Removing onFrame event handler

[rob]

Hi all,

I am using paper via javascript directly and am subscribing to onFrame events by something like:

paper.view.onFrame = this.onFrame

Could somebody please tell me what is the correct way to unsubscribe the handler?   I have tried:

paper.view.onFrame = null

But this leads to some unpredictable results when I have multiple listeners subscribed to onFrame events.  

Rob 

[Jonathan Puckey]

Hi Rob,

Could you post some code that shows these unpredictable results? I have tried the code in your email, but it seems to work fine…

greetings,

Jonathan

[rob]

Sure

So I have something like this defined:

    function Test(id) {

      this.id = id;

      that = this

      paper.view.onFrame = that.onFrame;

    }

    Test.prototype.stop = function() {

      paper.view.onFrame = null;

    };

    Test.prototype.onFrame = function() {

      console.log("On Frame: " + this.id);

    };

And then I create a couple of instances and invoke stop() on both:

  var test1, test2;

  test1 = new Test('test1');

  test2 = new Test('test2');

  test1.stop();

  test2.stop();

My expectation would be that I see no console output, because I have unsubscribed both listeners before they even start, but what I get out is:

On Frame: test1

On Frame: test1

...

...

...

So it seems only the last subscription is removed. Which kind of makes sense because I can't see how paper would know which of the subscriptions I wanted to cancel.

Regards

Rob

[Jonathan Puckey]

To accomplish this, you could do the following:

function Test(id) {

this.id = id;

var that = this;

this.onFrame = function() {

// since the this object refers to

// the view here, we need to use the

// 'that' variable defined above:

console.log(that.id);

};

paper.view.attach('frame', this.onFrame);

}

Test.prototype.stop = function() {

paper.view.detach('frame', this.onFrame);

};

var test1 = new Test('test1');

var test2 = new Test('test2');

test1.stop();

test2.stop();

But for some reason I still get 'test1' in the console once.. which might be a bug..

Sure

So I have something like this defined:

    function Test(id) {

      this.id = id;

      that = this

      paper.view.onFrame = that.onFrame;

    }

    Test.prototype.stop = function() {

      paper.view.onFrame = null;

    };

    Test.prototype.onFrame = function() {

      console.log("On Frame: " + this.id);

    };

And then I create a couple of instances and invoke stop() on both:

  var test1, test2;

  test1 = new Test('test1');

  test2 = new Test('test2');

  test1.stop();

  test2.stop();

My expectation would be that I see no console output, because I have unsubscribed both listeners before they even start, but what I get out is:

On Frame: test1

[rob]

Great thanks.

Did not know about the 'attach' and 'detach' functions on the view as they are not in the reference documentation.

Regards

Rob