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From Reinhard Brandst├Ądter <r.brandstaed...@gmx.at>
Subject Re: When to register EventListeners?
Date Sat, 11 Oct 2003 12:31:38 GMT
Thomas DeWeese wrote:

> Reinhard Brandst├Ądter wrote:
> 
>> So this means if I use the invokeLater() from the UpdateManager it's 
>> slower than directly modifying the document. 
> 
> 
>    No, it just means that you may have two threads modifying the same
> document at the same time.  Once the document is associated with the Canvas
> (and hence an UpdateManager) all modifications are tracked - it doesn't 
> matter
> what thread the changes are made in it tracks them.  However if the 
> modifications
> aren't made in the UpdateManager thread you will have multi-threading 
> issues.

Yep I've encountered some of these problems before ;-)

>  > As I mentioned before there
>  > is no need to immediately see the changes in the canvas as they are 
> made.
>  > But somehow this interferes with Java Scripting and Event handling.
> 
>   The update of the display is only ever done _after_ a Runnable completes
> so if you moved the "reconstruction" of the document into a runnable no 
> repaints
> would happen until the runnable completed.  This would also make your
> document "play nicely" with JavaScript and Event handling.  As it is
> your JavaScript and Events may be running on the same Document as you
> are constructing it!

Oh I see!

>   I would take one of three routes here:
> 
> 1) Don't load the document with setURI (do you even need to load something
>    from a URI?[*]), but load the document yourself, modify it and then 
> set it
>    with setSVGDocument.
> 2) Move all your code into a Runnable and run it in the UpdateManager 
> Thread.
> 3) Load the document with setURI, then deep clone the Document, then modify
>    the clone (which doesn't have to be in the UpdateManager Thread and the
>    changes won't be tracked by the Canvas).  Then you can set the clone 
> document
>    on the canvas.

I think 2 is the best way to do it....but how would this perform if the 
code in the Runnable is quite big? No issues on that?

I've tried something like 1 (isn't that quite similar to the code I 
submitted in my original posting, except the setURI?)

> [*] What is the document you are loading from the URI?  Is there any reason
>     that the document from the URI needs to be related to the document you
>     create on the fly?

This is from a older version when I used ECMA Script to handle events 
which was coded in a template file I loaded from URI.
As I said I'm playing around with different Script methods, so just now 
it makes no sense but I'm having ECMA Script and Java Script code...



-- 
Reinhard Brandstaedter   r.brandstaedter@gmx.at  GPG: 0x033B81DB
-    Student of Computer Science - J.K. University of Linz     -
-        <ICQ: 73059068>    <Mobile: +43 699 12419541>         -
-                  http://adelaide.dnsalias.net                -


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