Time flies like a arrow demonstration in WinForms

Question

Looking at Reactive Extensions to demonstrate javascript on Jeff Van Gogh's blog , I thought I would try it in C # / Winforms, but it doesn’t work so well.

I just injected this into the form constructor (with the installed Rx structure and link):

Observable.Context = SynchronizationContext.Current;
var mousemove = Observable.FromEvent<MouseEventArgs>(this, "MouseMove");
var message = "Time flies like an arrow".ToCharArray();

for(int i = 0; i < message.Length; i++)
{
    var l = new Label() 
            { 
                Text = message[i].ToString(), 
                AutoSize = true, 
                TextAlign = ContentAlignment.MiddleCenter 
            };
    int closure = i;
    mousemove
        .Delay(closure * 150)
        .Subscribe(e => 
            {
                l.Left = e.EventArgs.X + closure * 15 + 10;
                l.Top = e.EventArgs.Y;
                //Debug.WriteLine(l.Text);
            });
    Controls.Add(l);
}

When I move the mouse, the letters seem to move in random order, and if I uncomment the Debug line, I see several events for the same letter ...

Any ideas? I tried Throttle, but it doesn't seem to make any difference. Am I just asking too many WinForms to move all these tags around?

(Crossroads posted on Rx Forum )

Answer 1

, Rx Forum ( , ):

№1: . Observable.Context 4 . № 2: Javascript , Rx .

, , :

void Form1_Load(object sender, EventArgs e)
{
   Reactive("Time flies like an arrow");
}

private void Reactive(string msg)
{
    var mousemove = Observable.FromEvent<MouseEventArgs>(this, "MouseMove");
    var message = msg.ToCharArray();

    for(int i = 0; i < message.Length; i++)
    {
        var l = new Label()
        { 
            Text = message[i].ToString(), 
            AutoSize = true, 
            TextAlign = ContentAlignment.MiddleCenter 
        };
        int closure = i;
        mousemove
            .Delay(TimeSpan.FromSeconds(0.07 * i), Scheduler.Dispatcher)
            .Subscribe(e =>
            {
                l.Left = e.EventArgs.X + closure * 12 - 5;
                l.Top = e.EventArgs.Y + 15;
            });
        Controls.Add(l);
    }
}

ObserveOnDispatcher SubscribeOnDispatcher. Javascript, - .

UPDATE, ​​

---

, Rx:

private void Unreactive(string msg)
{
    var message = msg.ToCharArray();

    for(int i = 0; i < message.Length; i++)
    {
        var l = new Label()
        { 
            Text = message[i].ToString(), 
            AutoSize = true, 
            TextAlign = ContentAlignment.MiddleCenter 
        };
        Controls.Add(l);
        int closure = i;
        this.MouseMove += (s, e) => LabelDelayMove(closure, e, l);
    }
}

private void LabelDelayMove(int i, MouseEventArgs e, Label l)
{
    Point p = new Point(e.X + i * 12 - 5, e.Y - 15);
    var timer = new System.Threading.Timer((_) => LabelMove(l, p), null, i * 70, System.Threading.Timeout.Infinite);
}

private void LabelMove(Label l, Point location)
{
    this.BeginInvoke(new Action(() => l.Location = location));
}