Hi Mr. Yang,
Thank you very much. Now I make it work. I solved the first problem by using
myTextNode.addEventListener("DOMCharacterDataModified", scroll2, false) and
solved the second problem but adding one more Javascript function using your
code.
With best regards,
William
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>;
<[EMAIL PROTECTED]>
Sent: Tuesday, February 11, 2003 4:32 PM
Subject: FW: Can I call Javascript function from Batik Java code?
> Scanning your code, there are two obvious errors. If you haven't already,
> you should reference the specification for the ECMAScript binding to the
DOM
> Level 2 Events API:
> http://www.w3.org/TR/DOM-Level-2-Events/ecma-script-binding.html.
>
> The first problem is that you are listening for "MutationEvent" when you
> should be listening for "DOMCharacterDataModified". The DOM Level 2
Events
> spec is very confusing about which values to use and when, so I'm not
> surprised at this mistake. Ideally, you should test that the current DOM
> implementation supports the Mutation event module before bothering to use
my
> technique, since the listeners will otherwise never be called. For
> instance:
>
> if (!document.implementation.hasFeature("MutationEvents", "2.0"))
> alert("You need an SVG implementation that supports
MutationEvents!")
> else { ... };
>
> The second problem is that you are using the wrong syntax when registering
> you listener. In ECMAScript, an EventListener is simply a reference to a
> function that has parameter of Event type. So, when calling
> addEventListener(), you need to pass a "reference" to such a function.
This
> is different than when specifying the value of one of the onxxx event
> attributes, in which case you provide the actual code to use as the
> attribute value. For instance, if you have a function called Scroll2 that
> has just a single parameter of Event type, then your last line in item 3.
> would look like:
>
> myTextNode.addEventListener("DOMCharacterDataModified", Scroll2, false);
>
> Your actual listener function, Scroll, needs the value of the "elt"
> variable, but the definition of EventListener gives you no way to pass in
> that value? One (bad) way to work around this would be to make "elt" a
> global variable. Another (more elegant) way would be to create a new
> listener function that calls Scroll, like the following:
>
> var Scroll2 = function(e){Scroll(e, elt);};
>
> Or, you can change Scroll() itself to just take an Event parameter.
>
> Samuel C. Yang
> Echelon Corp. <http://www.echelon.com>
>
> email: <mailto:[EMAIL PROTECTED]>
> phone: 408-938-5314
> fax: 408-790-3430
>
>
> -----Original Message-----
> From: William Huang [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, February 11, 2003 10:24 AM
> To: Batik Users
> Subject: Re: Can I call Javascript function from Batik Java code?
>
>
> Hi Mr. Yang,
>
> Thank you very much for your suggestion. I tried but can't make it work.
> Maybe I am wrong somewhere: 1. I created a text node in Batik Java
> SVGOMTextElement text = (SVGOMTextElement)
> doc.createElementNS(svgNs, "text");
> text.setAttribute("id", "MyTextNode");
> text.setAttribute("x", "0");
> text.setAttribute("y", "0");
> text.setAttribute("visibility", "hidden");
> svgRoot.appendChild(text);
> 2. When I need to call the Javascript function, I fired the following
event
> Element textElement =
> svgDocument.getElementById("MyTextNode");
> DocumentEvent de = (DocumentEvent) svgDocument;
> MutationEvent ev =
> (MutationEvent)de.createEvent("MutationEvents");
> ev.initMutationEvent("DOMCharacterDataModified",
> true, // canBubbleArg
> false, // cancelableArg
> null, // relatedNodeArg
> null, // prevValueArg
> null, // newValueArg
> null, // attrNameArg
> ev.ADDITION);
> EventTarget t = (EventTarget) textElement;
> t.dispatchEvent(ev);
> 3. In Javascript, my code is as follows:
> var myTextNode = document.getElementById("MyTextNode");
> myTextNode.addEventListener("MutationEvent", Scroll(evt, elt), false)
Where
> Scroll(evt, elt) is my Javascript function.
>
> It seems that the code does not work. Could you tell me what is wrong with
> my code?
>
> With best regards,
> William
>
>
> ----- Original Message -----
> From: <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Monday, February 10, 2003 3:58 PM
> Subject: RE: Can I call Javascript function from Batik Java code?
>
>
> > Here's a method based on the standard (but optional) DOM Event type,
> > MutationEvents. It took me a little while to come up with it, but
> > I'll
> give
> > it to you for free :-).
> >
> > If your SVG processor supports the MutationEvents feature (you should
> > test for this, especially if you intend to also run on non-Batik SVG
> > engines), and has the right language bindings to the DOM (like Batik
> > does) then you can use a <text> element (probably with
> > visibility="hidden", and width and
> > height="0") to which you dispatch mutation events from Java, and to
which
> > you can attach an ECMAScript listener. The new text content specified
in
> > the event data can be used to carry any kind of message you want. You
can
> > use the same technique to go from ECMAScript to Java, too.
> >
> > Note that:
> >
> > (1) Using dispatchEvent() is more efficient that actually changing the
> > content of the <text> element.
> > (2) The <text> element should not have display="none", since then it
> > is
> not
> > supposed to receive any events. [However, Batik currently does allow
> > the
> > dispatchEvent() method to send events to a <text> element having the
> > display="none" attribute. I believe this is a bug. Also, I noticed
that
> in
> > Batik when you use the dispatchEvent() method to send a mutation event
> > for
> a
> > <text> element, the text element does not change its actual content,
> meaning
> > that the dispatched event is lying about the new (and possibly also
> > the
> old)
> > content of the element. This is probably acceptable behavior, since
> > the spec doesn't seem to say this can't happen, and it is more
> > efficient.
> Just
> > be sure that you don't accidentally treat the event data for such
> > <text> elements as being real text event data.]
> >
> > Samuel C. Yang
> > Echelon Corp. <http://www.echelon.com>
> >
> > email: <mailto:[EMAIL PROTECTED]>
> > phone: 408-938-5314
> > fax: 408-790-3430
> >
> > > -----Original Message-----
> > > From: William Huang [mailto:[EMAIL PROTECTED]]
> > > Sent: Monday, February 10, 2003 11:44 AM
> > > To: Batik Users
> > > Subject: Can I call Javascript function from Batik Java code?
> > >
> > >
> > > I changed the SVGImageElementBridge program to make the <a> element
> > > work as my application needs. However, I need to call one large
> > > Javascript function of mine at the end of my
> > > createSVGImageNode() method call. I can rewrite the Javascript
> > > function into Java, but that costs too much efforts. Is there a way
> > > to call Javascript function from Batik Java implementation? Thanks a
> > > lot.
> > >
> > > William
> > >
> > >
> > > --------------------------------------------------------------------
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> > >
> >
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> >
> >
>
>
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