Compass.ReadingChanged 事件

定義

命名空間:

Windows.Devices.Sensors

每次指南針報告新的感應器讀數時發生。

// 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) 

事件類型

TypedEventHandler<Compass,CompassReadingChangedEventArgs>

範例

下列範例示範如何使用 C# 和 XAML 建置的 UWP 應用程式註冊其 ReadingChanged 事件處理常式。

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);
    }
}

下列範例顯示 ReadingChanged 事件處理常式。

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";
        }
    });
}

備註

應用程式可以註冊此事件處理常式以取得感應器讀數。 應用程式必須建立所需的 ReportInterval。 這會通知感應器驅動程式應該配置資源以滿足應用程式的需求。

應用程式可以藉由設定 ReportInterval 屬性來設定此事件的頻率。