-attribute​

on_error: Optional[EventHandler[SensorErrorEvent]] = None

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

on_readingclass-attributeinstance-attribute​

on_reading: Optional[EventHandler[MagnetometerReadingEvent]] = None

Fires when a new reading is available.

event contains x, y, z magnetic field strengths (uT) and timestamp (microseconds since epoch).