向 Windows 窗体消息循环发送或发布消息 [英] Send or post a message to a Windows Forms message loop

问题描述

我有一个线程从命名管道中读取消息.这是一个阻塞读取，这就是为什么它在自己的线程中.当此线程读取消息时，我希望它通知主线程中运行的 Windows 窗体消息循环消息已准备就绪.我怎样才能做到这一点?在 win32 中，我会执行 PostMessage，但该功能在 .Net 中似乎不存在(或者至少我找不到).

I have a thread that reads messages from a named pipe. It is a blocking read, which is why it's in its own thread. When this thread reads a message, I want it to notify the Windows Forms message loop running in the main thread that a message is ready. How can I do that? In win32 I would do a PostMessage, but that function does not seem to exist in .Net (or at least I could not find it).

推荐答案

在 WinForms 中，您可以通过 Control.BeginInvoke.一个例子:

In WinForms you can achieve this with Control.BeginInvoke. An example:

public class SomethingReadyNotifier
{
   private readonly Control synchronizer = new Control();

   /// <summary>
   /// Event raised when something is ready. The event is always raised in the
   /// message loop of the thread where this object was created.
   /// </summary>
   public event EventHandler SomethingReady;

   protected void OnSomethingReady()
   {
       SomethingReady?.Invoke(this, EventArgs.Empty);
   }

   /// <summary>
   /// Causes the SomethingReady event to be raised on the message loop of the
   /// thread which created this object.
   /// </summary>
   /// <remarks>
   /// Can safely be called from any thread. Always returns immediately without
   /// waiting for the event to be handled.
   /// </remarks>
   public void NotifySomethingReady()
   {
      this.synchronizer.BeginInvoke(new Action(OnSomethingReady));
   }
}

上述不依赖于 WinForms 的更简洁的变体是使用 SynchronizationContext.在主线程上调用 SynchronizationContext.Current，然后将该引用传递给如下所示的类的构造函数.

A cleaner variant of the above which doesn't depend on WinForms would be to use SynchronizationContext. Call SynchronizationContext.Current on your main thread, and then pass that reference to the constructor of the class shown below.

public class SomethingReadyNotifier
{
    private readonly SynchronizationContext synchronizationContext;

    /// <summary>
    /// Create a new <see cref="SomethingReadyNotifier"/> instance. 
    /// </summary>
    /// <param name="synchronizationContext">
    /// The synchronization context that will be used to raise
    /// <see cref="SomethingReady"/> events.
    /// </param>
    public SomethingReadyNotifier(SynchronizationContext synchronizationContext)
    {
        this.synchronizationContext = synchronizationContext;
    }

    /// <summary>
    /// Event raised when something is ready. The event is always raised
    /// by posting on the synchronization context provided to the constructor.
    /// </summary>
    public event EventHandler SomethingReady;

    private void OnSomethingReady()
    {
        SomethingReady?.Invoke(this, EventArgs.Empty);
    }

    /// <summary>
    /// Causes the SomethingReady event to be raised.
    /// </summary>
    /// <remarks>
    /// Can safely be called from any thread. Always returns immediately without
    /// waiting for the event to be handled.
    /// </remarks>
    public void NotifySomethingReady()
    {
        this.synchronizationContext.Post(
                state => OnSomethingReady(),
                state: null);
        }
    }

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