ProgressBar 没有直观地显示所有步骤答案

【问题标题】：ProgressBar not visually showing all stepsProgressBar 没有直观地显示所有步骤
【发布时间】：2017-01-19 09:44:30
【问题描述】：

我制作了一个在 Autodesk Inventor 中创建 3D 模型的应用程序。我想添加一个进度条来向用户显示该过程已经完成了多少。

我遇到的问题是，当 Autodesk Inventor 中的进程消耗大量 CPU 时，进度条没有显示所有步骤，而是跳转（例如进一步 5 步）到最后。

有没有办法强制 windows 窗体显示所有步骤？还是这种行为不常见？

Private Sub
    ' Display the ProgressBar control.
    pbBuildProgress.Visible = True
    ' Set Minimum to 1 to represent the first file being copied.
    pbBuildProgress.Minimum = 1
    ' Set Maximum to the total number of files to copy.
    pbBuildProgress.Maximum = BodyComponents.Count
    ' Set the initial value of the ProgressBar.
    pbBuildProgress.Value = 1
    ' Set the Step property to a value of 1 to represent each file being copied.
    pbBuildProgress.Step = 1


    ' Start loop trough all body components
    For i = 0 To BodyComponents.Count - 1

        ' Some code here that does stuff in Autodesk Inventor

        ' Perform a step
        pbBuildProgress.PerformStep()

    Next
End Sub

【问题讨论】：

标签： vb.net progress-bar

【解决方案1】：

您应该考虑使用BackgroundWoker 报告进度：

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    ProgressBar1.Minimum = 0
    ProgressBar1.Maximum = 10

    BackgroundWorker1.WorkerReportsProgress = True
    BackgroundWorker1.RunWorkerAsync()

End Sub

Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork

    For i = 0 To 10

        Debug.Write(i)

        BackgroundWorker1.ReportProgress(i)

    Next

End Sub

Private Sub BackgroundWorker1_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged

    ProgressBar1.Value = e.ProgressPercentage

End Sub

这不是我需要做的事情，如果有更多经验的人有任何意见，我会非常乐意学习一两件事。

【讨论】：

【解决方案2】：

尝试在 .PerformStep() 之后更新您的进度条或表单。但是请注意，这需要很多时间，尤其是当您的最大值很大时。例如，也许您可以使用秒表并每 250 毫秒更新一次表单。

【讨论】：

您能解释一下吗？什么需要很多时间？表格的更新？那么添加多个（可能是不必要的）更新应该如何提供帮助？
绘制/更新表单需要很长时间。您应该防止表单进行不必要的更新，而不是强制更新；-) 例如，尝试使用 StopWatch 并仅每 250 毫秒执行一次更新（可能使用 Application.DoEvents）。这将防止您的应用程序冻结。
A Stopwatch 用于测量某事所花费的时间，而不是每 x 毫秒运行一次代码。你不应该使用Application.DoEvents()！这样做几乎总是不好的做法。请参阅：Keeping your UI Responsive and the Dangers of Application.DoEvents。

【解决方案3】：

一个常见的原因是 UI 线程的调用过于频繁，超出了它的处理能力。

对此的简单解决方法是量化你的进度百分比，下面我运行一个迭代 10 亿次但仅每 1000 万次迭代或 1% 发送一次 UI 更新的操作。

代码：

var steps = 1000000000;
var step = 1.0d / steps;
var percent = 0;
for (var i = 0; i < steps; i++)
{
    var percent1 = (int) (Math.Floor(i * step * 100));
    if (percent1 > percent)
    {
        // TODO invoke your UI progress bar update here
        Console.WriteLine("Updating: percent = {0}, i = {1}", percent1, i);
        percent = percent1;
    }
}

结果：

Updating: percent = 1, i = 10000000
Updating: percent = 2, i = 20000000
Updating: percent = 3, i = 30000000
Updating: percent = 4, i = 40000000
Updating: percent = 5, i = 50000000
Updating: percent = 6, i = 60000000
Updating: percent = 7, i = 70000000
Updating: percent = 8, i = 80000000
Updating: percent = 9, i = 90000000
Updating: percent = 10, i = 100000000
Updating: percent = 11, i = 110000000
Updating: percent = 12, i = 120000000
Updating: percent = 13, i = 130000000
Updating: percent = 14, i = 140000000
Updating: percent = 15, i = 150000000
Updating: percent = 16, i = 160000000
Updating: percent = 17, i = 170000000
Updating: percent = 18, i = 180000000
Updating: percent = 19, i = 190000000
Updating: percent = 20, i = 200000000

您可能还希望异步运行此类操作：

Task-based Asynchronous Programming

【讨论】：