BackgroundWorker.ReportProgress 方法

定义

命名空间:

System.ComponentModel

程序集:

System.ComponentModel.EventBasedAsync.dll

引发 ProgressChanged 事件。

重载

ReportProgress(Int32)	引发 ProgressChanged 事件。
ReportProgress(Int32, Object)	引发 ProgressChanged 事件。

ReportProgress(Int32)

Source:

BackgroundWorker.cs

引发 ProgressChanged 事件。

public:
 void ReportProgress(int percentProgress);

public void ReportProgress (int percentProgress);

member this.ReportProgress : int -> unit

Public Sub ReportProgress (percentProgress As Integer)

参数

percentProgress

Int32

已完成的后台操作所占的百分比，范围从 0% 到 100%。

例外

InvalidOperationException

将 WorkerReportsProgress 属性设置为 false。

示例

下面的代码示例演示如何使用 ReportProgress 方法向用户报告异步操作的进度。 此代码示例是为 BackgroundWorker 类提供的一个更大示例的一部分。

// Abort the operation if the user has cancelled.
// Note that a call to CancelAsync may have set 
// CancellationPending to true just after the
// last invocation of this method exits, so this 
// code will not have the opportunity to set the 
// DoWorkEventArgs.Cancel flag to true. This means
// that RunWorkerCompletedEventArgs.Cancelled will
// not be set to true in your RunWorkerCompleted
// event handler. This is a race condition.
if ( worker->CancellationPending )
{
   e->Cancel = true;
}
else
{
   if ( n < 2 )
   {
      result = 1;
   }
   else
   {
      result = ComputeFibonacci( n - 1, worker, e ) + ComputeFibonacci( n - 2, worker, e );
   }

   // Report progress as a percentage of the total task.
   int percentComplete = (int)((float)n / (float)numberToCompute * 100);
   if ( percentComplete > highestPercentageReached )
   {
      highestPercentageReached = percentComplete;
      worker->ReportProgress( percentComplete );
   }
}

// Abort the operation if the user has canceled.
// Note that a call to CancelAsync may have set 
// CancellationPending to true just after the
// last invocation of this method exits, so this 
// code will not have the opportunity to set the 
// DoWorkEventArgs.Cancel flag to true. This means
// that RunWorkerCompletedEventArgs.Cancelled will
// not be set to true in your RunWorkerCompleted
// event handler. This is a race condition.

if (worker.CancellationPending)
{   
    e.Cancel = true;
}
else
{   
    if (n < 2)
    {   
        result = 1;
    }
    else
    {   
        result = ComputeFibonacci(n - 1, worker, e) + 
                 ComputeFibonacci(n - 2, worker, e);
    }

    // Report progress as a percentage of the total task.
    int percentComplete = 
        (int)((float)n / (float)numberToCompute * 100);
    if (percentComplete > highestPercentageReached)
    {
        highestPercentageReached = percentComplete;
        worker.ReportProgress(percentComplete);
    }
}

' Abort the operation if the user has canceled.
' Note that a call to CancelAsync may have set 
' CancellationPending to true just after the
' last invocation of this method exits, so this 
' code will not have the opportunity to set the 
' DoWorkEventArgs.Cancel flag to true. This means
' that RunWorkerCompletedEventArgs.Cancelled will
' not be set to true in your RunWorkerCompleted
' event handler. This is a race condition.
If worker.CancellationPending Then
    e.Cancel = True
Else
    If n < 2 Then
        result = 1
    Else
        result = ComputeFibonacci(n - 1, worker, e) + _
                 ComputeFibonacci(n - 2, worker, e)
    End If

    ' Report progress as a percentage of the total task.
    Dim percentComplete As Integer = _
        CSng(n) / CSng(numberToCompute) * 100
    If percentComplete > highestPercentageReached Then
        highestPercentageReached = percentComplete
        worker.ReportProgress(percentComplete)
    End If

