Question

我们正在使用Rx来监控Silverlight应用程序中的活动，以便我们可以在一段时间不活动后向用户显示消息。

我们将事件（鼠标移动等）转换为可观察对象，然后将可观察对象合并在一起以创建单个（allActivity）可观察对象。然后，我们使用timepan限制allActivity observable，并且当系统在一段时间内处于非活动状态时，会预订某些通知。

如何在订阅后向此添加新的observable / sequence（以便订阅选择此内容而不取消订阅和重新订阅）。

e.g。将几个序列合并在一起，节流，订阅。现在为已订阅的observable添加一个额外的序列。

示例代码：

private IObservable<DateTime> allActivity;
public void CreateActivityObservables(UIElement uiElement)
{
    // Create IObservables of event types we are interested in and project them as DateTimes
    // These are our observables sequences that can push data to subscribers/ observers 
    // NB: These are like IQueryables in the sense that they do not iterate over the sequence just provide an IObservable type
    var mouseMoveActivity = Observable.FromEventPattern<MouseEventHandler, MouseEventArgs>(h => uiElement.MouseMove += h, h => uiElement.MouseMove -= h)
                                      .Select(o => DateTime.Now);

    var mouseLeftButtonActivity = Observable.FromEventPattern<MouseButtonEventHandler, MouseButtonEventArgs>(h => uiElement.MouseLeftButtonDown += h, h => uiElement.MouseLeftButtonDown -= h)
                                            .Select(o => DateTime.Now);

    var mouseRightButtonActivity = Observable.FromEventPattern<MouseButtonEventHandler, MouseButtonEventArgs>(h => uiElement.MouseRightButtonDown += h, h => uiElement.MouseRightButtonDown -= h)
                                             .Select(o => DateTime.Now);

    var mouseWheelActivity = Observable.FromEventPattern<MouseWheelEventHandler, MouseWheelEventArgs>(h => uiElement.MouseWheel += h, h => uiElement.MouseWheel -= h)
                                       .Select(o => DateTime.Now);

    var keyboardActivity = Observable.FromEventPattern<KeyEventHandler, KeyEventArgs>(h => uiElement.KeyDown += h, h => uiElement.KeyDown -= h)
                                     .Select(o => DateTime.Now);

    var streetViewContainer = HtmlPage.Document.GetElementById("streetViewContainer");
        var mouseMoveHandler = new EventHandler<HtmlEventArgs>(this.Moo);
        bool b = streetViewContainer.AttachEvent("mousemove", mouseMoveHandler);

    var browserActivity = Observable.FromEventPattern<Landmark.QDesk.ApplicationServices.IdleTimeoutService.MouseMoveHandler, HtmlEventArgs>(h => this.MyMouseMove += h, h => this.MyMouseMove -= h).Select(o => DateTime.Now);

    // Merge the IObservables<DateTime> together into one stream/ sequence
    this.allActivity = mouseMoveActivity.Merge(mouseLeftButtonActivity)
                                        .Merge(mouseRightButtonActivity)
                                        .Merge(mouseWheelActivity)
                                        .Merge(keyboardActivity)
                                        .Merge(browserActivity);
}

public IDisposable Subscribe(TimeSpan timeSpan, Action<DateTime> timeoutAction)
{
    IObservable<DateTime> timeoutNotification = this.allActivity.Merge   (IdleTimeoutService.GetDateTimeNowObservable())
                                                                .Throttle(timeSpan)
                                                                    .ObserveOn(Scheduler.ThreadPool);

    return timeoutNotification.Subscribe(timeoutAction);
}

Answer 1

Merge的重载包含IObservable＆lt; IObservable＆lt; TSource＆gt;＆gt;。使外部序列成为主题＆lt; IObservable＆lt; TSource＆gt;＆gt;当你想要添加另一个源时，请调用OnNext。 Merge运算符将接收源并订阅它：

var xss = new Subject<IObservable<int>>();
xss.Merge().Subscribe(x => Console.WriteLine(x));

xss.OnNext(Observable.Interval(TimeSpan.FromSeconds(1.0)).Select(x => 23 + 8 * (int)x));
xss.OnNext(Observable.Interval(TimeSpan.FromSeconds(0.8)).Select(x => 17 + 3 * (int)x));
xss.OnNext(Observable.Interval(TimeSpan.FromSeconds(1.3)).Select(x => 31 + 2 * (int)x));
...

Answer 2

最简单的方法是使用中间主题代替Merge来电。

Subject<DateTime> allActivities = new Subject<DateTime>();
var activitySubscriptions = new CompositeDisposable();

activitySubscriptions.Add(mouseMoveActivity.Subscribe(allActivities));
activitySubscriptions.Add(mouseLeftButtonActivity.Subscribe(allActivities));
//etc ...

//subscribe to activities
allActivities.Throttle(timeSpan)
             .Subscribe(timeoutAction);

//later add another
activitySubscriptions.Add(newActivity.Subscribe(allActivities));

Subject类如果收到任何OnError或OnCompleted，将停止从订阅的任何observable传递OnNext（以及进一步的OnError和OnCompleted）事件。

此方法与您的示例之间的主要区别在于，它在创建主题时订阅所有事件，而不是在订阅合并的observable时订阅。由于您示例中的所有可观察对象都很热，因此差异不应太明显。

订阅后添加可观察序列

2 个答案: