如何在Windows窗體上多線程（有效）？

Question

這一個給我一個很難。 的事情是，我有一個起着MIDI一些筆記代碼，我希望能夠暫停，所以我做了一個簡單的形式是這樣的：

namespace Music 
{ 
    public partial class Form1 : Form 
    { 

     static BackgroundWorker _bw = new BackgroundWorker 
     { 
      WorkerSupportsCancellation = true 
     }; 

     private void button1_Click(object sender, EventArgs e) 
     { 
      if (!Playing) 
      { 
       Playing = true; 
       _bw.DoWork += Start_Playing; 
       _bw.RunWorkerAsync("Hello to worker"); 
      } 
      else 
      { 
       Playing = false; 
       _bw.CancelAsync(); 
      } 
     } 

     static void Start_Playing(object sender, DoWorkEventArgs e) 
     { 
      //Plays some music 
     } 
    } 
} 

，當我點擊它開始播放，但無論我做什麼，都無法停止。但事情是，如果我在控制檯中做同樣的事情，它的工作就非常完美。

我錯過了什麼嗎？ 如何從表單中控制單獨的線程？

Answer 1

這似乎是工作...

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Linq; 
using System.Text; 
using System.Windows.Forms; 
using System.Threading; 

namespace WindowsFormsApplication2 
{ 
    public partial class Form1 : Form 
    { 
     private BackgroundWorker _bw = new BackgroundWorker { WorkerSupportsCancellation = true, 
      WorkerReportsProgress = true}; 
     public Form1() 
     { 
      InitializeComponent(); 

     } 

     private void button1_Click(object sender, EventArgs e) 
     { 
      if (_bw.IsBusy) 
      { 
       _bw.CancelAsync(); 
      } 
      else 
      { 
       _bw.ProgressChanged += new ProgressChangedEventHandler(_bw_ProgressChanged); 
       _bw.DoWork += new DoWorkEventHandler(_bw_DoWork); 
       _bw.RunWorkerAsync(); 
      } 
     } 

     void _bw_ProgressChanged(object sender, ProgressChangedEventArgs e) 
     { 
      textBox1.Text += (string)e.UserState; 
     } 

     void _bw_DoWork(object sender, DoWorkEventArgs e) 
     { 
      int count = 0; 
      while (!_bw.CancellationPending) 
      { 
       _bw.ReportProgress(0, string.Format("worker working {0}", count)); 
       ++count; 
       Thread.Sleep(2000); 
      } 
     } 
    } 
}