不可能的(我多么讨厌用这个词)跨线程错误?

我怀疑InvokedRrevoked可能在骗你。WinForm控件会推迟创建控件的底层Win32 HWND,直到方法调用真正需要它。如果HWND尚未创建,则InvokeRequired将返回false。

有关详细说明,请参阅: "Mysterious Hang or The Great Deception of InvokeRequired"

如果您的后台线程查询InvokeRequired 之前 UI线程导致控件延迟创建其HWND,InvokeRequired将(错误地)告诉您的后台线程它不需要使用Invoke()将控件传递回UI线程。当后台线程访问控件时,BAM! “InvalidOperationException:跨线程操作无效!”

UI线程可以手动强制控件为其创建HWND句柄。InvokeRequired将知道UI线程是控件的所有者:

Control control = new Control();
IntPtr handle = control.Handle; // if you ask for HWND, it will be created

大多数人看到这个错误后都会看到一件事,“你没有从主UI线程访问这个控件。”实际上,如果你愿意,你可以有100个UI线程(这个行为没有定义,但受支持)。panelMain很可能是在与(this)不同的线程上创建的;我看不到代码,但看起来你是在worker/线程中创建它的。

要确认该行为,请尝试以下操作:

Action addAction = new Action (
   new delegate { panelMain.Controls.Add(UCLoadingScreen); } )
if(panelMain.InvokeRequired)
{
   panelMain.Invoke(addAction); // Breakpoint here.
}
else
{
   addAction();
}

为不同的错误做好准备(与父线程不同的线程上的子控件,不确定会出现什么错误,但我非常确定会出现)。这不是一个解决方案。

然而,工厂会解决这个问题:

public void CreateControl<T>() where T : new()
{
    if(InvokeRequired)
    {
        return (T)Invoke(new Func<T>(CreateControl<T>()));
    }
    return new T();
}

编辑:panelMain可能不是线程的“违规者”,正如我所说,来自不同线程的养育控制会导致高度未定义的行为。确保所有控件都是在主窗体线程的上下文中创建的。

没有不可能的跨线程错误!

我希望这对你有用。 我想你的gui东西在一个线程上。只需初始化此单例,并在您想调用Control时依赖它。调用必需属性。

干杯,

-格雷格

public sealed class UiThread
{
  #region Singleton
  // Singleton pattern implementation taken from Jon Skeet's C# and .NET article www.yoda.arachsys.com/csharp/singleton.html

  UiThread() { }

  public static UiThread Instance { get { return Nested.instance; } }

  class Nested
  {
     // Explicit static constructor to tell C# compiler
     // not to mark type as beforefieldinit
     static Nested() { }

     internal static readonly UiThread instance = new UiThread();
  }
  #endregion

  int _uiThreadId = 0;

  public void SetUiThread(Thread thread)
  {
     if (_uiThreadId != 0)
        throw new ApplicationException("UI Thread has already been established!");

     if (thread.ManagedThreadId == 0)
        throw new ArgumentException("Unexpected thread id value of 0!");

     if (thread.IsBackground)
        throw new ArgumentException("Supplied thread should not be a background thread!");

     if (thread.IsThreadPoolThread)
        throw new ArgumentException("Supplied thread should not be a thread pool thread!");

     _uiThreadId = thread.ManagedThreadId;
  }

  /// <summary>
  /// It's possible for InvokeRequired to return false when running in background thread.
  /// This happens when unmanaged control handle has not yet been created.
  /// We second-guess Microsoft's implementation in this case, checking against foreground thread's Id.
  /// </summary>
  /// <param name="control">Control to check against.</param>
  public bool InvokeRequired(Control control)
  {
     if (control.InvokeRequired)
        return true;

     IntPtr unmanagedHandle = control.Handle;
     bool newResult = control.InvokeRequired;

     if (unmanagedHandle == IntPtr.Zero)
     {
        // Trace.WriteLine() call here forces unmanagedHandle's initialization, 
        //  even with optimizing compiler.
        Trace.WriteLine(string.Format("Control handle could not be established! Control was {0}.", control.ToString()));
     }

     bool retVal = InvokeRequired();

     // Break whenever the result of our check does not match theirs.
     Debug.Assert(retVal == newResult);

     // Return our InvokeRequired result over theirs 
     //   to keep with the tradition of updating controls from foreground only.
     return retVal;
  }

  /// <summary>
  /// Prefer to use overload with Control argument if at all possible.
  /// It's possible for InvokeRequired to return false when running in background thread.
  /// This happens when unmanaged control handle has not yet been created.
  /// We second-guess Microsoft's implementation in this case, checking against foreground thread's Id.
  /// </summary>
  public bool InvokeRequired()
  {
     if (_uiThreadId == 0)
        throw new ApplicationException("UI Thread has not been established!");

     return (Thread.CurrentThread.ManagedThreadId != _uiThreadId);
  }

}

使用

if (InvokeRequired)
{
  //invoke
}
else
{
  //do
}