Async/Await与WinForms ProgressBar

Question

我在过去使用BackgroundWorker得到了这种类型的东西,但是我想使用.NET 4.5的新async/await方法.我可能正在咆哮错误的树.请指教.

目标:创建一个组件,该组件将执行一些长时间运行的工作,并在执行工作时显示带有进度条的模态表单.该组件将获取窗口的句柄,以便在执行长时间运行的工作时阻止交互.

状态:请参阅下面的代码.在我尝试与windows进行交互之前,我以为自己做得很好.如果我把事情单独处理(即不要触摸!),一切都"完美"运行,但是如果我点击任一窗口,程序会在长时间运行结束后挂起.忽略实际交互(拖动),就好像UI线程被阻止一样.

问题:我的代码可以很容易修复吗？如果是这样,怎么样？或者,我应该使用不同的方法(例如BackgroundWorker)吗？

代码(Form1是带有ProgressBar和公共方法的标准表单,UpdateProgress,用于设置ProgressBar的值):

using System;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ConsoleApplication1
{
class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Starting..");
        var mgr = new Manager();
        mgr.GoAsync();
        Console.WriteLine("..Ended");
        Console.ReadKey();
    }
}

class Manager
{
    private static Form1 _progressForm;

    public async void GoAsync()
    {
        var owner = new Win32Window(Process.GetCurrentProcess().MainWindowHandle);
        _progressForm = new Form1();
        _progressForm.Show(owner);

        await Go();

        _progressForm.Hide();
    }

    private async Task<bool> Go()
    {
        var job = new LongJob();
        job.OnProgress += job_OnProgress;
        job.Spin();
        return true;
    }

    void job_OnProgress(int percent)
    {
        _progressForm.UpdateProgress(percent);
    }
}

class LongJob
{
    public event Progressed OnProgress;
    public delegate void Progressed(int percent);

    public void Spin()
    {
        for (var i = 1; i <= 100; i++)
        {
            Thread.Sleep(25);
            if (OnProgress != null)
            {
                OnProgress(i);
            }
        }
    }
}

class Win32Window : IWin32Window
{
    private readonly IntPtr _hwnd;
    public Win32Window(IntPtr handle)
    {
        _hwnd = handle;
    }
    public IntPtr Handle
    {
        get
        {
            return _hwnd;
        }
    }
}
}

Answer 1

在async与await关键字并不意味着"在后台线程上运行." 我有一个async/ await在我的博客的介绍,描述他们做的意思.您必须在后台线程上明确地放置CPU绑定操作,例如Task.Run.

此外,基于任务的异步模式文档描述了async代码的常见方法,例如进度报告.

class Manager
{
  private static Form1 _progressForm;

  public async Task GoAsync()
  {
    var owner = new Win32Window(Process.GetCurrentProcess().MainWindowHandle);
    _progressForm = new Form1();
    _progressForm.Show(owner);

    var progress = new Progress<int>(value => _progressForm.UpdateProgress(value));
    await Go(progress);

    _progressForm.Hide();
  }

  private Task<bool> Go(IProgress<int> progress)
  {
    return Task.Run(() =>
    {
      var job = new LongJob();
      job.Spin(progress);
      return true;
    });
  }
}

class LongJob
{
  public void Spin(IProgress<int> progress)
  {
    for (var i = 1; i <= 100; i++)
    {
      Thread.Sleep(25);
      if (progress != null)
      {
        progress.Report(i);
      }
    }
  }
}

请注意,该Progress<T>类型正确处理线程编组,因此不需要在其中进行编组Form1.UpdateProgress.

Answer 2

@ StephenCleary的回答是正确的.虽然,我不得不对他的答案做一点修改,以获得我认为OP想要的行为.

public void GoAsync() //no longer async as it blocks on Appication.Run
{
    var owner = new Win32Window(Process.GetCurrentProcess().MainWindowHandle);
    _progressForm = new Form1();

    var progress = new Progress<int>(value => _progressForm.UpdateProgress(value));

    _progressForm.Activated += async (sender, args) =>
        {
            await Go(progress);
            _progressForm.Close();
        };

    Application.Run(_progressForm);
}

Answer 3

private async void button1_Click(object sender, EventArgs e)
{
    IProgress<int> progress = new Progress<int>(value => { progressBar1.Value = value; });
    await Task.Run(() =>
    {
        for (int i = 0; i <= 100; i++)
            progress.Report(i);
    });
}

如果我错了，请纠正我，但这似乎是更新进度条的最简单方法。