Question

最近，我发现了一种方法，它在调度程序队列中执行所有挂起的消息，直到达到指定的优先级。我之前已经有过这样的代码，但他们使用完全不同的方法。这两个都是：

PushFrame方式：

/// <summary>
/// Enters the message loop to process all pending messages down to the specified
/// priority. This method returns after all messages have been processed.
/// </summary>
/// <param name="priority">Minimum priority of the messages to process.</param>
public static void DoEvents(
    DispatcherPriority priority = DispatcherPriority.Background)
{
    DispatcherFrame frame = new DispatcherFrame();
    Dispatcher.CurrentDispatcher.BeginInvoke(
        priority,
        new DispatcherOperationCallback(ExitFrame), frame);
    Dispatcher.PushFrame(frame);
}

private static object ExitFrame(object f)
{
    ((DispatcherFrame) f).Continue = false;
    return null;
}

来源：MSDN Library

阻止调用方式：

private static Action EmptyDelegate = delegate { };

/// <summary>
/// Processes all pending messages down to the specified priority.
/// This method returns after all messages have been processed.
/// </summary>
/// <param name="priority">Minimum priority of the messages to process.</param>
public static void DoEvents2(
    DispatcherPriority priority = DispatcherPriority.Background)
{
    Dispatcher.CurrentDispatcher.Invoke(EmptyDelegate, priority);
}

来源：Blog

哪个更好，这两个解决方案之间是否有任何功能差异？

更新：这是代号内联的第二位，如第一项所示，使其更短：

/// <summary>
/// Processes all pending messages down to the specified priority.
/// This method returns after all messages have been processed.
/// </summary>
/// <param name="priority">Minimum priority of the messages to process.</param>
public static void DoEvents2(
    DispatcherPriority priority = DispatcherPriority.Background)
{
    Dispatcher.CurrentDispatcher.Invoke(new Action(delegate { }), priority);
}

Answer 1

你回答了自己的问题。你选择的并不重要，因为两者在后台都是一样的。

两者都遇到了这个：

While (dispatcherFrame.Continue)
{
  Dispatcher.GetMessage();
  Dispatcher.TranslateAndDispatch();
}

然而，由于您不需要创建空委托，因此PushFrame更好一些。

DoEvents：Dispatcher.Invoke与PushFrame

1 个答案: