BackgroundWorker.OnProgressChanged(ProgressChangedEventArgs) 方法

定義

命名空間:

System.ComponentModel

組件:

System.ComponentModel.EventBasedAsync.dll

來源:

BackgroundWorker.cs

引發 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)

參數

e

ProgressChangedEventArgs

包含事件資料的 EventArgs。

範例

下列程式代碼範例示範如何使用 OnProgressChanged 方法來報告異步操作的進度。 此程式代碼範例是提供給 類別之較大範例的 AsyncOperationManager 一部分。

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

    OnProgressChanged(e);
}

protected void OnCalculatePrimeCompleted(
    CalculatePrimeCompletedEventArgs e)
{
    if (CalculatePrimeCompleted != null)
    {
        CalculatePrimeCompleted(this, e);
    }
}

protected void OnProgressChanged(ProgressChangedEventArgs e)
{
    if (ProgressChanged != null)
    {
        ProgressChanged(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

備註

引發事件會透過委派叫用此事件處理常式。 如需詳細資訊，請參閱 處理和引發事件。

OnProgressChanged 方法也允許衍生類別處理事件，而不用附加委派。 這是在衍生類別中處理事件的慣用技巧。

給繼承者的注意事項

當在衍生類別中覆寫 OnProgressChanged(ProgressChangedEventArgs) 時，請確定呼叫基底類別的 OnProgressChanged(ProgressChangedEventArgs) 方法，使已註冊的委派能接收到事件。

另請參閱

• ProgressChanged
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