c# - 利用 BackGroundWorker 跨线程调用 Winforms 控件上的 GUI 操作？

Question

灵感来自于我自己使用多线程 Winforms 应用程序的经验，以及诸如此类的问题

• Avoiding the woes of Invoke/BeginInvoke in cross-thread WinForm event handling?
• Avoid calling Invoke when the control is disposed

我想出了一个非常简单的模式，我想验证一下它的可靠性。

基本上，我正在创建(并在应用程序的整个生命周期内运行)一个 BGW，其唯一目的是同步调用请求。考虑:

public MainForm()
{
    InitializeComponent();
    InitInvocationSyncWorker();
}

private void InitInvocationSyncWorker()
{
    InvocationSync_Worker.RunWorkerAsync();
}

private void InvocationSync_Worker_DoWork(object sender, DoWorkEventArgs e)
{
    Thread.Sleep(Timeout.Infinite);
}

void InvokeViaSyncWorker(Action guiAction)
{
    InvocationSync_Worker.ReportProgress(0, guiAction);
}

private void InvocationSync_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    if (IsDisposed) return; //we're in the GUI thread now, so no race condition right?

    var action = (Action) e.UserState;
    action();
}

public void SomeMethodCalledFromAnyThread() //Sample usage
{
    InvokeViaSyncWorker(() => MyTextBox.Text = "Hello from another thread!"));    
}

诚然，这不是最经济的方法(像这样保持线程事件)，但如果它有效并且我没有遗漏任何东西，那肯定是我见过的最简单的方法。

非常感谢您的反馈!

Answer 1

没有必要为此打开一个线程。只需使用 SynchronizationContext，如下所示:

private readonly SynchronizationContext _syncContext;

public MainForm()
{
    InitializeComponent();

    _syncContext = SynchronizationContext.Current;
}

void InvokeViaSyncContext(Action uiAction)
{
    _syncContext.Post(o =>
    {
        if (IsHandleCreated && !IsDisposed) uiAction();
    }, null);
}

public void SomeMethodCalledFromAnyThread() //Sample usage
{
    InvokeViaSyncContext(() => MyTextBox.Text = "Hello from another thread!"));    
}