设置WinForms.Form所有者时出现跨线程异常-如何正确处理? [英] Cross-thread exception when setting WinForms.Form owner - how to do it right?

问题描述

我有一个主UI线程，该线程运行应用程序并创建主窗口表单(我们称其为W).我还有一个辅助线程，可以旋转并创建一个对话框(我们称其为B).

I have a main UI thread which runs the application and creates the main window form (let's call it W). I have also a secondary thread that I spin up and which creates a dialog box (let's call it B).

我想将对话框B的所有者设置为主窗口W. B所有者的设置发生在创建B的线程上.基本上:

I want to set the owner of the dialog B to be the main window W. The setting of Bs owner happens on the thread that created B. Basically:

b.Owner = w;

但这会引发跨线程异常，告诉我我正在尝试从错误的线程访问W对象.

but this throws a cross-thread exception telling me that I am tryng to access the W object from the wrong thread.

因此，我尝试通过在W上使用Control.Invoke在主UI线程上执行代码.但是然后，我遇到了同样的错误，告诉我我正在尝试从错误的线程访问B:

So I tried to execute the code on the main UI thread, by using a Control.Invoke on W. But then, I get the same error telling me that I am trying to access B from the wrong thread:

System.InvalidOperationException was unhandled by user code
  Message=Cross-thread operation not valid: Control 'B' accessed from a
  thread other than the thread it was created on.
  Source=System.Windows.Forms

我应该怎么做正确?

推荐答案

这是Winforms中的一个错误，Windows实际上支持使所有者成为在另一个线程上创建的窗口.有一种方法可以禁用该检查，您应该从不这样做.除非您必须这样做:

It's a bit of a bug in Winforms, Windows actually supports making the owner a window that was created on another thread. There's a way to disable that check, something you should never do. Except when you have to I suppose:

    private void button1_Click(object sender, EventArgs e) {
        var t = new Thread(() => {
            Control.CheckForIllegalCrossThreadCalls = false;
            var frm = new Form2();
            frm.Show(this);
            Control.CheckForIllegalCrossThreadCalls = true;
            Application.Run(frm);
        });
        t.SetApartmentState(ApartmentState.STA);
        t.Start();
    }

我不不知道这是否是100％安全的，可能是Winforms交互将事情搞砸了.您在这里未经测试的水域中，出没了许多穿线鲨鱼.

I do not know if this is 100% safe, there could be a Winforms interaction that screws things up. You are in untested waters here, infested with threading sharks.

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