The answer (as I understand your question, and I'm not sure I do) is
that the observer paradigm is based on the "observer" design pattern,
similar to attaching multiple functions to a standard Javascript
event. The "addObserver" function allows you to attach multiple
observers, each choosing how they would respond to a particular
event. You could consider a simple observer to be an abstract class
or interface, if you will. It is not itself a function, but rather a
class of functions, each responding to a different event.
In contrast, setting functions to be direct methods of the Draggable/
Sortable would require the developer to set those functions for each
instance, rather than setting a more global observer, and would limit
the programmer to one callback per "event."
I expect I mangled and misused proper terms, but I hope I clarified
more than I obfuscated. Perhaps someone else can explain it better
than I.
TAG
On Jun 14, 2006, at 11:50 AM, Jean-Philippe Encausse wrote:
Many thanks for your explaination.
There's something I don't understand about the scriptaculous API. May
be because
I'm a Java developer ;-)
Why do we have to do such things:
- Draggables.addObserver( ... )
or
- Sortable.onEmptyHover = function( ... ){ }
If I correctly understand the first one will be called for any drag on
a given element
The second will be called for any call to Sortable.onEmptyHover()
-> So If there is 2 drag action the observer will be called twice ?
That's strange ? Why the API doesn't allow to plug observer to the
Draggable or Sortable instance instead of the static "Class" ?
Something like:
var sortable = Sortable.create(....)
sortable.onEmptyHover = function( ... ){ }
Regards,
Jp
On 6/14/06, Tom Gregory <[EMAIL PROTECTED]> wrote:
Your best bet is to attach an observer, which may look something like
this:
var MyDragObserver = Class.create();
MyDragObserver.prototype = {
initialize: function(element) {
this.element = $(element);
},
onEnd: function (eventName, draggable, event) {},
onStart: function (eventName, draggable, event) {},
onDrag: function (eventName, draggable, event) {}
}
Draggables.addObserver(new MyDragObserver(elementId));
Or even be simpler:
Draggables.addObserver({onStart: someFunction, onDrag:
someOtherFunction});
Contrary to my previous advice, you may wish to set the flag on drag
rather than on start.
TAG
On Jun 14, 2006, at 9:21 AM, Jean-Philippe Encausse wrote:
> May I set directly callback "dragStart" and "dragEnd " in
> options of my Sortable.create ?
>
>
> On 6/14/06, Tom Gregory <[EMAIL PROTECTED]> wrote:
>>
>> On Jun 14, 2006, at 3:54 AM, Jean-Philippe Encausse wrote:
>>
>> > My 1st issue:
>> > ****************
>> >
>> > The Drag n Drop works very well but when I drop the LI, the
link is
>> > followed. Is there a cross browser way to stop the link event ?
>> > -> onChange is called too soon and onUpdate is never called.
>> > May be I will have to set a specific handle without links ?
>>
>>
>> dragStart fires on mousedown.
>> dragEnd (and thus onChange) fires on mouseup.
>> following the link occurs on click (and the events occur in this
>> order)
>>
>> You'll need to flag the element on dragStart to not follow, and
check
>> (and reset) your flag when handling the click.
>>
>>
>> TAG
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>>
>
>
> --
> Jean-Philippe Encausse - R&D Jalios SA
> Jp [at] encausse.net - http://www.encausse.com - http://
www.jalias.com
> GTalk: jp.encausse [at] gmail.com - SMS: sms [at] jp.encausse.net
> Mob: +33 6 82 12 56 99 Jalios: +33 1 39 23 92 83 Tel: +33 1 39 18
> 90 15
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--
Jean-Philippe Encausse - R&D Jalios SA
Jp [at] encausse.net - http://www.encausse.com - http://www.jalias.com
GTalk: jp.encausse [at] gmail.com - SMS: sms [at] jp.encausse.net
Mob: +33 6 82 12 56 99 Jalios: +33 1 39 23 92 83 Tel: +33 1 39 18
90 15
Do it Once, Use it Twice ~ Do it Twice, Make It Once
_______________________________________________
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