如何等到对话框真正关闭

Question

软件启动线程进行一些计算，然后显示另一个 Form 作为与 ShowDialog 的等待对话框。当 BackgroundWorker 线程完成其工作时，Form 在 RunWorkerCompleted 事件中关闭，另一个计算开始，另一个 Form 作为等待对话框（ShowDialog）。

问题是第一个等待对话框在第二个等待对话框关闭之前仍然可见。如何在第一个对话框真正关闭后等待显示第二个对话框？

简单的重现代码：

private BackgroundWorker _bgw = new BackgroundWorker();
private Form2 _msg = new Form2();
private Form3 _msg2 = new Form3();

public Form1()
{
    _bgw.DoWork += BgwDoWork;
    _bgw.RunWorkerCompleted += BgwRunWorkerCompleted;
    _bgw.RunWorkerAsync();
    _msg.ShowDialog();
}

private void BgwDoWork(object sender, DoWorkEventArgs e)
{
    System.Threading.Thread.Sleep(5000);
}

private void BgwRunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    _msg.Close();
    _msg2.ShowDialog();
}

Answer 1

请注意 ShowDialog() 是一个阻塞调用。当您显示 _msg2 时，您仍然没有从构造函数返回。

这是一个快速修复：

public Form1()
{
    _bgw.DoWork += BgwDoWork;
    _bgw.RunWorkerCompleted += BgwRunWorkerCompleted;
    _bgw.RunWorkerAsync();
    _msg.ShowDialog();
    _msg2.ShowDialog();   // here
}

private void BgwRunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    _msg.Close();
    //_msg2.ShowDialog();  // not here
}

如何等到对话框真正关闭

How to wait until the dialog is really closed

c#

multithreading

winforms

user-interface

showdialog