BackgroundWorker.OnProgressChanged(ProgressChangedEventArgs) 方法

定义

命名空间:

System.ComponentModel

程序集:

netstandard.dll, System.ComponentModel.EventBasedAsync.dll

Source:

BackgroundWorker.cs

引发 ProgressChanged 事件。

protected:
 virtual void OnProgressChanged(System::ComponentModel::ProgressChangedEventArgs ^ e);

protected virtual void OnProgressChanged(System.ComponentModel.ProgressChangedEventArgs e);

abstract member OnProgressChanged : System.ComponentModel.ProgressChangedEventArgs -> unit
override this.OnProgressChanged : System.ComponentModel.ProgressChangedEventArgs -> unit

Protected Overridable Sub OnProgressChanged (e As ProgressChangedEventArgs)

参数

e

ProgressChangedEventArgs

包含事件数据的一个 EventArgs 。

示例

下面的代码示例演示如何使用 OnProgressChanged 该方法报告异步操作的进度。 该代码示例是 AsyncOperationManager 类中的一个较大示例的一部分。

// This method is invoked via the AsyncOperation object,
// so it is guaranteed to be executed on the correct thread.
void CalculateCompleted(object operationState)
{
    CalculatePrimeCompletedEventArgs e =
        operationState as CalculatePrimeCompletedEventArgs;

    OnCalculatePrimeCompleted(e);
}

// This method is invoked via the AsyncOperation object,
// so it is guaranteed to be executed on the correct thread.
void ReportProgress(object state)
{
    ProgressChangedEventArgs e =
        state as ProgressChangedEventArgs;

    OnProgressChanged(e);
}

protected void OnCalculatePrimeCompleted(
    CalculatePrimeCompletedEventArgs e) =>
    CalculatePrimeCompleted?.Invoke(this, e);

protected void OnProgressChanged(ProgressChangedEventArgs e) =>
    ProgressChanged?.Invoke(e);

' This method is invoked via the AsyncOperation object,
' so it is guaranteed to be executed on the correct thread.
Private Sub CalculateCompleted(ByVal operationState As Object)
    Dim e As CalculatePrimeCompletedEventArgs = operationState

    OnCalculatePrimeCompleted(e)

End Sub


' This method is invoked via the AsyncOperation object,
' so it is guaranteed to be executed on the correct thread.
Private Sub ReportProgress(ByVal state As Object)
    Dim e As ProgressChangedEventArgs = state

    OnProgressChanged(e)

End Sub

Protected Sub OnCalculatePrimeCompleted( _
    ByVal e As CalculatePrimeCompletedEventArgs)

    RaiseEvent CalculatePrimeCompleted(Me, e)

End Sub


Protected Sub OnProgressChanged( _
    ByVal e As ProgressChangedEventArgs)

    RaiseEvent ProgressChanged(e)

End Sub

注解

引发事件会通过委托调用事件处理程序。 有关详细信息，请参阅 处理和引发事件。

该方法 OnProgressChanged 还允许派生类在不附加委托的情况下处理事件。 这是处理派生类中的事件的首选技术。

继承者说明

在派生类中重写 OnProgressChanged(ProgressChangedEventArgs) 时，请务必调用基类的方法，以便已注册的 OnProgressChanged(ProgressChangedEventArgs) 委托接收事件。

另请参阅

• ProgressChanged
• 操作方法：在后台运行操作
• 如何：在后台下载文件