进度条不起作用，即使程序所做的只是显示进度条

Question

我有一个表格，目前它除了打开什么都不做。该表单有 2 个控件 - 一个“关闭”按钮和一个进度条。但是，当我打开表格时，我什么也得不到。进度条只是坐在那里什么都不做。

我已经尝试过 Marquee（我知道它在 Windows 8 中可能无法使用）和 Continuous，但我都无法使用。

这就是我在程序启动时显示表单的方式 -

Sub main()

    Dim ProgressForm As New formProgress
    ProgressForm.ShowDialog()

End Sub

以下是进度条的属性。我是否错过了可以让这个酒吧工作的东西？谢谢。

其他信息

对于我的完整程序，我最初确实尝试对进度条使用块样式，但在尝试从 BackgroundWorker 更新进度条时，我不断收到以下错误。这就是为什么我试图让一个简单的 Marquee/Continuous 栏改为工作。

附加信息：跨线程操作无效：控件“proWorking”从创建它的线程以外的线程访问。

Answer 1

如果您使用选取框样式，则必须将 marqueeanimationspeed 设置为某个值

// 
        // progressBar1
        // 
        this.progressBar1.Location = new System.Drawing.Point(91, 118);
        this.progressBar1.MarqueeAnimationSpeed = 50;
        this.progressBar1.Name = "progressBar1";
        this.progressBar1.Size = new System.Drawing.Size(100, 23);
        this.progressBar1.Style = System.Windows.Forms.ProgressBarStyle.Marquee;
        this.progressBar1.TabIndex = 0;

并使用 marqueeanimationsspeed 0 的连续样式来停止它

Answer 2

要让进度条做某事（除了选取框样式），您需要设置 Value 属性。如果您有 .Minimum=0 和 .Maximum=100 则 .Value 为 50 意味着进度条是半满的。是否应该使用连续或块样式取决于视觉样式设置，并且在 Win 7 上并没有真正的区别（例如在 Win XP 下可能如此）。

选取框样式意味着您不知道您的任务已经进行了多远。然后进度条显示一个连续移动的片段（仅在运行时可见！！）。我刚刚在 Win 7 中对其进行了测试，它可以工作。

Answer 3

这是我与BackgroundWorker 和ProgressBar 和Label 一起使用的一个小样板。

Public Class BackgroundWorkerUI
Private args As New ProgressArgs

  Private Sub bw_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles bw.DoWork
    'set ProgressBar style to Marquee
    args.Style = ProgressBarStyle.Marquee
    bw.ReportProgress(0)  'triggers the progress changed event to update UI on correct thread
    'some long operation
    Threading.Thread.Sleep(5000)


    'Set ProgressBar style to Continuous
    args.Style = ProgressBarStyle.Continuous

    For i As Integer = 0 To 100

      If bw.CancellationPending Then
        e.Cancel = True
        Exit For
      End If

      args.Current = i
      args.Max = 100
      args.Status = String.Format("({0} of {1}) Updating...", args.Current, args.Max)
      bw.ReportProgress(0)

      'some operation
      Threading.Thread.Sleep(100)
    Next

  End Sub

Private Sub bw_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles bw.ProgressChanged
lblStatus.Text = args.Status
If args.Style = ProgressBarStyle.Marquee Then
  bar.Style = args.Style
  bar.MarqueeAnimationSpeed = 15
Else
  bar.Style = ProgressBarStyle.Continuous
  bar.Minimum = args.Min
  bar.Maximum = args.Max
  bar.Value = args.Current
End If
End Sub

Private Sub bw_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bw.RunWorkerCompleted
If e.Error IsNot Nothing Then
  MessageBox.Show(e.Error.Message, "Background Worker Exception", MessageBoxButtons.OK, MessageBoxIcon.Error)
Else
  If e.Cancelled Then
    lblStatus.Text = "Operation canceled"
  Else
    lblStatus.Text = "Done"
  End If
End If
End Sub


Private Sub BackgroundWorkerUI_FormClosing(sender As Object, e As FormClosingEventArgs) Handles Me.FormClosing
If bw.IsBusy Then

  Dim r = MessageBox.Show("A background process is still running. Are you sure you want to quit?", "Confirm", MessageBoxButtons.YesNo, MessageBoxIcon.Question)

  If r = Windows.Forms.DialogResult.Yes Then
    bw.CancelAsync()
  End If
  e.Cancel = True
End If
End Sub

Private Class ProgressArgs
Inherits EventArgs

Public Property Status As String
Public Property Current As Integer
Public Property Min As Integer
Public Property Max As Integer
Public Property Style As ProgressBarStyle

Public Sub New()
  Status = ""
  Current = 0
  Min = 0
  Max = 0
  Style = ProgressBarStyle.Continuous
End Sub
End Class
End Class