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

Exploiting the BackGroundWorker for cross-thread invocation of GUI actions on Winforms controls?(利用 BackGroundWorker 跨线程调用 Winforms 控件上的 GUI 操作?)

问题描述

灵感来自我自己使用多线程 Winforms 应用程序的经验，以及诸如

Inspired by my own experience with multithreaded Winforms applications, as well as questions such as

• 避免调用的麻烦/BeginInvoke 在跨线程 WinForm 事件处理中?
• 避免在释放控件时调用 Invoke

我想出了一个非常简单的模式，我想验证它的可靠性.

I've come up with a very simple pattern, whose soundness I would like to verify.

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

Basically I'm creating (and running throughout the application's lifetime) a BGW whose sole purpose is the synchronization of invoke requests. Consider:

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!"));    
}

当然，这不是最经济的方法(像这样保持线程活跃)，但如果它有效并且我没有错过任何东西，那肯定是我见过的最简单的方法.

Granted, it's not the most economical of approaches (keeping a thread alive like that), but if it works and I haven't missed anything, it sure is the simplest I've seen.

非常感谢您的反馈！

推荐答案

没有必要为此开一个线程.只需使用 SynchronizationContext，如下所示:

There's no need to open a thread just for that. Simply use SynchronizationContext, like so:

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!"));    
}

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