Question

我想显示在外部库中执行的计算进度。

例如，如果我有一些计算方法，并且我想在我的Form类中使用它作为100000个值，我可以写：

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }            

    private void Caluculate(int i)
    {
        double pow = Math.Pow(i, i);
    }

    private void button1_Click(object sender, EventArgs e)
    {
        progressBar1.Maximum = 100000;
        progressBar1.Step = 1;

        for(int j = 0; j < 100000; j++)
        {
            Caluculate(j);
            progressBar1.PerformStep();
        }
    }
}

我应该在每次计算后执行步骤。但是，如果我在外部方法中执行所有100000计算，该怎么办？如果我不想让这个方法依赖于进度条，我什么时候应该“执行步骤”？例如，我可以写

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void CaluculateAll(System.Windows.Forms.ProgressBar progressBar)
    {
        progressBar.Maximum = 100000;
        progressBar.Step = 1;

        for(int j = 0; j < 100000; j++)
        {
            double pow = Math.Pow(j, j); //Calculation
            progressBar.PerformStep();
        }
    }

    private void button1_Click(object sender, EventArgs e)
    {
        CaluculateAll(progressBar1);
    }
}

但我不想这样做。

Answer 1

我建议你看一下BackgroundWorker。如果你的WinForm中有一个很大的循环它会阻塞，你的应用程序看起来会被挂起。

查看BackgroundWorker.ReportProgress()以了解如何将进度报告回UI线程。

例如：

private void Calculate(int i)
{
    double pow = Math.Pow(i, i);
}

private void button1_Click(object sender, EventArgs e)
{
    progressBar1.Maximum = 100;
    progressBar1.Step = 1;
    progressBar1.Value = 0;
    backgroundWorker.RunWorkerAsync();
}

private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
    var backgroundWorker = sender as BackgroundWorker;
    for (int j = 0; j < 100000; j++)
    {
        Calculate(j);
        backgroundWorker.ReportProgress((j * 100) / 100000);
    }
}

private void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    progressBar1.Value = e.ProgressPercentage;
}

private void backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    // TODO: do something with final calculation.
}

Answer 2

从.NET 4.5开始，您可以使用async and await与Progress的组合来向UI线程发送更新：

private void Calculate(int i)
{
    double pow = Math.Pow(i, i);
}

public void DoWork(IProgress<int> progress)
{
    // This method is executed in the context of
    // another thread (different than the main UI thread),
    // so use only thread-safe code
    for (int j = 0; j < 100000; j++)
    {
        Calculate(j);

        // Use progress to notify UI thread that progress has
        // changed
        if (progress != null)
            progress.Report((j + 1) * 100 / 100000);
    }
}

private async void button1_Click(object sender, EventArgs e)
{
    progressBar1.Maximum = 100;
    progressBar1.Step = 1;

    var progress = new Progress<int>(v =>
    {
        // This lambda is executed in context of UI thread,
        // so it can safely update form controls
        progressBar1.Value = v;
    });

    // Run operation in another thread
    await Task.Run(() => DoWork(progress));

    // TODO: Do something after all calculations
}

目前，任务是实现BackgroundWorker所做的首选方式。

此处详细说明了任务和Progress：


Async in 4.5: Enabling Progress and Cancellation in Async APIs
  Stephen Cleary的
Reporting Progress from Async Tasks

Task parallel library replacement for BackgroundWorker?

Answer 3

嘿，有一个关于Dot Net珍珠的有用教程：http://www.dotnetperls.com/progressbar

与彼得达成协议，你需要使用一定数量的线程，否则程序就会挂起，有点挫败目的。

使用ProgressBar和BackgroundWorker的示例：C＃

{"type": "foo", "name": "spam", "value": 42}

Answer 4

存在Task，使用BackgroundWorker并不确定，Task更简单。例如：

ProgressDialog.cs：

   public partial class ProgressDialog : Form
    {
        public System.Windows.Forms.ProgressBar Progressbar { get { return this.progressBar1; } }

        public ProgressDialog()
        {
            InitializeComponent();
        }

        public void RunAsync(Action action)
        {
            Task.Run(action);
        }
    }

完成！然后，您可以在任何地方重用ProgressDialog：

var progressDialog = new ProgressDialog();
progressDialog.Progressbar.Value = 0;
progressDialog.Progressbar.Maximum = 100;

progressDialog.RunAsync(() =>
{
    for (int i = 0; i < 100; i++)
    {
        Thread.Sleep(1000)
        this.progressDialog.Progressbar.BeginInvoke((MethodInvoker)(() => {
            this.progressDialog.Progressbar.Value += 1;
        }));
    }
});

progressDialog.ShowDialog();

如何使用WinForms进度条？

4 个答案: