I could not figure out exactly how to implement that code, but I did figure
out a similiar way that works now:
textbox.prototype.bind=function(obj,fn){
return function(e){
fn.call(obj,e);
}
}
this.textboxRect.addEventListener("click",this.bind(this,this.handleEvent),false);
It works!
snapper wrote:
>
> ? So if the event is attached with:
> this.textboxRect.addEventListener("click",this,false);
>
> and I use your exact "bind" method,
> then the exact code for the handler is:
>
> textbox.prototype.handleEvent=bind(textbox,function(evt){
> alert(this);
> });
>
> The alert gives:
> [EMAIL PROTECTED]
>
> "this" is still not working... What is wrong here?
>
> Cameron McCormack-4 wrote:
>>
>> Hi.
>>
>> snapper:
>>> How can I get object reference instead of window reference in
>>> this.handleEvent(evt)?
>>>
>>> I have ECMAScript in a Batik SVG application using widgets. I noticed
>>> that
>>> the Carto textbox does not work in Batik due to event handing problems,
>>> so I
>>> am rewriting it. Andreas attached event handlers using the root element
>>> in
>>> all cases, which causes many problems. I am attaching events to the
>>> widget
>>> elements instead like this:
>>>
>>> this.textboxRect.addEventListener("click",this._handleEvent,false);
>>>
>>> The event handler in the textbox object does receive the event, but
>>> inside
>>> the this.handleEvent(evt), the "this" refers to the window object. We
>>> really
>>> want the reference to the textbox object.
>>>
>>> How can I get the reference to the textbox object inside the event
>>> handler
>>> in this case?
>>
>> This is normal behaviour: when you refer to this._handleEvent, it is
>> just a reference the function that has been stored in the 'this'
>> object–it has lost its association with the object. If you want to be
>> able to access the 'this' object from _handleEvent, you can refer to
>> the object from the closure when you assign it. For example:
>>
>> blah._handleEvent = function(evt) {
>> // refer to 'blah' in here
>> };
>>
>> I often use a function to bind the the 'this' variable to an object of
>> my choosing, so that I can do what you want to do.
>>
>> function bind(_this, f) {
>> var _ = function() {
>> return f.apply(_this, arguments);
>> };
>> _.toString = function() {
>> return "/* bound function */\n" + String(f);
>> };
>> return _;
>> }
>>
>> and then:
>>
>> blah._handleEvent = bind(blah, function() {
>> // now 'this' inside here will always refer to 'blah',
>> // regardless of how the function was called.
>> });
>>
>> --
>> Cameron McCormack, http://mcc.id.au/
>> xmpp:[EMAIL PROTECTED] ▪ ICQ 26955922 ▪ MSN [EMAIL PROTECTED]
>>
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>>
>>
>
>
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