End If

注解

如果需要后台操作来报告其进度，可以调用 ReportProgress 方法来引发 ProgressChanged 事件。 属性值 WorkerReportsProgress 必须为 true，否则 ReportProgress 将引发 InvalidOperationException。

由你来实施一种有意义的方法来衡量后台操作的进度，占完成的任务总数的百分比。

对 方法的 ReportProgress 调用是异步的，并会立即返回。 事件处理程序 ProgressChanged 在创建 BackgroundWorker的线程上执行。

另请参阅

• 如何：在后台运行操作
• 如何：在后台下载文件

ReportProgress(Int32, Object)

Source:

BackgroundWorker.cs

引发 ProgressChanged 事件。

public:
 void ReportProgress(int percentProgress, System::Object ^ userState);

public void ReportProgress (int percentProgress, object? userState);

member this.ReportProgress : int * obj -> unit

Public Sub ReportProgress (percentProgress As Integer, userState As Object)

参数

percentProgress

Int32

已完成的后台操作所占的百分比，范围从 0% 到 100%。

userState

Object

指示用户状态的唯一 Object。 作为 ProgressChangedEventArgs 的 UserState 属性返回。

例外

InvalidOperationException

将 WorkerReportsProgress 属性设置为 false。

示例

下面的代码示例演示如何使用 ReportProgress 方法向用户报告异步操作的进度。 此代码示例是为 ToolStripProgressBar 类提供的一个更大示例的一部分。

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    // This method will run on a thread other than the UI thread.
    // Be sure not to manipulate any Windows Forms controls created
    // on the UI thread from this method.
    backgroundWorker.ReportProgress(0, "Working...");
    Decimal lastlast = 0;
    Decimal last = 1;
    Decimal current;
    if (requestedCount >= 1)
    { AppendNumber(0); }
    if (requestedCount >= 2)
    { AppendNumber(1); }
    for (int i = 2; i < requestedCount; ++i)
    {
        // Calculate the number.
        checked { current = lastlast + last; }
        // Introduce some delay to simulate a more complicated calculation.
        System.Threading.Thread.Sleep(100);
        AppendNumber(current);
        backgroundWorker.ReportProgress((100 * i) / requestedCount, "Working...");
        // Get ready for the next iteration.
        lastlast = last;
        last = current;
    }

    backgroundWorker.ReportProgress(100, "Complete!");
}

Private Sub backgroundWorker1_DoWork(sender As Object, e As DoWorkEventArgs)
   ' This method will run on a thread other than the UI thread.
   ' Be sure not to manipulate any Windows Forms controls created
   ' on the UI thread from this method.
   backgroundWorker.ReportProgress(0, "Working...")
   Dim lastlast As [Decimal] = 0
   Dim last As [Decimal] = 1
   Dim current As [Decimal]
   If requestedCount >= 1 Then
      AppendNumber(0)
   End If
   If requestedCount >= 2 Then
      AppendNumber(1)
   End If
   Dim i As Integer
   
   While i < requestedCount
      ' Calculate the number.
      current = lastlast + last
      ' Introduce some delay to simulate a more complicated calculation.
      System.Threading.Thread.Sleep(100)
      AppendNumber(current)
      backgroundWorker.ReportProgress(100 * i / requestedCount, "Working...")
      ' Get ready for the next iteration.
      lastlast = last
      last = current
      i += 1
   End While
   
   
   backgroundWorker.ReportProgress(100, "Complete!")
 End Sub

注解

如果需要后台操作来报告其进度，可以调用 ReportProgress 方法来引发 ProgressChanged 事件。 属性值 WorkerReportsProgress 必须 true、或 ReportProgress 将引发 InvalidOperationException。

由你来实施一种有意义的方法来衡量后台操作的进度，占完成的任务总数的百分比。

另请参阅

• 如何：在后台运行操作
• 如何：在后台下载文件