Add additional string parameter into DispatcherTimer EventHandler

Question

How can I add extra string parameter into Dispatchertimer Eventhandler ?.

I would like achieve something like this:

string ObjectName = "SomeObjectName";
System.Windows.Threading.DispatcherTimer dispatcherTimer = new System.Windows.Threading.DispatcherTimer();
dispatcherTimer.Tick += new EventHandler(dispatcherTimer_Tick(ObjectName));

And function:

private void dispatcherTimer_Tick(object sender, EventArgs e, string ObjectName)
{
    [...]
}

How Can I achieve that?

Edit:

My intention is add some animation for moving object. I've got canvas with few objects. I can move this objects on canvas by mouse clicking, i would like to add animations for this movement.

@GaneshR. Unless `dispatcherTimer_Tick` was a function actually returning an `EventHandler` (which it isn't), that could never compile. — Chris, Jan 25 '15 at 15:43
@Chris Yup. I had created the dispatcherTimer_Tick method using ReSharper which returned an EventHandler — Ganesh R., Jan 25 '15 at 15:45

score 8 · Accepted Answer · edited May 23 '17 at 12:01

8

You can use a closure for that:

... 
{    
    string objectName = "SomeObjectName";
    var dispatcherTimer = new DispatcherTimer();

    dispatcherTimer.Tick += (sender, e) => { myTick(sender, e, objectName); };
}

private void myTick(object sender, EventArgs e, string objectName)
{
    [...]
}

Note, though, that the variable objectName is captured, rather than it's current value. That means if you do this:

... 
{    
    string objectName = "SomeObjectName";
    var dispatcherTimer = new DispatcherTimer();

    dispatcherTimer.Tick += (sender, e) => { myTick(sender, e, objectName); };
    objectName = "SomeOtherObjectName";
}

myTick will be called with SomeOtherObjectName, which might be counter-intuitive at a first glance. The reason for this is that, under the hood, a separate object instance with an objectName field is created -- very similar to what Chris' solution is doing explicitly.

edited May 23 '17 at 12:01

Community

1
1

answered Jan 25 '15 at 15:37

Heinzi

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@Chris: It's basically an implicit variant of what you are doing explicitly. – Heinzi Jan 25 '15 at 15:42
Yeah, just wish I had thought of that before my solution hehe. – Chris Jan 25 '15 at 15:47
imma just say, registering Lambda like that to this event has extreme limitations, for one, it can be registered multiple times and you cant unregistered it through -=, thus limiting you to an one time only use, just using an outer score field would be a simpler solution. – Xeorge Xeorge Apr 30 '20 at 10:51

score 1 · Answer 2 · answered Jan 25 '15 at 15:38

You can use this trick to pass along as much data as you'd like:

class Foo
{
    public string PropertyA { get; set; }
    public string PropertyB { get; set; }
    // ...

    public void OnTick( object sender, EventArgs e )
    {
        // logic here
    }
}

var f = new Foo() { PropertyA = "some stuff here",
                    PropertyB = "some more stuff here" };
dispatcherTimer.Tick += f.OnTick;

Obviously, if you only ever have one event handler for the same timer you could just as well store the required data in whatever class is using this.

score 0 · Answer 3 · answered Nov 07 '22 at 14:30

You could use the Tag property of DispatcherTimer

string ObjectName = "SomeObjectName";
System.Windows.Threading.DispatcherTimer dispatcherTimer = new System.Windows.Threading.DispatcherTimer();
dispatcherTimer.Tick += dispatcherTimer_Tick;
dispatcherTimer.Tag = ObjectName

Then

private void dispatcherTimer_Tick(object sender, EventArgs e)
{
    var timer = sender as DispatcherTimer;
    
    var objectName = (string)timer.Tag;
       
}

Add additional string parameter into DispatcherTimer EventHandler

3 Answers3