BackgroundWorker.OnProgressChanged(ProgressChangedEventArgs) 方法

定義

命名空間:

System.ComponentModel

組件:

netstandard.dll, 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

一個 EventArgs 包含事件資料的 。

範例

以下程式碼範例展示了使用此 OnProgressChanged 方法回報非同步操作進度的方法。 此程式碼範例是本類別更大範例 AsyncOperationManager 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

備註

發起事件會透過代理呼叫事件處理者。 欲了解更多資訊，請參閱 處理與提升事件。

此 OnProgressChanged 方法也允許衍生類別在不附加代理的情況下處理事件。 這是在衍生類別中處理事件的首選技術。

給繼承者的注意事項

在導出類別中覆寫 OnProgressChanged(ProgressChangedEventArgs) 時，務必呼叫基底類別的方法 OnProgressChanged(ProgressChangedEventArgs) ，讓註冊代理接收事件。

另請參閱

• ProgressChanged
• 如何在背景執行操作:
• 在背景中下載檔案