Compass.ReadingChanged Event

Definition

Namespace:

Windows.Devices.Sensors

Occurs each time the compass reports a new sensor reading.

// Register
event_token ReadingChanged(TypedEventHandler<Compass, CompassReadingChangedEventArgs const&> const& handler) const;

// Revoke with event_token
void ReadingChanged(event_token const* cookie) const;

// Revoke with event_revoker
Compass::ReadingChanged_revoker ReadingChanged(auto_revoke_t, TypedEventHandler<Compass, CompassReadingChangedEventArgs const&> const& handler) const;

public event TypedEventHandler<Compass,CompassReadingChangedEventArgs> ReadingChanged;

function onReadingChanged(eventArgs) { /* Your code */ }
compass.addEventListener("readingchanged", onReadingChanged);
compass.removeEventListener("readingchanged", onReadingChanged);
- or -
compass.onreadingchanged = onReadingChanged;

Public Custom Event ReadingChanged As TypedEventHandler(Of Compass, CompassReadingChangedEventArgs) 

Event Type

TypedEventHandler<Compass,CompassReadingChangedEventArgs>

Examples

The following example demonstrates how a UWP app built with C# and XAML registers its ReadingChanged event handler.

private void ScenarioEnable(object sender, RoutedEventArgs e)
{
    if (_compass != null)
    {
        // Establish the report interval
        _compass.ReportInterval = _desiredReportInterval;

        Window.Current.VisibilityChanged += new WindowVisibilityChangedEventHandler(VisibilityChanged);
        _compass.ReadingChanged += new TypedEventHandler<Compass, CompassReadingChangedEventArgs>(ReadingChanged);

        ScenarioEnableButton.IsEnabled = false;
        ScenarioDisableButton.IsEnabled = true;
    }
    else
    {
        rootPage.NotifyUser("No compass found", NotifyType.StatusMessage);
    }
}

The following example shows the ReadingChanged event handler.

async private void ReadingChanged(object sender, CompassReadingChangedEventArgs e)
{
    await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
    {
        CompassReading reading = e.Reading;
        ScenarioOutput_MagneticNorth.Text = String.Format("{0,5:0.00}", reading.HeadingMagneticNorth);
        if (reading.HeadingTrueNorth != null)
        {
            ScenarioOutput_TrueNorth.Text = String.Format("{0,5:0.00}", reading.HeadingTrueNorth);
        }
        else
        {
            ScenarioOutput_TrueNorth.Text = "No data";
        }
    });
}

Remarks

An application may register this event handler to obtain sensor readings. The application must establish a desired ReportInterval. This informs the sensor driver that resources should be allocated to satisfy the requirements of the application.

Applications can set the frequency of this event by setting the ReportInterval property.