Compass.ReadingChanged 事件

定义

命名空间:

Windows.Devices.Sensors

每次指南针报告新的传感器读数时发生。

// 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) 

事件类型

TypedEventHandler<Compass,CompassReadingChangedEventArgs>

示例

以下示例演示使用 C# 和 XAML 生成的 UWP 应用如何注册其 ReadingChanged 事件处理程序。

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);
    }
}

以下示例演示 ReadingChanged 事件处理程序。

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";
        }
    });
}

注解

应用程序可以注册此事件处理程序以获取传感器读数。 应用程序必须建立所需的 ReportInterval。 这会通知传感器驱动程序应分配资源以满足应用程序的要求。

应用程序可以通过设置 ReportInterval 属性来设置此事件的频率。